[This post is based on a question I got in response to a previous post but thought it deserved a short post on its own as there's a few interesting points.]
There’s been a lot of bad press recently for climate science but a lot of has focused on very minor issues. For example, most of the coverage on the UEA CRU email leak/theft/hack (so-called climategate) has focused on what some of the “skeptic” community wished was in the emails rather than what was really there. The Guardian has gone over some of the issues from the leak in depth in a recent series of articles, although this seems like a lot of focus on old issues. As Prof. Phil Jones himself said in a recent interview in The Sunday Times: “I wish people would read my scientific papers rather than my emails”. Glaciergate was equally blown out of all proportion given that the original claim only appeared in one sentence in a 3000 page report.
In the midst of all this, Nature printed a nice feature looking at the real big gaps in climate science (Schiermeier 2010), but it is behind a paywall, which is a shame because it’s a good piece. So, I thought I’d provide a very quick summary here.
Regional climate prediction
We still don’t have sufficient computing power to run models at high enough resolution to make projections on the scale that would be useful to policy makers. This is clearly required to make big infrastructure decisions.
Projections of precipitation patterns are really hard to make as they depend on temperature changes, circulation changes, radiative balance changes and pollution (and, therefore, cloud condensation nuclei) changes. Yet precipitation changes will probably have the biggest impact on society.
The effect of aerosols (i.e. small solid particles or liquid droplets suspended in the atmosphere) is a big unknown. Different types do different things and its not really certain whether they have a generally cooling effect – by reflecting away solar radiation – or a warming effect – by promoting more cloud growth and trapping more terrestrial heat. That said, any cooling effect would be very unlikely to reverse the warming impact of greenhouse gases.
The tree-ring controversy
This relates mostly to the “hockey stick” graph and the reliability of the palaeoclimate data we use to put our current climate into perspective. It’s important that we learn from past climate changes as we only have one atmosphere and can’t do experiments with it. But it is not easy to get palaeoclimate data (tree rings, ice cores, sediment cores) or to interpret them properly.
So what is the “consensus”?
In a certain sense, when people talk about the “scientific consensus about climate change” they really mean little more than our understanding of the greenhouse effect, our impact on it and that things are very likely to get messy in the future. All the details are still very much under investigation.
Schiermeier, Q. (2010). The real holes in climate science Nature, 463 (7279), 284-287 DOI: 10.1038/463284a