3 degrees more

.... Time to stop dreaming about 1.5C?.

On the evening of 12 June I watched a zoom presentation by (‘sir’ - I’m not big on honorifics) Peter Gluckman. He was talking about the need for better dialogue in Climate Change discussions if we want to make the right decisions. He called it “Science Diplomacy”. He’s the current president of the International Science Council and he argued that it’s not just our Climate we need to be concerned about. That’s just one of several interconnected drivers that are under stress by our increased energy demands. You can find more about it here.

He showed some very nice plots from this book, titled ‘3 Degrees More’. (thanks John Whit for the new link - updated 24 June - which includes the entire book)

The sub-title seems to give hope for the future, but I confess I haven’t got that far into it. Only the first 40 pages of about 300 were available on the preview I found.

The main point it makes in those first pages is that we’re now headed for a temperature increase of at least 3 degrees by century’s end, rather than the ‘aspirational’ 1.5 degree target agreed in Paris in 2015. And the effects are going to be more than twice as bad. Chapter one contained some very nice - if sobering - plots.

The first, below, is a great way of putting the recent man-made changes in temperature into a longer-term context. It starts about 20,000 years ago, as we approached the end of the last ice-age (strictly, the last ‘glacial’) and finishes about 10,000 years into the future. That’s a scarily steep and large step we’re currently climbing.

I chuckled to myself about the ambiguity of ‘here’ with the underlying map. The plot shows global temperature changes, but based on James Hansen’s estimates, I expect it might very well be a lot worse in Kazakhstan (or wherever that arrow happens to be pointing at on the map).

But I didn’t chuckle about that 3 degree step. It’s there because over a period of just two or three human lifespans, a significant fraction of the carbon reserves laid down over millions of years has been suddenly liberated to the atmosphere by fossil-fuel profiteers. As you can see, once we finally stop doing that, temperatures should gradually start to descend again. But it will take a hundred thousand years or more to get back to where we are now. Can we wait that long?

While I have your attention …

His next plot (below) includes some even more pessimistic scenarios of where we might be headed in the short term.

Finally, the plot below shows the measured changes in sea-level over the last two centuries. I include it here because one of my readers had recently argued that the rate of rise had not increased. That rate clearly has increased a lot since 1960, and it’s getting steeper all the time. As I mentioned a few weeks back, greenhouse gas emissions have doubled since the turn of the century, so it’s not surprising that the changes since 1960 have become more rapid. Emissions then were only 25 percent of today’s. More increases - increasingly rapid - are clearly in the pipeline ….