By Hiroko Tabuchi
A landmark United Nations report is expected to declare that reducing emissions of methane, the main component of natural gas, will need to play a far more vital role in warding off the worst effects of climate change.
The global methane assessment, compiled by an international team of scientists, reflects a growing recognition that the world needs to start reining in planet-warming emissions more rapidly, and that abating methane, a particularly potent greenhouse gas, will be critical in the short term.
It follows new data that showed that both carbon dioxide and methane levels in the atmosphere reached record highs last year, even as the coronavirus pandemic brought much of the global economy to a halt. The report also comes as a growing body of scientific evidence has shown that releases of methane from oil and gas production, one of the biggest sources of methane linked to human activity, may be larger than earlier estimates.
The report, a detailed summary of which was reviewed by The New York Times, singles out the fossil fuel industry as holding the greatest potential to cut its methane emissions at little or no cost. It also says that — unless there is significant deployment of unproven technologies capable of pulling greenhouse gases out of the air — expanding the use of natural gas is incompatible with keeping global warming to 1.5 degrees Celsius, a goal of the international Paris Agreement.
The reason methane would be particularly valuable in the short-term fight against climate change: While methane is an extremely potent greenhouse gas, it is also relatively short-lived, lasting just a decade or so in the atmosphere before breaking down. That means cutting new methane emissions today, and starting to reduce methane concentrations in the atmosphere, could more quickly help the world meet its midcentury targets for fighting global warming.
By contrast, carbon dioxide, the main greenhouse gas, lasts for hundreds of years in the atmosphere. So while it remains critical to keep reducing carbon emissions, which make up the bulk of our greenhouse gas emissions, it would take until the second half of the century to see the climate effects.
Over all, a concerted effort to reduce methane from the fossil fuel, waste and agricultural sectors could slash methane emissions by as much as 45 percent by 2030, helping to avoid nearly 0.3 degrees Celsius of global warming as early as the 2040s, the report says.
While cutting back on carbon dioxide emissions will remain urgent, “it’s going to be next to impossible to remove enough carbon dioxide to get any real benefits for the climate in the first half of the century,” said Drew Shindell, the study’s lead author and a professor of earth science at Duke University. “But if we can make a big enough cut in methane in the next decade, we’ll see public health benefits within the decade, and climate benefits within two decades,” he said.
“We’re still going wildly in the wrong direction, but we can turn that around very, very quickly,” Dr. Shindell said. “We could all use a climate success story.”