Extreme weather around the world

For a while now the climate scientists have been warning that global warming isn’t simply a matter of the weather getting a little warmer everywhere. Rather, the warming will vary from place to place and be accompanied by changes of weather patterns, especially rainfall. That is already happening. I have mentioned extreme weather events here before over the last year or so, and in fact the last few months have seen a cluster of extreme events which are causing great suffering across the Northern hemisphere.

We know that none of these can be ascribed to climate change with any certainty but there is a growing body of knowledge (e.g. IPCC, Climate Communication) which shows that we can confidently give the odds that a particular event would have happened without global warming, and the experts are quoting high odds against any of these happening under our old weather patterns. The combined odds against all of them happening by chance are infinitesimal.

The silver lining to this litany of disaster is that ordinary people are beginning to see for themselves that weird things are happening to their weather and are more willing to acknowledge that climate change is indeed here already, that it is looking scarier every year, and that we really should try harder to avert it.

Smile: In what seems like poetic environmental justice, a brown coal mine in Victoria’s Latrobe Valley has also been flooded after unusually heavy rain.

Don’t smile too broadly: James Hansen, one of the world’s pre-eminent climatologists, has warned that the future he predicted is here here already and it is worse than he expected, sooner than he expected – almost entirely because of extreme weather events:

In a new analysis of the past six decades of global temperatures, which will be published Monday, my colleagues and I have revealed a stunning increase in the frequency of extremely hot summers, with deeply troubling ramifications for not only our future but also for our present.

This is not a climate model or a prediction but actual observations of weather events and temperatures that have happened. Our analysis shows that it is no longer enough to say that global warming will increase the likelihood of extreme weather and to repeat the caveat that no individual weather event can be directly linked to climate change. To the contrary, our analysis shows that, for the extreme hot weather of the recent past, there is virtually no explanation other than climate change.

The rest of his Washington Post article is here and if you want the whole scientific  paper you can get it – free – here.

Heading for higher ground

I started my monthly survey a couple of days ago by mentioning that it was raining …
According to the BoM, Townsville Airport had 36 mm from 9.00 a.m. Thurs to 9.00 a.m. Friday and 91 mm from then to Saturday morning. It was patchy, though, with bands of rain coming through, and we measured 125 mm here from Friday morning to Saturday morning. That turned the bottom of our yard (near the bananas, which love water) into a floodway. Genuine Wet-season rain!

It has prompted a couple of colonies of small ants to head for higher ground – more than a couple, I’m sure, but those I saw were both on my window-sill. One trail was outside the window and the other emerged from under the sill inside the room, and went up and over it to points unknown. The ants in both trails were so small that I couldn’t see they were different species until I saw my photos on screen.

Species 1

Ants carrying eggs
Ants on the outer window sill, one (foreground) carrying a larva and one with an egg

Not all of them were carrying eggs or larvae. Some were returning for a second load, while others were apparently just moving with the crowd.

Ants on window-sill
Fellow-travellers. The white one may be newly emerged

Species 2

Ants of the other species, coming from inside the wall, are more uniformly brown and I think they were a little smaller, though it’s hard to pick the difference between 2.5mm and 2mm when they are all moving as fast as they can.

small brown ants with eggs
Three ants going upwards, one with eggs, and one returning.


two small brown ants
The slightly larger ant looking back down the trail may be a soldier guarding the line of workers.

Seeing ants heading for high ground is a classic warning of more rain to come, of course. The BoM agrees: the Low in the Gulf is expected to become a weak cyclone in a day or so and funnel a lot more rain our way. But the Dove Orchids didn’t flower early last week to warn us, as they are supposed to … I’m losing faith in their reliability, I’m afraid. Or maybe they just can’t react to changes in humidity when the average is 99%.

Remembering the floods

I wrote about extreme weather events and their connection to global warming two and a half months ago and a small coincidence leads me to revisit the topic. Today has been chosen as the day of remembrance for the disastrous SE Queensland floods a year ago, and a link on RealClimate took me yesterday to a paper by eminent climate scientist James Hansen which touches on something I’ve been thinking about for some  time: the fact that climate change should already be apparent to ordinary people.

First, the floods. Wikipedia has a good overview here with plenty of links to further information and the ABC has put together a terrific gallery of flood photos here. There’s not much point in trying to add to that coverage here. The floods certainly qualify as an ‘extreme weather event’ and were recognised as such in the major global report State of the Climate in 2010 from NOAA and the Bulletin of the American Meteorological Society. 

Hansen’s paper, Climate Variability and Climate Change: The New Climate Dice (November 2011) (pdf here) begins thus:

The “climate dice” describing the chance of an unusually warm or cool season, relative to the climatology of 1951-1980, have progressively become more “loaded” during the past 30 years, coincident with increased global warming. The most dramatic and important change of the climate dice is the appearance of a new category of extreme climate outliers. …

The greatest barrier to public recognition of human-made climate change is the natural variability of climate. How can a person discern long-term climate change, given the notorious variability of local weather and climate from day to day and year to year?

