Just back in May it seemed as though it would never stop raining. At our place we had 460mm (over 18 inches) in three days, most of it in about 27 hours. That’s 40% of the yearly average. But if you asked locals what the weather has been like this year most would likely say “hot and dry”. Indeed August it was a “most extraordinary month” in Australia generally:
“August saw particularly high day-time temperatures, with the national mean maximum being 3.20°C above average, which was 1.14°C above the previous record set in 2006”.
Though a bit fresh at nights we’ve already had 9 days of 30C plus temperature. This is what the temperature anomalies looks like for July to September:
Figure 1: Mean maximum temperature anomaly, July to September 2009
And you guessed it, where it’s been raining it has been cool:
Figure 2: Rainfall deciles, July to September 2009
In these parts we’ve had the pleasure of three dust storms.
While we have been having exceptionally hot weather, in some other parts of the world it’s been cool, notably in North America where my sister in Toronto reckons they haven’t really had a summer. As proof of her perceptions I found this NASA GISS map in a Tamino post:
Figure 3: World temperature anomaly, June to August 2009
If you lived in North America or even in Japan and thought global warming had been cancelled, you’d be wrong. As this NASA GISS graph shows, 2009 is tracking as the fifth warmest on record:
Figure 4: January – September mean surface temperature anomaly, 2009
Indeed you’ll note that (bottom right) since May the world temperature has been up there with 2005, the warmest in the NASA GISS record. (NASA GISS includes an estimate of the temperature in the Arctic, which nudges 2005 ahead of 1998.) In fact June to September was the hottest on record.
But as everyone knows, this short term stuff is really about the weather rather than the climate. You’ll remember a few weeks ago we looked at a story by Fred Pearce in New Scientist suggesting that the world may cool for the next decade. Fred must have had a bad night or come in late because it seems he got the import of the lecture completely wrong. At Climate Progress Jo Romm reports on an interview he had with Mojib Latif to clarify what Latif was on about. Latif hasn’t changed his tune from an earlier Nature article, where he displayed this graph:
Figure 5: Latif temperature forecasts
There are two important things to know about this graph. The first is that the points do not represent annual temperatures; rather they represent 10 year means. So Latif is not predicting annual temperatures. Insofar as he is predicting anything he works in 10 year means.
So the point for 2010 represents the average of 2005 to 2015. The graph ticks up quite steeply from there to 2015, which represents the average of 2010 to 2020.
Secondly, Latif reckons that’s where it ends. His methodology is useless beyond 2015. Beyond that I gather he is just joining up the dots, because he expects temperatures to catch up with the IPCC scenario in the long run.
So reports that he was predicting a “decade” or “decades” of cooling are quite misplaced. Romm says a more accurate headline would have been, “World poised to see accelerated warming in the coming decade.”
But that’s not what the lecture was about either. The Way Things Break puts it thus:
Latif’s presentation was concerned with decadal-scale climate predictions- concerning not only their potential value and viability but also the significant challenges that remain before we can make useful ones.
Latif is interested in why temperature does not always rise smoothly in sync with GHG levels, that is, in the decadal anomalies.
Just about everyone knows by now that these anomalies involve the ocean as the vast majority of the additional heat in global warming goes into the ocean. We are starting to get better at measuring ocean heat. A recent study tells an interesting story:
Figure 6: Total Earth Heat Content anomaly from 1950 (Murphy et al. 2009)
The Pearce article quotes Vicky Pope of the UK Met Office saying:
“In many ways we know more about what will happen in the 2050s than next year”
Last month that same UK Met Office unveiled what they thought we had in store for 2055 – the 4C world:
Figure 7: Regional temperature increase in a 4C world
Remember that the higher latitudes warm more than around the equator and the sea doesn’t warm nearly as much as the land. So that makes the temperature change over vast stretches of land rather frightening. Can you imagine what melting in Greenland would be like in this scenario?
Things should be going noticeably pear-shaped by the 2020s to the extent that even politicians will notice.
I have my eye on that yellow bit around SEQ which indicates a 7C rise. That would give us a summer average of about 36C, or roughly where Longreach is now, and there is no reason to think it would stop there. So many tipping points would have been breached there’s no telling where it would end.
So the hottish weather we have been having lately is not even a decent foretaste of what may be in store.