Concentrations held steady between the 1980s and 2005

Aug 23, 2012 08:56 GMT  ·  By
Fossil fuel reductions are probably responsible for a significant portion of methane’s long-term decline, the relationship between methane and ethane concentrations in the atmosphere indicates
   Fossil fuel reductions are probably responsible for a significant portion of methane’s long-term decline, the relationship between methane and ethane concentrations in the atmosphere indicates

Between the early 1980s and 2005, atmospheric scientists noticed a stagnation in methane concentrations increase high above Earth’s surface. Experts have tried to figure out why this happened ever since, but it's only now that a research group manages to provide a concrete explanation.

Methane amounts increased in the upper atmosphere for decades, simultaneous to global technological and industrial development patterns. However, at one point, the latter continued, while the former stopped. Scientists at the University of California in Irvine (UCI) now believe they know why.

According to the research group, the late-20th century stabilization was caused by the increased capture of natural gas from oil fields. This phenomenon most likely accounts for as much as 70 percent of the methane stagnation.

In a paper published in the August 23 issue of the top scientific journal Nature, the UCI group basically says that a change in fossil fuel use patterns was responsible for limiting the amount of the dangerous greenhouse gas in Earth's atmosphere.

Simulations show that methane (CH4) has around 20 times the warming potential of carbon dioxide (CO2). Fortunately (in a way), there are far lower amounts of CH4 in the air compared to CO2. Unfortunately, extended fossil fuel use is causing CO2 concentrations to increase steadily.

Localized and global atmospheric warming patterns are also attacking peatlands and permafrost at high latitudes. These soils contain billions upon billions of tons of methane stored within. As temperatures increase, the gas is released, further contributing to warming.

“We can now say with confidence that, based on our data, the trend is largely a result of changes in fossil fuel use,” UCI chemistry Professor Donald Blake, the senior author on the Nature paper, says.

He adds that methane – the main compound in natural gas – used to be burned off as a waste product until the 1970s. Beyond that time, it began being used as a power source, or for electricity production.

“The reason this is important is because methane is a potent greenhouse gas, second in importance only to carbon dioxide. We can’t make real progress on climate change without tackling carbon dioxide, but bringing methane under control would certainly help,” Isobel Simpson says.

The expert, a research associate at the university, was the lead author of the new paper. She explains that atmospheric methane levels began increasing again in 2007, for multiple reasons (direct pollution, peatland/permafrost melting, etc.)