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Climate Science : Todays and Tomorrows

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Title: Climate Science : Todays and Tomorrows


1
Climate Science Todays and Tomorrows
Peter Cox University of Exeter Met Office Chair
in Climate System Dynamics Mathematics Research
Institute
2
Outline
  • What We Now Know About Climate Change
  • The Changing Role of Climate Change Science
  • Informing Climate Change Adaptation Mitigation
  • Conclusions

3
The 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.
4
Natural factors cannot explain recent warming
5
Recent warming can be simulated when man-made
factors are included
6
Global 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..
7
Predicted Pattern of Global Warming
8
The Climate System has a long-memory so we
pass the problem on to future generations..
9
Future Carbon Dioxide Emissions based on
different Storylines of Economic Growth and
Environmental Policies
High Emission Futures
Intermediate A1B Scenario
Low Emission Futures
10
Global 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..
11
The 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 ?

12
The 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 ?

13
IPCC 4th Assessment Report Uncertainties in 21st
Century Global warming
Insensitive to Socioeconomics Until 2030
14
Informing 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.

15
IPCC 4th Assessment Report Probabilities and
Patterns of Global Warming
16
What determines the Uncertainty in Predictions
of Global Warming ?
17
Sources of Uncertainty in Prediction of Global
Warming
  • Climate feedback Uncertainty
  • Emissions Scenario Uncertainty
  • Initial Condition Uncertainty

18
Contributions 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
19
Informing Climate Change Mitigation
20
United 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

21
Climate 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
22
Neglected Links in the Mitigation Chain
  • Impacts as a function of GHG level (Vulnerability
    Assessment)?

23
Stern ReviewClimate Impacts and Tipping
Pointsdependence on CO2 stabilisation level
24
Vulnerability 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
25
Neglected 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).

26
What do we need to do to avoid the most damaging
impacts of climate change ?
27
Global Temperature Rise Predicted with HadCM3
Different emissions scenarios
2oC warmer than current
Environmentally Friendly SRES B1 Scenario
28
Global CO2 Emissions
10
8 GtC/yr now
8
6
Global CO2 Emissions (GtC/yr)?
4
2
2300
1900
2200
2000
1950
2100
2050
29
Global 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
30
The 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
31
Environmentally Friendly Scenario for the
Future
IPCC TAR, SRES B1, IMAGE model
32
Conclusions 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.

33
Conclusions 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.

34
THE END !
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