The recent global uptick in atmospheric methane levels is confirmed today by new figures from NIWA’s Baring Head station, near Wellington. Southern hemisphere methane rose by 0.7% over the two years 2007-2008. The video above, narrated by tropospheric chemist Katja Riedel gives an inside view of what goes on in and above the Baring Head lighthouse — well worth a view. The increase comes after a three year period when levels had appeared to stabilise, as NIWA’s graph shows:
From NIWA’s press release:
This […] 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 new figures confirm the global picture compiled by NOAA in the US. The increase is thought to be related to a return to wetter conditions in the tropics after a relatively dry period from 1999—2006 and warming in the Arctic. There’s a lot more background information on NIWA’s news page.