Turn Down The Heat: Why a 4C Warmer World Must Be Avoided

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Bill Hare, CEO of Climate Analytics, summarises the World Bank report Turn Down The Heat: Why a 4C Warmer World Must Be Avoided for The Climate Institute's Boardroom Lunch Conversation on 21 October …

Bill Hare, CEO of Climate Analytics, summarises the World Bank report Turn Down The Heat: Why a 4C Warmer World Must Be Avoided for The Climate Institute's Boardroom Lunch Conversation on 21 October 2013.

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  • Schellnhuber et al., 2012 „Turn Down the Heat: Why a 4°C Warmer World Must be Avoided “, A Report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics, 119 ppThis report provides a snapshot of recent scientific literature and new analyses of likely impacts and risks that would be associated with a 4° Celsius warming within this century. It is a rigorous attempt to outline a range of risks, focusing on developing countries and especially the poor. A 4°C world would be one of unprecedented heat waves, severe drought, and major floods in many regions, with serious impacts on ecosystems and associated services. But with action, a 4°C world can be avoided and we can likely hold warming below 2°C.
  • Schellnhuber et al., 2012 „Turn Down the Heat: Why a 4°C Warmer World Must be Avoided “, A Report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics, 119 ppThis report provides a snapshot of recent scientific literature and new analyses of likely impacts and risks that would be associated with a 4° Celsius warming within this century. It is a rigorous attempt to outline a range of risks, focusing on developing countries and especially the poor. A 4°C world would be one of unprecedented heat waves, severe drought, and major floods in many regions, with serious impacts on ecosystems and associated services. But with action, a 4°C world can be avoided and we can likely hold warming below 2°C.
  • Whentheobserveddataareadjustedtoremovetheestimatedimpactofknownfactorson short-term temperaturevariations (ElNiño/southern oscillation, volcanicaerosolsand solar variability), the global warmingsignalbecomesevenmore evident asnoiseisreduced.IPCC projectionsare in linewiththeadjustedtemperaturesobservations.Comparingclimateprojectionstoobservationsupto 2011Environ. Res. Lett. 7 (2012) 044035 (5pp)Stefan Rahmstorf, Grant Foster and Anny Cazenavehttp://iopscience.iop.org/1748-9326/7/4/044035/pdf/1748-9326_7_4_044035.pdfAbstractWeanalyse global temperatureandsea-level dataforthepastfewdecadesandcomparethemtoprojectionspublished in thethirdandfourthassessmentreportsoftheIntergovernmental Panel on Climate Change (IPCC). The resultsshowthat global temperaturecontinuestoincrease in goodagreementwiththebestestimatesofthe IPCC, especiallyifweaccountfortheeffectsofshort-term variability due totheElNi˜no/Southern Oscillation, volcanicactivityand solar variability. The rate ofsea-level riseofthepastfewdecades, on theotherhand, isgreaterthanprojectedbythe IPCC models. This suggeststhat IPCC sea-level projectionsforthefuturemay also bebiasedlow.Figurecaptions:Fig.1:Sealevelmeasuredbysatellitealtimeter (redwith linear trendline; AVISO datafrom (Centre National d’EtudesSpatiales) andreconstructedfromtidegauges (orange, monthlydatafrom Church and White (2011)). Tide gaugedatawerealignedtogivethe same meanduring 1993–2010 asthealtimeterdata. The scenariosofthe IPCC areagainshown in blue (thirdassessment) andgreen (fourthassessment); theformerhavebeenpublishedstarting in theyear 1990 andthelatterfrom 2000.Fig.2:Figure 3. Rate ofsea-level rise in pastandfuture. Orange line, based on monthlytidegaugedatafrom Church and White (2011). The redsymbolwitherrorbarsshowsthesatellitealtimetertrendof 3.2 ± 0.5 mm yr−1 during 1993–2011; thisperiodistooshorttodeterminemeaningfulchanges in the rate ofrise. Blue/greenlinegroupsshowthelow, midand high projectionsofthe IPCC fourthassessmentreport, eachforsixemissionsscenarios. Curvesaresmoothedwith a singularspectrumfilter (ssatrend; Moore et al 2005) of 10 years half-width.
