Thread by @KHayhoe

First, remember this is a synthesis report of the peer-reviewed literature. So these results were already out there: sea level rise accelerating; drought, heavy rain & extreme heat risks soaring, massive wildfires. They just hadn't been pulled together into one overwhelming list.

To those of us immersed in the field, the @IPCC's conclusions are no surprise; but for many, it's not until they see it all together, with the impacts on human life clearly laid out, that the penny drops. That's why these reports are so important and so powerful.

We are conducting an unprecedented experiment with the only home that we have. As far back as we can go in the paleoclimate record, there's no example of this much carbon going into the atmosphere this fast. Source: science2017.globalchange.gov/chapter/4

Global temperatures are rising faster than any time in the history of human civilization on this planet, and that's why climate change matters: because after the polar bear, we're next. foreignpolicy.com/2017/05/31/eve…

Our entire civilization is built on the assumption that climate varies within bounds that can be predicted based on the past. It's as if we've been driving down the road looking in the rearview mirror: but now we've hit a dangerous curve & our wheels are teetering on the edge.

Why has it taken so long for us to recognize the danger we are all in? There are a few reasons. The first is psychological distance: we humans are really good at dissociating from problems we see as far off in time, space, or relevance.

https://twitter.com/KHayhoe/status/1235206404765552640?s=20

Also, we scientists are often quite conservative & big synthesis reports like the IPCC are explicitly designed to focus on what everyone can agree on, which has typically been the less alarming possibilities. @NaomiOreskes & colleagues document this here: sciencedirect.com/science/articl…

This tendency to understatement in past reports has been so marked that they even coined a term for it: "erring on the side of least drama" or ESLD.

Then there's the fact that we scientists often assume everyone thinks like us. If we just tell them the facts, we assume, they'll get it. They'll understand why this is so bad, and they'll take action. Our job is done. theonion.com/sighing-resign…

But now, things are changing. We've realized that if we don't spell out the fact that it's our civilization we've put on the chopping block ourselves, in words that everyone can understand, emphasizing risks that matter to everyone on this planet, who will?

That's why the US National Climate Assessment had a chapter that I co-authored with @bobkopp that was literally called, "potential surprises". What's the bad stuff that could happen as a result of this unprecedented expt that we might not even know about?! science2017.globalchange.gov/chapter/15/

That's why I've created series of YouTube videos that explain the risks climate change poses to every US region, to my home of Canada, and to everyone on this planet.

That's why over 11,000 scientists wrote and signed this letter warning of a climate emergency last January. academic.oup.com/bioscience/art…

And that's why this new IPCC report is so blunt. Climate change isn't just one more priority on our already over-crowded list. It is a threat multiplier that affects every single other priority already on it, from the air we breathe to the food we eat.

The bottom line is this: to care about climate change, we only have to be one thing and that's a human living on this planet. And we're all that.

PS. some have pointed out, rightly, that we must recognize it hasn't been a level playing field. Over the last 30 years, the fossil fuel industry and others have poured huge amounts of money into literally manufacturing science denial. See: merchantsofdoubt.org

It's not because they genuinely have a problem with 200 years of very basic physics. It's because ...

https://twitter.com/KHayhoe/status/1402704303077347336?s=20

And that's why our communication must be two-pronged. We need to be aware of the risks--why would we act, otherwise? But we also have to be informed of the solutions--because if not, we'll just be paralyzed. That's why solution-oriented resources like @ProjectDrawdown are so key.