Global Warming: 1.5°C or less?

One of the most valuable posts I’ve seen recently at RealClimate is this one about the new IPCC Special Report on 1.5°C. The report has a lot to say that’s crucially important. The RealClimate report deals with only a bit of it; its genuine importance is spreading the word about the new report itself.

Multiple Testing

Suppose I showed you a close-up, on a live video feed, of where my shot at a target landed. The video is zoomed in on the target’s bulls-eye, and lo and behold, right there is my shot. No doubt about it: bulls-eye. I brag about what a good shot I am, and you’re impressed.

Then my cat gets on the table and accidentally zooms the camera view out to show the entire target (a cat? maybe not an accident). Now you can see that I took about 300 shots, they landed all over the place (some even missed the target completely), and one of them hit the bulls-eye. My guess: you would no longer be so impressed. You might even think my original camera view was misleading.

That, in essence, is how people still buy and sell the misleading claim that there was a “pause/hiatus/slowdown” in global surface temperature during the early 2000s. Some, I’d even venture to say most, do it without knowing what they’re doing. Some who have done it but have been told why it’s a problem, persist in doing it still. The former I’d call an honest mistake; the latter I’d call not just misleading, but deliberate deception.

Bhutan

Arctic Sea Ice for Suckers: Ron Clutz shows how to Hide the Decline

His method? A favorite climate denier trick: the one called “cherry-picking.”

Open Thread

For continued discussion of things that have gone on a while … Be nice.

Arctic Heating

News stories about the Arctic always seem to say either that the Arctic is warming twice as fast as the global average, or that it’s warming nearly twice as fast as the global average. That’s not correct.

Arctic warming is more like three to four times as fast as global warming.

For Greta

I want to feel safe.

When I walk home late at night.

When I sit on the subway.

When I sleep at night.

But I don’t feel safe.

Global Warming: Talk About It

From time to time I ask people a question to gauge how much they know about climate change: “What’s your best guess, how much has Earth’s average temperature changed since the year 1900?

Global Warming: How Long Do We Have Left?

It’s already bad. But when will things get so bad that it is obviously — obviously — the worst problem in the world? How long until we go over the cliff? That depends on how much we’ve heated up already, and how fast we’re getting hotter.

We have already reached dangerous levels. The heat waves throughout the northern hemisphere this summer have cost plenty, to the economy, in human suffering, ill health, even lives lost. The wildfires in California this year were much worse than they would have been without global warming. Just last year we set a new record for the total cost (adjusted for inflation) of billion-dollar climate-related disasters. They cost the U.S. over $300 billion.

As bad as it is already, extremely bad is yet to come. Some say it’ll be when total warming since pre-industrial times reaches 2°C, others say — and I agree with them, given the costs we’ve already seen — that we’ll cross that threshhold at 1.5°C. That’s the level at which the costs, both economically and in terms of human life and suffering, will threaten our ability to cope.

I am not a climate scientist

Reader “Deltaeus” expressed his frustration about many aspects of the “debate” about climate change, including the fact that there are shallow arguments all over the place. I’d like to respond to some of his comments.