  • FifthAssessment Report (2013):likely in the range 1.5°C to 4.5°C (high confidence)extremely unlikely less than 1°C (high confidence)very unlikely greater than 6°C (medium confidence)
  • FifthAssessment Report (2013):likely in the range 1.5°C to 4.5°C (high confidence)extremely unlikely less than 1°C (high confidence)very unlikely greater than 6°C (medium confidence)
  • Global surface temperature change for the end of the 21st century is likely to exceed 1.5°C relative to 1850 to 1900 for all RCP scenarios except RCP2.6. Warming will continue beyond 2100 under all RCP scenarios except RCP2.6Unlikely to exceed 2°C for RCP2.6 (medium confidence). Warming as likely as not to exceed 4°C for highest of new IPCC scenarios (RCP8.5) (medium confidence). {12.4} by 2080-2100 averageSince rate of warming by that time is over 0.5°C/decade and percentage probability for >4°C is already 62% for 2081-2100 obviously by 2100 exceeding 4°C is likely and grows to very likely past 2100 ...For emissions-driven runs uncertainty range of warming is bigger and median warming higher due to C-cycle feedbacks (2.6-4.7°C for concentration-driven and 2.5-5.6°C for emissions-driven runs 2081-2100 above 1986-2005).
  • Global mean sea level will continue to rise during the 21st centuryUnder all RCP scenarios the rate of sea level rise will very likely exceed that observed during 1971–2010 due to increased ocean warming and increased loss of mass from glaciers and ice sheetsFor RCP8.5 the rise by the year 2100 is 0.52 to 0.98mRate of rise during 2081–2100 of 8 to 16 mm/yrFor RCP2.6sea level rise for 2081−2100 likely in the range of 0.26 to 0.55mRelative to 1986–2005
  • Uncertainty still considerableFor highest scenario RCP8.5 sea-level rise is 0.5-1 m by 2100High end of uncertainty is hard to establish:“… it has been concluded that there is currently insufficient evidence to evaluate the probability of specific levels above the assessed likely range” (IPCC AR5 WG1 SPM)Observations show that Antarctica mass loss is accelerating, equivalent to 0.1 mm/yr of SLR over 1992-2001, to 0.4 mm/yr over 2002-2011. However, AR5 projections assume zero contribution from AntarcticaA “… collapse of marine-based sectors of the Antarctic ice sheet, if initiated, could cause global mean sea level to rise substantially above the likely range … this additional contribution would not exceed several tenths of a meter of sea level rise during the 21st century” (IPCC AR5 WG1 SPM)
  • Rahmstorf et al (2012) “Comparing climate projections to observations up to 2011”, Environ. Res. Lett. 7 (2012) 044035 (5pp)Figure 2. Sea level measured by satellite altimeter (red with lineartrend line; AVISO data from (Centre National d’EtudesSpatiales)and reconstructed from tide gauges (orange, monthly data fromChurch and White (2011)). Tide gauge data were aligned to give thesame mean during 1993–2010 as the altimeter data. The scenariosof the IPCC are again shown in blue (third assessment) and green(fourth assessment); the former have been published starting in theyear 1990 and the latter from 2000.Abstract We analyse global temperature and sea-level data for the past few decades and compare themto projections published in the third and fourth assessment reports of the IntergovernmentalPanel on Climate Change (IPCC). The results show that global temperature continues toincrease in good agreement with the best estimates of the IPCC, especially if we account forthe effects of short-term variability due to the El Ni˜no/Southern Oscillation, volcanic activityand solar variability. The rate of sea-level rise of the past few decades, on the other hand, isgreater than projected by the IPCC models. This suggests that IPCC sea-level projections forthe future may also be biased low.
  • Schellnhuber et al., 2012 „Turn Down the Heat: Why a 4°C Warmer World Must be Avoided “, A Report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics, 119 ppThis report provides a snapshot of recent scientific literature and new analyses of likely impacts and risks that would be associated with a 4° Celsius warming within this century. It is a rigorous attempt to outline a range of risks, focusing on developing countries and especially the poor. A 4°C world would be one of unprecedented heat waves, severe drought, and major floods in many regions, with serious impacts on ecosystems and associated services. But with action, a 4°C world can be avoided and we can likely hold warming below 2°C.
