Methane emissions are rising but not because of fossil fuels

Could wetlands and agriculture be behind spike in methane levels? Could wetlands and agriculture be behind spike in methane levels? Jason KS Leung
12 Oct
2016
Spiking methane levels are probably due to agriculture and wetlands, not fossil fuels, say experts

‘Major ongoing changes in methane budgets are occurring,’ write the authors of a new report on the sources of methane. Together with the US National Oceanic and Atmospheric Administration (NOAA), a team of atmospheric scientists traced the biggest emitters of methane back to microbial sources. In other words: wetlands, rice paddies and livestock.

‘Our results go against conventional thinking that the recent increase in atmospheric methane must be caused by increased emissions from natural gas, oil and coal production,’ says Euan Nisbet, greenhouse gas researcher at Royal Holloway and co-author of the study.

Methane is a greenhouse gas with powerful effects. Though it only causes around a tenth of total emissions, it traps 30 times more heat than the better-known pollutant, carbon dioxide. ‘Throughout the 20th century, methane was emitted in large amounts by leaks in the coal and gas industries,’ says Nisbet. ‘But by the beginning of this century it appeared that the amount of methane in the air was stabilising.’

cattleCattle grazing in Bahia, Brazil (Image: Ostill/Shutterstock)

However, since 2007 the levels of methane started to grow again and in 2014 the growth rate doubled. ‘The year 2014 was extreme,’ says Nisbet, ‘with large increases seen across the globe.’ According to the research, the emissions have changed location though, now increasing from the tropics and other sources. ‘Tropical wetland or agricultural emissions, or a combination of both, are likely the dominant causes of global methane rise from 2008 to 2014,’ the study notes.

Methane comes from microbes fermenting in the guts of livestock and in the stagnant water of wetlands, both processes which are dependent on the local temperature and rainfall. As the scale and pace of methane rise has been so high – outstripping the pace of wetlands and agriculture expansion in the tropics – the findings point to weather as being the likely cause. Particularly as the tropics have seen increasingly warmer, wetter seasons. For the experts, understanding tropical emissions is vital to predicting the speed of methane rise: ‘is this merely a weather oscillation, or is it a troubling harbinger of more severe climatic change?’ asks Nisbet.

Share this story...

Submit to FacebookSubmit to Google PlusSubmit to Twitter

Related items

Geographical Week

Get the best of Geographical delivered straight to your inbox every Friday.

Subscribe Today

EDUCATION PARTNERS

Aberystwyth UniversityUniversity of GreenwichThe University of Winchester

TRAVEL PARTNERS

Ponant

Silversea

Travel the Unknown

DOSSIERS

Like longer reads? Try our in-depth dossiers that provide a comprehensive view of each topic

  • The Air That We Breathe
    Cities the world over are struggling to improve air quality as scandals surrounding diesel car emissions come to light and the huge health costs of po...
    Diabetes: The World at Risk
    Diabetes is often thought of as a ‘western’ problem, one linked to the developed world’s overindulgence in fatty foods and chronic lack of physi...
    National Clean Air Day
    For National Clean Air Day, Geographical brings together stories about air pollution and the kind of solutions needed to tackle it ...
    The Nuclear Power Struggle
    The UK appears to be embracing nuclear, a huge U-turn on government policy from just two years ago. Yet this seems to be going against the grain globa...
    REDD+ or Dead?
    The UN-backed REDD+ (Reducing Emissions from Deforestation and Forest Degradation) scheme, under which developing nations would be paid not to cut dow...

MORE DOSSIERS

NEVER MISS A STORY - follow Geographical

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...

Geophoto

Iceland is a sparsely populated country with one of the…

Wildlife

Baltic seals and fish-eating bird populations are increasing and could…

Oceans

The UN has committed to completely stopping plastic waste from…

Wildlife

The world’s most endangered marine mammal has just been thrown…

Climate

Sixty-two of the natural World Heritage Sites are now at…

Oceans

In February 2015, maritime lawyer and cold water swimmer Lewis…

Climate

Water, water may be everywhere, but as Marco Magrini discovers,…

Energy

A deeper look at Scotland’s recent decision to ban the…

Climate

The discovery of increasing levels of ozone-depleting compounds being emitted…

Geophoto

November is a dark, quiet month, but it also marks…

Energy

Could human waste one day be fuelling our homes and…

Geophoto

Every year, the LPOTY awards celebrate the best in Britain’s…

Climate

At the 23rd Convention of the Parties (COP) climate change…

Oceans

Knowing where past coral reefs existed is a crucial component…

Oceans

Numerous low-lying Pacific islands have disappeared under rising seas

Oceans

In this exclusive film for Geographical, see how an unusually…

Climate

Marco Magrini considers why the recent devastation caused by hurricanes…

Geophoto

Country borders are some of the most controlled environments on…

Wildlife

Nature reserves and protected areas in Germany have lost 76…

Oceans

An investigation into shark fins and ray gills sold in…