This question assumes great practical importance, because of the need for the public to appreciate the significance of human-made global warming. Actions to stem emissions of the gases that cause global warming, mainly CO2, are unlikely to approach what is needed until the public perceives that human-made climate change is underway and will have disastrous consequences if effective actions are not taken to short-circuit the climate change.

He goes on to show two kinds of systematic change in climate: the averages have shifted and, at the same time, the odds of extreme events occurring have increased dramatically. This, of course, is the significance of his title: the climate dice have been loaded (biased) by global warming. He presents details of the changes which have already occurred and notes that, “The climate dice are now loaded to a degree that the perceptive person (old enough to remember the climate of 1951-1980) should be able to recognize the existence of climate change.” In particular, people should be noticing that extreme weather is far more common than it ever used to be.

He doesn’t quite ask, “Why don’t they notice?” but the question hovers there, waiting for an answer.

I have been trying to answer it myself since a random conversation a year ago. I was chatting to a youngish, intelligent person with a degree in natural sciences and a job in  GBRMPA, which looks after the Great Barrier Reef. I was quite surprised to find that she had not actually observed the effects of climate change. Then I found that she had spent her first ten years on a Pacific island, her next eight in Sydney, and another eight or so here in Townsville, so she hadn’t actually been anywhere long enough to notice a change in that location.

As I thought about that, I realised that she has lots of company. There are far fewer people who might reasonably be expected to notice climate change than we might at first think. A quick estimate goes like this:

  • Age group really has to be 40+, since anyone under ten in the early 1980s won’t remember the old norms. Change has occurred in the last thirty years, but it is the comparison with the pre-1980 baseline which makes it stand out strongly. That rules out more than 50% of the world’s population and perhaps even more than 50% of the world’s voters.
  • But also, those people have to have been living in the same general area for 40+ years, or have returned to it after some time away, because no-one in California will say, “It wasn’t like this when I was a kid,” if they grew up in Normandy, Queensland or even Virginia. How many Westerners are that stable? 50%?
  • Furthermore, the closer we live to nature, the more likely we are to notice its changes – but more and more of us are urbanised. Europe, Australia and the US are all more than 80% urbanised according to UN stats, while China, India and most of the developing nations are less than 40% urbanised. How many of the 50% of 50% are therefore likely to qualify as “perceptive”? Less than 50% in the West, certainly; perhaps more than 50% in less urbanised countries.
  • That leaves less than 10% of the world’s population in a position to recognise climate change from personal observation. And (unfortunately for the debate) most of those 10% are the rural poor of developing nations, the most frequent victims of climate change not the opinion-makers of industrialised nations.

Of course, Hansen’s statistics show that extreme weather events are going to increase very rapidly in number and severity as global warming continues. More and more of us will notice the effects in our daily lives. But that is not really good news.

Climate change and extreme weather events

For the last few years I, among others, have been looking at the news and wondering to what extent this, that or the other extreme weather event – the 2010 Russian heatwave, the Queensland floods, record flooding in Thailand, etc – was due to climate change. When I asked those who ought to know, the response was always, “There is probably some influence there but it is too hard to disentangle from natural variation, so you can’t just say that it was caused by global warming,” or words to that effect.

This week RealClimate reported on a scientific paper by Stefan Rahmstorf and Dim Coucou which puts statistically verifiable numbers on the feeling that, yes, global warming is making our weather more extreme. RealClimate’s report is a (relatively) non-technical introduction to the findings and it is linked to the paper itself if you want more.

My really short, really non-technical summary is that the number of record-breaking events increases in proportion to the rate at which the normal (average) conditions are changing. That matches my gut feeling very well, which naturally pleases me. But it simultaneously alarms me because it means that record-breaking events are going to get more and more frequent unless we can quickly and radically reduce our CO2 emissions.

Back to the science: the authors applied their technique to the Russian heatwave and found, “an approximate 80% probability that the 2010 July heat record would not have occurred without climate warming.” That quote is from  the abstract of the paper, meaning that it is in careful scientific language, i.e. there is an approximate 99.9% probability that they can back up every word of it.

The Comments on RealClimate posts are usually well worth reading. Two caught my eye this time:

(1) Comment 36: Ricky Rood looks at other ways in which the 2010 Russian heat wave was extreme:

The winter of 2010 and the spring of 2011 were characterized by very high food prices. An essay by Sarah Johnstone and Jeffrey Mazo entitled, Global Warming and Arab Spring, draws a convincing line that the pressure on food prices was a contributor to the start of the revolutions of the Arab Spring – the tumultuous uprising against many Arab governments. (also here) To diffuse the arguments that are sure to follow – this was a contributor, along with many other factors that came together to fuel a movement. This is the idea of climate extremes as a threat multiplier.

(2) Pete Dunkelberg says:

For a first approximation, an outlier [i.e. extreme event] in the direction of a trend tells you what’s coming. … Just from the shape of a bell curve (and this is far from original) one can see that you don’t have to move the mean very far in one direction for outliers on that side to become much more frequent. A one hundred year heat wave or flood readily becomes a ten or five year event. The new hundred year flood is going to drown people.

Now, how did that Chinese curse go? “May you live in interesting times” – was that it?