Madhara ya mabadiliko ya hali ya hewa

Faili:Risks and Impacts of Global Warming.png

Picha inayoonyesha hatari za madhara ya ongezeko la joto Duniani kutokana na Ripoti ya Tatu ya Jopo la Serikali mbalimbali kuhusu Mabadiliko ya Hali ya Anga. Mabadiliko ya baadaye ya Ripoti hii yanaonyesha kuwa hatari hiyo imeongezeka.

Madhara ya ongezeko la joto Duaniani na mabadiliko ya hali ya anga ni muhimu sana hasa kwa mazingira na maisha ya kibinadamu. Ushahidi unaoonyesha mabadiliko ya hali ya anga ni pamoja na rekodi muhimu ya kipimo joto, kupanda kwa maeneo yenye maji baharini, na kupungukuka kwa kiwango kilichofunikwa na theluji katika Ulimwengu wa Kaskazini. Kulingana na Ripoti ya Uchunguzi ya Nnne ya IPCC, "[nyingi]" kati ya maongezeko ya vipimo vya joto vya wastani Duniani tangu wakati wa katikati wa karne ya 20 huenda ikawa ni kwa sababu ya ongezeko tunaloliona la wingi wa gesi ya nyumba ya kijani inayotokana na binadamu". Inatibiriwa kuwa mabadiliko ya hali ya anga katika siku za usoni yatahusisha ongezeko la joto Duniani zaidi (yaani, mwenendo wa kupanda katika vipimo vywa joto vya wastani Duniani), kupanda kwa kiwango cha maji baharini, na uwezekano wa kupanda wa wingi wa baadhi ya matukio ya hali mbaya ya hewa. Mazingira huonekana kuwa kama na uwezekano mkubwa wa kuadhirika na mabadiliko ya hali ya anga. Mifumo ya kibinadamu huonekana kama yenye kubadilika katika uwezo wa o wa kukabiliana na mabadiliko ya hali ya anga ya siku za usoni. Ili kupunguza hatari ya uwezekano mkubwa wa mabadiliko makubwa ya hali ya anga katika siku za usoni, nchi nyingi zimebuni sera zinazolenga kupunguza uzalishaji wao wa gesi chafu.

Muhtasari

Katika kipindi cha miaka mia hivi kilichopita, rekodi ya joto imeonyesha mwelekeo wa hali ya anga ambapo kipimo cha joto kimepanda, yaani, ongezeko la joto Duniani. Mabadiliko mengine ambayo yameonekana ni pamoja na kupunguka kwa eneo la Aktiki, Kutolewa kwa gesi ya metheni katika eneo la Aktiki, kutolewa kwa gesi ya Kaboni iliyo ardhini katika maeneo yenyemchanga uliofanywa kuwa kama barafu na Kutolewa kwa gesi ya metheni katika vidonge donge vya pwani, na kupanda kwa eneo la bahari lenye maji. Kipimi cha joto cha wastani Duniani kinatabitriwa kupanda katika kipindi cha karne hii, pamoja na uwezekano wa visa vya matukio mabaya ya hali ya hewa, na mabadiliko ya ruwaza za mvua. Tukisonga kutoka hali ya maeneo makubwa Duniani hadi hali ya maeneo madogo, kuna ongezeko la uhakika kuhusu jinsi hali ya anga itabadilika. Uwezekano wa ongezeko la joto kuwa na matokeo ambayo hayakuwa yametarajiwa awali unaongezeka na kiwango, ukubwa na muda wa mabadiliko ya hali ya anga. Some of the physical impacts of climate change are irreversible at continental and global scales. Eneo la bahari lenye maji linatarajiwa kupanda hadi kati ya sentimita 18 na 59 (Incha 7.1 hadi 23.2) kufikia mwwisho wa karne ya 21. Kwa sababu ya ukosefu wa maarifa ya kutosha ya kisayansi, makisio haya ya kupanda huku kwa kiwango cha bahari chenye maji hayajumuishi mchango utakaofanywa na mabati ya barafu. Kupunguka kwa Slowing of the Mzunguko wa Kimeridia wa Kupinduka una uwezekano mkubwa wa kufanyika katika karne hii, lakini vipimo vya joto katika eneo la Atlantiki na Ulaya huenda vikawa vikubwa zaidi kwa sababu ya ongezeko la joto Duniani. Kwa joto Duniani kuongezeka kwa kiwango cha 1-4°C (ikilinganisha kipindi cha kati ya mwaka wa 1990 hadi waka wa 2000), kuna uwezekano wa wastani kwamba kuyeyuka kwa sehemu kwa Bati la barafu la Greenland kutatendeka kwa kipindi cha karne nyingi na milenia. Ikihusisha uwezekano wa mchango wa kuyeyushwa kwa sehemu ya Bati la barafu la eneo la Magharibi mwa Antaktiki, eneo lenye maji baharini litapanda kwa kiwango cha kati ya mita 4 na 6 au zaidi.

Matokeo yatakaodhihirika katika mifumo ya kibinadamu ya mabadiliko ya hali ya anga pengine yatazambazwa kwa pamoja. Baadhi ya maeneo na sekta yanatarajiwa kufaidika ilhali mengine yataathirika na gharama. Huku kukiwa na idadi zaidi za ongezeko la joto (zaidi ya 2-3°C, ikilinganishwa na viwango vya mwaka wa 1990), kuna uwezekano kuwa faida zitapungua na gharama kuongezeka. Maeneo ya urefu wa chini na maeneo ambayo hayajaendelea sana pengine yamo katika hatari kuu ya mabadiliko ya hali ya anga. Huku uwezo wa mifumo ya kibinadamu kukabiliana na athari za kubadilika kwa hali ya anga ni mkubwa, ingawa bei ya kufanya mabadiliko hayaeleweki kwa kina na yana uwezekano wa kuwa makubwa. Kuna uwezekano kuwa mabadiliko ya hali ya anga yatasababisha kupungua katika utofauti wa mifumo ya kiikolojia na kupotea kwa spishi nyingi. Uwezo wa kufanya mabadiliko wa mifumo ya kibaiolojia na mifumo ya Kijiofizikia inakadiriwa kuwa ya chini kuliko ya mifumo ya kibinadamu.

Athari za kimwili

Athari katika hali ya hewa

Kuongezeka kwa joto huenda kukaongeza kiasi cha usimbishaji Lakini haijulikani kwa kweli jinsi ongezeko la joto litakavyoathiri dhoruba. Dhoruba zinazopatikana nje ya maeneo ya Kitropiki hutegemea gredienti ya kipimo cha joto, ambacho kinatabiriwa kuwa dhaifu kuzidi katika Ulimwengu wa kaskazini huku kanda la ncha ya eneo la kaskazini mwa Ulimwengu likizidi kuwa na joto jingi kuliko maeneo mengine katika ulimwengu wa kasakazini.

Hali kali za hewa

Tazama pia: Saikloni ya kitropiki#Orodha ya ongezeko la joto Duniani na Orodha la rekodi za harikeni katika eneo la Kiatlantiki

Ongezeko la joto Duniani huenda limechangia mienendo ya majanda ya kimaumbile kama vilehali kali ya hewa.

Kulingana na makadiro ya siku zijazo ya mabadiliko ya hali ya anga, ripoti ya IPCC imetabiri mengi. Imetabiriwa kuwa katika maeneo mengi ya nchi, idadi ya vipindi vya joto au mawimbi ya joto yana uwezekano mkubwa wa kupanda. Kuna uwezekano kuwa:

• Maeneo mengi zaidi yataathirika na ukame
• Pia kutakuwa na matukio ya saikloni za Kitrpiki mengi
• Pia matukio ya kukithiri kwa kiwango cha kiwango chenye maji baharini (bila kuhesabu tsunami)

Nguvu ya dhoruba itakayosababisha hali kali ya hewa inazidi kuongezeka, kama vile kipimo cha nguvu zinazotolewa na harikeni. Kerry Emanuel anaandika kuwa nguvu zinazotokana na harikeni zinategemea sana kiwango cha joto, hivyo kuashiria ongezeko la joto Duniani. Hata hivyo, masomo zaidi yaliyofanywa na Emanuel kwa kutumia mifano zaidi ya mapato yalihitimisha kuwa kuongezeka huku kwa nguvu zinazotokana na na dhoruba katika miongo ya hivi karibuni hakuwezi kuhusishwa kwa kipekee na ongezeko la joto Duniani. Kufanywa kwa mifano ya harikeni pia kumetoa matokeo yanayofanana, kupata kuwa harikeni, zikundwa katika maeneo yanayotoa viwango vingi zaidi vya Kaboni monoksaidi (CO₂), vina nguvu zaidi, hata hivyo, idadi ya harikeni itapungua. Ulimwenguni kote, uwiano wa harikeni zinazofikia kiwango cha 4 au 5 – kikiambatana na kasi za upepo za zaidi ya mita 56 kila sekunde – umepnada kutoka 20% katika miaka ya 1970 hadi 35% katika miaka ya 1990. Usimbishaji nchini Marekani kutokana na harikeni umepanda kwa zaidi ya 7% katika karne ya ishirini. Kiwango ambacho hili limesababishwa na ongezeko la joto Duniani kinyume na Kuyumbayumba kwa Miongo mingi wa Kiatlantiki hauleweki vizuri. Baadhi ya utafiti umepata kuwa ongezeko la joto la uso wa bahari unaweza kuanzishwa na ongezeko la upepo wa kukata, hivyo basi kusababisha mabadiliko madogo au hata kutosababisha mabadiliko yoyote ya shughuli za harikeni. Hoyos pamoja na watafiti wengine. (2006) wamehusisha mwenendo wa ongezeko wa iadi ya harikeni za jamii ya 4 na 5 kwa kipindi kati ya 1970-2004 moja kwa moja na mwenendo wa vipimo vya joto vya uso wa bahari.

