Gwp* Should Not Be Adopted By The Ipcc

Generated Summary

This document critiques the use of GWP* (Global Warming Potential) as a measure of climate impact, particularly in the context of the Paris Agreement and the IPCC (Intergovernmental Panel on Climate Change). It argues that GWP* is counter-intuitive and could undermine efforts to reduce greenhouse gas emissions, especially those related to short-lived climate pollutants (SLCPs) like methane. The author, Geoff Beacon, raises concerns about the transparency of the IPCC process and the potential for GWP* to be misused, particularly by industries with large historic methane emissions, such as the oil and gas sector. The document explores the limitations of the Paris Agreement in addressing climate change and the importance of considering the full extent of greenhouse warming, including the role of ocean heat content and the impacts of SLCPs. It also examines how GWP100, the current standard, and GWP* measure different aspects of climate impact and how the choice of GWP metric affects climate policy. The author recommends against the adoption of GWP* by the IPCC, suggesting it could hinder effective climate action. The research approach is based on a review of the scientific literature, policy documents, and personal communications, and is presented in the format of a blog post.

Key Findings & Statistics

• GWP100 is a measure of the heating that is caused over 100 years by a particular climate pollutant relative to a similar amount of CO2.
• N2O has GWP100 of 298 because over 100 years 1 tonne of N2O causes 298 times more greenhouse warming than 1 tonne of CO2.
• Currently accepted values for methane are 34 for GWP100 and 86 for GWP20.
• More than 90% of the additional energy trapped in the climate system by raised greenhouse gas concentrations ends up in the oceans.

Other Important Findings

• The Paris Agreement’s central aim is to strengthen the global response to the threat of climate change by keeping a global temperature rise this century well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius.
• The Paris Agreement’s focus on surface temperature, GMST, does not account for all the threats of climate change, like the heat accumulated in the Earth by many past decades of the greenhouse effect.
• Switching from GWP100 to GWP* would weaken commitments that are given to reach ‘net-zero’ greenhouse gas emissions.
• GWP* combines the effects of the emissions of a mixture of greenhouse gases and relates these to equivalent emissions of CO2 that would cause similar effects.
• GWP* has two components, one for LLCPs (eg. CO2, N2O) and one for SLCPs (e.g. methane).
• The first component is the same as other measures like GWP100.
• The second component of GWP* tries to take account of the fact that SLCPs reside in the atmosphere for a limited time and their effect on GMST is short lived.
• Cutting methane emissions now will have little effect on GMST in 50 years’ time.
• GWP* has been designed to try to take account of this difference. It does so by relating the second component of GWP* to the rate at which emissions of SLCPs are changing: If SLCP emissions are falling GWP* is reduced. If SLCP emissions are rising GWP* is increased.
• Its definition makes it possible for GWP* to become zero or even negative, when neither emissions of CO2 nor methane are zero – if emissions of methane are falling fast enough.
• Adoption of GWP* would dismiss the strategy proposed by Xu and Ramanathan in Well below 2 °C: Mitigation strategies for avoiding dangerous to catastrophic climate changes.
• The Committee has not mentioned Ocean Heat Content since. Increased OHC would be another reason to reject the use of GWP*.

Limitations Noted in the Document

• The author is not a climate scientist and acknowledges that their reading of the science and policy context may be incorrect.
• The document is presented as a blog post, which may not undergo the same rigorous peer-review process as a scientific publication.
• The analysis relies on information from various sources, including the UK Government’s business department, which may have limitations in terms of data availability or scope.
• The document’s conclusions are based on a specific interpretation of the Paris Agreement and the IPCC process.
• The document does not provide an in-depth analysis of the scientific basis for GWP* or a detailed comparison with other GWP metrics.

Conclusion

The author’s central argument is that GWP* should not be adopted by the IPCC. The document makes a case against GWP*, highlighting potential issues with transparency, and emphasizing that it could undermine effective climate action. The author suggests that GWP* may be counter-intuitive, potentially allowing countries to claim net-zero emissions while continuing to emit significant amounts of greenhouse gases. The focus on surface temperature in the Paris Agreement and the potential for GWP* to downplay the importance of SLCPs are major concerns. The author emphasizes that the current focus on GWP100 should be maintained and a shift to GWP* could impede the progress of climate change mitigation. The document also calls attention to the critical role of ocean heat content, which is often overlooked in climate assessments. In conclusion, the author’s position is that GWP* is a flawed metric that could weaken climate commitments, and the IPCC should not adopt it. Instead, the author suggests that focusing on cutting CO2 and methane emissions, and extracting CO2 from the atmosphere should be prioritized.