Title: Climate Science : Todays and Tomorrows
1Climate Science Todays and Tomorrows
Peter Cox University of Exeter Met Office Chair
in Climate System Dynamics Mathematics Research
Institute
2Outline
- What We Now Know About Climate Change
- The Changing Role of Climate Change Science
- Informing Climate Change Adaptation Mitigation
- Conclusions
3The Human fingerprint on Climate Change is
Detectable natural factors cannot explain
recent global warming (i.e. since 1980), but this
warming is consistent with the anthropogenic
greenhouse effect.
4Natural factors cannot explain recent warming
5Recent warming can be simulated when man-made
factors are included
6Global Warming will not be uniform the land
will warm much more quickly than the ocean, and
the high-latitudes will warm more than the
tropics..
7Predicted Pattern of Global Warming
8The Climate System has a long-memory so we
pass the problem on to future generations..
9Future Carbon Dioxide Emissions based on
different Storylines of Economic Growth and
Environmental Policies
High Emission Futures
Intermediate A1B Scenario
Low Emission Futures
10Global Temperature Rise Predicted with HadCM3
Different emissions scenarios
High Emission Futures
2oC warmer than current
Low Emission Futures
Warming by 2100 depends critically on emissions
from now on, but has little impact on climate
change until 2030..
11The Changing Role of Climate Change Science
- Intergovernmental Panel on Climate Change (IPCC)
has largely been addressing the questions - - Is climate changing significantly ?
- - Are humans to blame ?
- The latest IPCC report answers a clear YES to
both these questions, and many are therefore
convinced of the need to act. - Scientists are now being asked much harder
question what should we do ?
12The Changing Role of Climate Change Science
- While this is not a question for scientists alone
to answer, science should provide the necessary
tools and information to inform policy decisions
(..otherwise policy will not be
evidence-based..)? - Arguably, standard century-timescale climate
prediction falls between two stalls, being - - too long-term and uncertain to inform regional
adaptation to climate change, and - - insufficiently focussed on probabilistic risk
assessment/vulnerabilities to inform mitigation. - What could we do instead ?
13IPCC 4th Assessment Report Uncertainties in 21st
Century Global warming
Insensitive to Socioeconomics Until 2030
14Informing Climate Change Adaptation
- We are already committed to significant
additional warming so we must adapt as well as
mitigate. - Adaptation will occur on regional scales
(high-resolution) and on decadal rather than
century timescales.
15IPCC 4th Assessment Report Probabilities and
Patterns of Global Warming
16What determines the Uncertainty in Predictions
of Global Warming ?
17Sources of Uncertainty in Prediction of Global
Warming
- Climate feedback Uncertainty
- Emissions Scenario Uncertainty
-
- Initial Condition Uncertainty
-
18Contributions to uncertainty in predicted
decadal mean temperature versus the lead-time of
the prediction
Total Uncertainty
Emissions Scenario Uncertainty
Initial Condition Uncertainty
Process/Parameter Uncertainty
19Informing Climate Change Mitigation
20United Nations Framework Convention on Climate
Change (UNFCCC)?
- The ultimate objective is.
- stabilization of greenhouse gas concentrations
in the atmosphere at a level that would prevent
dangerous anthropogenic interference with the
climate system
21Climate Prediction to Inform Mitigation Policy
Current Approach to Climate Prediction
Policy
Socioeconomics
Socioeconomics
GHG Emissions
Permitted GHG Emissions
Carbon Cycle Atm. Chemistry
Carbon Cycle Atm. Chemistry
GHG Concentrations
GHG Concentrations
Climate Model
Climate Model
GHG conc. scenarios to avoid dangerous Climate
Change
Climate Change
Climate Change
Impact Assessment
Vulnerability Assessment
Bodies on the street
22Neglected Links in the Mitigation Chain
- Impacts as a function of GHG level (Vulnerability
Assessment)?
23Stern ReviewClimate Impacts and Tipping
Pointsdependence on CO2 stabilisation level
24Vulnerability Assessment Impacts as a function
of Climate Change
Parry et al. 2001 http//www.greenpeace.org/raw/co
ntent/usa/press/reports/millions-at-risk.pdf
25Neglected Links in the Mitigation Chain
- Impacts as a function of GHG level (Vulnerability
Assessment)? - Permitted CO2 emissions as a function of
stabilisation level (dependent on carbon cycle
feedbacks).
26What do we need to do to avoid the most damaging
impacts of climate change ?
27Global Temperature Rise Predicted with HadCM3
Different emissions scenarios
2oC warmer than current
Environmentally Friendly SRES B1 Scenario
28Global CO2 Emissions
10
8 GtC/yr now
8
6
Global CO2 Emissions (GtC/yr)?
4
2
2300
1900
2200
2000
1950
2100
2050
29Global CO2 Emissions
- to avoid Dangerous Climate Change ?
10
8 GtC/yr now
8
Stabilisation at 450 ppmv requires a 60 cut in
global CO2 emissions by 2050
6
Global CO2 Emissions (GtC/yr)?
4
3 GtC/yr by 2050
..and continuous reductions beyond 2050
2
2300
1900
2200
2000
1950
2100
2050
30The CO2 Emissions Reduction Challenge
2003 6.4 billion people,Total emissions of 8
GtC/yr 1.23 tC/person
Global Mean
2050 8.5 billion people, 60 of Global CO2
emissions 0.37 tC/person
31Environmentally Friendly Scenario for the
Future
IPCC TAR, SRES B1, IMAGE model
32Conclusions I
- The Human fingerprint on Climate Change is now
clear - natural factors cannot explain recent global
warming (i.e. since 1980), but this warming is
fully consistent with warming due to
anthropogenic greenhouse gases. - Climate change is unjust
- the source of the problem is the industrialised
nations, but the worst impacts will be felt in
the developing world and by future generations. - Humankind still has a lot of choice over which
pathway of future CO2 emissions is followed - the range of plausible emissions pathways
results in a range of 2 to 6oC additional global
warming by 2100.
33Conclusions II
- To inform adaptation policy we need to develop
higher resolution climate forecasts on decadal
(rather than century) timescales, constrained
more effectively by modern observational data. - To inform mitigation policy (under the UNFCCC)
requires a reversal of the process typically used
for climate projections starting at climate
impacts/vulnerability and ending with diagnosed
permissible emissions. - Many climate scientists believe that a warming of
more than 2oC could be dangerous avoiding
such a warming requires a 60 cut in global CO2
emissions by 2050, and continuing reduction
thereafter - - this translates into a factor 4 reduction over
the 21st century in the CO2 emitted per unit of
energy production.
34THE END !