Before I write the second part of my discussion on drawing down atmospheric CO 2 , I thought I would promote this comment to a post. It’s highlighting a recent talk (video at the end of this post) by Kevin Anderson, Professor of Energy and Climate Change at the University of Manchester.

Kevin’s talk is very interesting and focuses on many of the things that I’ve been trying to highlight myself. Our current understanding is that how much we warm will depend largely on how much we emit, in total. If there is some level warming that we would like to have some chance of staying below (say 2oC) then that sets a carbon budget; it’s not that we have to get our annual emissions below some level, it’s that we have to ensure that our total/cumulative emissions don’t exceed this budget.

This is where it gets difficult. For 2oC we’ve already emitted more than half of the budget, and are currently running through the remaining budget at around 20-25% per decade. Hence, this isn’t something for the future; it’s something we have to start dealing with now (if we want to achieve it). Also, if we want to allow developing nations more time to grow first, and then address this later, the constraints on the developed world become even stronger.

What Kevin also points out is that most credible people think that a rise of 4oC would have almost catastrophic impacts; “we should avoid this at all costs“. This has implications for economic modelling: how do you cost something that we should avoid at all costs? It also suggests that if staying below 2oC is already going to be very difficult, continuing along our current emission trajecory will make it increasingly difficult to stay below 4oC – a level of warming that most regard as something we should avoid at all costs.

Kevin also discusses various options, like nuclear; showing that even though nuclear would be a very low carbon solution, we would need – if we want nuclear to provide a significant fraction of our future energy needs – to be building many more reactors than we currently are. Kevin’s talk also illustrates – I think – why many are very reluctant to accept the basic situation. Given our current understanding, it seems as though it will be very difficult – if not impossible – to address this without making significant changes to our lifestyles and standards of living. It seems highly unlikely that we will choose to do so. The consequence of this could then be that we will end up risking a level of warming that most regard as something that we should avoid at all costs, or we will eventually be forced to do things that, today, we would regard as unacceptable. The ultimate Catch-22. Of course, we could – I guess – just be lucky.

As usual, I’ve written far too much. If you’re interested in more, though, watch the video!