What the *? Should we be enticed by GWP*?.

Posted by on Aug 16, 2021 in Articles, Blog | 2 comments

Quantifying the effect of greenhouse gases (GHGs) on global warming, such as methane helps us to understand where we can best focus our efforts to combat climate change. Here I will be discussing the strengths and weaknesses of the way we measure greenhouse gas impacts for the second most significant gas, methane – whose inexorable rise is shown left.

There are well over 100 different GHGs, each having a varying warming effects – that is to say they absorb infrared light to different extents and in different parts of the electromagnetic spectrum. The lifetime of these gases in the atmosphere differs a lot: some like methane, CH4, are broken down by chemical processes in a relatively short time, around 12 years, and others like sulfur hexafluoride, SF6, are very long-lived, taking in the order of 3,200 years to be eliminated.

For carbon dioxide, CO2, there are a number of different ways that it is removed from the atmosphere, some relatively fast like dissolution in sea water over 30-80 years, and some very slow, such as weathering reactions with rocks over hundreds or thousands of years, so precisely pinning down its lifetime is still to be done. As a result CO2 is generally assumed to have a lifetime of at least a hundred years.

A further complication is that some of the breakdown products of these gases may be GHGs in their own right, for example, methane eventually breaks down into long-lifetime carbon dioxide (through a series of intermediate chemical processes primarily involving radical chemistry in the stratosphere) and water, with a very short lifetime, meaning that even after it has decayed, methane has a residual warming effect with variable persistence.

To simplify the process of calculating the combined effects of lots of different emissions, we have created a measure called the Global Warming Potential, GWP, for each of the greenhouse gases.

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The danger of perfection & the Manchester Climate Change Agency

Posted by on Aug 13, 2021 in Articles, Blog | 0 comments

In the week where the IPCC has issued its Sixth Assessment Report (AR6) which contains its starkest warning yet[1] about the risks from climate change and the urgency for action, I find myself thinking back to recent job application I was unsuccessful at.

I should point out that I am not really looking for a full-time role at this point. However, the job in question was for Director of the Manchester Climate Change Agency which has intrigued me ever since it was advertised at the back end of last year.

With the re-advertisement of the role, I thought a lot about how one might facilitate a process of decarbonization at a city-wide level and I did some background research on the Agency. In particular, I very much agreed with the Agency’s partnership approach, rather than a top-down or command-and-control style. So I threw my hat into the ring for the job. I should point out that I did have also some very considerable misgivings, which I intended to raise in the interview process, if I ever got that far.

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