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Overview of Climate Change Impacts
David A WarrilowDepartment for Environment, Food and Rural Affairs
Climate change and sustainable development
New Delhi, 7-8 April 2006
Widespread impacts on the natural world already evident
• Widespread melting of glaciers globally
• Increased river flow into the Arctic
• 8% loss of Arctic sea-ice in last decade
• Melting permafrost• Rising sea levels 1-2 cm per
decade• Earlier spring activity in plants
and animals
Recent economic losses substantialUK floods, autumn 2000• Insured loss £1bn
European floods 2002• 37 deaths• $16bn direct costsEuropean heat-wave 2003 • 35,000 deaths approx• $13.5bn direct costsCaribbean Hurricanes 2005 • More than 2000 deaths
• $76bn insured loss alone
• $300bn economic lossesHurricane Wilma, courtesy of NOAA
Extreme events are increasing in size/frequency
• European hot summer of 2003
• over 35,000 deaths• risk of such a summer
2-4 times greater with greenhouse gases.
Hadley Centre
Temperatures are predicted to continue to rise (1.4 to 5.8C by 2100, IPCC AR3)
Observed and predicted
European summer temperatures.
2003 type heat-waves will be
common by 2040
Impacts of climate change will be severe and widespreadFor India we found: • marked increase in both rainfall
and temperature over the 21st century projected.
• maximum increases in rainfall (10 to 30%) may occur over central India.
• temperatures projected to increase by 3 to 4C towards the end of the century.
• but behaviour of monsoon not well simulated.
Change in annual mean surface temperature by the 2080s compared to 1961-1990, from the IPCC A2 scenario.
Agriculture vulnerable to temperature increases and rainfall changes
• A 2 C rise in temperature decreases Indian wheat yield - Up to 6% in sub tropical areas- 17-18% in tropical areas
• For rice a 2 C rise projected to reduce yields by 10-16% and a 4°C rise led to a 21-30% reduction.
• Sensitivity to monsoon - 19% rainfall deficit in 2002
reduced Indian GDP by 3%
Human Health also vulnerable
• More incidences of malaria in areas that are already malaria-prone, and introduced into new areas.
• Sensitive to the arrival of the monsoon.
Transmission Window of Malaria in different states of Indiaa) base case, b) with climate change
Sea-Level rise and storm surges
Indian study showed:• Mean sea level rise for
Mumbai slightly less than 1mm/year and a possible decrease at Chennai, but no info on land movements.
• Storm surges show increase in number of high surges under climate change.
• Cyclone frequency and strength increases in the Bay of Bengal, particularly in the post-monsoon period.
Frequency Distribution of Maximum surges associated with each cyclone (2050)
Climate system instabilities
• far reaching effects
• tipping points hard to predict
Examples:
• Ocean circulation
• Ice sheet behaviour
• Carbon Cycle
• Methane Hydrates
• Acidification
• Population crashes
The direct effects of CO2
• CO2 affects the acidity of the ocean – it is already increasing. Negative impacts on coral reefs and plankton and hence the food chain. May also affect the carbon cycle.
• CO2 helps plants to grow, but quality of yield may be reduced. But growth also limited by water and nutrient availability.
Impacts depend strongly on socio-economic development pathway.
• Project developed four socio-economic scenarios in line with national plans for development, and associated projections for population and economic growth
Framework for visions of socio-economic change for India
Adaptation an essential but limited response
• Adaptation recognised as an essential response but not a substitute for mitigation
• No one solution • Not an easy option• Easier for new build• It has its limits
Avoiding Dangerous Anthropogenic Climate Change - Exeter conference 2005
• For different levels of climate change what are the key impacts?
• What would such levels of climate change imply in terms of greenhouse gas stabilisation concentrations and emission pathways required to achieve such levels?
• What options are there for achieving stabilisation of greenhouse gases at different stabilisation concentrations in the atmosphere?
See www.stabilisation2005.com
How much climate change is too much?1-2 C Above pre-industrial
Major impacts on ecosystems and species; wide ranging impacts on society, including developing county agriculture.
1.5 – 3 C Greenland ice-cap starts to melt irreversibly (7 m)
2 - 3 C Terrestrial carbon sink becomes a source.
2 - 3 C Major loss of coral reef ecosystem; considerable species loss; large impacts on agriculture; water resources; health; economies.
General increase in droughts and extreme rainfalls as temperature increases. Up to 88cm sea level rise in next 100 years.
1 - 4 C North Atlantic circulation collapses
2 - 4.5 C West Antarctic ice sheet collapses (5 m)
Conclusions• Climate change impacts are already being seen• Climate change will affect all sectors and all countries• Above 1-3 C rise many impacts could become critical.• System changes could generate major impacts but hard to
predict.• Sea level rise a significant long term issue• Ocean acidification a serious direct impact of CO2• Adaptation essential – but has its limits• Need to limit climate change – 2 C?• Without stabilisation of greenhouse gases at a level which
avoids dangerous anthropogenic climate change sustainable development will not be possible