Climate Change

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Climate Change

• Coastal Zones in Sub-Saharan Africa
• Natural History Museum and Royal Society
• Dave Griggs
• Director, Hadley Centre, Met Office

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Variation of the Earths surface for the past 140
years...
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Global mean surface temperatures have increased
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The Land and Oceans have warmed
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Precipitation patterns have changed
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Sea Levels have risen
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An increasing body of observations gives a
collective picture of a warming world and other
changes in the climate system

• Global-average surface temperature increased by
  about 0.6 ºC over 20th century
• 1990s warmest decade and 1998 warmest year in
  last 1000 years in Northern Hemisphere
• Over last 50 years night-time minimum
  temperatures increased by about 0.2 ºC per decade
• 10 reduction in snow cover ice since late 1960s
• Reduction of about two weeks in annual duration
  of lake and river ice over 20th century
• Widespread retreat of mountain glaciers during
  20th century

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• Northern Hemisphere spring and summer sea-ice
  extent decreased by 10-15 since 1950s
• 40 decline in late summer Arctic sea-ice
  thickness in recent decades
• Global-average sea level has increased by 10-20
  cm during 20th century
• 0.5-1 per decade increase in Northern Hemisphere
  mid-latitude precipitation during 20th century
• 2-4 increase in frequency of heavy precipitation
  events in Northern Hemisphere mid- and
  high-latitudes over latter half of 20th century

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Human activities have changed the composition of
the atmosphere since the pre- industrial era
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19 levels in atmosphere
30km
2.5 lat
3.75 long
The HadleyCentre thirdcoupled model HadCM3
1.25
1.25
20 levelsin ocean
-5km
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THE CLIMATE SYSTEM
The Met.Office Hadley Centre
ATMOSPHERE
Terrestrial radiation
Clouds
Greenhouse gases and aerosol
Solar radiation
Ice- sheets snow
Precipitation
Sea-ice
OCEAN
Biomass
LAND
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HADLEY CENTRE EARTH SYSTEM MODEL
1975
1985
1992
1997
Atmosphere
Atmosphere
Atmosphere
Atmosphere
Atmosphere
Atmosphere
Land surface
Land surface
Land surface
Land surface
Land surface
Ocean sea-ice
Ocean sea-ice
Ocean sea-ice
Ocean sea-ice
Sulphate aerosol
Sulphate aerosol
Sulphate aerosol
Non-sulphate aerosol
Non-sulphate aerosol
Carbon cycle
Carbon cycle
Atmospheric chemistry
Sulphur cycle model
Non-sulphate aerosols
Off-line model development Strengthening
colours denote improvements in models
Ocean sea-ice model
Land carbon cycle model
Carbon cycle model
Ocean carbon cycle model
Atmospheric chemistry
Atmospheric chemistry
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Most of the observed warming in the past 50 years
is attributable to human activities
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Global mean temperature changes
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Land areas are projected to warm more than the
oceans with the greatest warming at high latitudes
Annual mean temperature change, 2071 to 2100
relative to 1990 Global Average in 2085
3.1oC
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Global-average temperature and sea level are
projected to rise under all scenarios

• Global-average surface temperature projected to
  increase by 1.4 ºC
• to 5.8 ºC by 2100
• Rate of warming likely unprecedented in at least
  last 10,000 years
• Land areas will warm more than the global
  average
• Global average precipitation will increase over
  21st century
• Very likely to be more intense precipitation
  events
• Snow cover and sea-ice extent projected to
  decrease further
• Glaciers and icecaps projected to continue
  widespread retreat
• Global mean sea-level projected to increase by 9
  cm to 88 cm by
• 2100

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CO2 concentrations, temperature and sea level
continue to rise long after emissions are reduced
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More adverse than beneficial impacts on
biological and socioeconomic systems are projected
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World Population 6,056,528,577
The Challenge Sustainable Management of an
Ever- Changing Planet
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Increased risk of floods, potentially displacing
tens of millions of people, due to sea level rise
and heavy rainfall events, especially in Small
Island States and low-lying deltaic areas.
Bangladesh is projected to lose about 17 of its
land area with a sea level rise of one meter -
very difficult to adapt due to lack of adaptive
capacity
projected
present
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• Food production needs to double to meet the needs
  of an additional 3 billion people in the next 30
  years

Climate change is projected to decrease
agricultural productivity in the tropics and
sub-tropics for almost any amount of warming
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• Wood fuel is the only source of fuel for one
  third of the worlds population
• Wood demand will double in the next 50 years
• Forest management will become more difficult due
  to an increase in pests and fires

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Climate change is projected to decrease water
availability in many arid- and semi-arid regions

• One third of the worlds population is now
  subject to water scarcity

Population facing water scarcity will more than
double over the next 30 years
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Estimated 10-15 of the worlds species could
become extinct over the next 30 years

• Biodiversity underlies all ecological goods and
  services

Climate change will exacerbate the loss of
biodiversity
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Agricultural Lands
Coastal Zones
Forest Lands
Freshwater Systems
Arid Lands Grasslands
Food and Fiber Production Provision of Clean and
Sufficient Water Maintenance of
Biodiversity Maintenance of Human Health Storage
and cycling of Carbon, Nitrogen, Phosphorus
Climate change will affect the ability of
ecological systems to provide a range of
essential ecological goods and services
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Developing countries are the most vulnerable to
climate change

• Impacts are worse - already more flood and
  drought prone and a large share of the economy is
  in climate sensitive sectors
• Lower capacity to adapt because of a lack of
  financial, institutional and technological
  capacity and access to knowledge
• Climate change is likely to impact
  disproportionately upon the poorest countries and
  the poorest persons within countries,
  exacerbating inequities in health status and
  access to adequate food, clean water and other
  resources.
• Net market sector effects are expected to be
  negative in most developing countries

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Projected concentrations of CO2 during the 21st
century are two to four times the pre-industrial
level
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Projected levels of atmospheric CO2 during the
next 100 years would be higher than at anytime in
the last 440,000 yrs
Projected (2100)
CO2 Concentration (ppmv)
Current (2001)
(BP 1950)
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Projected Temperatures During the 21st Century
Are Significantly Higher Than at Any Time During
the Last 1000 Years