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Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy F. Niehörster, N. Ranger, L. A. Smith
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Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Dec 21, 2015

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Page 1: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy

F. Niehörster, N. Ranger, L. A. Smith

Page 2: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Outline

Talking to Policy Makers:

What do they ask for?

What do they understand?

Essentials of uncertainty analysis

Remaining challenges

Page 3: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

The Example: A Policy Brief

Policy Brief 2December 2009

What do they ask for?

In preparation for the COP15 in Copenhagen it was asked how much global emissions of greenhouse gases will have to fall from present levels to create a reasonable chance (i.e. a 50 per cent probability) of avoiding a rise in global average temperature of more than 2°C above its pre-industrial levels.

Available on: www.lse.ac.uk/grantham

Page 4: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

What do they understand?

Example from the executive summary:

“Given the uncertainties in both the science and the economics, it is essential that any policy framework for climate change mitigation incorporates, from the outset, mechanisms to update the long-term goal, in a transparent fashion, in response to new developments in the science or economics, while holding policy-makers accountable for their actions.”

...

Page 5: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Presenting Uncertainty

Review of uncertainty of IPCC and Meinshausen et al (2006) for reaching certain temperature limits given stabilized GHG concentrations.

For negotiations the implied emission pathways were needed!

Page 6: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Emission Pathways

Offering a variety of options for decision making !

Page 7: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

The MAGICC Model

Highlighting the basics of the approach

Page 8: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Main results

Estimated median temperature response to emission pathways

Page 9: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Uncertainty analysis

Lower(!) bounds of uncertainty for single emission pathways by exploring parametric uncertainty related to scientific uncertainty (e.g. climate sensitivity)

Page 10: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Uncertainty analysis

Sensitivity of the findings to different assumptions is necessary.Here: different scenarios for aerosols lead to different answers

Page 11: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Remaining challenges

Is looking for the 50% Isopleths really what your risk averseness implies?

Understanding the science of uncertainty

Enhance understanding of model uncertainties

Page 12: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Conclusions

Talking to Policy Makers is not as bad as you think!

But if you do so, don’t forget the essentials of uncertainty analysis

Remaining challenges (always make sure you have some!)

Page 13: Understanding the relevance of climate model simulations to informing policy: An example of the application of MAGICC to greenhouse gas mitigation policy.

Content of the Policy Brief

1. Mitigating climate change through reductions in greenhouse gas emissions: background

2. Mitigating climate change through reductions in greenhouse gas emissions: climate science constraints on annual global emissions targets for 2020 and 2050

3. Mitigating climate change through reductions in greenhouse gas emissions: economic assessment of emissions targets

Annex 1 The approach and its implications for the conclusions

Annex 2 Key information for 20 emissions paths