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NIWA Says Greenhouse Gas Methane On The Rise Again

NIWA Says Greenhouse Gas Methane On The Rise Again

The concentration of methane in the atmosphere is rising, according to measurements made by NIWA.

NIWA has today released measurements from its globally significant Baring Head station showing that southern hemisphere atmospheric methane increased by 0.7% over the two-year period 2007–08. While this increase may not sound like much, it is about 35 times more than all the methane produced by New Zealand livestock each year.

This is significant in that it follows a three-year period of no growth, and accounts for more than half of the growth observed over the ten years 1999–2008 (1.2%). Methane is the second most important contributor to global warming behind carbon dioxide, though its abundance in the atmosphere is far lower. Additional methane traps twenty one times more heat over 100 years than the same mass of carbon dioxide (CO2 ).

“The evidence we have shows that methane in the atmosphere is now more than double what it ever was during the 800,000 years before 1700AD” says NIWA Principal Scientist, Dr Keith Lassey. This is based on analyses of ancient air trapped in polar ice that has been extracted and dated.

The trends observed by NIWA at Baring Head are consistent with global trends. It is the global atmospheric concentration of greenhouse gases that determines the risk of climate change. The US National Oceanic and Atmospheric Administration (NOAA) reported that global methane concentrations rose in both 2007 and 2008 after a ten-year lull.

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NOAA report that drier than normal conditions in the tropics from 1999–2006 probably limited emissions from microbes in tropical wetlands while from 2007 wetter tropics and warmer Arctic conditions have led to increased emissions overall. The wetter tropics were at least partly a result of a La Niña weather pattern of 2007 and 2008.

Other factors are at work in increasing atmospheric methane levels: global growth in commercial livestock farming, mining of fossil fuels, leaks from urban gas networks, and continued burn-offs of tropical rainforest.

ENDS

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