In a new climate change report from the Intergovernmental Panel on Climate Change, scientists paint a dire picture of the future of atmospheric warming. The United Nations report predicts global temperatures will rise by more than 1.5 degrees Celsius above pre-industrial levels in the next two decades and points to two gases as the biggest culprits: carbon dioxide and methane. 

Robert Howarth is a professor of ecology and environmental biology at Cornell University and a faculty fellow at Cornell’s Atkinson Center for Sustainability. He studies the greenhouse gas footprint of methane extracted from shale formations such as the Marcellus shale. Howarth authored a study in Biogeosciences demonstrating that increased emissions from the oil and gas industry prompted a global spike in atmospheric methane.

Howarth says:

“Human activity has increased methane proportionately more than carbon dioxide over the past century, and methane levels continue to rise rapidly — driven largely by emissions from fossil fuels and agriculture.

“The IPCC for the first time highlights the importance of reducing methane emissions to meet the UN COP 21 goal established in Paris in December 2015 to keep warming well below 2 degrees Celsius.

“According to the report, it is likely the Earth has already warmed by 1.07 degrees Celsius relative to the period of 1850-1900. Carbon dioxide and methane are the two most important drivers of this increase, with carbon dioxide contributing 0.75 degrees and methane 0.5 degrees. Other greenhouse gases are far less important, and sulfur dioxide emissions have contributed to a cooling of 0.5 degrees.

“Lowering methane emissions is critical to avoid a rapid warming as society reduces carbon dioxide emissions, since reduction in carbon dioxide is accompanied by a decrease in sulfur dioxide emissions.

“Cutting methane emissions by 40 to 45% by 2030 would almost immediately slow the rate of global warming, and shave 0.3 degrees off of the increase in global temperature by 2040, according to a UNEP report from May 2021.”

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