Ongezeko la majanga yanayotokana na hali kali ya hewa husababishwa hasa na ongezeko la idadi ya watu katika kila eneo mraba, na matarajio ya kuongezeka kwingi zaidi katika katika siku za usoni. Shirika la Dunia la Somo la Hali ya Hewa linaelezea kuwa “ingawa kuna ushahidi wa na dhidi ya kuwa na ishara inayoweza kupimika ya kianthropojeniki katika hali ya anga ya rekodi ya saikloni ya kitropiki hadi wa leo, hakuna hitimisho maalum linaloweza kufanywa kuhusu hoja hii.” Pia waliifanya kuwa wazi kuwa “hakuna saikloni moja ya kitropiki ambayo inayoweza kuhusishwa moja kwa moja na mabadiliko ya hali ya anga.”

Thomas Knutson na Robert E. Tuleya wa NOAA walisema mnamo mwaka wa 2004 kuwa ongezeko la joto uliowezeshwa na gesi za nyumba za kijani kibichi huenda zikasababisha ongezeko la matukio ya dhoruba za jamii ya 5 ambazo husababisha uharibifu mwingi. Mnamo mwaka wa 2008, Knutson pamoja na watafiti wengine. Alipata kuwa idadi ya harikeni za Kiatlantiki na dhoruba za Kitropiki zingepungua kufuatia ongezeko la joto litakalosababishwa na gesi za nyumba za kijani kibichi katika siku za usoni. Vecchi na Soden wanapata kuwa makadirio ya upepo wa kukata, ambayo yanapoongezeka yanapunguza saikloni za kitropiki, pia kunabadilisha mifano iliyotabiriwa ya ongezeko la joto. Kuna makadirio ya ongezeko la idadi ya upepo wa kukata katika Atlantiki ya Kitropiki na Pasifiki ya Mashariki inayohusishwa na kupungua kwa kipimo cha Mzunguko wa Walker, na pia kupungua kwa kukata kwa upepo katika eneo la magharibi na kati la Pasifiki. The study does not make claims about the net effect on Atlantic and East Pacific hurricanes of the warming and moistening atmospheres, and the model-projected increases in Atlantic wind shear.

Hatari kubwa zaidi ya hali kali ya hewa haimaanishi hatari kubwa iliyo wazi ya hali ya hewa ambayo haifanani na ile ya wastani. Hata hivyo, ushahidi ni wazi kuwa hali kali ya hewa na mvua ya wastani pia vinaongezeka. Kuongezeka kwa idadi ya joto kunatarajiwa kuzalisha mawimbi makali zaidi juu ya ardhi na idadi kubwa zaidi ya dhoruba kali sana.

Kuongezeka kwa uvukizi

Kuongezeka kwa maji yanayotokana na uvukizi katika eneo la Boulder, Colorado.

Katika kipindi cha karne ya 20th, viwango vywa uvukizi vimepungua duniani kote ; hili linadhaniwa na wengi kuweza kuelezewa kupitia kufifia Duniani. Kadiri hali ya anga inavyozidi kuwa moto na sababu za kufifia Duniani kunapunguzwa, , uvukizi utazidi kwa sababu ya bahari yenye joto zaidi. Kwa sababu Dunia ni mfumo uliofungwa hili litasababisha viwangi vingi zaidi vya mvua, pamoja na mmomonyoko. Mmomonyoko huu, kwa upande mwingine, unaweza katika maeneo ya kitropiki ambao yamo hatarini (hasa Barani Afrika) kusababisha kuenea kwa majangwa. Kwa upande mwingine, katika maeneo mengine, ongezeko la mvua litasababisha kukuwa kwa misitu katika maeneo kavu yenye majangwa.

Wanasayansi wamepata ushahidi kuwa ongezeko la uvukizi kunaweza kusababisha hali ya hewa kali zaidi kadiri ongezeko la joto Duniani linapoendelea. Ripoti ya kila mwaka ya tatu ya IPCC inasema: "...wingi wa wastani Duniani wa mvuke na usimbishaji unakadiriwa kuongezeka katika karne ya 21. Kufikia nusu ya pili ya karne ya 21, kuna uwezekano kuwa usimbishaji utakuwa umeongezeka katika maeneo ya kilatitiudi ya kati nay a juu ya kaskazini na Antarctica katika majira ya baridi. Katika latitiudi za chini ikuna kupunguka na kuongezeka katika maeneo juu ya ardhi. Tofauti kubwa zaidi za mwaka mmoja hadi mwingine za usimbishaji ina uwezekano wa kufanyika katika maeneo mengi ambapo ongezeko la usimbishaji wa wastani umetabiriwa."

Gharama itakayotokana na hali kali zaidi ya hewa

Tazama pia: Orodha ya harikeni ghali zaidi za Kiatlantiki

Kwa mujibu wa maelezeo ya Shirika la Kimataifa la Somo la Hali ya Hewa, “Ongezeko la hivi karibuni la athari ya kijamii kutokana na saikloni za kitropiki imesababishwa hasa na ongezeko la ukolezi wa idadi ya watu na miundombinu katika maeneo ya pwani.” Pielke pamoja na watafiti wengine. (2008) alilinganisha uharibifu wa harikeni za Marekani wa kati ya miaka 1900–2005 na viwango vywa mwaka wa 2005 na alipata kuwa hakukuwa na mwenendo uliobaki wa uharibifu uliobaki. Miaka ya 1970 na 1980 ilijulikana hasa kwa sababu idadi yao ndogo ya uharibifu ikilinganishwa na miongo ya awali. Muongo wa 1996–2005 una idadi ya pili ya uharibifu ikilinganishwa na miongo 11 ya awali, huku muongo wa miaka ya 1926–1935 pekee ukiipita kwa kigharama. Dhoruba iliyosababisha uharibifu mwingi zaidi ni harikeni ya Miami ya mnamo mwaka wa 1926, ikiwa na uharibifu takriban dola bilioni 157 bilioni.

Jarida la Bima la Marekani lilitabiri kuwa “hasara zinazotokna na majanga zinafaa kutarajiwa kuongezeka maradufu kila miaka 10 kwa sababu ya ongezeko la gharama ya ujenzi, ongezeko la idadi ya mijengo, na mabadiliko ya tabia zao.” Chama cha Watoaji Bima cha Uingereza (ABI) limetaja kuwa kupunguza uzalisaji wa kabini kunaweza kupungua 80% ya gharama za nyongeza za kila mwaka zinazotokana na saikloni za kitropiki kufikia miaka ya 2080. Gharama pia inapanda kwa sababu ya kujenga katika maeneo wazi kama vile pwani na maeneo tambarare yaliyofurika. ABI inadai kuwa kupunguza kwa udhaifu dhidi ya baadhi ya madhara ya mabadiliko ya hali ya anga, kwa mfano kupitia mijengo dhabiti zaidi na ulinzi dhidi ya mafuriko ulioboreshwa zaidi, pia kunaweza sababisha kupunguza matumizi ya pesa baada ya muda mrefu.

Mabadiliko ya hali ya anga katika maeneo madogo

Harikeni ya kwanza iliyorekodiwa katika eneo la Kusini la Kiatlanitiki, "Catarina", iliyoathiri Brazil mnamo Machi mwaka wa 2004

Katika Ulimwengu wa kaskazini, eneo la kaskazini la kana ya Aktiki ambayo ni (nyumbani kwa watu 4,000,000) imekuwa na ongezeko la joto la kati ya 1°C na 3°C (1.8°F na 5.4°F) katika kipindi cha miaka 50 iliyopita. Kanada, Alaska na Urusi hivi sasa zinapitia hatua ya uyeyukaji wa mchanga ambao ni kama barafu. Hili linaweza kuharibu mifumo ya kiikolojia na kwa kuongeza shghuli za bacteria katika udongo zinaweza kusababisha maeneo haya kuwa vyanzo vya kaboni badala ya vitumiaji vya kaboni. Utafiti (ulichapishwa katika jarida la Sayansi) kuhusu mabadiliko katika udongo uliofanywa kuwa kama barafu wa eneo la magharibi la Siberia unaonyesha kwamba inazidi kupungua katika maeneo ya kusini, hivyo kupelekea kwa hasara ya kupotea kwa kariibu 11% ya takriban mito 11,000 ya Siberia tangu mwaka wa 1971. Wakati uo huo, Siberia ya magharibi ipo katika hatua ya kwanza ambapo udongo ulikuwa kama barafu unaunda maziwa mapya, ambayo mwishow yanaanza kupotea kama katika eneo la mashariki. Isitoshe, kuyeyuka kwa udongo ambao umekuwa kama barafu mwishowe kutasababisha Kutolewa kwa gesi ya metheni kutoka kwa maeneo majimaji yaliyofanywa kuwa kama mawe na barafu.

