“Methane is far more potent than carbon dioxide as a greenhouse gas, capturing more of the sun’s relative force, but it persists for less time in the atmosphere.” – A news report
Because environmentalists, activists, politicians, and even scientists themselves give more emphasis on carbon dioxide as the primary culprit of climate change, methane has been placed in the sideways.
“Methane has no direct effects on the climate or the biosphere (and) it is considered to be of no importance.” That was what stated in the first survey in 1971 on the possibility of inadvertent human modification of climate. Likewise, the gas was not mentioned in the index of the major climatology book of the time, H.H. Lamb’s “Climate Past, Present and Future.”
It wasn’t until in 2001, when the UN-sponsored 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,” said Dr. Constancio Asis, Jr., a recipient of the 2011 Norman E. Borlaug International Agricultural Science and Technology Fellowship Award.
A bad news: “While carbon dioxide in the atmosphere has increased steadily, methane concentrations grew relatively slowly throughout the 2000s, but since 2007 have grown ten times faster. Methane increased faster sill in 2014 and 2015,” said a report published in www.theconversation.com.
Another bad news: “Remarkably, this growth is occurring on top of methane concentration that are already 150% higher than at the start of the Industrial Revolution (now around 1,834 parts per billion),” the report added.
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 (AFP).
In 2015, the IPCC said methane accounted for about 16% of global greenhouse gas emissions. In comparison, carbon dioxide accounted for more than three-quarters of plant-warming emissions.
“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 was first scientifically identified by Italian physicist Alessandro Volta in 1776. He collected some “flammable air” from the marsh straddling Italy and Switzerland. It wasn’t until in 1778 that he was able to isolate the pure gas. The person credited for naming it as “methane” was German chemist August Wilhelm von Hofmann who derived the name from methanol.
Today, everyone know that 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.
Culprits
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 as a primary food source.
The Global Methane Budget thinks so, too. “The increase is largely driven by the grown in food production,” it says.
One example is rice production. In fact, the IPCC considered rice cultivation as a major contributor to global warming. “An estimated 19% 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.”
Although not all rice is grown in flooded conditions, 90% of rice land globally is at least temporarily flooded. On average, the soil is fully waterlogged for about four months each year.
“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.”
Cattle
Livestock are another major contributor of methane. 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.
President of the National Academy of Sciences 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. The raising of these animals along with sheep, carabao, and swine has contributed to the methane production in the Philippines.
Among these animals, cattle are by far the largest contributors to global enteric methane emissions, as they are the most numerous and have a much larger body size relative to other species such as sheep and goats.
A recent study showed that emissions of methane from livestock are larger than previously thought. An AFP report said: “Revised calculations of methane produced per head of cattle show that global livestock emissions in 2011 were 11% higher than estimates based on data from IPCC.”
Prof. Dave Reay, from the University of Edinburgh, was quoted as saying: “As our diets become more meat- and dairy-rich, so the hidden climate cost of our food tends to mount up.” He added: “Cows belching less methane may not be as eye-catching as wind turbines and solar panels, but they are just as vital for addressing climate change.”
To which Nicholas Stern, author of the 2006 Stern Review on Climate Change, also suggested: ““People will need to turn vegetarian if the world is to conquer climate change.” – (To be concluded)
