WHAT WOULD BE THE IMPACTS OF CLIMATE CHANGE ASSUMING NO, OR SOME, OR MUCH EMISSIONS CONTROL AND SEQUESTRATION? Martin parry Co-Chair, Working Group II, IPCC

Global mean temperature predictions Ensembles of four predictions of global mean temperature resulting from business as usual changes in greenhouse gases following on from observed changes since 1860 (orange curves). The addition of sulphate aerosol cooling is shown in the red curves. Hadley Centre for Climate Prediction and Research

Global mean precipitation predictions Ensembles of four predictions of precipitation (rainfall and snowfall) resulting from business as usual changes in greenhouse gases following on from observed changes since 1860 (blue curves). The addition of sulphate aerosol cooling is shown in the green curves. Hadley Centre for Climate Prediction and Research

Change in annual temperatures for the 2050s The change in annual temperatures for the 2050s compared with the present day, when the climate model is driven with an increase in greenhouse gas concentrations equivalent to about a 1% increase per year in CO 2. The picture shows the average of four model runs with different starting conditions. Hadley Centre for Climate Prediction and Research

Observed change in annual precipitation for the 2050s The change in annual precipitation for the 2050s compared with the present day, when the climate model is driven with an increase in greenhouse gas concentrations equivalent to about a 1% increase per year in CO 2. The picture shows the average of four model runs with different starting conditions. Hadley Centre for Climate Prediction and Research

IMPACTS UNDER NO MITIGATION

Annual runoff Percentage change in 30-year average annual runoff by the 2080s. Percentage change in 30-year average annual runoff by the 2080s. University of Southampton

Population under extreme water stress Change, due to climate change, in the number of people living in countries with extreme water stress s 2050s 2080s Population (millions) University of Southampton

Crop yield change 2020s, ) 2050s,2080s

2020s2050s2080s % change in prices from 1990 baseline – s2080s2020s2080s s Cereal production (mmt) Reference scenario Climate change scenario 2020s2050s2080s Additional millions of people at risk of hunger Additional people at risk of hunger under the climate change scenario (0 = Projected reference case). Projected global cereal production for reference case and the climate change scenario. Percentage change in global cereal prices under the climate change scenario (0 = Projected reference case).

People at risk from sea-level rise Percentage change in the number of people at risk under the sea-level rise scenario and constant (1990s) protection (left bar) and the sea-level rise scenario and evolving protection (right bar). 2050s2020s2080s % increase Middlesex University / Delft Hydraulics

IMPACTS UNDER SOME/MUCH MITIGATION

Emissions and concentrations of CO 2 from unmitigated and stabilising emission scenarios Unmitigated emissions 750 ppm stabilisation550 ppm stabilisation Hadley Centre for Climate Prediction and Research

Global average temperature rise from unmitigated and stabilising emission scenarios Global temperature change (°C) 3 1 Unmitigated emissions 750 ppm stabilisation550 ppm stabilisation Hadley Centre for Climate Prediction and Research

Temperature rise Annual average, from the present day to the 2080s Hadley Centre for Climate Prediction and Research c Unmitigated Emissions c c Stabilisation of CO 2 at 550ppm Stabilisation of CO 2 at 750ppm

Change in precipitation Annual average, from the present day to the 2080s c Unmitigated Emissions c c Stabilisation of CO 2 at 550ppm Stabilisation of CO 2 at 750ppm Hadley Centre for Climate Prediction and Research

Changes in river runoff from the present day to the 2080s Unmitigated emissions Stabilisation of CO 2 at 750 ppm Stabilisation of CO 2 at 550 ppm –75–50–25–5 to Change in annual runoff (%) University of Southampton

Changes in water stress from the present day to the 2080s Billions of people Increased water stress Decreased water stress University of Southampton Unmitigated Emissions 750 ppm Stabilisation550 ppm Stabilisation

Changes in crop yield from the present day to the 2080s Unmitigated emissions Stabilisation of CO 2 at 750 ppm Stabilisation of CO 2 at 550 ppm University of East Anglia Potential change in cereal yields (%) 10 – 5 0 – – – – – 0 5 – 2.5 No data

Global number of people flooded under three emissions scenarios People flooded (millions/year) 2020s2050s2080s Unmitigated emissions 750 ppm stabilisation550 ppm stabilisation University of Middlesex No climate change

People flooded by region Southern Mediterranean West Africa East Africa South Asia SE Asia People flooded (millions/year) Unmitigated emissions 750 ppm stabilisation550 ppm stabilisation No climate change University of Middlesex

Island people flooded Caribbean Indian Ocean small islands Pacific small islands People flooded (thousands/year) University of Middlesex Unmitigated emissions 750 ppm stabilisation550 ppm stabilisation No climate change

Malaria transmission Change in duration of season, 2080s Unmitigated emissions Stabilisation at 750 ppm Stabilisation at 550 ppm 2 to 5 months1 to 2 months–2 to –1 months–5 to –2 months London School of Hygiene and Tropical Medicine

