Global Warming:
the Science, the Impacts
and the Politics
John Houghton
University of California, Irvine
20 February 2003
The Science of
Global Warming
Variations of the Earth’s surface temperature
for the past 1,000 years
SPM 1b
The Greenhouse Effect
Solar radiation
Long-wave
radiation
Concentration of Carbon Dioxide and Methane
Have Risen Greatly Since Pre-Industrial Times
Carbon dioxide: 33% rise
BW 5
The MetOffice. Hadley Center for Climate Prediction and Research.
Methane: 100% rise
700
600
Double pre-industrial CO2
500
Lowest possible CO2
stabilisation level by 2100
400
CO2 now
300
10
Temperature
difference
200
0
from now °C
–10
160
120
80
40
Time (thousands of years)
Now
100
CO2 concentration (ppm)
The last 160,000
years (from ice
cores) and the
next 100 years
CO2 in 2100
(with business as usual)
The Enhanced Greenhouse Effect
Solar (S) and longwave (L) radiation in Wm-2 at the top of the atmosphere
S
236
L
236
S
236
L
232
S
236
L
236
T = -18°C
TS = 15°C
CO2 x 2
CO2 x 2
TS = 15°C
DTS ~ 1.2K
S
236
L
236
CO2 x 2
+ Feedbacks
H2O (+60%)
Ice/Albedo (+20%)
Cloud?
Ocean?
DTS ~ 2.5K
IPCC Synthesis Report
Estimated solar irradiance variations 1750-2000
Simulated annual global mean surface temperatures
The climate system
The effect of the Mt. Pinatubo eruption
(June 1991) on global temperature
The Impacts of
Global Warming
Contributions to sea level rise
(metres), 1990-2100
ESTIMATED FOR IS92a SCENARIO
Thermal Expansion
Glaciers
Greenland
Antarctica
TOTAL
0.28
0.16
0.06
–0.01
0.49
Sea-level transgression scenarios for Bangladesh
Adapted from Milliman et al. (1989).
People at Risk from
a 44 cm sea-level rise by the 2080s
Assuming 1990s Level of Flood Protection
Projected changes in annual temperatures for the 2050s
BW 11
The projected change in annual temperatures for the 2050s compared with
the present day, when the climate model is driven with an increase in
greenhouse gas concentrations equivalent to about 1% increase per year in CO2
The MetOffice. Hadley Center for Climate Prediction and Research.
Global water use, 1900–2000
5500
5000
4500
4000
3500
3
km /year 3000
2500
2000
1500
1000
500
0
1900
Total use
Agricultural use
Industrial use
Domestic use
1920
1940
1960
1980
(from Shiklomanor (1988))
2000
Irrigated cropland
appears red in this
satellite photograph,
made over the Nile
where it flows through
the Sudan. In the past
70 years, a variety of
irrigation projects have
increased the
agricultural
productivity of this dry
region. More than half
of the increase in the
world’s agricultural
productivity during the
past few decades has
come from irrigation.
From PR Crosson and NJ Rosenberg, 1989
Changes in rainfall with doubled CO2 (CSIRO model)
160
140
40°N
40°S
Australian
land
points
120
100
Change in
frequency
(%)
80
60
40
20
0
–20
0.2-0.4
0.4-0.8
0.8-1.6
1.6-3.2
3.2-6.4 6.4-12.8 12.8-25.6 >25.6
Daily rainfall class (mm day–1)
Percent of the continental USA with a much above normal
proportion of total annual precipitation from
1-day extreme events (more than 2 inches or 50.8mm)
BW 7
Karl et al. 1996
The 1997/98 El Niño - strongest on record
El Niño years
La Niña years
BW 14
*As shown by changes in sea-surface temperature (relative to the 1961-1990 average) for
the eastern tropical Pacific off Peru
Estimate (after Myers) of environmental refugees
in a greenhouse-affected world (by ~2050)
Country or region
Bangladesh
Egypt
China
India
Other Delta Areas and Coastal Zones
Island States
Agriculturally-Dislocated Areas
Total
Refugees
(millions)
15
14
30
30
10
1
50
150
IPCC Synthesis Report
What can we do about
Global Warming?
