Improving climate models and predictions
Francis Sedgemore, Monday 2 November 2009
You may find this difficult to believe, but climate science is not conducted within the pages of the Guardian or Daily Mail, or on the websites of the world’s more opinionated bloggers. But for those without ready access to the ongoing debate among scientists, one could be forgiven for thinking that it is. Even the sagacious Clive James is at it now (“I’m not a climate scientist, but…”).
Climate predictions rely on models of the Earth’s atmosphere, and models are, owing to the complexity of the natural world and the limited computational power at our disposal, idealised representations of reality. However, simplified though they can sometimes be, climate models are subject to continuous development and refinement as we learn more about the Earth system. Uncertainties in the predictions made with the aid of models are thereby reduced.
Contrary to the claims of anthropogenic climate change sceptics and outright deniers, the science of global warming is settled. What continues to be debated are the finer details of the processes involved and their complex interactions. These are of course crucial, and there is much discussion within the Earth science community about uncertainties in climate models, and the impact these have on predictions which will have huge social and economic ramifications.
In a recent issue of the American Geophysical Union’s house journal Eos, Columbia University researcher Lisa Goddard and others discuss among other things the issue of uncertainty, and the difficulty in making predictions with climate models.
“Although scientific effort never will eliminate uncertainty, it can better estimate uncertainty. This is especially true at the time scales of seasons to decades, which are the most actionable time scales. These are the time scales at which incremental adaptation can evolve with the help of appropriate state-of-the-art climate predictions.”
Goddard and her colleagues go on to stress that climate science is inherently probabilistic in nature, and, as such, individual models cannot be used for point-specific climate forecasting. This crucial point must be hammered into the dense skulls of pundits and policymakers who cannot seem to cope with anything other than simple, binary logic. What is needed, say the authors, is for decision makers to learn how to treat information about future climate as a range of possibilities.
Eos is available only to members and affiliates of the AGU, and owing to copyright restrictions I cannot reproduce the entire Goddard et al. article here. This is unfortunate, as in my opinion it would help raise the public’s awareness and understanding of climate change to have such discussions among experts visible in the public domain.
Further reading
Goddard et al., “The Urgent Need for Improved Climate Models and Predictions”, Eos 90, 343 (2009)
Feed the writer! 
Monday 2 November 2009 at 15:56 UTC
I’m genuinely trying to come to a view on this, though I lean towards scepticism. You say ‘the science of global warming is settled’. Can you please be more specific?
Do you think it’s settled that man-made carbon is definitely affecting temperature?
Or are you making the more urgent point that the above is true and that this will lead to dangerous rises in temperature?
I’m a historian by training and the layman’s problem that I have with the global warming case is that, at least in this country, the wine-producing warmth of the medieval period and the mini-ice age of the 16th century both pre-date carbon emissions. Why should temperature changes have a different cause this time and also be so much more dangerous for us?
I do realise this debate is being conducted pretty much permanently somewhere on the internet but it would be nice to read something from a known and trusted source!
Monday 2 November 2009 at 16:02 UTC
“Do you think it’s settled that man-made carbon is definitely affecting temperature?”
Yes; observed climate change cannot be explained otherwise, given our understanding of atmospheric and oceanic physics and chemistry. Natural variations are smaller in scale, and much slower than what we are observing.
The Mediaeval warm period and mini ice age were regional, not global phenomena, and are thus irrelevant.
Monday 2 November 2009 at 16:18 UTC
How do we know the Mediaeval warm period and mini ice age were regional not global? I was under the impression that the evidence pointed to the little ice age occurring in various parts of the globe.
Conversely, how do we know the current data are global not regional?
Monday 2 November 2009 at 16:42 UTC
Because the records available show it to be the case. And in the future, with a globally warming planet, we might well see regional exceptions to the rule, possibly including another little ice age.
The little ice age was a less than one degree cooling of the northern hemisphere, relative to late 20th century levels, with particularly cold snaps confined to particular regions. Regional variations such as this are in large part due to changes in atmospheric and oceanic circulation.
As for the modern day, we have temperature sensors everywhere across the planet, including radiometers aboard Earth-observing satellites that give us ocean surface temperatures to 0.1 degree accuracy. Putting together a global average temperature is a complex, statistical process, but one well understood and reliable.
Monday 2 November 2009 at 16:47 UTC
Thanks
Tuesday 3 November 2009 at 18:24 UTC
Historicism relies on models of human behaviour, and models are, owing to the complexity of the human mind and the limited computational power at our disposal, idealised representations of reality. However, simplified though they can sometimes be, these Hegelian theories are subject to continuous development and refinement as we learn more about the patterns inherent in all events. Uncertainties in the predictions made with the aid of models are thereby reduced.
Bit unfair, I know, but just saying. “Reduction in uncertainty” is nothing to boast about.
Tuesday 3 November 2009 at 18:33 UTC
“Reduction in uncertainty” means increased accuracy, or making the error bars smaller. That is a lot to boast about!
Comparing scientific methodology with some idle thoughts thunk up by some tortured soul during an extended lunch is more than a bit unfair.
Wednesday 4 November 2009 at 13:59 UTC
Are there any sceptics worth paying attention to?
For example, Roy Spencer had a post the other day which left me feeling uncertain.
Wednesday 4 November 2009 at 14:24 UTC
There is a consensus among jobbing climate scientists that the bulk of observed climate change is due to human influence. But at the same time there is lively debate about the details, just as there should be. To my mind, “climate sceptics” are to “climate change deniers” as “intelligent design” is to “creationism”.
And, on that note, Roy Spencer has spoken of “intelligent design” in sympathetic tones, contrasting this with “evolutionism”. He has said:
These are the words of a man who clearly has no understanding of the scientific theory of evolution by natural selection. If you’re asking if I take him seriously, the answer is no, I do not.
The words of Spencer quoted above are largely content free, and begin with a statement which simply isn’t true. The analysis of complex systems is a challenging pursuit, but categorical statements such as that made by Spencer cannot be justified. He is also misrepresenting the IPCC scientists who contributed to the AR4 report.
The problem, when it comes to the public’s understanding of the Earth’s climate, is that climate change deniers and so-called “sceptics” are addressing themselves to an almost exclusively lay audience – i.e., they are putting the climate science community on trial in the court of public opinion, and, given the way the media and polity work, one denier can have the same public influence as a large number of research-active experts.
Deniers and sceptics employ tried and tested rhetorical devices to shift the goal posts when their arguments are shown up for what they are, and have no shame in distorting science for ideological ends.
Friday 6 November 2009 at 20:25 UTC
“What continues to be debated are the finer details of the processes involved and their complex interactions.”
Well, that and what the proper response should be. Some proponents of AGW have taken on a harsh anti-capitalist look. I think many people who call themselves sceptics are simply sceptical of the fact that, suddenly, there is a new castastrophe that can only be solved by adopting the very same economic policies that these same people have been pushing for decades.