Kabla ya mwezi Machi mwaka wa 2004, hakuna saikloni ya kitropiki ambayo ilikuwa imewahi kuonekana katika bahari ya Kusini ya Atlantiki. Saikloni ya Atlantiki ya kwanza kutokea kusini mwa ikweta iliathiri Brazil mnamo tarehe 28 Machi, mwaka wa 2004 ikiwa na upepo wa kasi la 40 m/s (Kilomita 144 kwa kila saa), ingawa baadhi ya wasomi wa Kibrazili wa hali ya anga wanakana kuwa ilikuwa harikeni. Mifumo ya ufuatiliaji ingeongezwa hadi kilomita 1,600(maili 1,000) zaidi kulekea upande wa kusini. Hakuna makubaliano kuhusu ikiwa harikeni hii inahusishwa na mabadiliko ya hali ya anga, lakini muundo mmoja wa hali ya anga unaonyesha kuongezeka kwa kuanza kwa saikloni za kitropiki katika eneo la Kusini la Atlantiki kwa sababu ya ongezeko la joto Duniani kufikia mwisho wa karne ya 21.

Kurudi nyuma na Kupotea kwa Theluji

Mapu ya mabadiliko ya upana wa theluji milimani tangu mwaka wa 1970. Kupungua kwa upana kumeonyeshwa katika rangi ya machungwa na rangi nyekundu, kuongezeka kumeonyeshwa kwa rangi ya bluu.

Katika nyakati za kihistoria, theluji ilikuwa katika wakati wenye kipindi cha baridi kati ya mwaka wa 1550 na mwaka wa 1850, kipindi kinachojulikana kama Enzi ndogo ya Barafu. Baada ya hapo, hadi mwaka wa 1940, theluji Duniani kote ilizidi kurudi nyuma kadiri hali ya anga ilipozidi kuwa moto. Kurudi nyuma kwa theluji kulipungua na mara nyingi kufanya kinyume na kuanza kusonga mbele kati ya mwaka wa 1950 na mwaka wa 1980 Dunia ilipopoa kidogo. Tangu mwaka wa 1980, kurudi nyuma kwa theluji kumezidi na sasa kumeonekana katika kila pemebe Duniani, huku kukitishia kuwepu kwa theluji kokote Duniani. Utaratibu huu umefanyika kwa kasi zaidi tangu mwaka wa 1995.

Bila kuhesabu kofia za barafu na mabati ya barafu ya Aktiki na Antaktiki, eneo la jumla la theluji Duniani kote imepungua kutoka 50% tangu mwisho wa karne ya 19. Kwa sasa viwango vya kupungua kwa theluji na urari wa hasara ya kiwango umekuwa ukiongezeka katika maeneo ya Andes, Alps, Pyrenees, Himalayas, Milima ya Rocky na Cascades za Kasakazini.

Kupotea kwa theluji hausababishi tu kuanguka kwa ardhi, mafuriki ya haraka na kufurika kwa maziwa ya theluji, lakini pia kunasababisha mabadiliko ya mitiririko ya maji katika mito. Maji kutokana na theluji yanapungua katika msimu wa jua wakati ambapo ukubwa wa theluji unapungua, upungufu huu tayari unaonekana katika maeneo mengi. Theluji inabaki na maji milimani katika miaka yenye usimbishaji, kwa sababu barafu inayofunika theluji inafanya jiwe la barafu lisiyeyuke. Katika miaka kavu na yenye joto jingi, theluji inabadilisha idadi ndogo zaidi za usimbishaji kwa kutoa maji mengi zaidi yaliyoyeyushwa.

Kuyeyuka kwa theluji ya maeneo ya Hindu Kush na Himalaya ambayo ni chanzo cha maji cha mito mikuu ya Kati, Kusini, Mashariki na Asia ya Kusini Mashariki wakati wa ukame. Kuongezeka kwa uyeyushaji kungesababisha mitiririko mingi zaidi kwa kipindi cha miongo mingi zaidi, ambapo "baadhi ya maeneo yenye watu wengi zaidi Duniani yataishiwa na maji'" kadiri theluji ambayo ni vyanzo vya mito inayeyushwa. Muinuko wa Kitibeti una hifadhi ya ukubwa wa tatu zaidi Duniani. Vipimo vya joto pale vinaongezeka mara nne haraka kuliko katika eneo lingine nchini Uchina, na kurudi nyuma kwa theluji unafanyika kwa kasi ikilinganishwa na mahali pengine Duniani.

Kulingana na ripoti ya Reuters, theluji za Himalaya ambazo ndizo vyanzo vya mito mikubwa zaidi Barani Asia, mito Ganges, Indus, Brahmaputra, Yangtze, Mekong, Salween na Manjano – inaweza kupungua kadiri vipimo vya joto vinavyoongezeka. Takriban watu bilioni 2.4 wanaishi katika bonde la mifereji wa mito ya Himalaya Uhindi, Uchina, Pakistan, Bangladesh, Nepal na Myanmar huenda zikawa na mafuriko yakifuatiwa na ukame katika miongo ijayo. Nchini Uhindi pekee, mto wa Ganges unatoa maji ya kunywa na kilimo kwa zaidi ya watu milioni 500 million. Imekubalika, hata hivyo, kuwa ongezeko la maji kutoka theluji za Himalaya kila msimu ulisababisha ongezeko la uzalishaji wa kilimo katika eneo la Uhindi ya kasakazini katika kipindi chote cha karne ya 20.

Kurudi nyuma kwa theluji ya milima, hasa katika eneo la magharibi kaskazini la Marekani, Ardhi ya Franz-Josef Land, Asia, the Alps, the Pyrenees, Indonesia na Afrika, na maeneo ya kitropiki na yanayokaribia kuwa ya kitropiki katika Bara la Marekani Kusini, imetumika kama ushahidi wa ongezeko la joto Duniani tangu mwisho wa karne ya 19. Theluji nyingi zinapotea kwa sababu ya kuyeyuka na hivyo kusababisha wasiwasi zaidi kuhsu rasilimali za maji katika maeneo haya yenye theluji katika siku zijazo. Katika eneo la Magharibi la Marekani ya Kaskazini theluji katika laini ya 47 zimeonekana kurudi nyuma.

Kurudi nyuma kwa theluji la Helheim Glacier, nchini Greenland

Ijapokuwa ya kuwa karibu na umuhimu wao kwa Idadi ya watu, theluji za milima na mabonde za latititudi zenye joto jingi zinchangia kiwango kidogo cha barafu ya theluji Duniani. Takriban 99% inapatikana katika mabati makuu ya barafu ya maeneo ya Kipola na chini ya kipola ya Antaktika na Greenland. Mabati haya yanayoendelea mfululizo huwa katika eneo la kilomita 3 (maili 1.9) au zaidi kwa upana, hufunika maeneo ya kipola na chini ya kipola ya ardhi. Kama mito inayotoka katika mito mikubwa, theluji nyingi za kutoka hubeba barafu kutoka sehemu za mwisho za bati la barafu hadi baharini.

Kusonga nyuma kwa theluji kumeonekana katika theluji hizi za kutoka, hivyo kusababisha ongezeko la kiwango cha barafu inayotoka katika theluji. Katika Greenland wakati tangu mwaka wa 2000 umefanya kurudi nyuma kwa theluji nyingi kubwa amabazo hapo awali hazikuwa hazisongi. Theluji tatu zimefanyiwa utafiti: Helheim, Jakobshavn Isbræ na Kangerdlugssuaq, ambazo zinaondoa maji katika 16% ya Bati la Barafu la Greenland. Picha za setelaiti na picha zilizochukuliwa kutoka juu angani kutoka miaka ya 1950 na 1970 zinaonyesha kuwa sehemu ya mbele ya theluji ilikuwa imebaki katika eneo moja kwa miongo mingi.Katika miaka ya 2001 ilikuwa imeanza kurudi nyuma kwa haraka sana, kiwango cha kilomita 7.2 (maili 4.5) kati ya mwaka wa 2001 na mwaka wa 2005. Pia imeongeza kasi yake ya kurudi nyuma kutoka mita 20(futi 66) kwa siku hadi mita 32(futi 100) kwa siku. Jakobshavn Isbræ katika eneo la Greenland magharibi ilikuwa ikisonga katika kasi ya zaidi ya mita 24(futi 79 kila siku) tangu mwaka wa 1950 bila kuvunjika. Ulimi wa theluji ulianza kuvunjika mnamo mwaka wa 2000, na kusababisha kuvunjika kabisa kwa mnamo mwaka wa 2003, ingawa kiwango cha kurudi nyuma kiliongezeka maradufu mnamo hadi mita 30 (futi 98) kila siku.

