Global%20Warming%20

1
Global WarmingPolitical hype or reality?

• The Fernhurst Society
• - 5 April 2007 -
• John Clement

2
Global warming - questions

• What is happening?
• What are the reasons?
• What is likely to happen from now on?
• What can we do?

3
Whats happening? Observable warming
Trending strongly above long-term averages since
mid 70-s
4
NOT the Earths long-term climate cycle
000 years before present
This cycle is driven by Earths orbit changes
5
Whats happening? Consistent observations
Similar trending since mid 70-s by three
independent measures
6
What are the reasons? The climate system
7
What are the reasons? Radiation balance
8
Solar radiation at poles and equator
SUNS RAYS
Near the equator, the Suns rays are spread out
over a smaller area, so the heating is more
intense
The Earths climate systems in the atmosphere and
oceans transport heat between the equator and
the poles - and produce the weather
9
Range of global temperatures
10
What are the reasons? Is it solar radiation?
11
What are the reasons? Solar radiation?
0.2
0.1
0
Solar radiation has been stable for the last
50 years
12
What is the reason?
13
What is the reason? The greenhouse effect?
14
What is the reason? The greenhouse effect?
15
(No Transcript)
16
Greenhouse gas increases through Industrial Age

• CO2 roughly constant at 280 ppm until 1800
• then rising rapidly to 380 ppm
  today, and
• further yet.
• Methane 800 ppb until 1800,
• now 1,750 ppb.
• Nitrous oxide 270ppb until 1800 now 310 ppb
• Lower atmosphere ozone increased around 30 over
  the same period.

17
(No Transcript)
18
Greenhouse gases Predicted warming effect over
the next 100 years
Methane 24
Carbon dioxide 63
Nitrous oxide 10
Others 3
CO2 is the major contributor
19
Volcanoes also affect the atmosphere
20
Volcanic aerosols in the atmosphere
5 4 3 2 1 0
5 4 3 2 1 0
1883 Krakatau
1991 Mt. Pinatubo
1980 Mt. St. Helens
Estimated cooling effect, Wm
21
Whats happening? Observable warming
Suspected effect of atmospheric particulates
Trending strongly above long-term averages since
mid 70-s
22
Climate models - improving
23
Natural factors alone do not explain the pattern
of global warming since industrialisation
24
CO2 in the atmosphere long term stability until
industrialisation
The Industrial Age
25
CO2 from fossil fuels rapid rise since 1950
26
Addition of man-made factors to models duplicates
observations
27
Q. Global Warming?
Change between 1750 and 2000

A. Man-made gases dominate
28
Global warming - questions

• What is happening?
• What are the reasons?
• What is likely to happen from now on?
• What can we do?

29
Global warming

• What is happening?
• What are the reasons?
• What is likely to happen from now on?
• What can we do?

30
What is likely to happen from now on?

• Depends on what we do.
• Slowing down GHG emissions, particularly carbon,
  will mitigate future temperature rises but
  there is a lot of momentum already embedded in
  the climate system.
• Adaptation will be needed for coming changes in
• rainfall patterns
• - glaciers and sea-ice
• - sea-levels
• - land temperatures
• - food crop, forest and animal ranges
• - human impacts livelihoods, wealth and health

31
RainfallGlaciers and sea-iceSea levelsLand
temperatures
32
Rainfall - changing
33
UK precipitation by 2080s
34
European summer rainfall outlook - 2080s
35
RainfallGlaciers and sea-iceSea levelsLand
temperatures
36
Glaciers melting
16,700 in the world 13,500 are in retreat
37
Gangotri glacier, Himalayas a case study
38
Himalayan glaciers - critical
39
Himalayan glaciers - critical
Himalayan glaciers feed 7 of Asias great
rivers - The Ganges - The Indus - The
Brahmaputra - The Salween - The Mekong - The
Yangtze - The Yellow river
2.3 billion people
40
RainfallGlaciers and Sea-iceSea levelsLand
temperatures
41
Sea ice also melting
1.3 million km2 Arctic ice lost since mid-70s
42
Arctic sea-ice, maybe disappearing by 2080s
43
West Antarctic and Greenland ice sheets
1,000 years to melt , but..
6m sea level rise 7m sea level
rise
44
Oceans - The north Atlantic Conveyor
45
Hypothetical collapse in ocean currents
46
Best forecasts of Atlantic circulation
its OK!
47
RainfallGlaciers and sea-iceSea levelsLand
temperatures
48
Components of sea level rise
49
Long-term momentum of sea-level rises
50
IPCC estimates of global mean sea-level rise
51
North Sea storm surges by 2080
52
RainfallGlaciers and sea-iceSea levelsLand
temperatures
53
European hot summers human activity has roughly
doubled the chances
54
European summer temperatures rising
2003
55
Global warming - questions

• What is happening?
• What are the reasons?
• What is likely to happen from now on?
• What can we do?

56
What can we do?

• Avoid unnecessary carbon
• Be prudent with necessary carbon
• Offset and seuester as much carbon as possible
• Adapt

57
CO2 emissions reductions - the only route to
stable concentrations.
750
Business as usual
650
Constant 1990 emissions
550
CO2 concentration (ppm)
450
50 1990 emissions
350
? Pre-industrial concentration
250
1990
2010
2030
2050
2070
2090
Year
58
No getting away from it future warming
59
What can we do?

• Avoid unnecessary carbon
• Be prudent with necessary carbon
• Offset and sequester as much carbon as possible
• Adapt
• Cross fingers for approx. 200 years!

60
The End

• The Fernhurst Society
• - 5 April 2007 -
• A presentation by John Clement