While carbon dioxide remains the undisputed chief offender behind recent climate change, other greenhouse gases – methane, ozone-depleting substances, and nitrous oxide – also measurably contribute to the crisis.
Today, CO2’s warming influence is equivalent to the heat from nearly nine trillion 100-watt incandescent light bulbs placed across Earth’s surface. The combined influence of the other greenhouse gases is equivalent to the heat from about five trillion bulbs.
A new study, conducted by scientists Stephen Montzka, Ed Dlugokencky, and James Butler of NOAA‘s Earth System Research Laboratory in Boulder, Colorado – and published online this week in Nature—shows that taking active steps to reduce emissions of those other gases could slow down anticipated changes in the environment.
“We know that recent climate change is primarily driven by carbon dioxide emitted during fossil-fuel combustion, and we know that this problem is going to be with us a long-time because carbon dioxide is so persistent in the atmosphere,” Montzka said. “But lowering emissions of greenhouse gases other than carbon dioxide could lead to some rapid changes for the better.”
But is it possible?
Scientists know that stabilizing the warming effect of CO2in the atmosphere would require a decrease of about 80 percent in human-caused CO2 emissions – in part because some of the carbon dioxide emitted today will remain in the atmosphere for thousands of years. In contrast, cutting all long-lived non-CO2 greenhouse gas emissions by 80 percent could diminish their climate warming effect substantially within a couple of decades. Cutting both CO2 and non-CO2 greenhouse gas emissions to this extent could result in a decrease in the total warming effect from these greenhouse gases this century, the new paper shows.
The new review paper describes the major human activities responsible for these emissions, and notes that such steep cuts (80 percent) would be difficult. Without substantial changes to human behavior, emissions of the non-CO2 greenhouse gases are expected to continue to increase.
The scientists also noted in the paper the complicated connections between climate and greenhouse gases, some of which are not yet fully understood. The non-CO2 gases studied have natural sources as well as human emissions, and climate change could amplify or dampen some of those natural processes, Dlugokencky said. Increasingly warm and dry conditions in the Arctic, for example, could thaw permafrost and increase the frequency of wildfires, both of which would send more methane and carbon dioxide into the atmosphere.
“The long-term necessity of cutting carbon dioxide emissions shouldn’t diminish the effectiveness of short-term action. This paper shows there are other opportunities to influence the trajectory of climate change,” Butler said. “Managing emissions of non-carbon dioxide gases is clearly an opportunity to make additional contributions.”
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Cheryl Kaften is an accomplished communicator who has written for consumer and corporate audiences. She has worked extensively for MasterCard (News - Alert) Worldwide, Philip Morris USA (Altria), and KPMG, and has consulted for Estee Lauder and the Philadelphia Inquirer Newspapers. To read more of her articles, please visit her columnist page.Edited by
Jennifer Russell