  • Schellnhuber et al., 2012 „Turn Down the Heat: Why a 4°C Warmer World Must be Avoided “, A Report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics, 119 ppThis report provides a snapshot of recent scientific literature and new analyses of likely impacts and risks that would be associated with a 4° Celsius warming within this century. It is a rigorous attempt to outline a range of risks, focusing on developing countries and especially the poor. A 4°C world would be one of unprecedented heat waves, severe drought, and major floods in many regions, with serious impacts on ecosystems and associated services. But with action, a 4°C world can be avoided and we can likely hold warming below 2°C.
  • Schellnhuber et al., 2012 „Turn Down the Heat: Why a 4°C Warmer World Must be Avoided “, A Report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics, 119 ppThis report provides a snapshot of recent scientific literature and new analyses of likely impacts and risks that would be associated with a 4° Celsius warming within this century. It is a rigorous attempt to outline a range of risks, focusing on developing countries and especially the poor. A 4°C world would be one of unprecedented heat waves, severe drought, and major floods in many regions, with serious impacts on ecosystems and associated services. But with action, a 4°C world can be avoided and we can likely hold warming below 2°C.
  • Nelson, G. C., Rosegrant, M. W., Koo, J., Robertson, R., Sulser, T., Zhu, T., … Lee, D. (2010). The Costs of Agricultural Adaptation to Climate Change.Objective showing that 8.5% decrease in total production will have detrimental consequences for per capita calories availabilityFor per capita availability, population projections used for the calculation are below UN projections (1.7 against 1.9).Per capita availability decreases steeply due to a global decrease in food production by the 2050s when global temperature is 2 degrees above pre-industrial levelIf African population was to remain constant between 2010 and 2050, per capita kcal availability would be between 2 and 3 times higher
  • Awp Assets wealth householdsAbp  Assets bottom (poor) householdsHouseholds driven into poverty traps do not have the capacity to cope and recover Carter, M. R., Little, P. D., Mogues, T., & Negatu, W. (2007). Poverty Traps and Natural Disasters in Ethiopia and Honduras. World Development, 35(5), 835–856. doi:10.1016/j.worlddev.2006.09.010Hallegatte, S., & Przyluski, V. (2010). The Economics of Natural Disasters Concepts and Methods. Washington, DC.
  • Schellnhuber et al., 2012 „Turn Down the Heat: Why a 4°C Warmer World Must be Avoided “, A Report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics, 119 ppThis report provides a snapshot of recent scientific literature and new analyses of likely impacts and risks that would be associated with a 4° Celsius warming within this century. It is a rigorous attempt to outline a range of risks, focusing on developing countries and especially the poor. A 4°C world would be one of unprecedented heat waves, severe drought, and major floods in many regions, with serious impacts on ecosystems and associated services. But with action, a 4°C world can be avoided and we can likely hold warming below 2°C.
