Saturday, August 14, 2021

The IPCC Understated the Need to Cut Emissions From Methane and Other Short-Lived Climate Pollutants, Climate Experts Say

Also, note that methane decays to carbon dioxide, a long-lived greenhouse gas.


 By Phil McKenna
August 12, 2021


The Intergovernmental Panel on Climate Change missed a key opportunity to underscore the urgent need for rapid reductions in emissions of methane and other short-lived climate pollutants in the roll out of a seminal report on the science of climate change on Monday, climate experts say.

The report, the first installment of the IPCC’s Sixth Assessment Report, included the United Nations body’s starkest warnings yet on the increasing impacts of climate change, which are manifested in this summer’s floods, wildfires and heat waves.

But even if the IPCC missed an opportunity to underscore the need to quickly address methane, a White House climate advisor said reducing emissions of the gas is a top priority for the Biden Administration.  

The assessment included a chapter on methane and other short-lived climate pollutants (SLCPs), something previous assessments had not. SLCPs are greenhouse gases and other pollutants that typically remain in the atmosphere for less than two decades, unlike carbon dioxide which can remain in the atmosphere for centuries. Carbon dioxide is the primary driver of climate change, but SLCPs can be far more potent—hundreds to thousands of times more effective at trapping heat in the atmosphere than carbon dioxide. 

And an executive summary for policy makers of the nearly 4,000-page report noted that “strong, rapid and sustained reductions” in emissions of methane, the short-lived climate pollutant that has contributed the most to climate change, would “limit the warming effect.”

However, the 41-page summary otherwise focused almost exclusively on the impact that carbon dioxide has and will continue to have on the climate. The near-exclusive focus on carbon dioxide in the summary for policymakers stands in stark contrast to a recent United Nations report that concluded that methane reductions are the best, and perhaps the only, way to reduce global warming in the near-term.

“I’m disappointed that they left so much work to the policymakers to have to interpret,” Durwood Zaelke, president of the Institute for Governance and Sustainable Development, said. Zaelke served as a peer reviewer of the full IPCC report but did not review the summary for policymakers. “It’s going to be up to the scientists working for the government to be able to pull out the focus on methane and other short-lived climate pollutants.”

IPCC spokeswoman Katherine Leitzell said this week’s “Working Group I” report on the science of climate change was the first of three reports. More information on methane and other short-lived climate pollutants will be included in the third report, she said, which focuses on mitigating climate change and is due out early next year.

“The aspects related to methane are indeed limited, and focused on the climate system response to a set of five scenarios for greenhouse gas emissions,” Leitzell said.  “However, there is an entire chapter (Chapter 6) dedicated to SLCFs (short-lived climate forcers) and their influence on the climate system, for the first time in a WGI (Working Group I) report.”


The chapter also notes that methane and other short-lived climate pollutants released this year will have “at least as large” an impact on climate change over the next 10 to 20 years as current carbon dioxide emissions.

The extreme potency, combined with the limited time these pollutants stick around in the atmosphere, mean that efforts to reduce their emissions will have a significant and almost instantaneous climate impact. Conversely, there is a lag of 20 to 30 years before  the effects on the climate of reductions in carbon dioxide emissions are apparent. This is due in part to the long atmospheric lifetime of carbon dioxide; even if you stop emitting CO2 today, carbon dioxide that has already accumulated in the atmosphere will remain there for centuries. 



No comments:

Post a Comment