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Extreme CO2 Levels Could Trigger Clouds 'Tipping Point' and 8C of Global Warming (carbonbrief.org)
If atmospheric CO2 levels exceed 1,200 parts per million (ppm), it could push the Earth's climate over a "tipping point", finds a new study. This would see clouds that shade large part of the oceans start to break up. From a report: According to the new paper published in the journal Nature Geoscience, this could trigger a massive 8C rise in global average temperatures -- in addition to the warming from increased CO2. The only similar example of rapid warming at this magnitude in the Earth's recent history is the Paleo-Eocene Thermal Maximum 55m years ago, when global temperatures increased by 5-8C and drove widespread extinction of species on both the oceans and land.
However, scientists not involved in the research caution that the results are still speculative and that other complicating factors could influence if or when a tipping point is reached. The threshold identified by the researchers -- a 1,200ppm concentration of atmospheric CO2 -- is three times current CO2 concentrations. If fossil fuel use continues to rapidly expand over the remainder of the century, it is possible levels could get that high. The Representative Concentration Pathways 8.5 scenario (RCP8.5), a very high emissions scenario examined by climate scientists, has the Earth's atmosphere reaching around 1,100ppm by the year 2100. But this would require the world to massively expand coal use and eschew any climate mitigation over the rest of this century. Further reading: A state-of-the-art supercomputer simulation indicates that a feedback loop between global warming and cloud loss can push Earth's climate past a disastrous tipping point in as little as a century.
However, scientists not involved in the research caution that the results are still speculative and that other complicating factors could influence if or when a tipping point is reached. The threshold identified by the researchers -- a 1,200ppm concentration of atmospheric CO2 -- is three times current CO2 concentrations. If fossil fuel use continues to rapidly expand over the remainder of the century, it is possible levels could get that high. The Representative Concentration Pathways 8.5 scenario (RCP8.5), a very high emissions scenario examined by climate scientists, has the Earth's atmosphere reaching around 1,100ppm by the year 2100. But this would require the world to massively expand coal use and eschew any climate mitigation over the rest of this century. Further reading: A state-of-the-art supercomputer simulation indicates that a feedback loop between global warming and cloud loss can push Earth's climate past a disastrous tipping point in as little as a century.
USA could be 100% clean and it won't matter if China and India keep polluting. So this is all fucking pointless.
There is an abundance of scientists, but no names; so who the 'f are they?
Climate change is real, but you need to read any single study or model with a bit of a "let's see if this gets confirmed by other groups" before believing it.
This is the flip side of that "scientific consensus" thing that the deniers keep not understanding. Science is about replication, and the real science comes when other scientists look at a result and say "yes, that makes sense, we can confirm it with our own modeling and measurements."
This is one group, with one model. Too early to call it doomsday yet.
The publisher made it freely available -- a pleasant rarity.
Note that the focus of the paper appears to be a possible explanation for extreme temperature changes in the past, not that there's a credible chance of this happening any time in the near future.
As someone who has a degree in botany and has worked in greenhouses that were maintained at 1500ppm. You should know that CO2 levels become dangerous at 5000 ppm, not 1200ppm.
It becomes dangerous to life and health at 40,000ppm.
https://www.cdc.gov/niosh/npg/...
From the abstract it looks like a doomsday prediction. Predicting an 8 K increase (+265c) in global temperature is an extraordinary claim and would require extraordinary evidence.
It's not even an extraordinary claim; it's an extraordinary hypothesis.
Past the doomsday headline, the story says :
"The paper emphasises that large uncertainties remain and the results they find are very much preliminary. Because they are using a high-resolution large-eddy simulation their model lacks many other factors contained in global climate models that operate over larger geographic scales.
"Specifically, climate models suggest that large-scale subsidence in the atmosphere – colder air becoming denser and moving towards the ground – weakens as the world warms. This has the effect of lifting up and cooling cloud tops, which counteracts possible stratocumulus breakup. While the paper tries to account for this, the weakening of subsidence that occurs is uncertain and varies across climate models."
Really, I'm not sure why this is even a story making the news. "Here's some scientists trying to figure out feedback loops in a greenhouse regime that is far from where we currently are, and here's an possible result that is interesting but has yet to be rigorously modelled, much less tested."
If all of you will think way back to where we first were supposed to be alarmed about global warming, it was exactly because too much CO2 was supposed to lead to runaway warming.
Well obviously that never happened, and this new paper is admission that fundamental concern was misplaced In fact now we see we need to get to a very high CO2 level we probably cannot even reach, to MAYBE risk a CO2 rise because of cloud interaction (the idea is only theoretical). It's quite apparent at this point that interaction of CO2 with a real world atmosphere is quite a lot more complex than any climate scientist is willing to admit.
