Is there any kind of weather climate change DOESN’T cause?

Posted by Graham Thompson — 24 February 2014 at 12:23pm - Comments
All rights reserved. Credit: Greenpeace
more of that wet stuff

Funny how environmental issues can rocket to the top of the news agenda when UK property prices might be affected. Sorry, that probably came across as slightly cynical, but that’s been the pervading atmosphere in the flooding stories for most of the last month.

After lying repeatedly about their cuts to the flood defence budget, the government have since been casting around wildly for someone else to blame. Labour, surely, must have some role in this disaster? The Environment Agency’s run by an old new Labour guy, can we blame him? Well, they gave it a go, and were partly successful, but the chances are that if the government hadn’t cut the Environment Agency’s budget, and dredging had continued at whatever level the locals were asking for, the floods would still have been pretty severe, because they were caused by the most rainfall in any two consecutive months for centuries.

Which, in turn, was probably caused by climate change, according to the Met Office and the Centre for Ecology and Hydrology.

So middle England is on the sharp end of climate impacts for once. And not just middle England. The floodwaters encircled the PM’s old school and were lapping at the walls of the Queen’s holiday cottage. This could significantly increase pressure on the government to, you know, actually do something, and so the climate deniers have been out in force to try to obfuscate the issue.

I’m not a climate scientist, so I won’t be going into detail about the wobbles in the jet stream or the thermohaline conveyor, but the denier talking points are a bit more basic than that, and so here’s the basics.

And they are genuinely basic.

Firstly, the planet is currently accumulating heat at the rate of four Hiroshima bombs every second. Whilst most of this goes into the deep ocean, clearly all weather is influenced by this extra heat, and so all weather events are caused by climate change to some degree.

More heat means more evaporation, which means more precipitation (rain to you and me, snow if you’re a penguin) and therefore floods. Also, too, more heat in the oceans means the water expands, which means higher sea levels and therefore, floods. And then there’s the increase in water from land ice melting into the sea, although, whilst it adds up to thousands of cubic miles, it’s not contributing on the same scale as the thermal expansion. But, through several mechanisms, climate change will cause flooding.

BUT, say the deniers, didn’t some climate scientists say that climate change would cause droughts? Yes, yes they did. Well remembered. And it will.

There is no contradiction here unless the drought and the flood happen in the same place at the same time.

It’s similar to the temperature issue. Whilst global warming does necessitate warming at the global level, it doesn’t mean everywhere will get warmer to the same degree – the poles are warming much faster than the equator, and will continue to do so - and some areas may get colder, when weather patterns change, causing the long cold periods in the US, or oceanic currents shift, which may cause the UK to become a lot colder for many years, perhaps centuries.

So it is with rainfall. We will get more, as a planet, but not evenly spread, and some places will get less. And even places which get more are likely to get it in more intense bursts, and may suffer from more periods of drought than they used to, even though they’re getting more rain overall.

All of this points to an unpleasant aspect of climate change which is frequently ignored in favour of more simplistic caricatures of the phenomenon. Whilst we will get more heat and more rain overall, it will not be evenly distributed. Britain is likely to be warmer and wetter, but it might be colder or drier, and even if it is warmer and wetter, we may still get more droughts and more cold snaps than we are used to. Worse still, the spread is uneven through time as well as space. So long as the causes of climate change are allowed to continue accumulating, the global climate will not settle into a new pattern. The weather will continue changing, and so adapting to the changes will be a continuous process, where whatever made sense last year may not work next year.

This ‘lumpiness’ in the weather is what leads climate deniers to complain that any weather can be used as evidence for climate change, even opposite extremes such as droughts and floods, or cold snaps and heat waves. They claim that, if any weather can be attributed to climate change, then the theory isn’t falsifiable. And they’re almost right, but not quite.

There are certain types of weather which will become less frequent due to climate change.

Firstly, and most obviously, there’s global temperature decrease. If the entire globe, including the oceans and the atmosphere, underwent a sustained drop in temperature, that would require some explanation.

Secondly, sustained periods of normal, predictable, moderate weather. These still happen, but they should get rarer and rarer as the heat energy in the climate system builds up.

So what the deniers should be looking for in order to falsify Anthropogenic Global Warming through observation is either a drop in global average temperature or sustained periods when the weather doesn’t do anything particularly unusual.

In a shifting climate, normal is the new weird.

Which reminds me of another common denier question ‘what is the ideal temperature for the world?’ This is generally asked in a patronising tone which implies assuming there is an ideal temperature is somehow naïve or arrogant.

The ideal temperature, without a shadow of a doubt or any probabilistic hedging, is the temperature your society, infrastructure and agriculture were designed for.

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