A stormy future?

Gareth at Hot Topic has blogged about the range of recent extraordinary weather events around the world (see Fire and rain). And there have been plenty of news reports bringing this to our attention. The Russian heat wave and fires. The floods in Pakistan and China.

Many are asking if this is just coincidental. Or should we attribute them, at least in part, to global warming resulting from human activity. Peter Stott at the Guardian (Climate change: how to play our hand?) and John Scott at Discovery News (Russian Heat, Asian Floods Share Common Cause) say we should.

However, no one is making a direct attribution. Rather they are say that global warming is likely to increase the incidence of extreme weather events. And perhaps that is what we are seeing now.

Climate as “average weather”

Climate is not the same thing as weather. It’s more the “average weather.” As has been said “A single rainy day does not make a wet climate”. Nor does an extra cold winter “prove” that global warming has stopped. Although I have noticed that a cold winter does bring out the climate change deniers in droves.

When we talk about climate change we are referring to trends averaged over many years. Usually 20 – 30 years, but even longer when data is sparse or “noisy”.

So a few extreme weather events in themselves don’t indicate global climate change. It’s just that when the frequency of such events increase as they currently appear to, one suspects this is the result of the changed climate.

The reports of the Intergovernmental Panel on Climate Change (IPCC) point out that:

“simple statistical reasoning indicates that substantial changes in the frequency of extreme events (and the maximum feasible extreme, e.g., the maximum possible 24-hour rainfall at a specific location) can result from relatively small shift of the distribution of a weather or climate variable.”

The last IPCC report illustrated this with the figure below (see Box TS.5 Figure 1 – AR4 WGI Technical Summary.):

These curves represent the distribution of probability of different weather events. Temperature is described here but other weather factors such as rainfall, etc. could be used.

So even a relatively small increase in average global temperature – represented by going form the lefts hand curve to the right hand one – will increase the frequency of extreme events. In this case hot weather.

Of course, this figure is idealised. The probability distributions may be more complex. And regional effects may come into play. For example, there is a suggestion that increased global temperatures could cause a reduction in the ocean currents such as the Gulf Stream. This could actually bring colder temperatures to Europe.

A dangerous future – politically as well as weather-wise

Jean-Pascal van Ypersele, vice-president of the IPCC, describes the current extreme weather events as ones which:

“reproduce and intensify in a climate disturbed by greenhouse gas pollution. Extreme events are one of the ways in which climatic changes become dramatically visible.”

This was one of the main messages I got from James Hansen‘s recent book Storms of My Grandchildren: The Truth About the Coming Climate Catastrophe and Our Last Chance to Save Humanity (see Thinking of our grandchildren). The effects of climate change will not be just a gradual increase in global temperatures. It will also be increased frequency of extreme weather events. This, together with the projected increase in sea levels, will inevitably cause widespread disruption to human societies.

Personally I think this, and the inevitable political and social disruption it will cause globally, is the most frightening aspect of climate change.

See also: The dire probabilities of unusual weather


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11 responses to “A stormy future?

  1. “So a few extreme weather events indicate global climate change. It’s just that when the frequency of such events increase as the currently appear to, one suspects this is the result of the changed climate.”

    There are a few typos here.
    You obviously meant to say “a few extreme weather event ‘do not’ indicate global climate change.

    and you left the y off “they currently appear”


  2. other article on recent extreme weather events



    Pix of Pakistan flooding here.
    Here’s a map

    There’s an interesting article and comments at Only In It For The Gold that is related.
    “The Name of the Problem


  3. Thanks Sailrick for the check. I should really pay more attention.


  4. By the logic of that graph we can also predict that there will be NO more extreme cold weather events, right?

    Let’s examine the data and see if that is the case…..

    oh dear.


  5. StewartP – you didn’t read my post properly did you? I made quite clear that climate change can have regional effects such as, for example, disruption if the Gulf Stream. And I made clear, as did the IPCC report, that this is by necessity an idealized presentation.

    So you are completely mistaken with your interpretation. I guess willingly do.


  6. Ken, I’d hate to be mistaken.
    So regional cold weather anmalies are because of Global Warming, as well as extreme hot weather anomalies. And the graph is idealised, so it serves as a visual example of all our worst fears, but must not be used to interpret what the lines plotted represent. So it’s less of a graph representing any actual data, and more of a visual aid. That’s why it is OK for the graph to put in bold the hot data on the right, but say nothing of the cold data on the left.
    Have I got it right now? And you are also able to divine my motives.


  7. StewartP – welcome to the real world. It is complex and simple answers won’t work. Even when idealized figures help to illustrate the problems.

    As for your motives – no I don’t understand them. You seem angry about something.

    Perhaps you can help. Why are you reacting that way? Why are you upset about an attempt by the IPCC to explain a problem?


