Tuesday, May 10, 2011

Shades of grey

There were a few comments on my last (epic) climate change post that seem to misunderstand the way in which science is done—especially as regards catastrophic anthropogenic climate change.

The main problem is that there is a certain amount of polarisation in the positions—how else can one possibly describe the "climate deniers" label (without using a goodly number of swearwords)?

So, let me try to explain some very fundamental points about this particular debate...
  1. Climate change

    No one really believes that the climate is entirely static; it quite obviously isn't, or we wouldn't have seasons or ice ages. Or, for that matter, the Mediaeval Warm Period and Little Ice Age.

    The climate changes, that is a fact: the question is, what makes it change?

  2. Anthropogenic

    Are these changes—indeed, can these changes—be triggered by human activity? If so, to what extent and, if these changes are significant, are they good or bad?

  3. Catastropic

    If these changes are both significant and bad—for given definitions of "bad"—then how catastrophic are they? Do they threaten the existence of our species (or others)? or are they just mildly inconvenient?

    And how catastrophic are these changes, in terms of allocating our scarce resources? Is it better to mitigate or to adapt?

Sensibly, all of these questions should be answered. Where a mechanism of change is encountered, then data should be gathered to test the hypotheses.

So, what do we know?

Well, actually we know extremely little.

We know that the Earth has been both considerably hotter and considerably colder in the past; it has also been very slightly hotter and very slightly colder.

We do know that when a very slightly hotter period became a very slightly colder period, then millions of humans died.

But, the problem is that we can't actually take tremendously accurate readings because there were no instruments to do so. We also know that, even where we try to reconstruct temperature series with proxies, our picture of the plant's climate covers a very short period of time geologically and is, not to put too fine a point on it, woefully inadequate.

Even where we do have direct measurements, we don't know how accurate those are. If you were to believe surfacestations.org—or, indeed, Anthony Watts's so-to-be-published paper—then there may be significant problems with this surely simple data set.

Thus, one of the main problems is that we don't really know whether there has, actually, been any significant warming over the last century—we think that it has been about 1°C but we are not really certain. Not least because the scientists don't seem to be tremendously good at understanding statistical analysis.

We do think that the increase in CO2 emissions by humans over the last century has the potential to increase global temperatures through, for instance, well-understood theories such as the Greenhouse Effect. But we don't know to what extent CO2 actually affects the climate through that mechanism.

Nor do we know what feedbacks are inherent in the system: or whether they are positive or negative.

In short, we don't know much—except that we are spending billions of pounds a year on trying to fund a mitigation solution to something that we don't even know is a problem.

I intend to pick up this baton again, but let's be clear—we are arguing questions of degree here, not absolutes.

8 comments:

TheFatBigot said...

Splendid summary, Mr Kitchen.

There are signs that the tide is finally turning. The message seems to be getting through that there has been no warming trend for almost as long as the last warming trend existed and that this is not consistent with the entrail readings made by the prophets of doom and their computerised offal models.

Still a long way to go, of course.

Suboptimal Planet said...

Very well said, DK.

Though I enjoy your swear-blogging rants, you are at your most persuasive when you exercise restraint.

Gnostic said...

This is the most succinct and easy to understand summation of the problem I've seen, DK. Bravo!

John East said...

Dare I say that you neglected the question, "If man made global warming is happening, is it a bad thing?"
I don't know the answer, but when the net winners and net losers are considered perhaps we could end up with a positive?
I would certainly welcome a warmer UK, although a warmer northern hemisphere, melting the ice packs and shutting down the gulf stream conveyor, would be a bit of a bummer were this to happen. Again, we just don't know, so it might be better to invest in efficient energy consumption, a plus if we warm or cool, rather than in bird shreaders.

Ed P said...

Good summary. The doubtful accuracy of the surface temperature stations, many of which have remained in the same locations despite major (heat output) changes around them, must be corrected. Satellite data is showing just how inaccurate these surface measurements have become. I believe this problem is due more to ignorance than fraud, however, IPCC policy is based to a large extent upon their corrupted measurements!

Chuckles said...

DK, on point 1. - I was under the impression that one of the major claims about anthropogenic CO2 emissions was that prior to mankind spewing such into the atmosphere, all was balmy, serene and in equilibrium, and that this foul and malevolent human-induced upsetting of the climate equilibrium is one of the main reasons why 'WE MUST DO SOMETHING NOW!!!'

I certainly recall it being a reason for the tenacious defence of the hockey stick - the handle was nice and flat and unchanging?

alan said...

An excellent summary.

Another point is the problem of forecasting.

To forecast the future warming/cooling various guesses are required on population growth, economic growth, fossil fuel usage etc.

The forecast of future temperatures not only assumes the historical data is correct, but also assumes very optimistic economic growth and increases in fossil fuel usage.

Het said...

Agree with John East:

it might be better to invest in efficient energy consumption

Isn't that what people have always been doing? The important word is invest. If we can produce an engine that gets more miles per gallon, won't that sell more easily and earn a return for the investor? The problem is when the government takes people's money and uses it to subsidise your bird shredders, making it easy to get a return on something that isn't actually in demand.