Methane, Ozone and the Carbon Budget for 1.5 degrees (MOC1.5)

Lead Research Organisation: University of Reading
Department Name: Meteorology

Abstract

It will be very challenging to keep global temperatures from rising more than 2 degrees above pre-industrial levels, and even more so to achieve the ambition of restricting temperatures below a 1.5 degree increase. While restricting carbon dioxide emissions must form the central part of any strategy, reducing other greenhouse gases such as methane can play an important role. Reducing levels of methane can increase the removal of carbon dioxide from the atmosphere. This happens in two ways. Decreasing methane will decrease surface temperatures reducing the carbon dioxide lost from soils and leaves (for carbon dioxide this is already accounted for, but for methane this has previously been neglected). Decreasing methane will decrease levels of ozone, a gas that is poisonous to plants (and people), and hence increase plant growth.

This project will use computer models of the chemistry of the atmosphere, of vegetation growth, and of the carbon cycle to simulate the total climate impact (including the increased carbon uptake) of a realistic methane reduction scenario. This will give policymakers a better understand of the climate impacts of methane reduction and allow them to better judge the balance between carbon dioxide and methane mitigation measures in the total package of climate policy solutions.

A useful co-benefit of this project will be to calculate the air quality benefits (to people and crops) of the methane mitigation.

Planned Impact

The main beneficiaries will be those involved in designing potential climate policies (such as Department of Business Energy and Industrial Strategy (BEIS), Defra, Environment Agency, Committee on Climate Change). These will benefit by being able to identify non-CO2 options for mitigating climate change towards a 1.5 degree ambition. As the largest scope for mitigating methane is in developing countries (India, Brazil, Indonesia), this work could also benefit DfID and FCO. We will also make the results available to a range of international policy initiatives including the OECD, and EU.

The UN ambition to restrict temperature rise to around 1.5 degree will require action on non-CO2 pollutants as well as CO2. The PI and Co-Is were all involved in the IPCC 5th Assessment report (AR5) as Lead Author or Co-Authors. They will advertise the findings of MOC1.5 to colleagues on the UNFCCC 1.5 degree report to ensure it informs that assessment.

MOC1.5 will complement the work carried out under the Hadley Centre Climate Programme (HCCP) and relevant results from MOC1.5 will gain further impact by being communicated to BEIS and Defra through HCCP communication channels.
 
Description Achieving climate goals such as limiting future temperature rises to 2 degrees (or even 1½ degrees) will require very large cuts in carbon dioxide emissions. Strongly reducing man-made emissions of methane as well will mean the cuts in carbon dioxide can be slightly less steep and hence are more likely to be feasible. Methane is a global warming gas, and also reacts chemically to produce ozone. Ozone is also a global warming gas as well as being damaging to plant growth and human health. In this study we show that reducing methane directly affects climate and additionally allows the plants to take more carbon dioxide out of the atmosphere. We also show methane reduction will improve human health and crop yields. The extra allowable carbon emissions from CH4 mitigation can make a substantial difference to the feasibility or otherwise of achieving the Paris climate targets.
• We find a simple robust relationship between extra allowable carbon emissions and change in the 2100 CH4 concentration
• The differing effects of CH4 and CO2 on land carbon storage lead to an additional increase in the allowable carbon emissions with CH4 mitigation.
• Mitigation of CH4 emissions has co-benefits for human and ecosystem health.
Exploitation Route The work has been cited by the IPCC special report on 1.5 degrees and the special report on climate change and land
Sectors Environment

 
Description AGU Fall Meeting 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Presentation to scientific conference
Year(s) Of Engagement Activity 2017