Climate Sensitivity: How hot will it get?

How much will global warming warm the globe? And why is this such a fiddly question to answer? In a new study, a team of 25 researchers have managed to home in on a temperature. But ultimately Earth's future depends on our decisions today.


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==CREDITS==

Coal power plant footage by Phil MacDonald
Clouds footage by eRobb3
Glacier footage by OpenEarth

[ScopeofScience]

Nice one, Adam! It's important for people to understand what 'uncertainty' means when scientists use the term, since it has a pretty different meaning than how most people use it. Its.. precise uncertainty.

[ClimateAdam]

I'm extremely climate sensitive. hbu?

[ChewonThat]

Every fraction of a degree makes a huge difference for our planet!🔥🌏

[vernonbrechin]

Thank you for sharing the findings from this recent paper. You did an excellent job of explaining it.

My impression is that the researchers primarily focused on climate sensitivity to just CO2 and not to CO2 Equivalent (CO2e) that includes atmospheric methane levels as well as the other trace greenhouse gases. They didn't consider the reinforcing feedback mechanisms such as methane emitted from Arctic permafrost and from shallow seas in the polar regions. If they were considered then the rate of temperature rise would likely be greater.

I believe you could have been more clear regarding how soon the temperatures are expected to rise into the new range that they determined.

[ascarmada]

Maybe another interesting question may be models about the consequences. Everyone talks about sea-level, but what about the culmination of stressors which will lead to system breakdown. So climate sensitivity might impact ecologic sensitivities (like pests) impacting economic sensitivities (like supply chain disruption) impacting social stability etc. Of cause these are uncertain and caotic systems, they always have been, but they where somewhat stable (most of the time) and it seems we are facing socio-economic tipping points which will collapse our societies much faster than sea-level rise will collapse our flood defences. Do you know any studies about these sensitivity - chains?

[QuantCoder]

This is a very good presentation of a complicated topic. Whatever sensitivity is, the answer to "How hot wil it get?" depends heavily upon what people choose to continue to emit in the form of greenhouse gases. And <i>what</i> is the uncertainty range of <i>that</i> input?

[localterrane]

When you stack climate sensitivity on top of just how quickly this change is happening... damn!

[davidalearmonth]

I heard that there is a chance that cloud formation could be disrupted and that we might see as high as a 12 degree Celsius increase.

[AllAboutClimate]

Excellent explanation thanks Adam! I was very excited when the Sherwood et al. study came out. I'm always impressed by your ability to simplify complex topics!

[guidoreichstadter]

Ugh. Nothing personal but this is an emergency. This study did -not rule out sensitivity higher than 3.9C, it said that it is outside the 66% likliehood bound -at around 5-18% probability. A bit like saying I've ruled out the possibility of blowing my brains out before putting a gun to my head and pulling the trigger because I haven't found a bullet in 5 of 6 chambers.

You completely dropped the opportunity to explain what a precautionary approach to existential risk is- which is why we knew everything- we needed to know to take emergency action on climate since the 1st IPCC report in 1990 and indeed since the 1979 Charney report published before I was born.

And 1.5C is "relatively safe" ? What kind of hubris or moral timidity could lie beneath a completely irresponsible statement like that?
Safe for whom? When the Arctic is already tipping? Certainly not the 1/4 of the Earths population, the small & subsistence farmers who depend on the stability of the global weather for their next meal. Where is the justice in this? We, the ordinary folk in the rich industrial countries are complicit in perpetrating the most monstrous international crime-- by failing to take ALL NECESSARY ACTION to IMMEDIATELY end our government's criminal sacrifice of the global South and future generations on the alter of fossil fueled economic growth. It's nothing short of our common moral duty we owe ourselves and those we love.

Damages and existential risk scale nonlinearly & discontinuously with heating. In a few short decades we have already moved outside the global climate regime that has existed for the entire history of human civilization. There's not a chance in hell that we will hold to anything close to a 1.5C limit without immediate, widespread, and fundamentally revolutionary changes in all major aspects of global politics, economics, and society. Why don't you tell your viewers that plain truth? Anything less just serves as cover for the status quo of government delay and inaction.

The idea that the world has agreed to limit heating to 2C is the greatest mass delusion in history. The governments of the world have signed a paper recognizing a responsibility to do so- and then failed to take the substantive action necessary to do it, rather, they've pledged a course of action guaranteed to far exceed it. They are choosing sacrifice the Earth, its people, and the next generation to the preservation of unending fossil fueled economic growth. Here's some context missing from this video: our current global path puts us on track for median to upper end heating of 3-5C within the lives of children today. This video was the perfect opportunity to tell people what Hell on Earth awaits them and their children along the current path: the wholesale loss of entire ecosystems, the rendering uninhabitable of vast swathes of the planet now home to billions, and the collapse of organized societies around the world into famine, civil war, and fascism if we don't put aside the blind optimism, the empty hopes and the wishful thinking, and get serious about what it's going to take to pull out of this nosedive: we the people must organize and take back power from the stupid, corrupt, cynical and cowardly governments of the world hell bent on our own destruction!

[shaunaburton]

It seems like there would be so many variables that it would be hard to pinpoint it like idiots starting wildfires, ocean currents changing, volcanoes erupting etc.

[johncoviello]

Thank you Adam. However, I think the upper limit for global warming is far higher than 3.9 C because there are positive feedback loops like massive CO2 and CH4 releases from frozen deposits that could kick global warming into a much higher gear than we're in right now. Also, what happens when we go to clean energy and many of the aerosols disappear? That's good for another degree C warming.

[doodle]

so the narrower estimate means we gotta pull our act together faster than what we're even trying to do right now. you best beleive the governmnents are clinging to the lowest possible estimate right now

[emanwelae]

Thank you for your videos and links. You’re helping me breathe.

[ascarmada]

Isn't it easy to rule out 1.5°C as we are almost there already (noaa says 1.42°C 2019 over land compared to 20ct average which translates to 1.22°C above pre-industrial average says metoffice) ? So if there is an almost 0% chance for 1.5°C but still a 10% chance for > 5°C the risk is leaning towards more desaster ?

[SpeedOfTheEarth]

narrower... mayhaps say tighter next lmao 😅

[QuantCoder]

I've read references to three sensitivities, one overall, like the ECS_{2X} discussed, but one for land and one for oceans. I can understand ECS_{2X} as a figure of assessment. But isn't the land one more important for planning purposes? If I recall (Schmittner, Urban, et al, 2011) the land sensitivity is typically much more than oceans, so when spatially averaged (is that right?) you get an ECS_{2X} which is closer to oceans than land. How come the land one doesn't feature more prominently?

[musicscientist]

I have a question I want to start a climate change movement virtually but I don't know how to get started I have a lot of information about climate change but I wanted to know how you think I should go about it

[jakegreek]

Before I watched the first 14 seconds of this video, I had already liked and shared it onto Facebook

[qbas]

Is it fair to say that basing on at least 2.9 degrees warming with doubling the CO2 levels we can expect at least 1.45C warming with today levels (50% not 100%)?