Intergovernmental Panel on Climate Change
Third Assessment Report 2001
Scientific assessment includes:
Summary for Policymakers (SPM)
Technical Summary (TS)
14 chapters
20 pages
60 pages
780 pages
prepared by 123 Co-ordinating Lead Authors & Lead
Authors, 516 Contributing Authors, 21 Review Editors
& 420 Expert Reviewers..
SPM agreed ‘line by line’ at Plenary Intergovernmental
Meeting at Shanghai, January 2001, with delegates from 99
countries and 50 scientists representing the Lead Authors.
IPCC Website
• http://www.ipcc.ch
UNITED NATIONS FRAMEWORK CONVENTION
ON CLIMATE CHANGE Rio de Janeiro : June 1992
ARTICLE 2: OBJECTIVE
The ultimate objective of this Convention .... is to
achieve, .… stabilization of greenhouse gas
concentrations in the atmosphere at a level that would
prevent dangerous anthropogenic interference with
the climate system.
•Such a level should be achieved
within a time-frame sufficient :
• to allow ecosystems to adapt
naturally to climate change.
• to ensure that food production
is not threatened, and
• to enable economic development
to proceed in a sustainable manner.
Global carbon emissions from fossil fuel
Global carbon emissions from fossil fuel use, 1850 to 1990, and for scenarios to 2100, in GtC.
For each scenario, the range shows the difference between gross and net emissions.
From IIASA/WEC Global Energy Perspectives 1998.
Four Principles governing
International Agreements
•
•
•
•
Precautionary Principle
Principle of Sustainable Development
Polluter Pays Principle
Principle of Equity
Carbon Emissions
per capita per annum in 2000
(tonnes C)
USA
UK
China
India
5.5
2.5
0.7
0.3
World Average
1.0
Carbon dioxide contraction for 450 ppm & convergence
by 2030 to globally equal per capita emissions rights
Saving Energy in Buildings
• Use of white surfaces to reduce air
conditioning
• Low-energy lighting
• Better insulation and control of space
heating
• More efficient appliances
Important Energy Technologies
• Renewable Technologies
– Wind – onshore & offshore
Marine – wave and tidal
Energy Crops
Energy from Waste
PV Solar
• Other Technologies
– Combined Heat and Power
– Carbon Sequestration
– Fuel Cells
– Hydrogen fuel infrastructure
– Decentralised or Local Generation
Biomass
Local solar energy supply
Solar
cell array
Light
~1m2
~100 W peak power
+
-
Car battery
T.V.
Refrigerator
Energy Supply: Shell Scenario
Sustained Growth Scenario
exajoules
Surprise
1500
Geoth.
Solar
Biomass
1000
Wind
Nuclear
Hydro
500
Gas
Oil & NGL
Coal
Trad Bio.
0
1860
1880
1900
1920
Source: Shell International Limited.
1940
1960
1980
2000
2020
2040
2060
COST OF EMISSIONS REDUCTIONS
Estimated Cost of 60% reduction by 2050
On assumption of average economic growth at historic
annual rate of 2.25%,
estimated loss of 0.02% from the growth rate
equivalent to loss of 6 months’ GDP growth over 50 yrs
UK govt Policy Innovation Unit Energy Review 2002 para 7.115
GLOBAL WARMING
Cost of impacts
~1% GNP (DCs)
~2-5% GNP (LDCs)
Plus other less quantifiable but important impacts
Action required
Energy efficiency and conservation
Change to non-fossil-fuel energy sources
Aforestation & Limit deforestation
Move to Sustainable Consumption
Cost of action
<1% GNP
Global Warming Presents a Challenge to:
•
•
•
•
scientists
industry and technologists
governments
everybody
Message from Industry
“No single company or country can solve
the problem of climate change.
It would be foolish and arrogant to
pretend otherwise.
But I hope we can make a difference not least to the tone of the debate - by
showing what is possible through
constructive action.”
John Browne, BP, Berlin, 30 September 1997
Reasons for optimism
- Commitment of scientific community
- Necessary technology available
- God’s commitment to his creation
‘Nobody made a greater
mistake than he who did
nothing because he could
only do a little’
Edmund Burke