Bahari

Jukumu la bahari katika ongezeko la joto Duniani ni la utata. Bahari hutumika kama eneo ambapo kaboni monoksaidi huingia, na kuchukua nyingi ambayo ingebaki katika anga, lakini ongezeko la CO₂ limesababisha aside kuongezeka baharini. Aidha, kadiri kiwango cha joto cha bahari kinavyongezeka, zinashindwa kuchukua ndani CO₂ nyingi. Ongezeko la joto Duniani inatabiriwa kuwa na athari nyingi kwa bahari. Baadhi ya athari zinazoendelea ni ongezeko la eneo la bahari lenye maji kwa sababu ya upanuzi unaosababishwa na joto na kuyeyuka kwa theluji na mabati ya barafu, na kuongezeka kwa joto katika uso wa bahari, hivyo kusababisha ongezeko la tofauti za vipimo vya joto. Athari zingine zinazowezekana ni kubadilika kwa mzunguko wa bahari katika eneo kubwa.

Kupanda kwa kiwango cha maji baharini

Huku kipimo cha joto cha wastani kikipanda, kiasi cha maji katika bahari kinapanuka, na maji zaidi yanaingia ambapo hapo awali yalikuwa yamefungiwa katika thluji za ardhi, kwa mfano, Greenland na mabati ya barafu ya Antaktiki. Kwa theluji nyingi Ulimwenguni kote, kupoteza kiasi cha 60% hadi mwaka wa 2050 umetabiriwa. Wakato uo huo, makadirio ya jumla kiwango cha kuyeyuka kwa barafu katika eneo la Greenland ni {{|239|+/-|23|Kilomita za kikiubi}} kila mwaka, hasa katika Greenland ya Mashariki. Bati la barafu la eneo la Antaktiki, hata hivyo, linatarajiwa kuwa kati karne ya 21 kwa sababu ya ongezeko la usimbishaji. Chini ya Ripoti Maalum ya IPCC kuhusu Matukio ya Uzalishaji (SRES) A1B, kufikia miaka ya kati ya 2090 eneo lenye maji baharini kitafikia kati ya mita 0.22 na 0.44 (incha 8.7 hadi 17) juu ya viwango vya mwaka 1990, na hivi sasa vinaongezeka kwa kiwango cha milimita 4 (incha 0.16) kila mwaka. Tangu mwaka wa 1900, ongezeko la kiwango cha maji baharini kimepanda kwa kiwango cha wastani cha milimita 1.7 (Incha 0.067) kila mwaka; tangu mwaka wa 1993, picha za anga za setalaiti za TOPEX/Poseidon zinaonyesha kiwango cha karibu milimita 3(incha 0.03) kila mwaka.

Kiwango chenye maji baharini kimepanda zaidi ya mita 120 (futi 390) tangu kiwango cha juu zaidi cha mwisho cha Kitheluji takriban miaka 20,000 iliyopita. Kiasi kikubwa cha hayo kilifanuika kabla ya miaka 7000 iliyopita. Kiwango cha joto cha Dunia kilipungua baada ya Kiwango cha Juu zaidi cha Hali ya Anga cha Holocene, kusababisha kupunguka kwa kiwango cha maji baharini cha mita 0.7+/0.1 au Incha 28+/3.9 kati ya miaka 4000 na 2500 kabla ya wakati wa leo. Kutoka kipindi cha miaka 3000 iliyopita hadi mwanzo wa karne ya 19, kiwango cha maji baharini hakikubadilika, kikiwa kinaymbayumba kwa sehemu ndogo tu. Hata hivyo, Kipindi cha Kati chenye Joto huenda kilisababishamay kupanda kidogo kwa kiwango cha maji baharini; ushahidi umepatikana katika Bahari ya Pasifiki wa ongezeko wa pengine mita 0.9 (Futi 2 incha 11) juu ya viwango vya sasa katika 700 BP.

Katika jarida lililochapishwa mnamo mwaka wa 2007, mtafiti wa hali ya anga James Hansen pamoja na watafiti wengineo. Alidai kuwa barafu katika fito haiyeyuki katika njia ya kufuata utaratibu au kwa kuelekea upande mmoja maalum, lakini kwa mujibu wa rekodi ya kijiolojia, mabati ya barafu huweza kuwacha kuwa dhaifu ghafla wakati ambapo kiwango fulani maalum kinapitwa.Katika jarida hili Hansen pamoja na watafiti wengine. wanasema:

Hofu yetu kuwa visa vya BAU GHG vinaweza kusababisha ongezeko kubwa la kiwango cha maji baharini katika karne hii (Hansen 2005) linatofautiana na makadirio ya IPCC (2001,2007) yanayotabiri mchango mdogo au mchango usiokuwepo wa kupanda kwa kiwango cha maji baharini katika karne ya ishirini na mbili katika Greenland na Antaktika. Hata hivyo, uchambuzi na makadirio ya IPCC yanatofautiana na makadirio ya (2001, 2007), ambayo yanatazamia kuwa na mabadiliko kidogo au hata kutokuwa na mabadiliko yoyote ya ongezeko la kiwango cha maji baharini katika karne ya ishirini na mbili kutoka eneo la Greenland na Antaktika. Hata hivyo, IPCC uchambuzi na makadiro ya IPCC hayaelezei vizuri kwa fizikia isoyofuata njia moja ya barafu majimaji ya kuvunjika kwa bati la barafu, vijito vya barafu na kabati za barafu ambazo husababisha mmomoyoko, na pia haziambatani na ushahidi wa anga wa palaeo ambao tumewasilisha kuhusu ukosefu wa tofauti kati ya kulazimisha kwa mabati ya barafu na kupanda kwa kiwamgo cha maji baharini.

Kupanda kwa kiwango cha maji baharini kwa sababu ya kuanguka kwa bati lingesambazwa katika njia isiyo sawa duniani kote. Kupoteza The loss of mass in the region around the ice sheet would decrease the gravitational potential there, reducing the amount of local sea level rise or even causing local sea level fall. The loss of the localized mass would also change the moment of inertia of the Earth, as flow in the Earth's mantle will require 10-15 thousand years to make up the mass deficit. This change in the moment of inertia results in true polar wander, in which the Earth's rotational axis remains fixed with respect to the sun, but the rigid sphere of the Earth rotates with respect to it. This changes the location of the equatorial bulge of the Earth and further affects the geoid, or global potential field. A 2009 study of the effects of collapse of the West Antarctic Ice Sheet shows the result of both of these effects. Instead of a global 5-meter sea level rise, western Antarctica would experience approximately 25 centimeters of sea level fall, while the United States, parts of Canada, and the Indian Ocean, would experience up to 6.5 meters of sea level rise.

A paper published in 2008 by a group of researchers at the University of Wisconsin lead by Anders Carlson used the deglaciation of North America at 9000 years before present as an analogue to predict sea level rise of 1.3 meters in the next century, which is also much higher than the IPCC predictions. However, models of glacial flow in the smaller present-day ice sheets show that a probable maximum value for sea level rise in the next century is 80 centimeters, based on limitations on how quickly ice can flow below the equilibrium line altitude and to the sea.

Ongezeko la joto

From 1961 to 2003, the global ocean temperature has risen by 0.10 °C from the surface to a depth of 700 m. There is variability both year-to-year and over longer time scales, with global ocean heat content observations showing high rates of warming for 1991 to 2003, but some cooling from 2003 to 2007. The temperature of the Antarctic Southern Ocean rose by 0.17 °C (0.31 °F) between the 1950s and the 1980s, nearly twice the rate for the world's oceans as a whole . As well as having effects on ecosystems (e.g. by melting sea ice, affecting algae that grow on its underside), warming reduces the ocean's ability to absorb CO₂.

Ongezeko la asidi

Ocean acidification is an effect of rising concentrations of CO₂ in the atmosphere, and is not a direct consequence of global warming. The oceans soak up much of the CO₂ produced by living organisms, either as dissolved gas, or in the skeletons of tiny marine creatures that fall to the bottom to become chalk or limestone. Oceans currently absorb about one tonne of CO₂ per person per year. It is estimated that the oceans have absorbed around half of all CO₂ generated by human activities since 1800 (118 ± 19 petagrams of carbon from 1800 to 1994).

In water, CO₂ becomes a weak carbonic acid, and the increase in the greenhouse gas since the Industrial Revolution has already lowered the average pH (the laboratory measure of acidity) of seawater by 0.1 units, to 8.2. Predicted emissions could lower the pH by a further 0.5 by 2100, to a level probably not seen for hundreds of millennia and, critically, at a rate of change probably 100 times greater than at any time over this period.

There are concerns that increasing acidification could have a particularly detrimental effect on corals (16% of the world's coral reefs have died from bleaching caused by warm water in 1998, which coincidentally was the warmest year ever recorded) and other marine organisms with calcium carbonate shells.

