Methane warms climate even more than previously thought
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Methane’s contribution to the global warming is higher than previously thought because the greenhouse gas’s true climate warming potential has so far been underestimated, new research has revealed.
According to a study led by researchers from the University of Reading, methane, the main component of natural gas, is actually 32 times more potent as a climate warming agent than carbon dioxide, instead of 28 times as previously believed.
That means that methane’s contribution to global warming is 25 per cent higher than previously estimated.
Tackling man-made methane emissions is therefore even more important if the continuing climate change is to be halted.
The study, published in the latest issue of the journal Geophysical Research Letters, revealed that in addition to absorbing infrared energy emitted by the Earth, methane also absorbs thermal energy from solar rays as they reach the lower parts of the atmosphere.
“Clouds play a particularly important role in causing this enhanced warming effect,” said Professor Ellie Highwood from the University of Reading, one of the co-authors of the study.
“Clouds reflect some of the sun’s rays back towards space, but by absorbing some of these scattered rays low down in the atmosphere, methane has an extra warming effect – a factor that was not considered by earlier studies.”
Methane, while much scarcer in the atmosphere than the number one climate-change culprit carbon dioxide, has long been feared for its climate warming potency. The modern civilisation has caused an increase in concentrations of the gas in the atmosphere through agriculture, especially cattle farming and rice cultivation. However, methane also leaks from oil and gas wells.
Available data suggest that concentrations of methane in the atmosphere have more than doubled since the 18th century. The contribution of man-made methane emissions to global warming is about one third of that of carbon dioxide emissions.
“These new calculations are important, not only for quantifying methane’s contribution to human-induced climate change, but also for countries looking to reduce their emissions to meet international targets on climate change, especially if those countries are significant emitters of methane,” said Professor Keith Shine, Regius Professor of Meteorology and Climate Science at the University of Reading.
“Our research re-affirms the scientific basis for focusing on carbon dioxide emissions, but also highlights that methane must not be ignored if the world wants to consider all options to curb global warming.”
The news is even more worrying as recent data suggests that global methane emissions are sharply rising, unlike emissions of carbon dioxide, which have flattened out over the past few years.
Between 2014 and 2015, concentrations of methane in the atmosphere have increased by over 10 parts per billion compared to the situation in the 2000s.
Researchers say that the majority of these emissions comes from agriculture, predominantly from cattle farming and rice cultivation; however, some 30 per cent of those emissions leak from oil and gas wells during drilling.