  • Global mean surface warming above 2°C under RCP2.6 is unlikely (medium confidence). Global mean surface warming above 4°C by 2081–2100 is unlikely in all RCPs (high confidence) except for RCP8.5 where it is as likely as not (medium confidence). Global warming reaches 0.6°C [0.0 to 1.2°C] under the RCP2.6 extension where sustained negative emissions lead to a further decrease in radiative forcing, reaching values below present-day radiative forcing by 2300. See  For RCP2.6, the models project an average 50% (range 14– 96%) emission reduction by 2050 relative to 1990 levels. It is about as likely as not that sustained globally negative emissions will be required to achieve the reductions in atmospheric CO2 in RCP2.6 

Transcript

  • 1. Turn Down The Heat: Why a 4oC World Must Be Avoided Bill Hare, CEO, Climate Analytics gGmbH, Berlin The Climate Institute Boardroom Lunch Conversation Monday 21 October 2013
  • 2. 3
  • 3. 4°C – World Bank Report • Observed • Ten times more area experiences extreme heat compared to 40 years ago • Significant economic damages on the poorest countries from high temperatures over last few decades • Rate of sea level rise now well above range projected in IPCC AR4 and TAR assessment reports • Regional sea-level rise since 1950s higher than the global mean in Pacific
  • 4. IPCC AR5: Greater evidence of human influence since IPCC AR4 in 2007 • Extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. • The evidence for human influence has grown since AR4. 5
  • 5. Consistent global warming in line with IPCC projections (Rahmstorf et al., 2012)
  • 6. IPCC AR5: Has the warming slowed down? • Observations show slower rate of warming over the past 10-15 year, but… – Past decade: warmest on record – Last three decades each warmer than the other and warmer than any since 1850. • IPCC WGI findings repudiate claims of climate science denialists that recent reduction in rate of warming undermines climate science 7
  • 7. AR5: Recent warming ”slowdown” or “hiatus” • Past decade: warmest on record • Periods of slowdowns and accelerations occur regularly • These are related to variations in forcing (e.g. volcanic eruptions, solar activity) and to internal redistribution of heat in ocean, causing natural variations of surface warming, and Global Average surface temperature (°C) compared to average over 1850-2012 8
  • 8. Ocean warming has continued over past 10-15 years Change in global average upper ocean heat content (1022 J) 9
  • 9. IPCC AR5: How warm will it get? • Likely to exceed 1.5°C (and 2°C) for all new IPCC scenarios except the lowest (called RCP2.6) • Warming will continue beyond 2100 under all RCP scenarios except RCP2.6 • Warming likely to exceed 4°C by 2100 for highest of new IPCC scenarios (RCP8.5) • If carbon cycle feedbacks include range of warming is higher • 2.5-5.6°C in 2081-2100 above 1986-2005 or 3.1-6.2°C above pre-industrial 10
  • 10. Heading towards 4oC • Recent greenhouse gas emission trends and recent emission projections imply higher 21st century emission levels – International Energy Agency’s 2012 assessment indicated that in the absence of further mitigation action there is a 40% chance of warming exceeding 4°C by 2100. • a 10% chance of exceeding 5°C 11
  • 11. IPCC AR5: Sea level rise • Global mean sea level will continue to rise during the 21st century – Under all RCP scenarios the rate of sea level rise will very likely exceed that observed during 1971–2010 – 0.5 to 1m rise by 2100 projected for highest IPCC scenario (RCP8.5) • Rate of rise during 2081–2100 of 8 to 16 mm/yr – 0.26 to 0.55m rise by 2100 projected for lowest IPCC scenario (RCP2.6) • Relative to 1986–2005 12
  • 12. Caution: Sea-level rise risk • Uncertainty still considerable • High end of uncertainty is hard to establish as recognised in AR5: – “… it has been concluded that there is currently insufficient evidence to evaluate the probability of specific levels above the assessed likely range. ” (IPCC AR5 WG1 SPM) • Within a 2000 year timeframe about 2.3m of sea level rise per oC of global warming can be expected.
  • 13. Observed sea level change at top of range projected in IPCC assessment reports
  • 14. 4°C – World Bank Report • Projected (World Bank: 4°C report) • Warming >3°C by 2100 and possibly >4°C by 2100 • One in five chance with present pledges of above 4°C • One metre of sea level rise by 2100 • Further rise of several metres in following centuries • Regional sea-level rise about 20% larger in tropical oceans than global mean
  • 15. 4°C – World Bank Report • Warming more pronounced over land • Regional projections >6°C in Africa, the Middle East, & Amazon) • Warming of 2+°C projected to lead to severe and widespread droughts over many densely populated areas • e.g. Europe, eastern USA, South East Asia, and Brazil • Ocean acidification rises to levels higher than known from Earth history leading to major damages to ocean food production
  • 16. Reducing ocean acidification damages Mitigation
  • 17. 4°C – World Bank Report • Dramatic increase in intensity and frequency of high-temperature extremes • All tropical islands in the Pacific, tropical South America, central Africa likely to regularly experience heat waves of unprecedented magnitude and duration. • Coolest summer months in 2080–2100 in most continental regions substantially hotter than the warmest experience today
  • 18. 4°C – World Bank Report Societal and ecosystem impacts: Poor affected most • Sea-level rise potentially severe for small island states and cities highly vulnerable to extreme flooding • Water scarcity substantially amplified – (particularly Northern & Eastern Africa, Middle East, & South Asia) • Significant risk for global food security: • large negative crop yield impacts anticipated in India, Africa, but also United States & Australia
  • 19. 4°C – World Bank Report • Societal and ecosystem impacts: – Ocean acidification and warming leads to regional extinction of entire coral reef ecosystems: • impacts on coastal and fishing communities and tourism – Likely large-scale biodiversity loss: dramatic reduction in ecosystem services.