In November 2009 an article in Science by scientists at Canada's Department of Fisheries and Oceans reported they had found very low levels of the building blocks for the calcium chloride that forms plankton shells in the Beaufort Sea. Fiona McLaughlin, one of the DFO authors, asserted that the increasing acidification of the Arctic Ocean was close to the point it would start dissolving the walls of existing plankton: "[the] Arctic ecosystem may be risk. In actual fact, they'll dissolve the shells." Because cold water absorbs CO2 more readily than warmer water the acidification is more severe in the polar regions. McLaughlin predicted the acidified water would travel to the North Atlantic within the next ten years.

Kukoma kwa mzunguko wa kijoto

There is some speculation that global warming could, via a shutdown or slowdown of the thermohaline circulation, trigger localized cooling in the North Atlantic and lead to cooling, or lesser warming, in that region. This would affect in particular areas like Scandinavia and Britain that are warmed by the North Atlantic drift.

The chances of this near-term collapse of the circulation are unclear; there is some evidence for the short-term stability of the Gulf Stream and possible weakening of the North Atlantic drift. However, the degree of weakening, and whether it will be sufficient to shut down the circulation, is under debate. As yet, no cooling has been found in northern Europe or nearby seas. Lenton et al. found that "simulations clearly pass a THC tipping point this century".

Kumalizika kwa oksijeni

The amount of oxygen dissolved in the oceans may decline, with adverse consequences for ocean life.

Matokeo ya kichanya

Tazama pia: Kubadilika kwa ghafla wa hali ya anga

Some observed and potential effects of global warming are positive feedbacks, which contribute directly to further global warming. The IPCC Fourth Assessment Report states that "Anthropogenic warming could lead to some effects that are abrupt or irreversible, depending upon the rate and magnitude of the climate change." This is largely because of the existence of these positive feedbacks.

Metheni kutolewa kutoka maeneo ya majimaji baada ya myeyusho wa barafu

Tazama pia: Kutolewa kwa metheni kutoka eneo la Aktiki

Western Siberia is the world's largest peat bog, a one million square kilometer region of permafrost peat bog that was formed 11,000 years ago at the end of the last ice age. The melting of its permafrost is likely to lead to the release, over decades, of large quantities of methane. As much as 70,000 million tonnes of methane, an extremely effective greenhouse gas, might be released over the next few decades, creating an additional source of greenhouse gas emissions. Similar melting has been observed in eastern Siberia . Lawrence et al. (2008) suggest that a rapid melting of Arctic sea ice may start a feedback loop that rapidly melts Arctic permafrost, triggering further warming.

Metheni inayotolewa kutoka haidreti

Methane clathrate, also called methane hydrate, is a form of water ice that contains a large amount of methane within its crystal structure. Extremely large deposits of methane clathrate have been found under sediments on the ocean floors of Earth. The sudden release of large amounts of natural gas from methane clathrate deposits, in a runaway greenhouse effect, has been hypothesized as a cause of past and possibly future climate changes. The release of this trapped methane is a potential major outcome of a rise in temperature; it is thought that this might increase the global temperature by an additional 5° in itself, as methane is much more powerful as a greenhouse gas than carbon dioxide. The theory also predicts this will greatly affect available oxygen content of the atmosphere. This theory has been proposed to explain the most severe mass extinction event on earth known as the Permian–Triassic extinction event. In 2008, a research expedition for the American Geophysical Union detected levels of methane up to 100 times above normal in the Siberian Arctic, likely being released by methane clathrates being released by holes in a frozen 'lid' of seabed permafrost, around the outfall of the Lena River and the area between the Laptev Sea and East Siberian Sea.

Matokeo ya mzunguko wa kaboni

There have been predictions, and some evidence, that global warming might cause loss of carbon from terrestrial ecosystems, leading to an increase of atmospheric CO₂ levels. Several climate models indicate that global warming through the 21st century could be accelerated by the response of the terrestrial carbon cycle to such warming. All 11 models in the C4MIP study found that a larger fraction of anthropogenic CO₂ will stay airborne if climate change is accounted for. By the end of the twenty-first century, this additional CO₂ varied between 20 and 200 ppm for the two extreme models, the majority of the models lying between 50 and 100 ppm. The higher CO₂ levels led to an additional climate warming ranging between 0.1° and 1.5 °C. However, there was still a large uncertainty on the magnitude of these sensitivities. Eight models attributed most of the changes to the land, while three attributed it to the ocean. The strongest feedbacks in these cases are due to increased respiration of carbon from soils throughout the high latitude boreal forests of the Northern Hemisphere. One model in particular (HadCM3) indicates a secondary carbon cycle feedback due to the loss of much of the Amazon Rainforest in response to significantly reduced precipitation over tropical South America. While models disagree on the strength of any terrestrial carbon cycle feedback, they each suggest any such feedback would accelerate global warming.

Observations show that soils in England have been losing carbon at the rate of four million tonnes a year for the past 25 years according to a paper in Nature by Bellamy et al. in September 2005, who note that these results are unlikely to be explained by land use changes. Results such as this rely on a dense sampling network and thus are not available on a global scale. Extrapolating to all of the United Kingdom, they estimate annual losses of 13 million tons per year. This is as much as the annual reductions in carbon dioxide emissions achieved by the UK under the Kyoto Treaty (12.7 million tons of carbon per year).

It has also been suggested (by Chris Freeman) that the release of dissolved organic carbon (DOC) from peat bogs into water courses (from which it would in turn enter the atmosphere) constitutes a positive feedback for global warming. The carbon currently stored in peatlands (390-455 gigatonnes, one-third of the total land-based carbon store) is over half the amount of carbon already in the atmosphere. DOC levels in water courses are observably rising; Freeman's hypothesis is that, not elevated temperatures, but elevated levels of atmospheric CO₂ are responsible, through stimulation of primary productivity.

Tree deaths are believed to be increasing as a result of climate change, which is a positive feedback effect. This contradicts the previously widely-held view that increased natural vegetation would lead to a negative-feedback effect.

Mioto ya misituni

The IPCC Fourth Assessment Report predicts that many mid-latitude regions, such as Mediterranean Europe, will experience decreased rainfall and an increased risk of drought, which in turn would allow forest fires to occur on larger scale, and more regularly. This releases more stored carbon into the atmosphere than the carbon cycle can naturally re-absorb, as well as reducing the overall forest area on the planet, creating a positive feedback loop. Part of that feedback loop is more rapid growth of replacement forests and a northward migration of forests as northern latitudes become more suitable climates for sustaining forests. There is a question of whether the burning of renewable fuels such as forests should be counted as contributing to global warming. Cook & Vizy also found that forest fires were likely in the Amazon Rainforest, eventually resulting in a transition to Caatinga vegetation in the Eastern Amazon region.

Kurudi nyuma kwa barafu

The sea absorbs heat from the sun, while the ice largely reflects the sun rays back to space. Thus, retreating sea ice will allow the sun to warm the now exposed sea water, contributing to further warming. The mechanism is the same as a black car heating up faster in sunlight than a white one. This albedo change is also the main reason why IPCC predict polar temperatures in the northern hemisphere to rise up to twice as much as those of the rest of the world. In September 2007, the Arctic sea ice area reached about half the size of the average summer minimum area between 1979 to 2000. Also in September 2007, Arctic sea ice retreated far enough for the Northwest Passage to become navigable to shipping for the first time in recorded history. The record losses of 2007 and 2008 may, however, be temporary. Mark Serreze of the US National Snow and Ice Data Center views 2030 as a "reasonable estimate" for when the summertime Arctic ice cap might be ice-free. The polar amplification of global warming is not predicted to occur in the southern hemisphere. The Antarctic sea ice reached its greatest extent on record since the beginning of observation in 1979, but the gain in ice in the south is exceeded by the loss in the north. The trend for global sea ice, northern hemisphere and southern hemisphere combined is clearly a decline.

Athari ya sulfuri kwa sprei za mkebe

Sulfur aerosols, especially stratospheric sulfur aerosols have a significant effect on climate. One source of such aerosols is the sulfur cycle, where plankton release gases such as DMS which eventually becomes oxidised to sulfur dioxide in the atmosphere. Disruption to the oceans as a result of ocean acidification or disruptions to the thermohaline circulation may result in disruption of the sulfur cycle, thus reducing its cooling effect on the planet through the creation of stratospheric sulfur aerosols.

Athari za matokeo ya hasi

Following Le Chatelier's principle, the chemical equilibrium of the Earth's carbon cycle will shift in response to anthropogenic CO₂ emissions. The primary driver of this is the ocean, which absorbs anthropogenic CO₂ via the so-called solubility pump. At present this accounts for only about one third of the current emissions, but ultimately most (~75%) of the CO₂ emitted by human activities will dissolve in the ocean over a period of centuries: "A better approximation of the lifetime of fossil fuel CO₂ for public discussion might be 300 years, plus 25% that lasts forever". However, the rate at which the ocean will take it up in the future is less certain, and will be affected by stratification induced by warming and, potentially, changes in the ocean's thermohaline circulation.

Also, the thermal radiation of the Earth rises in proportion to the fourth power of temperature, increasing the amount of outgoing radiation as the Earth warms. The impact of this negative feedback effect is included in global climate models summarized by the IPCC.

