It is time to stop quivering in our boots in pointless fear of the future and just roll up our sleeves and build it.
- Ray Pierrehumbert

Wednesday, August 18, 2010

When it Rains it Pours

Harvey Taylor sends along a link to an article entitled "Magnitude of Pakistan Floods is Unprecedented". If we consider the Russia and Pakistan catastrophes as part of the same event, we have easily thirty million people directly affected and loss of life in the tens of thousands.

We also have more ammunition for claiming a very high weirdness index for the event.

Two especially interesting quotes:
We had an extraordinary event in northern Pakistan, where ten times the normal annual rainfall for one of those areas fell in four days. This is unprecedented. And, of course, you see the similar sorts of things happening in Africa, in Asia, in Central America. The farmers no longer know when to plant, because the rains don’t come at the time they used to come. All these are the kind of effects of climate change that we’ve feared and are beginning to come to pass, I’m afraid. - John Holmes, UN Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator

Just to give you a sense of how bad the rain was that caused this flooding initially, on the 28th of July, there was 318 millimeters of rain just on one day. To put that into context, the record, all-time record, for rain in Peshawar, which is where this number is from, for one month, the month of July, was 217 millimeters. So it rained more in one day than it had ever rained in an entire month for the monsoon season. The floods that have ensued—and there’s been two waves of these floods now—there’s no government in the world that could have prepared for this or that could have responded to this in the way that we would have liked it to. - Mosharraf Zaidi columnist for The News of Pakistan and Al-Shorouk of Egypt
Rolling a thirteen

Australian Prof. Steven Sherwood of UNSW says the same sort of thing I have been trying to say very nicely in a statement recently quoted on Dot Earth:
The “loading the dice” analogy is becoming popular but it misses something very important: climate change also allows unprecedented (in human history) things to happen. It is more like painting an extra spot on each face of one of the dice, so that it goes from 2 to 7 instead of 1 to 6. This increases the odds of rolling 11 or 12, but also makes it possible to roll 13. What happens then? Since we have never had to cope with 13’s, this could prove far worse than simply loading the dice toward more 11’s and 12’s. I’m not sure whether or not what is happening in Russia or Pakistan is a “13″ yet, but 13’s will eventually arrive (and so will 14’s, if carbon emissions continue to rise).
I think we have just rolled our first thirteen. I don't know how to prove it. (update - or maybe our second, if you count Australia last year)

I can define a fourteen easily. We will have rolled a fourteen when there is no controversy at all about whether the given event was in the range of unforced natural variability.

My attempt to raise this issue at Kloor's went like this:

As the climate, i.e., the distribution of weather events, changes rapidly, the space occupied by the tails of the distribution sweep out territory that were not meaningfully in the distribution before.

So we will occasionally see things we could not have seen before, and some of them may be things we have not imagined before. We will see not only known but previously unlikely conditions (e.g. extreme heat), but also previously unsuspected vulnerabilities (smoke).

It is impossible to predict what these weird events will be. The simulation models are too coarse and too conservative, and we wouldn’t know what to look for in their output anyway. You can’t really do statistical attribution on single events, and causality is pretty complicated in a tightly coupled system. So it’s hard to say much about this beyond that we should not only expect the unexpected, we should expect a great deal more of it.

Sherwood's analogy is very succinct and expresses the same point.


David B. Benson said...

That's alotta water.

Need more climate disruption?
Keep burning coal...

Gareth said...

Re the Holmes comment: worth reading What's happened to the seasons? from the Economist's Intelligent Life magazine for an amplification.

Hank Roberts said...

> unforced natural variability

You need a time span and a rate of change to define "natural variability" usefully -- say only the tranquil Holocene?

Michael Tobis said...

Yeah, I actually thought about putting "late Holocene" or "later Holocene" in there. The usual tradeoff between precision and effectiveness. Or better "the historical period", perhaps, as a compromise.

Michael Tobis said...

I found the image on a random aggregator about Morton Salt; I do not know who the artist is.

watchingthedeniers said...

Shall we call it the "2010 Climate disaster"? Russia, Pakistan, China, Niger, European floods and fires...

As an Australian I'm deeply concerned about the coming fire season (November forward).

Little progress has been made to build community shelters or reduce fuel in Victoria.

This follows a Royal Commission report into the 2009 fires that stated parts of the state were no longer safe for human habitation due to the era of mega-fires.

Bye bye holocene, hello anthropocene.


Dean said...

So who can explain in common language - to the media por ejemplo - why extreme weather events are particularly difficult to reach a high level of confidence on trends and what causes them?

It occurred to me to compare with polls - where they talk about being within 3-4% because of the number of people they called. There are only a few dozen extreme events even in a very bad year, and what would the percentage error range be in a poll if they only called 40 people?

L. Carey said...

RE "We will have rolled a fourteen when there is no controversy at all about whether the given event was in the range of unforced natural variability."

If that's the criteria for a 14, one only has to look at the first half dozen comments at DotEarth to see that we will never reach the point of rolling a 14 - the denial-bots and concern trolls (including RPJr) will never admit a connection, no matter what happens.

Aaron said...

“Loading the dice” is the wrong metaphor.

Global warming puts more energy into the weather systems allowing more combinations of events to occur. AGW is not “Loading the dice”, it is giving Mother Nature more dice to roll. If with the CO2 at 350 ppm in 1964, Mother Nature had 2 dice and “12 was the largest number she could roll, now she has 3 dice (energy), and can roll an 18. At some point, she will.

As CO2/CH4 concentrations in the atmosphere increase, we keep handing Mother Nature more dice (more energy in the weather system) and at some point she will be able to roll a 24, and then a 30. . . . And, at some point she will.

Michael Tobis said...

Aaron, that is actually an oversimplification. The weather is driven by differences of temperature between latitudes.

So if global warming warms the poles more than the equator, the actual energy imbalance could arguably get smaller, even though the energy in the system is slightly larger.

On the other hand, the atmosphere warms more at the surface, so that means decreased static stability.

You really have to look at the details to make predictions.

I had expected weaker large scale organization and stronger small scale organization, and I have seen lots of other people making similar predictions. More recently, and this also makes intuitive sense to me, I have heard of a poleward retreat of the jet.

That this would contribute to massive meridional excursions kinda sorta makes sense, but I haven't heard of it as a consensus position and I never suspected it until now.

I think any large scale rapid change is going to lead to huge problems, whether heating or cooling. The total energy in the system actually doesn't change that much. The way it moves around changes a lot.

Steve Bloom said...

Here's a good article on the poleward shift of the atmospheric circulation, written by the guy who did the attribution study.

IMHO this effect is cause for declaration of a planet-wide emergency, but what do I know.

Steve Bloom said...

The just-announced study finding that plant productivity is decreasing (paywalled, but Joe Romm has a good discussion), primarily due to increasing drought, is among the effects expected from the change in circulation.

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