Further proof that what we were told to worry about, should never have been a concern to start with. We seriously need to stop our focus on CO2 and start re-examining real sources of pollution again and focus on those.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
The problem here is that studies like this are based on *simulations* not observations of repeatable experiments.
True. It's a math model and should be treated as such. Simulations can be very useful but it's important to know the limits and assumptions that go into the model.
What we have here is a set of theories, which really cannot be proven beyond doubt.
Not true. Presuming the model is accurate it should be making testable predictions about what will happen as the climate chances in the coming years. If the model predictions fits the data we gather well then we have reasonable confidence that it is accurately modeling the real world. Problem is that because the consequences of letting climate change run unchecked are potentially so severe (presuming the model is accurate) we cannot risk actually testing it fully so at some point we'll have to extrapolate and take actions. But we're going to find out at least the early predictions whether we want to or not because some changes are already too late to stop.
If we are being honest here, climate change science is, at best, an educated guessing game, not a proven beyond a doubt set of scientific laws, and specifically I mean "man made climate change."
No it really is not just a guess unless you think every hypothesis is "just a guess". A lot of the science in the field is simply documenting changes that absolutely ARE occurring, many of which were predicted by those same models that you are calling guesswork. The model makes predictions which absolutely can be checked.
The critics of this science have some valid points. Past high profile predictions of our demise from climate change have been wildly over blown, there seems to be a bias towards "making news" in order to get research grants, and little attention is paid to the views of those who disagree with the consensus.
Most of the critics do not actually make or hold valid counter points. They mostly simply are seeking to reinforce their confirmation bias for various reasons. If they were serious about disputing the science the way to do that is present their own alternative testable hypothesis and back it up with data. The scientists are doing this and the critics by and large are not. Since the critics cannot be bothered to actually do the science their opinions (rightly) get ignored.
Simulations have serious limits.
Yes they do. That doesn't mean they are useless. I used to do simulations for a living in a previous job. There is a famous saying that "all models are wrong but some models are useful". If you insist on perfection in the climate models despite them giving you good and actionable data, you are completely missing the point. Newtonian physics isn't the most perfect model we have but it's still extremely useful and gives reasonably accurate testable predictions. A lot of the climate science is throwing off a lot of very useful data and we ignore it at our peril.
This is actually several dozens of groups coming up with similar modeling and conclusions over the last few years, though yes they differ a small bit they are all saying the same thing. It's not one single study saying this. False characterization.
Not merely dozens of groups, there are hundreds of groups running climate models (possibly thousands: the main models are open source.).
They are all saying the same thing, if by that you mean "human generated greenhouse gasses, primarily carbon dioxide, are increasing the Earth's greenhouse effect, and having a warming effect on the climate."
Yes, that part is a clear scientific consensus, well understood, and replicated by many groups.
It is this new result (this paper), suggesting a new feedback mechanism only operating at much higher carbon dioxide levels, of which I am saying "a single study".
And not merely one study: it is one study of which the authors of the study themselves emphasize how preliminary the results are.
Triassic: 1750 ppm CO2. Temp 3 C above modern level.
Jurassic: 1950 ppm CO2. Temp 3 C above modern level.
Cretaceous: 1700 ppm CO2. Temp 4 C above modern level.
Paleogene: 500 ppm CO2. Temp 4 C above modern level.
Neogene: 280 ppm CO2. Temp 0 C above modern level.
Quaternary Period: 250 ppm CO2. Temp 0 C above modern level.
Then you get to the Modern Period. Frankly we are still living in an Ice Age.
No. Current CO2 levels are abnormally low compared to Earths Geologic History.
The clouds on Venus are not water but sulfuric acid.
Over geological timescales, yes. Not during an icehouse glacial/interglacial period like we've been in for the entire history of the human species though. Warm things up dramatically, and we'll likely toggle to the planets hothouse state where such CO2 levels *are* fairly normal.
Once we get there, it might not be that bad - though the climate seems to have been a lot less stable in that state, with CO2 levels varying wildly, ecosystems changing frequently, and vast continent-spanning deserts not exactly being super rare. And even if we luck into tropics extending into Canada - the tropics are generally not actually considered a lovely place to live full time. The diseases alone put a damper on things.