Matokeo mengine

Kiuchumi na kijamii

Tazama pia: Uchumi wa ongezeko la joto Duniani

Indigenous populations in high-latitude areas are already experiencing significant adverse impacts because of climate change. The impact of future climate change on human systems will likely be unevenly distributed. Africa is probably the most vulnerable continent to future climate change. Developing countries are probably more vulnerable to climate change than developed countries. With warming of 1-2°C above 1990-2000 levels, it is likely that key negative impacts would be experienced in some regions, e.g., Arctic nations and small islands. In other regions, some population groups would be threatened by this level of warming, e.g., high-altitude communities and coastal-zone communities with significant levels of poverty. Above 2-3°C warming, it is likely that most countries would experience net negative impacts.

The total economic impacts of climate change are highly uncertain. Typical estimates of climate change impacts are of a change in gross world product of plus or minus a few percent. Small changes in gross world product could be associated with relatively large changes in national economies.

Bima

An industry very directly affected by the risks is the insurance industry. According to a 2005 report from the Association of British Insurers, limiting carbon emissions could avoid 80% of the projected additional annual cost of tropical cyclones by the 2080s. A June 2004 report by the Association of British Insurers declared "Climate change is not a remote issue for future generations to deal with. It is, in various forms, here already, impacting on insurers' businesses now." It noted that weather risks for households and property were already increasing by 2-4 % per year due to changing weather, and that claims for storm and flood damages in the UK had doubled to over £6 billion over the period 1998–2003, compared to the previous five years. The results are rising insurance premiums, and the risk that in some areas flood insurance will become unaffordable for some.

Financial institutions, including the world's two largest insurance companies, Munich Re and Swiss Re, warned in a 2002 study that "the increasing frequency of severe climatic events, coupled with social trends" could cost almost US$ 150 billion each year in the next decade. These costs would, through increased costs related to insurance and disaster relief, burden customers, taxpayers, and industry alike.

In the United States, insurance losses have also greatly increased. According to Choi and Fisher (2003) each 1% increase in annual precipitation could enlarge catastrophe loss by as much as 2.8%. Gross increases are mostly attributed to increased population and property values in vulnerable coastal areas, though there was also an increase in frequency of weather-related events like heavy rainfalls since the 1950s.

Usafiri

Roads, airport runways, railway lines and pipelines, (including oil pipelines, sewers, water mains etc) may require increased maintenance and renewal as they become subject to greater temperature variation. Regions already adversely affected include areas of permafrost, which are subject to high levels of subsidence, resulting in buckling roads, sunken foundations, and severely cracked runways.

Athari kwa kilimo

Tazama pia: Usalama wa chakula, Chakula dhidi ya kuni, na Shida ya bei za vyakula Duniani 2007–2008

Chakula

Climate change is expected to have a mixed effect on agriculture, with some regions benefitting from moderate temperature increases and others being negatively affected. Low-latitude areas are at most risk of suffering decreased crop yields. Mid- and high-latitude areas could see increased yields for temperature increases of up to 1-3°C (relative to the period 1980-99). According to the IPCC report, above 3°C of warming, global agricultural production might decline, but this statement is made with low to medium confidence. Most of the agricultural studies assessed in the Report do not include changes in extreme weather events, changes in the spread of pests and diseases, or potential developments that may aid adaptation to climate change.

An article in the New Scientist describes how rice crops might be strongly affected by rising temperatures. At a 2005 Conference held by the Royal Society, the benefits of increased atmospheric carbon dioxide concentrations were said to be outweighed by the negative impacts of climate change.

Mgao wa athari

In Iceland, rising temperatures have made possible the widespread sowing of barley, which was untenable twenty years ago. Some of the warming is due to a local (possibly temporary) effect via ocean currents from the Caribbean, which has also affected fish stocks. By the mid-21st century, in Siberia and elsewhere in Russia, climate change is expected to expand the scope for agriculture. In East and Southeast Asia, crop yields could increase up to 20%, while in Central and South Asia, yields could decrease by up to 30%. In drier areas of Latin America, productivity of some important crops is expected to decline, while in temperate zones, soybean yields are expected to increase. In Northern Europe, climate change is expected to initially benefit crop yields.Subsistence and commercial agriculture are expected to be adversely affected by climate change in small islands. Without further adaptation, by 2030, production from agriculture is projected to decline over much of southern and eastern Australia, and parts of eastern New Zealand. Initial benefits are projected in western and southern areas of New Zealand.

In North America, over the first few decades of this century, moderate climate change is projected to increase aggregate yields of rain-fed agriculture by 5-20%, but with important variability among regions. According to a 2006 paper by Deschenes and Greenstone, predicted increases in temperature and precipitation will have virtually no effect on the most important crops in the US

In Africa, climate change is expected to severely compromise agricultural production and access to food. Africa's geography makes it particularly vulnerable, and seventy per cent of the population rely on rain-fed agriculture for their livelihoods. Tanzania's official report on climate change suggests that the areas that usually get two rainfalls in the year will probably get more, and those that get only one rainy season will get far less. The net result is expected to be that 33% less maize—the country's staple crop—will be grown. Alongside other factors, regional climate change - in particular, reduced precipitation - is thought to have contributed to the conflict in Darfur. The combination of decades of drought, desertification and overpopulation are among the causes of the conflict, because the Baggara Arab nomads searching for water have to take their livestock further south, to land mainly occupied by farming peoples.

Pwani na maeneo yaliyo chini

For historical reasons to do with trade, many of the world's largest and most prosperous cities are on the coast. In developing countries, the poorest often live on floodplains, because it is the only available space, or fertile agricultural land. These settlements often lack infrastructure such as dykes and early warning systems. Poorer communities also tend to lack the insurance, savings or access to credit needed to recover from disasters. With future climate change, it is likely that densely populated coastal areas will face increased risk of sea level rise and damages due to more intense extreme weather events. Due to differences in adaptive capacity, adaptation of the coasts of developing countries will probably be more difficult than for the coasts of developed countries. A 2006 study by Nicholls and Tol considers the effects of sea level rise:

[...] The most vulnerable future worlds to sea-level rise appear to be the A2 and B2 [IPCC] scenarios, which primarily reflects differences in the socio-economic situation (coastal population, Gross Domestic Product (GDP) and GDP/capita), rather than the magnitude of sea-level rise. Small islands and deltaic settings stand out as being more vulnerable as shown in many earlier analyses. Collectively, these results suggest that human societies will have more choice in how they respond to sea-level rise than is often assumed. However, this conclusion needs to be tempered by recognition that we still do not understand these choices and significant impacts remain possible.

Uhamiaji

Some Pacific Ocean island nations, such as Tuvalu, are concerned about the possibility of an eventual evacuation, as flood defense may become economically unviable for them. Tuvalu already has an ad hoc agreement with New Zealand to allow phased relocation.

In the 1990s a variety of estimates placed the number of environmental refugees at around 25 million. (Environmental refugees are not included in the official definition of refugees, which only includes migrants fleeing persecution.) The Intergovernmental Panel on Climate Change (IPCC), which advises the world’s governments under the auspices of the UN, estimated that 150 million environmental refugees will exist in the year 2050, due mainly to the effects of coastal flooding, shoreline erosion and agricultural disruption (150 million means 1.5% of 2050’s predicted 10 billion world population).

Njia ya kaskazini magharibi

Arctic ice thicknesses changes from 1950s to 2050s simulated in one of GFDL's R30 atmosphere-ocean general circulation model experiments

Melting Arctic ice may open the Northwest Passage in summer, which would cut 5,000 nautical miles (9,000 km) from shipping routes between Europe and Asia. This would be of particular benefit for supertankers which are too big to fit through the Panama Canal and currently have to go around the tip of South America. According to the Canadian Ice Service, the amount of ice in Canada's eastern Arctic Archipelago decreased by 15% between 1969 and 2004.

In September 2007, the Arctic Ice Cap retreated far enough for the Northwest Passage to become navigable to shipping for the first time in recorded history.

In August, 2008, melting sea ice simultaneously opened up the Northwest Passage and the Northern Sea Route, making it possible to sail around the Arctic ice cap. The Northwest Passage opened August 25, 2008, and the remaining tongue of ice blocking the Northern Sea Route dissolved a few days later. Because of Arctic shrinkage, the Beluga group of Bremen, Germany, announced plans to send the first ship through the Northern Sea Route in 2009.

Maendeleo

The combined effects of global warming may have particularly harsh effects on people and countries without the resources to mitigate those effects. This may slow economic development and poverty reduction, and make it harder to achieve the Millennium Development Goals.

In October 2004 the Working Group on Climate Change and Development, a coalition of development and environment NGOs, issued a report Up in Smoke on the effects of climate change on development. This report, and the July 2005 report Africa - Up in Smoke? predicted increased hunger and disease due to decreased rainfall and severe weather events, particularly in Africa. These are likely to have severe impacts on development for those affected.

