Leo Hickman has collected a number of seemingly sensible statements from climate scientists about the claims that the recent unusual weather in the USA can be attributed to anthropogenic climate change. Says Leo,
This week, scientists have been queuing up, it seems, to explain how the wildfires in Colorado, the heatwave across the eastern seaboard, and the “super derecho” are all indicative of “what global warming looks like”. Most pulled back, though, from directly blaming global warming for such weather events.
This more sensible approach sits in contrast to articles elsewhere on the Guardian’s website. For instance, this screechy vignette of what happens in the mind of Bill McKibben:
Global warming is underway. Are we waiting for someone to hold up a sign that says “Here’s climate change”? Because, this week, we got everything but that:
• In the Gulf, tropical storm Debby dropped what one meteorologist described as “unthinkable amounts” of rain on Florida. Debby marked the first time in history that we’d reached the fourth-named storm of the year in June; normally it takes till August to reach that mark.
• In the west, of course, firestorms raged: the biggest fire in New Mexico history, and the most destructive in Colorado’s annals. (That would be the Colorado Springs blaze: the old record had been set the week before, in Fort Collins.) One resident described escaping across suburban soccer fields in his car, with “hell in the rearview mirror”.
• The record-setting temperatures (it had never been warmer in Colorado) that fueled those blazes drifted east across the continent as the week wore on: across the Plains, there were places where the mercury reached levels it hadn’t touched even in the Dust Bowl years, America’s previous all-time highs.
• That heatwave was coming at just the wrong time, as farmers were watching their corn crops get ready to pollinate, a task that gets much harder at temperatures outside the norms with which those crops evolved. “You only get one chance to pollinate over 1 quadrillion kernels,” said Bill Lapp, president of Advanced Economic Solutions, a Omaha-based commodity consulting firm. “There’s always some level of angst at this time of year, but it’s significantly greater now and with good reason. We’ve had extended periods of drought.”
McKibbin’s recent twitter feed has been reading like a latter-day Revelations. Indeed, if isn’t enjoying the spectacle of homes and fields going up in smoke, he’s nonetheless milking it.
But such screeching isn’t going to convince anyone else, and doesn’t seem to come with the blessing of the scientists quoted by Hickman. Kerry Emmanuel, Peter Stott,Michael Mann, Clare Goodess, Doug Smith, Michael Oppenheimer, Harold Brooks, and Michael F. Wehner were each far more reluctant to make an unequivocal attribution of any event to human induced climate change than McKibben was. Mike Mann is perhaps the keenest to make the link, but typifies the response:
I like to use the analogy of loaded dice. Here in the US, we’ve seen a doubling in the frequency of record-breaking heat, relative to what we would expect from chance alone. So far this year, we’re seeing those records broken at nearly 10 times the rate we would expect without global warming. So there is no question in my mind that the “signal” of climate change has now emerged in our day-to-day weather. We are seeing the loading of the random weather dice toward more “sixes”. We are seeing and feeling climate change in the more extreme heat we are witnessing this summer, the outbreak of massive forest fires like the one engulfing Colorado over the past week, and more extreme weather events like the Derecho that knocked out power for millions in the eastern US during a record-breaking heat spell.
The scientist is saved from having to do anything as silly as linking a single event or series of events to a single cause by invoking probability — the ‘loaded dice’ analogy. Oppenheimer makes the same point:
The link between extreme events which have occurred recently and the build-up of the greenhouse gases is best represented by the “loading the dice” analogy – as the world warms, the likelihood of occurrence (frequency), intensity, and/or geographic extent of many types of extreme events is increasing. The events are individual data points in a broader pattern, akin to pixels on a computer screen. You can’t say much from any one pixel, but a picture emerges when you step back and look at the pattern. That said, for a few types of extreme events, particularly heat waves, it is sometimes possible to connect the pixel to the bigger picture more directly. The best case is the European heat wave of 2003. According to computer simulations of climate, the likelihood that such an event would occur was about doubled by the buildup of the greenhouse gases. A few other events have been examined using similar techniques, including the 2010 heat wave in Russia.
As for the willingness of scientists to make such statements: as the climate signal due to the ever-increasing greenhouse effect strengthens and emerges more and more from the noise in the system, and as statistical techniques for doing such “fingerprinting” studies as I mention above improves, scientists have become more confident in making such claims, which is to be expected.
