Skyrocketing methane emissions raise concerns over climate change targets
Image credit: Daniel Schwen
Emissions of methane, a greenhouse gas 28 times more powerful than CO2, have been sharply rising over the past few years, raising concerns over the efficiency of climate change-beating efforts.
While emissions of CO2 seem to be flattening out, concentrations of methane in the atmosphere have increased by over 10 parts per billion between 2014 and 2015 compared to the situation in the 2000s.
Researchers say that the majority of these emissions comes from agriculture, most prominently from cattle farming and rice cultivation, however, some 30 per cent of those emissions leak from oil and gas wells during drilling.
“For the past two years especially, the growth rate has been faster than for the years before. It’s really intriguing,” said Marielle Saunois, from the University of Versailles Saint Quentin in France, who led the team behind the report published in the journal Environmental Research Letters. “Why this change happened is still not well-understood.”
The rising concentrations of methane may thwart the world's struggle to keep average global temperatures from rising beyond 2 °C compared to pre-industrial times. Climate scientists fear that a higher increase would wreak havoc with the climate, causing severe socioeconomic impact.
The researchers said data reveal a sudden upsurge in methane emissions following a relatively flat period between 2000 and 2006.
“The levelling-off we’ve seen in the past three years for carbon dioxide emissions is strikingly different from the recent rapid increase in methane,” said Professor Robert Jackson, from the US Stanford University, a co-author of the report.
“When it comes to methane, there has been a lot of focus on the fossil fuel industry, but we need to look just as hard if not harder at agriculture. The situation certainly isn’t hopeless. It’s a real opportunity.”
The researchers said the rising methane emissions could be related to the growing number of cows farmed by the global agricultural industry. While in 1994, there were 1.3 billion cows living on the planet, the number has risen to 1.5 billion by 2014.
Rice cultivation in Asia could also be a major contributor.
Some of the gas comes from natural sources such as the melting permafrost.
The team has called for the international community to pay as careful attention to methane emissions as it pays to CO2.
Strategies designed to curb CO2 concentrations in the atmosphere are being implemented all over the world. In the UK, it has been calculated, that energy from wind farms prevented almost 36 million tonnes of CO2 from being emitted into the atmosphere by coal and gas-fired plants over a six year period. The amount is equivalent to taking 2.3 million combustion engine cars from the roads.
The study, by Edinburgh University researchers, claims to be the ‘most accurate of its kind to date’ as it uses real, rather than estimated, energy output figures, detailing figures for every half hour.
The data, coming from National Grid 2008 to 2014 figures, show that the UK government underestimates carbon savings from wind turbines by 3.4 million tonnes, which equals emissions generated by 220,000 cars. On the other hand, the methodology used by the Scottish government overestimates the saving, the study says.
“Until now, the impact of clean energy from wind farms was unclear,” said study leader Camilla Thomson.
“Our findings show that wind plays an effective role in curbing emissions that would otherwise be generated from conventional sources, and it has a key role to play in helping to meet Britain’s need for power in future.”
The analysis was published in Energy Policy and supported by the Engineering and Physical Sciences Research Council.