Mifumo ya kiikolojia

Tazama pia: Hatari ya kuangamia kutokana na ongezeko la joto Duniani

Unchecked global warming could affect most terrestrial ecoregions. Increasing global temperature means that ecosystems will change; some species are being forced out of their habitats (possibly to extinction) because of changing conditions, while others are flourishing. Secondary effects of global warming, such as lessened snow cover, rising sea levels, and weather changes, may influence not only human activities but also the ecosystem. Studying the association between Earth climate and extinctions over the past 520 million years, scientists from the University of York write, "The global temperatures predicted for the coming centuries may trigger a new ‘mass extinction event’, where over 50 per cent of animal and plant species would be wiped out."

Many of the species at risk are Arctic and Antarctic fauna such as polar bears and Emperor Penguins. In the Arctic, the waters of Hudson Bay are ice-free for three weeks longer than they were thirty years ago, affecting polar bears, which prefer to hunt on sea ice. Species that rely on cold weather conditions such as gyrfalcons, and Snowy Owls that prey on lemmings that use the cold winter to their advantage may be hit hard. Marine invertebrates enjoy peak growth at the temperatures they have adapted to, regardless of how cold these may be, and cold-blooded animals found at greater latitudes and altitudes generally grow faster to compensate for the short growing season. Warmer-than-ideal conditions result in higher metabolism and consequent reductions in body size despite increased foraging, which in turn elevates the risk of predation. Indeed, even a slight increase in temperature during development impairs growth efficiency and survival rate in rainbow trout.

Rising temperatures are beginning to have a noticeable impact on birds, and butterflies have shifted their ranges northward by 200 km in Europe and North America. Plants lag behind, and larger animals' migration is slowed down by cities and roads. In Britain, spring butterflies are appearing an average of 6 days earlier than two decades ago .

A 2002 article in Nature surveyed the scientific literature to find recent changes in range or seasonal behaviour by plant and animal species. Of species showing recent change, 4 out of 5 shifted their ranges towards the poles or higher altitudes, creating "refugee species". Frogs were breeding, flowers blossoming and birds migrating an average 2.3 days earlier each decade; butterflies, birds and plants moving towards the poles by 6.1 km per decade. A 2005 study concludes human activity is the cause of the temperature rise and resultant changing species behaviour, and links these effects with the predictions of climate models to provide validation for them . Scientists have observed that Antarctic hair grass is colonizing areas of Antarctica where previously their survival range was limited.

Mechanistic studies have documented extinctions due to recent climate change: McLaughlin et al. documented two populations of Bay checkerspot butterfly being threatened by precipitation change. Parmesan states, "Few studies have been conducted at a scale that encompasses an entire species" and McLaughlin et al. agreed "few mechanistic studies have linked extinctions to recent climate change." Daniel Botkin and other authors in one study believe that projected rates of extinction are overestimated.

Many species of freshwater and saltwater plants and animals are dependent on glacier-fed waters to ensure a cold water habitat that they have adapted to. Some species of freshwater fish need cold water to survive and to reproduce, and this is especially true with Salmon and Cutthroat trout. Reduced glacier runoff can lead to insufficient stream flow to allow these species to thrive. Ocean krill, a cornerstone species, prefer cold water and are the primary food source for aquatic mammals such as the Blue Whale. Alterations to the ocean currents, due to increased freshwater inputs from glacier melt, and the potential alterations to thermohaline circulation of the worlds oceans, may affect existing fisheries upon which humans depend as well.

The white lemuroid possum, only found in the mountain forests of northern Queensland, has been named as the first mammal species to be driven extinct by man-made global warming. The White Possum has not been seen in over three years. These possums cannot survive extended temperatures over °C 30 (°F 86), which occurred in 2005. A final expedition to uncover any surviving White Possums is scheduled for 2009.

Misitu

Pine forests in British Columbia have been devastated by a pine beetle infestation, which has expanded unhindered since 1998 at least in part due to the lack of severe winters since that time; a few days of extreme cold kill most mountain pine beetles and have kept outbreaks in the past naturally contained. The infestation, which (by November 2008) has killed about half of the province's lodgepole pines (33 million acres or 135,000 km²) is an order of magnitude larger than any previously recorded outbreak and passed via unusually strong winds in 2007 over the continental divide to Alberta. An epidemic also started, be it at a lower rate, in 1999 in Colorado, Wyoming, and Montana. The United States forest service predicts that between 2011 and 2013 virtually all acre 5 million (km² 20 000) of Colorado’s lodgepole pine trees over five inches (127 mm) in diameter will be lost.

As the northern forests are a carbon sink, while dead forests are a major carbon source, the loss of such large areas of forest has a positive feedback on global warming. In the worst years, the carbon emission due to beetle infestation of forests in British Columbia alone approaches that of an average year of forest fires in all of Canada or five years worth of emissions from that country's transportation sources .

Besides the immediate ecological and economic impact, the huge dead forests provide a fire risk. Even many healthy forests appear to face an increased risk of forest fires because of warming climates. The 10-year average of boreal forest burned in North America, after several decades of around 10,000 km² (2.5 million acres), has increased steadily since 1970 to more than 28,000 km² (7 million acres) annually.. Though this change may be due in part to changes in forest management practices, in the western U.S., since 1986, longer, warmer summers have resulted in a fourfold increase of major wildfires and a sixfold increase in the area of forest burned, compared to the period from 1970 to 1986. A similar increase in wildfire activity has been reported in Canada from 1920 to 1999.

Forest fires in Indonesia have dramatically increased since 1997 as well. These fires are often actively started to clear forest for agriculture. They can set fire to the large peat bogs in the region and the CO₂ released by these peat bog fires has been estimated, in an average year, to be 15% of the quantity of CO₂ produced by fossil fuel combustion.

Milima

Mountains cover approximately 25 percent of earth's surface and provide a home to more than one-tenth of global human population. Changes in global climate pose a number of potential risks to mountain habitats. Researchers expect that over time, climate change will affect mountain and lowland ecosystems, the frequency and intensity of forest fires, the diversity of wildlife, and the distribution of water.

Studies suggest that a warmer climate in the United States would cause lower-elevation habitats to expand into the higher alpine zone. Such a shift would encroach on the rare alpine meadows and other high-altitude habitats. High-elevation plants and animals have limited space available for new habitat as they move higher on the mountains in order to adapt to long-term changes in regional climate.

Changes in climate will also affect the depth of the mountains snowpacks and glaciers. Any changes in their seasonal melting can have powerful impacts on areas that rely on freshwater runoff from mountains. Rising temperature may cause snow to melt earlier and faster in the spring and shift the timing and distribution of runoff. These changes could affect the availability of freshwater for natural systems and human uses.

Uzalishaji wa Kiikolojia

According to a 2003 paper by Smith and Hitz, it is reasonable to assume that the relationship between increased global mean temperature and ecosystem productivity is parabolic. Higher carbon dioxide concentrations will favourably affect plant growth and demand for water. Higher temperatures could initially be favourable for plant growth. Eventually, increased growth would peak then decline. According to the IPCC report, a global average temperature increase exceeding 1.5-2.5°C (relative to the period 1980-99), would likely have a predominantly negative impact on ecosystem goods and services, e.g., water and food supply. Research done by the Swiss Canopy Crane Project suggests that slow-growing trees only are stimulated in growth for a short period under higher CO₂ levels, while faster growing plants like liana benefit in the long term. In general, but especially in rainforests, this means that liana become the prevalent species; and because they decompose much faster than trees their carbon content is more quickly returned to the atmosphere. Slow growing trees incorporate atmospheric carbon for decades.

Ukosefu wa maji

Tazama pia: Ukosefu wa maji

Sea level rise is projected to increase salt-water intrusion into groundwater in some regions, affecting drinking water and agriculture in coastal zones. Increased evaporation will reduce the effectiveness of reservoirs. Increased extreme weather means more water falls on hardened ground unable to absorb it, leading to flash floods instead of a replenishment of soil moisture or groundwater levels. In some areas, shrinking glaciers threaten the water supply. The continued retreat of glaciers will have a number of different effects. In areas that are heavily dependent on water runoff from glaciers that melt during the warmer summer months, a continuation of the current retreat will eventually deplete the glacial ice and substantially reduce or eliminate runoff. A reduction in runoff will affect the ability to irrigate crops and will reduce summer stream flows necessary to keep dams and reservoirs replenished. This situation is particularly acute for irrigation in South America, where numerous artificial lakes are filled almost exclusively by glacial melt.Kigezo:Ref harv Central Asian countries have also been historically dependent on the seasonal glacier melt water for irrigation and drinking supplies. In Norway, the Alps, and the Pacific Northwest of North America, glacier runoff is important for hydropower. Higher temperatures will also increase the demand for water for the purposes of cooling and hydration.

In the Sahel, there has been an unusually wet period from 1950 until 1970, followed by extremely dry years from 1970 to 1990. From 1990 until 2004 rainfall returned to levels slightly below the 1898–1993 average, but year-to-year variability was high.

