To kick off the new term, how about some new data, just in from the US National Climatic Data Centre, showing annual temperature anomalies up to last year (2011):
A couple of interesting points about this chart. First, it shows clearly that the land has warmed more than the ocean. This is as predicted by the theory: the ocean takes a lot longer to warm up. Notice also that for the land, the different between the temperatures over the last decade and the typical temperatures a century ago is more than +1ºC. Oh, and notice that for the American audience they’ve included temperatures in Farenheit as well as Centigrade. If you’re interested in more, here’s the full report.
Here’s another chart:
This one is from an excellent post over at SkepticalScience.com, “A Comprehensive Review of the Causes of Global Warming“, which looks at a number of recently published papers that weigh up the relative contributions of human influences and natural influences on climate change. Notice that some of these assessments calculate that the natural influence is negative – i.e. we would expect a slight cooling if it weren’t for all those greenhouse gases we’re emitting. By the way, SkepticalScience.com is an excellent place to go to look up what the science says in response to lots of different myths about climate change.
Finally, in preparation for some discussion of climate models, here’s a great introduction to climate modeling, “How do Climate Models Work?“, written by Kate over at ClimateSight. We’ll be discussing some of the things she talks about in class over the next couple of weeks.