Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Climate Change impacts for emission paths that peak and decline Authors: Chris Hope, Judge Business School, University of Cambridge Rachel Warren, Tyndall Centre, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ Jason Lowe, MetOffice Hadley Centre (Reading Unit), Department of Meteorology, University of Reading, Reading, RG6 6BB and the AVOID WS1 Team AVOID is funded by the Department of Energy and Climate Change and the Department for Environment, Food and Rural Affairs The Scenarios • Emission scenarios: varied year in which emissions peak globally, the rate of emission reduction (R), and the minimum level to which emissions are eventually reduced (H or L). • Focused on 2015-2044 (centred on 2030) 2035-2064 (centred on 2050) 2070-2099 (centred on 2085) Scenarios: A1B, and policy scenarios • 2030.R2.H, 2030.R5.L, • 2016.R2.H, 2016.R4.L and 2016.R.Low Percentage Emission Changes Relative to 1990 in the reference and policy scenarios Percentage change in emissions of CO2 equivalents relative to 1990 150% 100% A1B Hadley 2030.R2.High 2030.R5.Low 50% 0% 2000 2016.R2.High 2016.R4.Low 2050 -50% -100% Year 2100 2016.R5.Low Temperature implications: Jason Lowe’s analysis showed that … Probability Year … A1B 2016.R 2030.R (2%H, 4%L, 5%L) (2%H, 5%L) of remaining below 2 degrees 2100 1% 30, 43, 45% 7, 17% of remaining below 3 degrees 2100 1% 87, 91, 91% 63, 76% of remaining below 4 degrees 2100 46% 98, 99, 99% 93, 96% Temperature implications Jason Lowe’s work told us: • Under A1B temperatures are likely to reach 34C • 2030 peaking insufficient for 2C and have chance of 1 in 3 to 4 of exceeding 3C • 2016 targets effective at avoiding 3C, chance of exceeding falls to 1 in 10 • Only most stringent R=5% 2016 scenario has 45% chance to meet 2C target • All avoid temperatures reaching 4 degrees with high confidence (>=98%) except for 2030 2% L which leaves a 7% chance of more than 4C. The earlier the peak in emissions, the greater the avoided impacts % of impacts avoided % of impacts avoided 80 70 60 50 40 30 20 10 2016-5-L Cooling requirements Soybean productivity Decreased crop suitability Coastal mangrove Coastal flood risk Fluvial flood risk Increased water scarcity 0 2030-5-L AVOID is funded by the Department of Energy and Climate Change and the Department for Environment, Food and Rural Affairs The earlier the peak in emissions, the greater the avoided impacts % change in flood risk Change in fluvial flood risk 300 250 200 150 100 50 0 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 Year A1b 2016-2-H 2030-5-L 2030-2-H 2016-4-L 2016-5-L 2100 5000.0% 4000.0% 3000.0% 10th percentile 50th percentile 2000.0% 90th percentile 1000.0% o m iti ga tio n 20 20 50 16 R 20 20 50 30 N o R m 20 iti ga 50 tio n 21 20 00 16 R 21 20 00 30 R 21 00 0.0% N Flooding increase Global coastal flood plain population in the 2020s, 2050s and 2080s under the different sea-level rise scenarios Net global losses of saltmarsh by the 2080s due to sea-level rise, including uncertainty Saltmarsh loss 50.0% 40.0% 30.0% 10th percentile 50th percentile 90th percentile 20.0% 10.0% 0.0% No mitigation 2016.R 2030.R Key message: Date at which emissions peak critical • Example: water stress: by the 2080s, the 2016R scenarios remove 38-41% of the increases in water stress forcecast under A1B (HadCM3 50% outcome) whereas the 2030R scenarios remove only 33%. • Example, coastal zone: avoided impacts in terms of people experiencing coastal flooding are large, about 43% by the 2080s in the 2016.R scenarios, where in the 2030.R scenarios it is 30%. • Example, biodiversity: 55-77% of climate change induced extinction risks in European plants avoided in 2016R scenarios compared to 44% under 2030.R Date at which emissions peak critical • Avoided impacts resulting from reducing emissions from A1B scenario to 2016R scenarios are greater than for the 2030R scenarios • …in all three of the sectors: water stress, coasts, biodiversity • Hence date at which emissions peak is more important than the rate of subsequent emissions reduction in determining the avoided impacts Scope of the PAGE2002 model • The major greenhouse gases. • Economic, non-economic and catastrophic impacts. • Time horizon of 2200. • Probabilistic calculations •Eight world regions Inputs to PAGE model • Emissions of greenhouse gases • Atmospheric residence time of greenhouse gases • Sensitivity of the climate system • Cooling effect of sulphates • Impacts as a function of temperature change Inputs to the PAGE2002 model • Discount rates and equity weights: • The Stern runs used a ptp rate of 0.1% per year and an EMUC of 1. Gives a mean discount rate of about 1.5% per year, varying over time and across regions. • The AVOID runs used triangular distributions for both. ptp rate of <0.1,1,2> % per year. EMUC of <0.5,1,2>. Gives a mean discount rate of about 3% per year Structure of the PAGE2002 model Select an abatement and adaptation policy Global and regional temperature Impacts Costs of abatement Costs of adaptation Costs The earlier the peak in emissions, the greater the avoided impacts Equity-weighted Global Impacts (year 2000) trillion US$ Economic benefits of avoided impacts PAGE 2002 A1B 35 30 25 20 15 10 5 0 20 0 2 2016r2high 2030r2high 40 0 2 60 0 2 Year 80 0 2 00 1 2 PAGE-valued equity-weighted impacts under the AVOID policy scenarios compared to the SRES reference scenario A1B A1B 9.00E+07 A1B 5% 8.00E+07 A1B 95% 2016r2high Equity-weighted Global Impacts (year 2000) million US$ 7.00E+07 2016r2high 5% 6.00E+07 2016r2high 95% 2016r4low 5.00E+07 2016r4low 5% 4.00E+07 2016r4low 95% 2016r5low 3.00E+07 2016r5low 5% 2.00E+07 2016r5low 95% 2030r2high 1.00E+07 2030r2high 5% 0.00E+00 20 0 2 2030r2high 95% 40 0 2 60 0 2 Year 80 0 2 00 1 2 2030r5low 2030r5low 5% 2030r5low 95% Economic evidence: Date at which emissions peak critical • PAGE also confirms that the date at which global emissions peak is a stronger driver of avoided impacts than is the rate at which emissions are subsequently reduced • A1B: equity weighted climate change impacts reach ~$32 trillion year 2000 US$ (range 29-83 trillion $$) or ~4% of global GDP by 2100 (1-12%) • By 2100 policy scenarios in which emissions peak in 2016 avoid ~ 20 trillion (19-19.7 across scenarios) US2000$. (The 5-95% range is 4.6-54 trillion) compared to A1B. • i.e. 2.6-2.7% of 2100 GDP (range 0.6-7.4%GDP). Thus two thirds of impacts may be avoided. • By 2100 policy scenarios in which emissions peak in 2030 avoid ~15 trillion (14-16) US2000$ (3.5--45 trillion) compared to the A1B • i.e. 2.0-2.2% of year 2100 GDP (range 0.5-6.1). Thus half of the impacts may be avoided. CONCLUSION • Date at which emissions peak is more important than the rate of subsequent emissions reduction in determining the avoided impacts • Demonstrated with INDEPENDENT economic and physically based impacts analyses AVOID is funded by the Department of Energy and Climate Change and the Department for Environment, Food and Rural Affairs