Millions at Risk in the 2080s

The Cost of Stabilising CO 2 Concentrations

The effect of different global economic pathways Regional enterprise: high pop, mod. growth, (A2) Local stewardship: semi- sustainable dev, low pop (B2)

A2 in 2050s B2 Pop 11.3 billion Pop 11.3 billion GDP 82 tr $ GDP 82 tr $ primary energy 970 GJ/yr primary energy 970 GJ/yr carbon 16 GtC/yr carbon 16 GtC/yr Pop 9.3 billion Pop 9.3 billion GDP 110 tr $ GDP 110 tr $ primary energy 870 GJ/yr primary energy 870 GJ/yr carbon 11 GtC/yr carbon 11 GtC/yr

Additional People at Risk of Hunger under the SRES A2 and B2 Scenarios

Costs of 550 Stabilisation assuming different development pathways

Conclusions : Stabn at 750 does not avoid most effects. Stabn at 750 does not avoid most effects. Stabn at 550 does, but at considerable cost (= c.20 times Kyoto reductions). Stabn at 550 does, but at considerable cost (= c.20 times Kyoto reductions). Sustainable development (cf SRES B2 pathway) needs also to be part of the solution Sustainable development (cf SRES B2 pathway) needs also to be part of the solution

The Shortfall in Global Cereal Production for Reference Case and the SRES Scenarios

Millions at Risk in the 2050s

Conclusions : 2 Invest in adaptation, to increase resilience to climate change: technology (eg GM), engineering (eg water use efficiency), institutions. These are win-win (eg drought-proofing). Invest in adaptation, to increase resilience to climate change: technology (eg GM), engineering (eg water use efficiency), institutions. These are win-win (eg drought-proofing). Invest especially in key vulnerable regions and sectors: Africa, Indian subcont., small islands; water, food, coastal settlement. Invest especially in key vulnerable regions and sectors: Africa, Indian subcont., small islands; water, food, coastal settlement. Revise the adaptation/mitigation emphasis: Revise the adaptation/mitigation emphasis:

Change in vegetation biomass from present day to the 2230s –8–5–3–11358 kgC/m 2 ITE Edinburgh c Stabilisation of CO 2 at 550ppm Stabilisation of CO 2 at 750ppm c

Vegetation dieback Unmitigated emissions 750 ppm stabilisation550 ppm stabilisation ITE Edinburgh

Uptake of carbon by vegetation –1 –2 – Transfer of carbon to vegetation (GtC/yr) Unmitigated emissions 750 ppm stabilisation550 ppm stabilisation ITE Edinburgh

Changes in vegetation biomass between the present day and the 2080s –8–5–3–11358 kgC/m 2 –8–5–3–11358 kgC/m 2 –8–5–3–11358 kgC/m kgC/m 2 ITE Edinburgh Unmitigated EmissionPresent Day Stabilisation of CO2 at 750 ppmStabilisation of CO2 at 550 ppm

Changes in river runoff from the present day to the 2230s –75–50–25–5 to Change in annual runoff (%) University of Southampton c Stabilisation of CO 2 at 550ppm Stabilisation of CO 2 at 750ppm c

Changes in water stress from the present day to the 2080s Unmitigated emissions Stabilisation of CO 2 at 750 ppm Stabilisation of CO 2 at 550 ppm Stressed country with decrease in stress Country moves to stressed class Stressed country with increase in stress University of Southampton

Conclusions : 3 Foster adaptation to avoid increased inequality (autonomous adaptn=more unequal effects of climate change). Foster adaptation to avoid increased inequality (autonomous adaptn=more unequal effects of climate change). Foster increased resilience (especially in the tail): a) seek the sub-optimal (eg drought resistant/non-max yield crop varieties); b) (many) small vs (few) large actions; c) promote stability (vs growth?). Foster increased resilience (especially in the tail): a) seek the sub-optimal (eg drought resistant/non-max yield crop varieties); b) (many) small vs (few) large actions; c) promote stability (vs growth?).

Rate of sea-level rise 2080s2110s2140s2170s2200s2230s Rate of sea-level rise (cm/century) Unmitigated emissions 750 ppm stabilisation550 ppm stabilisation

Global wetland losses s2050s2080s2110s2140s2170s2200s2230s Fraction of wetland area lost (%) Unmitigated emissions 750 ppm stabilisation550 ppm stabilisation University of Middlesex

Coastal flooding Change from the present day to the 2080s Unmitigated emissions Stabilisation at 750 ppm Stabilisation at 550 ppm University of Middlesex

Malaria transmission season Estimated for the present day (falciparum) London School of Hygiene and Tropical Medicine

People at risk of malaria additionally from climate change s2050s2080s Additional people at risk (millions) Unmitigated emissions 750 ppm stabilisation550 ppm stabilisation London School of Hygiene and Tropical Medicine