I recently posted on the foolish claims of Andrew Bolt that climate change had ceased in 1998. Among the points I made was that Bolt had used work of a certain German institute to back his claims when elementary care would have showed Bolt that, although this institute had argued that the rate of growth in warming might undergo a temporary slowing - the rate of increase was expected to resume and in no way rejected claims that long run climate was driven by atmospheric CO2 levels.
The distinction between medium term climatic trends and longer-term trends are beautifully discussed in the current NewScientist. The editorial to this issue argues that medium term climate forecasts – forecasts over the next 10 years or so - are a function of oceanic temperature oscillations whereas, yes, longer-term changes are driven by CO2 concentrations.
Short-term trends do suggest a future moderation in the rate of temperature increase but this implies nothing at all about longer-term temperature changes which are still inexorably forecast to continue to rise. NewScientist’s argument is that such short-term forecasts should be accurately reported even if sloppy commentators such as Andrew Bolt use this information to try to dispel the anthropogenic global warming hypothesis. Who could sensibly disagree? If temperatures do take a temporary dip this might create a slowing in impulses to manage climate but it is better to try to educate the public on the distinction between medium and long-term trends.
Long-term trends are driven by CO2 concentrations but medium term trends – whether the drought will continue to impact adversely on the Murray-Darling Basin – is a function of what is happening in the oceans. It takes a long time for the temperature of the oceans to change so the ability to predict what will happen iks not an impossibility. Most of the medium term climate on earth results from energy exchanges between oceans and atmosphere rather than overall changes in the temperature of the planet. The drought in Australia is then attributable to low water temperatures north ofr Australia and the expected duration of the drought can be understood by understanding these slowly involving temperatures.
I recommend the NewScientist article – a good read.