  8. Ken, you are an atheist, like me. Many atheists get angry when fundamental Christians try and mix church and state. When they want unfounded dogma to control they way we live and think.
    The IPCC are about as internally consistant and reliable as the Bible. In this post, unlike other posts in your excellent blog, you seem to be wanting your butter and the money for your butter. If the concept of the graph is accurate then yes, we will see record hot weather. But then the effectgraph equally demonstrates the end of record colds. But, no Ken, you produce the card of “regional effects”. How are we to differentiate between what is global warming and what are regional effects? Can you appreciate how it seems like cherry picking the data?
    Not angry. Weary


  9. Stewart, as I said you haven’t read the post carefully. The graph is illustrative, not accurate. It’s not a description of data. That was made very clear.

    Interesting take on the IPCC reports though. I have never seen cherry picking in them. Far from it. The discussion of extreme weather events is all probability based. How could it be otherwise.

    The confirmation of global warming is seen in the temperature trends (and atmospheric CO2 levels). The data on extreme weather events is far more complex. And a lot if it is not yet available.

    Want to see cherry picking? Listen to all the denier claims proliferating through the northern winter. A cold snap in Washington proves climate change us not occurring or that the globe is cooling! Some of these characters have woken up to the fact they can extend their season by switching to the southern hemisphere during the summer. Others just close down over the summer.

    You may be pissed off that some commentators say that the increased incidence of heat waves and other extreme events is consistent with the scientific expectations. They are not say it is caused directly.

    Contrast what with the cherry picking claims of the deniers.

    As I said. The real world is not simple.


  10. By the logic of that graph we can also predict that there will be NO more extreme cold weather events, right?


    The IPCC are about as internally consistant and reliable as the Bible.

    Wrong again. Science and religion work differently.
    Why don’t you know this?
    Trying to label scientists and peer-reviewed research under religious terms is dishonest and plain stupid.
    Save that sort of nonsense for the science deniers. They do it all the time.

    Portraying Science as Faith and Consensus as Dogma
    Since the ideas proposed by deniers do not meet rigorous scientific standards, they cannot hope to compete against the mainstream theories. They cannot raise the level of their beliefs up to the standards of mainstream science; therefore they attempt to lower the status of the denied science down to the level of religious faith, characterizing scientific consensus as scientific dogma . As one HIV denier quoted in Maggiore’s book remarked,

    “There is classical science, the way it’s supposed to work, and then there’s religion. I regained my sanity when I realized that AIDS science was a religious discourse. The one thing I will go to my grave not understanding is why everyone was so quick to accept everything the government said as truth. Especially the central myth: the cause of AIDS is known.”

    Others suggest that the entire spectrum of modern medicine is a religion.

    Deniers also paint themselves as skeptics working to break down a misguided and deeply rooted belief. They argue that when mainstream scientists speak out against the scientific “orthodoxy,” they are persecuted and dismissed. For example, HIV deniers make much of the demise of Peter Duesberg’s career, claiming that when he began speaking out against HIV as the cause of AIDS, he was “ignored and discredited” because of his dissidence. South African President Mbeki went even further, stating: “In an earlier period in human history, these [dissidents] would be heretics that would be burnt at the stake!”.

    “Evolution is a theory of desperation for those that refuse to accept the obvious — we were created for a purpose. To believe in evolution requires faith because the origin of life and the production of new information through mutation has not been demonstrated under any conceivable circumstance. Is evolution then a science or a religion? Many have stated it is the latter. Evolution has unquestionably been spawned by atheistic philosophy, and is the key instrument used by secular humanism to explain the existence of humans independent of God.”

    How are we to differentiate between what is global warming and what are regional effects? Can you appreciate how it seems like cherry picking the data?

    Maybe there’s a decades-long conspiracy of scientists all over the globe producing mountains of peer-reviewed research involving all of the physical sciences and operating with the full support of every single scientific community on the planet (including NASA) that is involved in cherry-picking data to fool you and steal your money in a sekrit communist plot!!!

    Yeah, maybe!

    Or maybe you’re just….completely wrong and simply don’t know what you are talking about?


  11. Stewart, cold weather anomalies are not a consequence of climate disruption – well at least until something ghastly happens like a major ocean current stopping or reversing.

    The indication of global warming is simply a numbers game. In the period that the world broke the record for the number of high temperature records, 17, there was only 1 cold temperature record. 17 to 1.

    Nobody expects that the relationship should always be 1 to 1 for high and low records. But for the last quite-a-while it’s been running between 2 to1 and 5 to 1. Unless we see a reversal of this trend which would be required to get the ratio closer to 1 to 1 for a longer period, the obvious conclusion is that things are getting warmer.


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