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.

Climate Change a will affect all sectors and countries

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)

Stabilisation requires urgent pro-active measures

Business as usual (A2)

Stabilisation of greenhouse gas concentrations and climate system inertia

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