Thursday, 28 February 2008

Whether the Weather be Hot (or Cold)...

It's said that interest in the weather is a part of being British and I think that's true. We talk about it constantly and we are perhaps more aware of it here than in many other parts of the world. The topic of "climate change" unfortunately generates a deal more heat than light, so to speak. It has been another mild winter here in NW Europe - there has been no snow in London and only a few days of frost and fog.

While January 2007 was the mildest since 1916, January 2008 was incredibly wet. February 2008 has been one of the sunniest ever and, of course, above the long-term average in terms of temperature. However, while this winter has been mild over Britain and Scandinavia, it has been much colder and snowier over North America and China. Indeed, levels of Arctic sea ice have increased considerably and, aided by a pool of exceptionally cold air over NW Greenland, sea ice has expanded and thickened too.

Those who argue against what they see as the "myth" of climate change have jumped on these facts as proof that man-made climate change is false and that solar activity (or the lack of it) is a far more significant factor. We will soon know if global cooling can be directly connected to solar activity as we are scheduled to move into a decreasing level of sunspot activity from 2012. If the "solar theorists" are right, the mild winter experienced by Britain will be an anomaly and snow will return.

More reasoned climatologists, while not disputing the role of the Sun in shaping our weather, consider other factors. One gaining more importance is the jet stream. The main Northern Hemisphere jet has been proved to have a huge influence on Britain's weather. In the summer of 2007, the jet remained close to the UK. Depressions or atlantic storms were forced near to the British Isles and the result was extensive and considerbale rainfall. This winter, the main jet has generally been well to the north leaving Britain on the "warm" side of the jet keeping our weather mild and benign.

The existence of the jet stream has only been known since the Second World War. Scientists are struggling to understand how the jet stream behaved in past historical times. Where was it during the Little Ice Age for example ? Can the LIA purely be explained in terms of decreased solar activity and increased volcanic activity or were changes in the jet stream a factor ?

The question is one of cause and effect - we see the jet stream oscillate frequently today and now understand the role of Rossby Waves but what happened in the past ?

I see this blizzard (as it were) of scientific argument and data and remain confused and concerned as to the future and it's not surprising the non-scientific community is equally uncertain as to how to respond. What concerns me first of all is the rate of climate change - temperature and the amount of carbon dioxide in the atmosphere is rising at a phenomenal (in geological terms) rate. Even if the "solar theorists" are right and the Earth will start to cool, it's arguable that damage has already been done and that will manifest itself episodically in the decades to come.

The fact also remains that a mild winter doesn't mean a lot in terms of spring or summer. While it seems improbable that summer 2008 will be as severe as summer 2007, the next danger comes from heat. It seems inevitable to me that London will face a prolonged heatwave at some point in the next five to ten years and this may very well cause thousands of deaths in a city which seems chronically ill-prepared for such an eventuality.

We must also encourage science to redouble its efforts to understand the complex mechanism that is our climate. Detailed and accurate forecasting of future trends and probablilities is vital if politicians are to take appropriate action.

1 comment:

Andy Cooke said...

People hiding behind natural climate swings like solar forcing do annoy me (note: I'm not suggesting that you are - you're merely highlighting it. Thought I'd best add that in as my read through of what I wrote looked as though I were having a pop at you).
The best analogy is that we're standing on an escalator that sometimes moves slowly down, sometimes slowly up. It's moving slowly up at the moment (solar forcing).

However, we're also striding up the escalator at the same time (about ten times the speed of the escalator). So deniers who point out that the escalator is moving aren't wrong. They're just not successfully justifying why we shouldn't slow our upward exertion - we're going upwards slowly anyway, so accelerating the process isn't really helpful :-)

The most irritating thing at all is that the best way forward is not even being talked about: Many of the pro-business/technology/globalisation types are in the "denier" camp; most of the "accepter" camp are in the Green mode of denigrating globalisation and technological solutions and pressing us away from them.

But the IPCC report and the SRES scenarios are pretty damn explicit. Four main families of projected futures, split into a two-by-two matrix:
Increased globalisation = "1" types (A1 and B1)
Decreased globalisation/divided world = "2" types (A2 and B2)

(A and B denote levels of environmental awareness and focus on environmental technologies)

The A1 family is further split: A1F (fossil fuel reliance), A1T (push for technological solutions to energy generation), A1B (balanced between "F" and "T"). The B families assume "T" (eg B1 could be read as B1T).

There's then three key variables: globalisation (or lack of it), technological solutions (or their lack) and environmental awareness (or lack). We can see the effects of each variable by changing it and keeping the others the same.

From A1F to A1T (the only family where this split is investigated and therefore available), the projected 21st century rise in temperature and sea level change from:
A1F: +2.4 to 6.4 degrees C (average +4.0C); +26 to 59 cm.
A1T: +1.4 degrees to 3.8 C (average +2.4C); +20 to 45 cm.
A useful help from the technology angel, there (about -1.6C)

Looking between B1 to B2
for the globalisation difference (otherwise we'd have to pick which A1 scenario to use):

B1: +1.1 to 2.9C (ave 1.8C); +18 to 38 cm
B2: +1.4 to 3.8C (ave +2.4C); +20 to 43cm

So globalisation helps by a further -0.6C (comparing the middle A1 scenario (A1B) with A2 has the same .6C benefit).

On Environmental awareness, comparing A1T to B1 (B1 assumes technological solutions):
A1T: +1.4 degrees to 3.8 C (average +2.4C); +20 to 45 cm.
B1: +1.1 to 2.9C (ave 1.8C); +18 to 38 cm

Saving 0.6C again.

(comparing A2 to B2 gives a 1.0C benefit, so about 0.8C on average).

So we should push for an environmentally aware, technological/non-fossil fuel sourced, globalised world.

Moving from globalisation to the self-contained/divided/localised strategy championed by many Greens hurts the planet to the tune of 0.6C. Eschewing technological solutions further hurts it by 1.6C. The environmental awareness bit - which they do at least support - of ~0.8C is overwhelmed by the 2.2C that they'd incur if they got their way.

Sorry. End of rant.
Nice article, though. Food for thought (well, it triggered me off on this :) )