Cutting methane emissions

By Henrylito D. Tacio
“Obama to create first methane limits for gas drilling.” That’s the title of a recent news report dispatched by the Associated Press.
Relying on the Clean Air Act, the administration of President Barack Obama “laid out a blueprint for the first regulations to cut down on methane emissions from new natural gas wells, aiming to curb the discharge of a potent greenhouse gas by roughly half.”
According to the report, the White House set a new target for the United States to cut methane emissions by 40 percent to 45 percent by 2025, compared to 2012 levels. “To meet that goal,” wrote Josh Lederman, author of the report, “the Environmental Protection Agency will issue a proposal affecting oil and gas production, while the Interior Department will also update its standards for drilling to reduce leakage from wells on public lands.”
“There are significant, highly cost-effective opportunities for reducing methane emissions from this sector. We’re confident we can do this in a cost-effective way,” Dan Utech, Obama’s climate and energy advisor, was quoted as saying.
Why is there so much ado about methane? In the past, it was not given much prominence in climate change meetings. In fact, it was not mentioned in the early days of the issue.
“Methane has no direct effects on the climate or the biosphere (and) it is considered to be of no importance,” concluded the first survey in 1971 on the possibility of inadvertent human modification of climate. Likewise, the gas was not cited in the index of the major climatology book of the time, H.H. Lamb’s Climate Past, Present and Future.
It wasn’t until 2001, when the Intergovernmental Panel on Climate Change (IPCC) submitted its report, that methane was given much attention. “One of the most potent greenhouse gases on Earth,” the report said.
“Methane absorbs heat 21 times more than carbon dioxide and it has 9-15 year life time in the atmosphere over a 100-year period,” says Dr. Constancio Asis, Jr., a recipient of the 2011 Norman E. Borlaug International Agricultural Science and Technology Fellowship Award.
The Journal Science reported that atmospheric concentration of methane has more than doubled during the last 300 years and is increasing at an annual rate of about 1 percent each year.
Another study, which appeared in the journal Geophysical Research Letters, said that methane’s effect on warming the world’s climate may be double what is currently thought. The new interpretations reveal methane emissions may account for a whopping third of the climate warming “from well-mixed greenhouse gases” between the 1750s and today.
Both carbon dioxide and methane are considered greenhouse gases (GHGs), which also include chlorofluorocarbons (CFCs) from air conditioners and refrigerators, and the nitrogen compound, nitrous oxide, from burning fossil fuels and fertilizers. Ground-level ozone, produced by burning fossil fuels, is also considered a greenhouse gas.
“Even if we were able to stop them tomorrow, these greenhouse gases will continue to have an effect for centuries,” Secretary-General Michel Jarraud of the UN World Meteorological Organization said in a statement quoted by the Agence France Presse.
“What has fueled the rapid rise of methane from an obscure trace gas to a major factor in past, present and future climate change?” wondered Dr. Gavin Schmidt, a research scientist at the NASA Goddard Institute for Space Studies and Center for Climate Systems Research, Columbia University in New York.
First some basics: methane is a very simple molecule (one carbon surrounded by four hydrogen atoms) and is created predominantly by bacteria that feed on organic material. “In dry conditions, there is plenty of atmospheric oxygen, and so aerobic bacteria which produce carbon dioxide are preferred,” explained Dr. Schmidt.
But in wet areas such as swamps, wetlands and in the ocean, there is not enough oxygen, and so complex hydrocarbons get broken down to methane by anaerobic bacteria. “Some of this methane can get trapped (as a gas, as a solid, dissolved or eaten) and some makes its way to the atmosphere where it is gradually broken down to carbon dioxide and water vapor in a series of chemical reactions,” Dr. Schmidt said.
An article written by William F. Ruddiman explores the possibility that methane emissions started to rise as a result of anthropogenic activity 5000 years ago when ancient cultures started to settle and use agriculture, rice irrigation in particular, as a primary food source.
“Rice is a plant that grows best in wet soil, with its roots flooded,” explains L. Hartwell Allen, an American soil scientist at the Crops Genetics and Environmental Research Unit in Gainesville, Florida. “But flooded rice crops emit substantial amounts of methane to the atmosphere.”
In fact, rice fields are one of the major contributors of methane in the atmosphere. “An estimated 19 percent of world’s methane production comes from rice paddies,” admits Dr. Alan Teramura, a botany professor at the University of Maryland. “As populations increase in rice-growing areas, more rice – and more methane – are produced.”
Livestock are another major contributor of methane from farming. In 2006, the amount of methane emitted by farm animals alone exceeded that of the iron, steel, and cement industries combined. “Livestock are one of the most significant contributors to today’s most serious environmental problems,” said Henning Steinfeld, a senior UN official.
National Academy of Sciences president Ralph Cicerone has indicated the contribution of methane by livestock flatulence and eructation to global warming is a “serious topic.” Cicerone, an atmospheric scientist, said: “Methane is the second-most-important greenhouse gas in the atmosphere now. The population of beef cattle and dairy cattle has grown so much that methane from cows now is big. This is not a trivial issue.”
The digestive system of ruminant animals such as cattle and goats contain anaerobic bacteria and thus produce methane gas. A single cow belches out 100 gallons of methane gas a day.
“Over the last 30 years, methane has gone from being a gas of no importance, to — in some researchers’ eyes, at least — possibly the most important greenhouse gas both for understanding climate change and as a cost-effective target for future emission reductions,” noted Dr. Schmidt, who works on models of the climate system and their application to problems of past, present and future climate change.
Today is the right time to control methane emissions. “If we control methane, which is viable, then we are likely to soften global warming more than one would have thought, so that’s a very positive outcome,” said Dr. Drew Shindell, a climatologist at NASA’s Goddard Institute for Space Studies, Columbia University in New York.