Climate change impacts on society

1. Overview of Climate
Change Impacts
David A Warrilow
Department for Environment, Food and Rural Affairs
Climate change and
sustainable development
New Delhi, 7-8 April 2006

2. 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

3. Recent economic losses substantial
UK floods, autumn 2000
• Insured loss £1bn
European floods 2002
• 37 deaths
• $16bn direct costs
European heat-wave 2003
• 35,000 deaths approx
• $13.5bn direct costs
Caribbean Hurricanes 2005
• More than 2000 deaths
• $76bn insured loss alone
• $300bn economic losses
Hurricane Wilma, courtesy of NOAA

4. 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

5. 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

6. Impacts of climate change will be severe and widespread
For 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.

7. Climate Change a will affect all sectors and countries

8. 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%

9. 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 India
a) base case, b) with climate change

10. 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)

11. Climate system instabilities
• far reaching effects
• tipping points hard to predict
Examples:
• Ocean circulation
• Ice sheet behaviour
• Carbon Cycle
• Methane Hydrates
• Acidification
• Population crashes

12. 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.

13. 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

14. 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
s to prepare for
ply
nity
nal

15. 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

16. 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 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.
2 - 3 C Terrestrial carbon sink becomes a source.
1 - 4 C North Atlantic circulation collapses
2 - 4.5 C West Antarctic ice sheet collapses (5 m)

17. Stabilisation requires urgent pro-active measures

18. Stabilisation of greenhouse gas
concentrations and climate system inertia

19. 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