Is the claim about Methane valid?

Part 1: Introduction

Carbon dioxide is not the only greenhouse gas whose presence in the atmosphere is blamed on Mankind. Another is methane (CH4). And so, after a mountain of evidence showed that carbon dioxide levels above 300 ppm do not cause global warming, [1] climate fear-mongers looked for another man-made product that might bolster their cause. They came up with methane as an even more serious ‘warmer’ than carbon dioxide. And methane levels, we are told, have already doubled. The main ‘new’ sources of methane are from our agriculture, largely from our herds of cattle and from flooded rice paddies. Adding to these, but in smaller amounts, are emissions from waste dumps and leaks from coal mining and natural gas production.

The IPCC’s Summary for Policy Makers 2007 stated:

‘The global atmospheric concentration of methane has increased from a pre-industrial value of about 715 ppb to 1732 ppb in the early 1990s, and is 1774 ppb in 2005. The atmospheric concentration of methane in 2005 exceeds by far the natural range of the last 650,000 years (320 to 790 ppb) as determined from ice cores. Growth rates have declined since the early 1990s, consistent with total emissions (sum of anthropogenic and natural sources) being nearly constant during this period. It is very likely that the observed increase in methane concentration is due to anthropogenic activities, predominantly agriculture and fossil fuel use, but relative contributions from different source types are not well determined.’[2]

As a consequence, many ‘warmers’ took note of the first part of this, neglecting the latter half, and called for humans to reduce their intake of meat. Naturally, vegetarians also climbed on the bandwagon, and there was a spate of newspaper articles in western countries.

The case against methane stems from a claim that past emissions currently contribute 15-20% of the enhanced greenhouse effect and reinforced by another: that, although it started later than the rise in CO2, a current large increase in emissions of methane means that its contribution has been catching up fast despite the fact that a recent study by Dlugokencky, et al shows that atmospheric methane was at a steady state of 1751 ppbv between 1999 and 2002.”[3] EPA used ppbv (parts per billion by volume) because that gives a much bigger number (1.75 parts per million looks a bit insignificant compared to 385 parts per million for CO2).

Methane, then, has given the ‘warmers’ something else to attack in our society.

And we should all become veges to save the planet.

But how important is methane as far as possible climate change effects?

Part 1: Introduction | Part 2:The IPCC’s Argument | Part 3: Methane chaos | Part 4: Science and references