Afya

Climate change currently contributes to the burden of disease and premature deaths. Economic development will affect how effective adaptation to climate change will be. According to the IPCC report, it is likely that:

• climate change will bring some benefits, such as reduced cold deaths.
• the balance of positive and negative health impacts will vary from one location to another.
• adverse health impacts will be greatest in low-income countries.
• the negative health impacts of climate change will outweigh the benefits, especially in developing countries. Some examples of negative health impacts include increased malnutrition, increased deaths, disease and injury due to heat waves, floods, storms, fires and droughts, and increased frequency of cardio-respiratory diseases.

According to a 2009 study by UCL academics, climate change and global warming pose the biggest threat to human health in the 21st century.

Athari za moja kwa moja za ongezeko la kipimo cha joto

The most direct effect of climate change on humans might be the impacts of hotter temperatures themselves. Extreme high temperatures increase the number of people who die on a given day for many reasons: people with heart problems are vulnerable because one's cardiovascular system must work harder to keep the body cool during hot weather, heat exhaustion, and some respiratory problems increase. Global warming could mean more cardiovascular diseases, doctors warn. Higher air temperature also increase the concentration of ozone at ground level. In the lower atmosphere, ozone is a harmful pollutant. It damages lung tissues and causes problems for people with asthma and other lung diseases.

Rising temperatures have two opposing direct effects on mortality: higher temperatures in winter reduce deaths from cold; higher temperatures in summer increase heat-related deaths. The net local impact of these two direct effects depends on the current climate in a particular area. Palutikof et al. (1996) calculate that in England and Wales for a 1 °C temperature rise the reduced deaths from cold outweigh the increased deaths from heat, resulting in a reduction in annual average mortality of 7000, while Keatinge et al. (2000) “suggest that any increases in mortality due to increased temperatures would be outweighed by much larger short term declines in cold related mortalities.” Cold-related deaths are far more numerous than heat-related deaths in the United States, Europe, and almost all countries outside the tropics. During 1979–1999, a total of 3,829 deaths in the United States were associated with excessive heat due to weather conditions, while in that same period a total of 13,970 deaths were attributed to hypothermia. In Europe, mean annual heat related mortalities are 304 in North Finland, 445 in Athens, and 40 in London, while cold related mortalities are 2457, 2533, and 3129 respectively. According to Keatinge et al. (2000), “populations in Europe have adjusted successfully to mean summer temperatures ranging from 13.5°C to 24.1°C, and can be expected to adjust to global warming predicted for the next half century with little sustained increase in heat related mortality.”

A government report shows decreased mortality due to recent warming and predicts increased mortality due to future warming in the United Kingdom. The 2003 European heat wave killed 22,000–35,000 people, based on normal mortality rates. Peter A. Stott from the Hadley Centre for Climate Prediction and Research estimated with 90% confidence that past human influence on climate was responsible for at least half the risk of the 2003 European summer heat-wave.

Kuenea kwa magonjwa

Tazama pia: Magonjwa ya kitropiki

Global warming may extend the favourable zones for vectors conveying infectious disease such as dengue fever, West Nile virus, and malaria. In poorer countries, this may simply lead to higher incidence of such diseases. In richer countries, where such diseases have been eliminated or kept in check by vaccination, draining swamps and using pesticides, the consequences may be felt more in economic than health terms. The World Health Organization (WHO) says global warming could lead to a major increase in insect-borne diseases in Britain and Europe, as northern Europe becomes warmer, ticks—which carry encephalitis and lyme disease—and sandflies—which carry visceral leishmaniasis—are likely to move in. However, malaria has always been a common threat in European past, with the last epidemic occurring in the Netherlands during the 1950s. In the United States, Malaria has been endemic in as much as 36 states (including Washington, North Dakota, Michigan and New York) until the 1940s. By 1949, the country was declared free of malaria as a significant public health problem, after more than 4,650,000 house DDT spray applications had been made.

The World Health Organisation estimates 150,000 deaths annually "as a result of climate change", of which half are in the Asia-Pacific region. In April 2008, it reported that, as a result of increased temperatures, the number of malaria infections is expected to increase in the highland areas of Papua New Guinea.

Watoto

In 2007, the American Academy of Pediatrics issued the policy statement Global Climate Change and Children's Health:

Anticipated direct health consequences of climate change include injury and death from extreme weather events and natural disasters, increases in climate-sensitive infectious diseases, increases in air pollution–related illness, and more heat-related, potentially fatal, illness. Within all of these categories, children have increased vulnerability compared with other groups.

On 2008-04-29, a UNICEF UK Report found that global warming is already reducing the quality of the world's most vulnerable children's lives and making it more difficult to meet the UN Millennium Development Goals. Global warming will reduce access to clean water and food supplies, particularly in Africa and Asia. Disasters, violence and disease are expected to be more frequent and intense, making the future of the world's poorest children more bleak.

Usalama

Tazama pia: Bodi ya Ushauri ya Kiserikali

The Military Advisory Board, a panel of retired U.S. generals and admirals released a report entitled "National Security and the Threat of Climate Change." The report predicts that global warming will have security implications, in particular serving as a "threat multiplier" in already volatile regions. Britain's Foreign Secretary Margaret Beckett argues that “An unstable climate will exacerbate some of the core drivers of conflict, such as migratory pressures and competition for resources.” And several weeks earlier, U.S. Senators Chuck Hagel (R-NB) and Richard Durbin (D-IL) introduced a bill in the U.S. Congress that would require federal intelligence agencies to collaborate on a National Intelligence Estimate to evaluate the security challenges presented by climate change.

In November 2007, two Washington think tanks, the established Center for Strategic and International Studies and the newer Center for a New American Security, published a report analysing the worldwide security implications of three different global warming scenarios. The report considers three different scenarios, two over a roughly 30 year perspective and one covering the time up to 2100. Its general results conclude that flooding "...has the potential to challenge regional and even national identities. Armed conflict between nations over resources, such as the Nile and its tributaries, is likely..." and that "Perhaps the most worrisome problems associated with rising temperatures and sea levels are from large-scale migrations of people -- both inside nations and across existing national borders."

A 2009 study questions the assumption that rising temperatures and violence are linked. Richard Tol and Sebastian Wagner collected data on climate and conflict in Europe between the years 1000 and 2000. They concluded that until the mid-18th century, there was a significant negative correlation between the number of conflicts and average temperature, but after that no statistically meaningful relationship can be observed. Tol and Wagner argue that the relationship between warfare and colder weather disappears around the time of the industrial revolution, when agriculture and transport improve dramatically. The Economist suggests that the lesson of their research is that climate-induced conflict can be minimised by continuing the process of crop improvement.

See also

Jumla Athari kwa ustaarbau, nibadamu na Dunia Tathmini ya Watu wa Kiasili Indigenous Peoples Climate Change Assessment Initiative Kikanda Tathmini ya Athari ya Mabadiliko ya Hali ya Angakatika eneo la Aktiki Madhara ya ongezeko la joto Duniani nchini Australia Kivalina dhidi ya shirika la ExxonMobil Corp., na wengineo. Tathmini ya Kitaifa ya Kubadilika kwa Hali ya Anga (Marekani)

Sayansi Pampu ya Kibaiolojia Oceanic anoxic event PRECIS (Providing Regional Climates for Impacts Studies) Solubility pump

External links

• Ecological Impacts of Climate Change - National Academy of Sciences
• EPA: Health and Environmental Effects of Global Warming
• What climate change does - IRIN
• How climate change works - IRIN
• Gathering Storm - the humanitarian impact of climate change - IRIN
• The Impacts of Global Warming and Climate Change from The Nature Conservancy
• "Anthropogenic Effects on Tropical Cyclone Activity" (Kerry Emanuel)
• "The Climate of Man", The New Yorker (2005): Part 1, Part 2, Part 3
• American Meteorological Society's Environmental Science Seminar Series (Oct 2005): "Hurricanes: Are They Changing and Are We Adequately Prepared for the Future?"
  • "How are hurricanes changing with global warming?" (Kevin E. Trenberth)
  • "Changes in hurricane intensity in a warming environment" (Judith Curry)
  • "Hurricanes and Climate" (Kerry Emanuel)
• Oliver James, The Guardian, June 30, 2005 Face the facts: For many people climate change is too depressing to think about, and some prefer to simply pretend it doesn't exist
• Mark Lynas, The Guardian, March 31, 2004, "Vanishing worlds" Story about a vanishing Peruvian glacier
• See the impacts of climate change happening now on three Australian ecosystems: 'Tipping Point', Catalyst, ABC-TV
• Effects of global warming on skiing
• Elevated levels of atmospheric CO₂ decrease the nutritional value of plants
• Royal Society, June 30, 2005, "Ocean acidification due to increasing atmospheric carbon dioxide"
• Time Magazine's "Global Warming: The Culprit?" (Time Magazine, October 3, 2005, pages 42–46)
• Glaciers Not On Simple, Upward Trend Of Melting sciencedaily.com, Feb. 21, 2007 "Two of Greenland's largest glaciers (Kangerdlugssuaq and Helheim) shrank dramatically ... between 2004 and 2005. And then, less than two years later, they returned to near their previous rates of discharge.
• Climate Change: Coral Reefs on the Edge An online video presentation by Prof. Ove Hoegh-Guldberg, University of Auckland