Thursday, 29 May 2014

Trying to understand Climate Change (I)

There is no doubt that climate change is becoming one of the most important issues on the news agenda, and rightly so: if there's one thing we can be sure about, it's that this is an issue that needs to be addressed. But, beyond that, I find it very hard to understand what's going on. What exactly is causing climate change? How exactly is our climate changing? And what should we, as individuals and as a global society, do about it?

There are a few reasons I think that make this such a complex topic. Firstly, there are numerous components to our climate system, and the components are notoriously 'chaotic' (i.e. if the model used to make predictions is just slightly inaccurate, the resulting predictions may be wildly inaccurate). As such, the exact details of the issue at hand tend to be vague and uncertain. Secondly, because the issue is not exactly clear, it's hard to know how to address it: should we attempt to resolve it, or is mitigation the most we can hope for? How much do we need to reduce our CO2 emissions by to be safe? And some questions are made even more complex by the political agendas surrounding them: Should we invest in renewables or is nuclear a better alternative? How much responsibility should lie with developing nations compared to developed nations?

What I'd like to do is start looking into these issues more, to gain a better understanding of what our best science tells us is going on. So I've started by looking at the papers from the IPCC (Intergovernmental Panel on Climate Change), who aim to provide a rigorous and balanced scientific view on climate change and its impacts. In particular, I've taken a look at their most up-to-date report, the Fifth Assessment report, in order to help me get a better understanding of the scientific consensus.

I've picked out a few claims from the report that I think set the landscape for how our best science views climate change. You'll see that claims have been usefully qualified by confidence and probabilistic measures:
  • "Warning of the climate system is unequivocal...The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentration of greenhouse gases have increased."
  • "It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century."
  • "Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions."
  • As a result of the changes in climate in the recent decades, with high confidence: a large fraction of terrestrial and freshwater species face increased extinction; and low-lying areas will increasingly experience adverse impacts such as submergence, coastal flooding, and coastal erosion. 
  • In addition, also with high confidence, all aspects of food security are potentially affected by climate change; and climate change is expected to lead to increases in ill-health in many regions and especially in developing countries with low income, as compared to a baseline without climate change.
I'm sure none of this is a surprise to you, and it wasn't much of a surprise to me either. But, for me, seeing these claims in a well-reputed scientific report, rather than as second-hand claims in an article (or blog-post!) certainly helped give these claims more grounding.

And that comment, I think, touches upon another reason that makes climate change such a complex topic: it's so hard to know whether what you read and hear is true, or whether it has in some way been corrupted, either intentionally or inadvertently. Indeed, as suggested by George Monbiot's recent criticism of James Lovelock's latest book, even the most highly-respected sources may get their facts wrong.

So on that note, here are the links to the original documents of the IPCC's Fifth Assessment Report - or at least their Summary for Policy Makers - for you to take a look at yourself:

Part 1: The Physical Science Basis
Part 2: Impacts, Adaptation and Vulnerability
Part 3: Mitigation of Climate Change

And here is the link to the website:

Next time, I'll be looking at the ideas of the fascinating and sparky James Lovelock so keep a look out.

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