  • 20. Rapidly emerging risks • Disruption of ocean and ecosystems due to warming and ocean acidification – Interfering with global ocean production and damaging marine ecosystems. • By 2100 surface waters of the ocean could be nearly 150 percent more acidic, resulting in a pH that the oceans haven’t experienced for more than 20 million years. – Already being observed • Observed reduction in the habitat for tropical pelagic fishes (e.g tuna). – Reductions in oceanic food production could have very negative consequences for food security.
  • 21. Rapidly emerging risks • Collapse of coral reef systems in the next several decades. – Combined effects of ocean warming and acidification – Limiting warming to 1.5oC may not be sufficient to protect majority of reefs – Substantial losses of coral reefs for 1.5-2°C from both heat and ocean acidification effects, with a majority coral systems no longer viable at current locations • Most coral reefs appear unlikely to survive by the time 4°C warming is reached.
  • 22. Probability of severe bleaching during a given year increase rapidly with warming 1.6oC and ca 450 ppm CO2 2.3oC and ca 550 ppm CO2 Meissner, K. J., T. Lippmann and A. Sen Gupta (2012). "Large-scale stress factors affecting coral reefs: open ocean sea surface temperature and surface seawater aragonite saturation over the next 400 years." Coral Reefs 31: 309-319.
  • 23. Small Island States • Combined effects of sea level rise and other climate changes likely to have far ranging adverse consequences with increasing loss and damages – Loss of shoreline, saltwater intrusion and inundation of settled and agricultural areas and impacts on infrastructure. – Increased vulnerability to diseases – Economic decline due to loss of tourism assets, population displacement and decreased agricultural productivity
  • 24. Results from World Bank Study of three regions 25
  • 25. Key Findings Across the Regions • Unusual and unprecedented heat extremes projected to increase substantially, with adverse effects on humans and ecosystems • Water availability expected to decline by 20% for many regions under a 2°C warming and 50% under a 4°C warming • Agricultural yield and nutritional quality projected to decrease in the three regions studied under a 1.5-2°C world, with negative influences on economic growth and poverty eradication
  • 26. % of GLOBAL land area with heat extremes in the summer months Rapid rise between 2030s (around 1.5°C) and 2040s (around 2°C) but large further increase towards 4°C Multi-model mean (thick line), individual models (thin lines) above (JJA) RCP2.6 (left) and RCP8.5 (right).
