Sunday, May 27, 2007

Still confused on climate science? Read this.

A few days ago, on the networking site LinkedIN, someone asked the question: do you believe in climate change? Of course, climate science is not a matter of beliefs of opinions. But I thought it would be worth answering the question, especially given that many of the users of the site, who also posted their answers, seemed a bit confused by the conflicting views they hear in the media.

This is what I answered. I think it might generally be useful as a starting point for anyone who is still in doubt.

The science of climate change is now so solid, that there isn’t much of a point discussing whether or not the climate is changing and if it’s caused by humans, in the same way we wouldn’t discuss here whether smoking causes cancer or not.
Even governments like the US have accepted the reports by the world’s main authority on this issue, the Intergovernmental Panel on Climate Change (IPCC), and recognise the impact humans are having on the atmosphere. What the US is still debating is what precisely to do about it.

For those who are still feeling sceptical or "agnostic" about the science – which is a normal reaction to have, given the unthinkable nature of what scientists are saying – I would recommend this page from the New Scientist magazine. These are very good for addressing some of the common concerns that were expressed in some of the previous answers.

If you want to go a bit further, you can browse this page from Real Climate, a website run by scientists, which has links to further useful sources of information:

Your question asking whether we need to tackle climate change or adapt to it is interesting. The answer is that we need both. No matter what decision politicians take now, and even if we were to stop all greenhouse gas emissions immediately – which is clearly not possible – we would still have a certain degree of climate change because of the emissions that have gone into the atmosphere for many years, and which will continue to have an impact on the climate.

To the inevitable changes we will have to adapt, for example by adjusting our agricultural practices, making our infrastructure, housing and cities more resilient to heat waves or water shortages and resettling people who will be at risk from sea level rise. At the same time, we have to make a decision of what level of climate change – and what level of damages to nature, economies and society -we are really prepared to accept.

Temperatures could increase by the end of the century by less than 2 degrees Celsius, or by 3, 4 and up to 5-6 degrees. The temperature increase is linked to the so-called concentration of greenhouse gases in the atmosphere that we (or rather, our elected politicians) will eventually agree to aim for. The difference between a 2 degree Celsius change and a 5 degree change is enormous.

Based on the state of the science, many policy makers have identified 2 degrees as a critical threshold. Although at this level changes will be very serious for some countries (especially very poor ones, that have fewer means to adapt to changes in food production, for example), they will be relatively more manageable than changes above this temperature.

Here is a link to a useful and clear illustration of what difference temperature changes mean in terms of what impacts they will have (pdf document).

That’s why keeping temperature increases below that 2 degree Celsius threshold is the official goal of the European Union, and why the US has been asked to discuss it. For the time being, the US has not committed to any specific temperature goal or greenhouse gas concentration goal. But eventually it will have to.

I personally think it is very important for LinkedIN users (and society at large, of course) to be able to discuss their government positions on this issue in a well-informed way. No matter what people do for a living, chances are that at some point virtually everybody have to put in practice measures to reduce emissions, or to adapt to changes, both in their professional and personal life.

These issues are rapidly moving away from being “just for the specialists” to something that affects everyone – and rightly so. For those who have children, it may also be useful to try to think about what a temperature change of 2, 3, 4, 5 or 6 degrees will really mean for them.