When the Old Man asked what the odds were, Tamino very helpfully put a scientific gloss on answers which were no great surprise at the cave. To help you if you missed it, here are some baseline numbers for the odds of some climate impacts by 2040:

  • 65% chance of temperatures increasing by more than 0.5C from now.
  • 87% cumulative chance that the increase will be greater than 0.3C.
  • 90% chance that sea level rise will be greater than 10cm, 50% that it will be between 10-20cm.
  • 85% cumulative chance that Arctic sea ice extent will decline by more than 10%.
  • No clear indication that tropical cyclone activity will reduce, increase or stay the same. (it does change if you use different rulers to measure it).
  • 60% cumulative chance that life in the oceans will decline by up to 25%.
  • 60% cumulative chance that global forest area will decline by more than 10%.

Looked at as a package, the picture is not encouraging. These are not dramatic exaggerations or unrealistic expectations. You may feel that some of these things are more likely to come about than others. On the other hand, you may recognise that the odds are good that most or all of these things will happen in tandem with one another, as they all relate to how the change in climate is changing the systems within which our civilization functions.

Now you can turn those odds around; odds against a temperature rise of >0.3C, a sea level rise of >10cm, and an Arctic sea ice loss of >10%, are about 1 in 10; not a great prognosis.

There are other climate impacts which can be considered as important, too, though the odds are rather harder to calculate for some of them; once again, the marker is set at 2040: What are the odds of the following:

  • the Palmer Drought Severity Index (the ‘standard’ measure of drought occurrence) showing an increase in globally drought-affected areas of more than 10%?
  • ocean acidity levels (pH) increasing by more than10%?
  • the number of persons displaced by climate impacts or development related to climate increasing by more than 20%?
  • the economic cost of coastal damage to life and property increasing (at net present values) by more than 20%?

The Old Man would guess that the odds for each of these is probably comparable to the previous set of impacts; I await discussion with bated breath.

What is the point of bringing these things up? How significant are changes to individual measures at these relatively modest levels? It could be argued that a 10% increase in drought-afflicted areas is not ‘catastrophic’ (unless you depend on the land for a livelihood) in a global picture. The same argument could be made for any one of these impacts; in itself, no one impact need necessarily be seen to be a ‘disaster’.

But we aren’t talking about one, or even a couple, of highly likely climate impacts by 2040; we’re considering all of them, happening at the same time, together. And there’s no consideration of feedback effects, ‘knock-ons’ or, save us all, some or all of these impacts being worse than this ‘gentle change’ scenario suggests.

Two fairly obvious thoughts spring to mind. Firstly, the environmental and human consequences of such a collective transformation in the global ‘system’ will intermingle; the ‘big picture’ is far worse than the sum of the nasty little parts. It’s as if the planet has been run over by a large truck. The injuries sustained are none of them, individually, going to kill the patient, but the compound effect of all that trauma makes the odds of pulling through a whole lot lower.

The second thought is that the Economic A&E department is going to struggle to cope with all this damage. The recent reports on the economic costs of mitigation (or adaptation) have tended towards considering these in a 100-year timeframe. The argument here is that the likely compounded cost of climate change by 2040, even with some mitigation, is more than enough to justify immediate action to reduce emissions, and, beyond this, is of a far greater value than the Stern, IPCC or other assessments have allowed for.

The break-even line should be measured at 2040, not 2100. The chances are very good that nothing we can do about mitigation will prevent at least some of these impacts and costs by this time. But they are also quite good that we could see some real benefits from immediate action soon after this. As this is likely to coincide with the effective termination of readily-accessible oil and gas reserves (at current usage rates), there is a benefit for energy providers and resource managers, who can set a target deadline for the implementation of an 80% transfer of primary energy and fuel sources. It is also within the lifetimes of a large proportion of the world’s population. It is more real and more relevant.

So now it is your turn; the goalposts are going to move towards us, to 2040. What do we need to do, what policies need to be adopted, what messages need to be transmitted, to reach a state of the global human/environmental/climate system in 2040 which is, at the very least, no longer out of control?

Be loved.