A look at the graph of global temperature over the past century shows just how exceptional the past five years have been. And the trend may be getting steeper, though we won’t know for some years yet.
Two years ago, Independent Australia published the latest plot of global temperatures. Along with a graph outlining the rising pattern, it was argued that if trends continue, as they are likely to do, the Great Barrier Reef has little chance of surviving beyond 2030 as more than a sad remnant in its southern reaches.
Even if we suddenly got serious about reducing greenhouse gas emissions the warming will still continue for two to four decades and the damage would only be deferred.
The greater danger is that this warming will tip into being irreversible if it is not soon addressed. In that case, our grandchildren would inherit a very different and far more hostile world.
In the meantime, the "debate" is intensifying. However, it was not intense enough to make the recent Australian election the "climate election" some of us hoped it would be. On the contrary, it was a head-in-the-sand election decided on frivolities, lies and traditional allegiances.
The strike is gaining enough traction to frighten the defenders of the present order. Professional denialist Andrew Bolt has made a despicable and potentially dangerous personal attack on Greta Thunberg. Political pressure, then, is still building.
So how is the world going? Is the global warming slowing, or still following the alarming upward trend? Or is it even speeding up?
Here is the graph maintained by Dr Mikako Sato of Columbia University in the United States, updated to June 2019.
There was a very big spike around 2016, reaching over 1.3°C. That’s when the Reef bleached, twice, and there were big mortalities of coastal mangroves and offshore kelp forests, which are also very important breeding habitats. Ancient alpine heaths and Gondwana forests of Tasmania burnt last summer. Rivers are drying up.
The world cooled slowly through 2017 and by December 2018, it was almost back to the trend. The trend is not normal. The trend is a rate of warming of 0.18°C per decade. The 2018 temperature anomaly of over 1.1°C was still well above the average through the first decade of the century, which averaged around 0.9°C. Normal would be an anomaly of 0°C, near the bottom of the graph.
However, if you look closely, you will see that the temperature is again increasing and has nearly reached 1.2°C. It did not even get back to the trend and it’s heading back up. If the trend still applied, it ought to have dropped below the trend for a year or two, say down near 1.0°C (which is still much too hot).
Remember the hiatus in warming that climate deniers claimed was happening during the noughties? That was always a crude lie because they started their graphs at 1998 when a super-el-niño pushed the temperature up. If they had started their graphs in 1996 or 1999 they would have had to say there is rapid warming. But that would be wrong too. What counts is the trend averaged over five-ten years, which irons out most of the wiggles. You can see that the warming was actually continuing through the noughties, perhaps at a slightly slower rate.
2011-2013 were below trend, though still hot. A concern at that time was what might happen when the "pause" ended. We found out. The temperature increased so rapidly through 2014-2016 it was the biggest single jump in the whole 140-year record.
The fact that the temperature did not even return to the trend line before heading up again, raises the concern that the old trend no longer applies. Perhaps the trend is now steeper. We don’t know. We’ll have to wait and see. We are doing a massive, high-risk experiment with our home planet. There is no Planet B.
If the rate of warming has increased it would suggest we may already have crossed a tipping point, in which the natural responses to warming only increase the warming. If that were true, our situation would be grim.
Let us hope the climate has not tipped into runaway warming. We know there are tipping points out there, after which human efforts to stop the warming would be increasingly futile, we just haven’t known where they are.
It is reason to get fully serious, politically. Greta Thunberg says to the "leaders" who refuse to lead, "I want you to panic". She’s right. This is a grave global emergency.
Despair and paralysis are not an option. We must keep working to stop the insanity. Only in that way will we find out if we can save our civilisation. Spread the word, talk to people, support the students’ big climate strike on September 20.
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