It’s a yes-but-no-but answer to Hickman’s question — Is it now possible to blame extreme weather on global warming?
Indeed, the answer — which depends to some extent on who you ask — is more complicated than the question permits an answer to.
The real answer is no, of course. But let’s imagine that it was possible, and we could say that we could attribute events to AGW. What then?
Even if science could do this, would its answer be any more instructive? Let’s imagine that the dice analogy holds true, and that it is possible to say that the extreme weather in the USA is X times more likely… Does it make Bill McKibben’s imploring the world to act any more rational?
No, this is a greed problem. In the last five years, Exxon has made more money than any company in history. For the moment, Exxon and other’s desire to keep minting money – and our politicians’ desire for a share of that cash – has conspired to keep our government, and most others, from doing anything to head off the crisis.
In other words,should we head off this ‘crisis’ if it is possible to say that extreme weather has been increased by our CO2 emissions?
The problem is created by asking climate scientists to pass judgements on human greed, and politician’s intransigence. McKibben does it it explicitly, Hickman does it by implication. The expectation is that science can be instructive — that once we can establish that there are links between our emissions and weather extremes, we know we have to ‘do something’ about it.
But this is a mistake. The real question to ask is ‘are we more vulnerable to climate extremes’, to which the answer is…
The problem is epitomised by Michael F. Wehner’s answer.
This risk of extreme weather, particularly very severe heat waves, has already changed significantly due to human induced global warming. For instance, the chances of the 2003 European summer heat wave, responsible for as many as 70000 additional deaths, at least doubled and likely increased by a factor of 4 to 10. The chances of the 2010 Russian and 2011 Texas events also undoubtedly increased. While these events could have occurred without the human changes to the climate, it is important to know that the amount of climate change that we have experienced so far is very small to what is projected to occur by the middle and end of this century. By 2100, today’s most extreme weather events will seem relatively normal.
I only wish that I could be around long enough to see his prognostication fail to come to pass. Failing that, I will be content to go to my deathbed having seen the deaths attributed to the European heat wave of 2003 instead attributed to the failure to look after people. It’s quite simple: you can make sure that people have enough water to drink and that there are ample fans or air conditioning units available. Few — if any — of those 70,000 deaths can be attributed to ‘the weather’, which can in turn be attributed to CO2 emissions. The preoccupation with climate distorts our priorities, and our understanding of how we relate to the natural world.
On the view evinced by Hickman’s correspondents, we seem to be passive objects, shoved around by the dynamics of the climate. But this is a self-evidentially a misconception. There are many places in the world where the elderly and infirm survive hotter and drier places than Europe in the summer of 2003. And there are places on the planet which are hotter and drier than Colorado. What ‘climate change looks like’ cannot be understood merely in terms of the magnitude of the climatic phenomena. As I pointed out in my previous post, in order to understand environmental ‘impacts’, you need to understand what it is impacting upon. If you take the view that humans are passive/stupid, then it follows that you will overestimate the impact.
Climate ‘ideology’ is what loads the dice, and loads the question. Climate ‘extremes’ have become part of environmentalism’s mythology because it holds that we cannot survive them, and that they happen to us. In reality, however, what determines a climate extreme’s ‘impact’ is determined by our ability to cope with the climate. A simple thought experiment proves the point: what would have happened if the same wildfires and drought had happened in a much poorer part of the world? The answer is that there would have been many times the number of casualties.
It’s of no comfort to the people whose lives have been turned upside down by the weather, of course. But such things are a decreasing fact of human life, in spite of what doomsayers tell us. So, perhaps we do face an increase in the frequency and intensity of climate ‘extremes’. But their potential impact reduces by a greater factor each time we give the matter thought. In which case, reducing our vulnerability to climate by a factor of 4X at the cost of increasing the frequency and intensity of extremes by X seems to me to be a price worth paying. But don’t expect climate scientists to agree.
UNPDATE: Judith Curry has some interesting comments on ‘what global warming looks like’. Interesting that another journalist was canvassing scientists’ views but decided not to publish Curry’s sober comments… Only doom sells papers, after all.