Weather is not climate (climate is what you expect, while weather is what you get) but bizarre weather can be a sign of a changing climate. In fact, Hansen showed a while ago (see my discussion here) that if the climate is warming, which no reasonable person seriously doubts any more, then we will get more extreme weather events – and you can read ‘more extreme weather events’ two ways, because they will individually be more extreme and there will also be more of them.
This is being borne out very close to home for me. I noted recently that Townsville had had the coldest May day in 22 years. Early this week we had the wettest July day in more than 70 years. The Townsville Bulletinreported that …
More than six times the total average July rainfall was dumped across Townsville in just 24 hours with an average of 89mm clocked from 9am Monday [July 9] to 9am [Tuesday]. More than 40 regions from Bowen to Cairns were drenched with over 100mm of rain …
Daily rainfall records were set along the northern coastline … With 145mm, Innisfail recorded their wettest July day in 125 years while Lucinda totalled 141mm, making it their heaviest rain in 118 years. Burdekin residents also saw record-breaking falls with Home Hill’s wettest July day in 87 years and Ayr’s heaviest falls in 59 years.
Just a little less locally, cane farmers fear another wet winter will reduce their yield and delay their harvest. But wet winters are part of the longer-term climate change on which our extreme weather is superimposed.
The BoM publishes interactive Climate Trend Maps and playing with them is simultaneously kind of fun, instructive and perturbing. Here are some maps to to think about, if you haven’t time to play:
Queensland annual rainfall, diminishing rapidly along the coast except up around Cooktown – but the *winter* rainfall is actually increasing, although not as much as the annual total is decreasing. Spring rain is not changing much, so the decreased annual rainfall is actually a large decrease in Summer-Autumn (our Wet), partially compensated by a small increase in Spring (on the North coast) and Winter.
At the same time our maximum temperatures are trending higher in all seasons (click here and toggle through the seasons).
So are sea surface temperatures, which is one reason coral reef scientists despair about the future of the Great Barrier Reef – e.g. the Statement from the 12th International Coral Reef Symposium in Cairns, 9-13 July 2012.
It’s a year this week since Yasi crossed the coast between Townsville and Cairns, affecting both cities to an extent but devastating the smaller towns in between, especially Tully and Cardwell. It was the biggest cyclone ever to cross the Australian coastline, though perhaps not the most intense.
Our own memories of the event are of trepidation, anxiety, relief and a lot of inconvenience and hard labour. We spent hours beforehand preparing the house and yard, as best we could, for the wind and rain. We lost mains power halfway through the afternoon, cooked and ate dinner by gas stoves and lanterns, listened apprehensively as the wind built through the evening, and got as much sleep as we could during the night – which wasn’t much.
The wet season I was greeting a month ago has been playing hide and seek ever since. We have had very little rain out of it so far, although areas around Townsville have had a little more, and have been watering our garden most weeks. Insect life in the garden has reacted accordingly: a slight increase in numbers because there’s really not much more food around, and a bigger increase in variety because it really is a change of season.
Butterflies: some Migrants, Crows and Ulysses, one or two Cairns Birdwing and Blue-banded Eggfly, and the first Eurema and female Common Eggfly for many months; a slight increase in Hesperidae; lots of Pale Triangles; very few Chocolate Soldiers (for the first month I can remember, they don’t outnumber all the rest).
After last night I am sure the Wet is here. We had a cracker of a thunderstorm in the small hours – say 2.30 to 4.00 – which made us wander round the house closing windows and unplugging computers and so on, and flooded our banana plantation. It overflowed our little rain-gauge, so we must have had more than 60 mm.*
It follows a good storm in the evening of last Sunday (only 10 – 20 mm but a great light-show), 60 mm in three days a week earlier (which cancelled ‘Carols By Candlelight’), and 15 mm in the last week of November, all adding up to more rain than we have had altogether in the previous seven months. In between the downpours we’ve had very hot days, 32 – 35C, and hot nights, going down to 24 – 26C, with constant high humidity.
The only surprise about all this is that it has arrived almost a month later than normal – but the variability of the monsoon’s timing is itself normal, so it’s not a big surprise.
* P.S. The official figure, for the airport, is 92 mm in the 24 hours to 9.00 this morning.
It has been a long dry cool winter but things are beginning to change.
A bedroom window looks out towards Mt Stuart and it gives us our first glimpse of the weather every morning. Blue sky? Obvious. Clouds? Ditto. No Mount Stuart? One of us will turn to the other and say, ‘Someone has stolen Mount Stuart!’
It’s an old family joke, going back to the time when one of the children was engrossed in a (very primitive) computer game called Where in the World is Carmen Sandiego? which entailed solving outrageous crimes all over the world: ‘Someone has stolen the Eiffel Tower’, etc. Back in the real world and the present … if we can’t see Mt Stuart, cloud has come right down over it. That is a wet-season phenomenon and it happened last Sunday for the first time in months. It happened again on Thursday morning just to show it wasn’t an aberration, but we returned to cool dry conditions again this weekend.
The plants are preparing for a change, too. The Macadamia has been flowering, the Poplar Gum has lost its bark and is losing leaves (for the first time since Yasi, incidentally), the native Wisteria is flowering fit to bust, the Callistemon is doing well, etc. Many of our trees here lose their leaves, come into flower and then come into new leaf in a matter of a few weeks around the end of the dry season. Those are traditional autumn and spring changes, of course and ‘ought’ to be six months apart.
As I’ve said before, our seasons align very poorly with European-style spring-summer-autumn-winter. An artist friend of mine researched local Aboriginal season descriptions some years ago. I don’t remember them all but they were (roughly) pre-Wet, Wet, post-Wet growing season, drying-off and cool dry. Much more appropriate!