Rethink how to measure the impact of methane on climate

Methane ball-and-stick model. Credit: Ben Mills / Public Domain

Greenhouse gases lose the effects of global warming at varying rates, like boxers whose punching power declines throughout their careers. Therefore, to compare the potential for climate change in gas with carbon dioxide, the most common greenhouse gas, international negotiators have taken measurements to measure the impact on global warming over a 100-year period. Criteria are often used.

A new Stanford University study published on January 26 Environmental research letter This approach shows that it underestimates the importance of methane in achieving the Paris Agreement’s climate goals by up to 87%. Instead, scientists are proposing to use a 24-year time frame instead, in line with the goal of keeping global temperatures below 1.5 degrees Celsius below pre-industrial levels. Researchers argue that their approach will ensure that emissions of methane, a powerful but relatively short-lived gas, are correctly weighted over the period prior to exceeding such temperature thresholds. ing. This allows countries to prioritize reductions in methane emissions more quickly. This is an important step towards slowing down. Global warming..

Below, lead author Sam Avanesie and senior author Rob Jackson will help the history of current global warming potentials and how policy makers readjust their efforts to tackle climate change. I will explain about such things.

Jackson is a professor of energy and environment at Stanford University School of Global Energy and Environmental Sciences Michelle and Kevin Douglas, and a senior researcher at the Stanford Woods Institute for Environmental Studies and the Precoat Energy Institute. Avanesie has a PhD. A student in Applied Physics and Earth Systems Science working in Jackson’s lab.

Why is a 100-year period commonly used as a measure of emissions?

Jackson: Carbon dioxide stays in the atmosphere for thousands of years. Nitrous oxide tends to last for about a century. The life of methane is close to 10 years. The 100-year time frame is a compromise and a convenient number of rounds to allow for the different lifespans of greenhouse gases.

Abernesi: Returning to the initial report of the Intergovernmental Panel on Climate Change, the 20-, 100-, and 500-year periods were used as typical examples of time-selectable periods. It seems that 100 years was chosen for the Kyoto Protocol and its subsequent climate policy, mainly because it is an intermediate value between these three.

If international climate change agreements such as the Paris Agreement target temperature targets, why were they not included in the time range of emission metrics that specifically describe those targets?

Abernesi: That question led me to this study and wrote this dissertation. One answer is that there was no way to do this before a database of potential future climate path scenarios was developed. I think the other aspect is that the goals of the Paris Agreement are ambiguous enough that we need to select one specific aspect to focus on. We saw the temperature target, but we also have the goal of zero net emissions.

How will the 24-year period change the way countries determine their climate change efforts and what the world needs to do to achieve the goals set by the Paris Agreement?

Jackson: We need to reduce carbon dioxide emissions in all near and far scenarios. However, the more aggressive the temperature target, the more important the powerful, short-lived greenhouse gases such as methane. To keep global temperature rise below 1.5 or 2 degrees Celsius above pre-industrial levels (the two goals of the Paris Agreement), countries need to work to reduce methane emissions. In fact, some countries have not yet made any promises of methane.

Abernesi: Using a shorter period, such as 24 years, will change the scale of commitments already made by significantly assessing methane reduction. It will also align the commitment with the temperature targets of the Paris Agreement. This will give countries that have aggressive methane mitigation plans and pledges to take action to reduce methane more highly valued and therefore more incentive.

What are some examples of how and why political perspectives and vested interests support a particular period?

Abernesi: Since the variation release The metric is very large over a period of 20 to 100 years, so there is a great opportunity to use the best numbers for your application. Perhaps countries with huge dairy and agricultural industries will disregard methane and prefer to use a 100-year time frame. Those who want to focus on methane, such as opponents of liquefied natural gas, will prefer the 20-year period.

What are some possible examples of how policy makers can use your approach to plan specific climate goals, such as net zero emissions?

Abernesi: Our approach is specific to policy makers climate Set temperature stabilization goals and use these emission metrics to define the meaning of net zero emissions.

Jackson: The Biden administration’s clear goal is to stabilize global temperature rise below 1.5 ° C. Still, the EPA uses a GWP of 25 methane, which is below the commonly used value over a 100-year period. Value of EPA methane Mitigation measures are at least three times lower than the stage of achieving the administration’s goals.

New ways to compare greenhouse gases may help achieve the goals of the Paris Agreement

For more information:
Global temperature targets need to determine the duration of greenhouse gas emission indicators. Environmental research letter (2022). DOI: 10.1088 / 1748-9326 / ac4940

Quote: Rethink how methane affects climate (February 9, 2022).

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Rethink how to measure the impact of methane on climate

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