  • 27. Key Findings Across the Regions • Terrestrial ecosystems: warming to shift systems, alter species composition leading to extinction – Savanna ecosystems particularly exposed as early as the 2030s • Sea-level rise: more rapid than previously projected – 50 cm by the 2050s may be unavoidable (results of past emissions). – Limiting warming to 2°C may limit global rise to about 70-100cm by 2100. – Higher Sea-level rise near Equator in combination with storm surges and tropical cyclones will increase risks
  • 28. Agricultural and Nutritional Quality • Crop production systems under increasing pressure to meet growing global demand. • Significant crop yield impacts already being felt at +0.8 °C warming. • Higher atmospheric levels of CO2 could result in lower protein levels of some grain crops. • Warming above 1.5-2°C increases risk of reduced crop yields and production losses in Sub-Saharan Africa and South Asia. • Likely strong, adverse repercussions on food security and negative influence on economic growth and poverty reduction in impacted regions. 29
  • 29. Food security threatened: Severe decrease in per capita calories availability 3,000 -21,4% Production in 000,000 tons Per capita calories availability 2,500 2,000 2010 1,500 2050 (no climate change) 2050 (with climate change) 1,000 500 Only -8.5% Total production (000,000 tons) Per capita availability (kcal/cap/year) for 2050 projected population 30
  • 30. Development Implications • Sub-Saharan Africa´s food production systems are increasingly at risk – Significant yield reductions under 2°C warming, strong adverse repercussions on food security • South East Asian rural livelihoods are faced with mounting pressures as sea levels rise and important marine ecosystem services lost. • South Asian populations exposed to increasing risks – Disturbances to the monsoon system and rising peak temperatures put water and food resources at severe risk. – In deltaic areas, populations exposed to multiple threats of increasing tropical cyclone intensity, sea-level rise, heat extremes and extreme precipitation. – Multiple impacts can have severe negative implications for poverty eradication in the region. 31
  • 31. Climate shocks roll back development • Climate shocks (for example droughts or cyclones) have the potential to drive poor households into poverty traps – Wealthy households - with higher coping capacity (access to funding, education, or networks) - projected to recover faster • Climate shocks could potentially increase social inequalities and roll back development progress • Assessing socioeconomic and climate vulnerabilities is crucial for successful adaptation 32
  • 32. 4°C – World Bank Report Conclusions: • No certainty that adaptation to a 4°C world is possible • Warming of 4°C can still be avoided: studies show technically and economically feasible pathways to hold warming likely below 2°C.
  • 33. Urgency of mitigation • UNEP 2012: – Current pledges when projected into the future lead to 3 to 5°C warming • World Energy Outlook 2012: – Full lock-in of CO2 emitting infrastructure allowed for 2°C (450ppm) pathway by 2017
  • 34. Is below 2°C feasible? • Emissions reductions in 2020 for a 2°C and 1.5°C pathway are similar but diverge rapidly afterwards. • Closing the 2020 emissions gap entirely remains technically and economically feasible – Can only be achieved by increasing ambition and action beyond the current pledges
  • 35. Can warming be limited below 1.5oC? • Lowest of the WGI scenarios (RCP2.6) indicates global warming can be limited below 1.5°C above pre-industrial levels – Emission reduction by 2050 of average 50% (range 14– 96%) relative to 1990 levels needed (RCP2.6) • Negative emissions may be required after 2050 – “As likely as not that sustained globally negative emissions will be required to achieve the reductions in atmospheric CO2 in RCP2.6” 36
  • 36. Why are 2020 emission levels important? UNEP Emissions Gap Report 2012 • Gap between emissions pledges and pathways towards 1.5 and 2°C increased since last year by 2 GtCO2e, • Emissions need to be reduced by about 15% from present levels by 2020 to be in line with 1.5 or 2°C. • If emissions too high in 2020 it becomes very costly and possibly infeasible to meet the warming goals.
  • 37. Delay possible? All "later action" pathways indicate urgency • Studies looking at returning below 1.5°C do not indicate the luxury of delay • “Later action" comes at the expense of – Higher overall costs – Higher technological dependency – Pressure on future policy requirements and societal choices – Higher climatic risks • For 1.5°C, immediate action and energy efficiency are key.
  • 38. Australian climate policy in context http://www.climateactiontracker.org/
  • 39. Conclusions • Science shows that failure to reduce CO2 emissions leads into very high-risk territory: – High potential for societal disruptions – Rapidly increasing risk of crossing tipping points in physical, biological and human syste,s – Will lead us to climate regimes not experienced in human history – Knowledge about the precise impacts and risks at high levels of warming is very incomplete – Risks rise rapidly with warming 40
  • 40. Climate Analytics Science based policy to prevent dangerous climate change Mission: Synthesize and advance scientific knowledge in the area of climate change and on this basis provide support and capacity building to stakeholders. By linking scientific and policy analysis, we provide state-of-the art solutions to global and national climate change policy challenges. 41
  • 41. Additional slides 42