A more immediate problem is the transition period, which tends to be a really traumatic event, with 90+% global extinction rates. Consider that an old-growth forest can't migrate very quickly, and when the trees go, so do most of the species that live there. And moving further from the equator chasing your optimal average temperature, also subjects you to more dramatic seasons. The Amazon Rainforest evolved to deal with a few degrees of seasonal variation - even if it could migrate to North America chasing the right average temperature, the seasons would kill most of it.
For a whole lot of species it *will* be the end of the world, and that's going to be really rough for us, perched on top of a global ecosystem that's already quite shaky from human-caused pollution and extinctions.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
I, for one, am glad that we have a cartoonist to settle these debates once and for all.
The problem here is that studies like this are based on *simulations* not observations of repeatable experiments.
You are talking about two different things here, and I think it's worth clearly disentangling the two.
One is the specific paper being discussed here, which proposes a new feedback mechanism that operates only at high carbon dioxide concentrations, much higher than those in the present era. This one is indeed a simulation, and the authors themselves emphasize that it is speculative and needs to be studied further. In particular, this feedback mechanism may have applicability to understanding paleoclimate events.
but you seem to go on to be to take a pot-shot at climate science, and climate models in general.
What we have here is a set of theories, which really cannot be proven beyond doubt.
Science doesn't, and can't, "prove things beyond doubt."
What science really does is make models (what the general populace calls "theories"), and then test the models against measurements. The models that explain the measurements better are kept, and the ones that don't are discarded. A scientific theory is never "proven beyond doubt"; in real science, every model is subject to being discarded when a better model comes along, or when new measurements are made that the old model can't explain.
Science is really a process of progressive iteration: the models get better and better as we understand more.
If we are being honest here, climate change science is, at best, an educated guessing game, not a proven beyond a doubt set of scientific laws, and specifically I mean "man made climate change."
Here is where you switch from discussing the paper in question, and go on to take pot shots at climate science.
Unless you mean "all science is at best an educated guessing game", no. The basic points of climate science, and specifically "man made climate change," are well understood, and well supported by evidence. The basic physics has been known for over a century, the basic model is over fifty years old now and well supported by evidence. The detailed models are working at accounting for details at progressively finer scales, but the basics are well understood.
The critics of this science have some valid points.
The main (or at least the loudest) "critics" of the science in the past have consisted almost entirely of people whose "science" is driven by ideology and funded by fossil-fuel companies, and they have proven to be wrong so many times over and over that their main problem is nobody takes them seriously. If they have "some valid points", those points have been so overwhelmed by the tidal wave of ideologically-driven garbage that they are entirely invisible.
Past high profile predictions of our demise from climate change have been wildly over blown,
When you talk about "high profile" predictions, I think you're now moving into yet a different rant, which is a critique of media coverage of the science. Ignoring what the media considers "high profile", the actual predictions done by real science have, so far, mostly been accurate.
there seems to be a bias towards "making news" in order to get research grants,
You are confusing the science with the media attention. The paper in question is a good case in point. Notice how the headline on the article is "Extreme CO2 levels could trigger clouds ‘tipping point’ and 8C of global warming"-- that's "making news". And then read the actual paper, which has a single sentence talking about the possibility of this happeni
CO2 levels over geologic time spans are usually much, much higher on Earth than the current 400 ppm. Levels in the thousands PPM are more normal.
Nobody human cares what's been more normal for the planet any more than anyone thinks it will be the end of the planet if CO2 increases. The concern is that it will be the end of humanity, or at least our dominance. Levels in the thousands of PPM are harmful to humans, starting at 1,000 PPM and becoming acute around 5,000 PPM. What is normal or natural is irrelevant. It's this period of abnormally low CO2 that has permitted us to flourish, and if we want to continue to do so, we're going to have to keep it low.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
No. But it will be expensive and disruptive.
Sooner or later we're going to need to pick out what places we'll try to save, and what places aren't worth saving. For the places we are going to try to save, we'll have to invest in infrastructure to mitigate some of the effects of climate change. For the places we aren't going to try to save, individuals can either try to survive with what they have, or move. If they survive, they'll have to invest and make changes in their lifestyle - such as limiting water usage and trucking in water if they are in an area where drought has caused water tables to fall, to raising their houses by the coast in order to survive hurricanes and king tides.
Where is the control Earth without humans against which to verify these models?
If you want to say global warming is essentially a consensus, I'll agree. But this study is still an outlier. 8C warming is considerably higher than most projections. They say that it's because they included a factor that other models didn't include, but that's going to need considerable confirmation.
That said, don't trust the models when the warming projected gets over 2C warming, as they are then operating beyond the range within which they have been validated. And expect that there are feedback loops, both positive and negative, that will become important in that range which haven't been needed up until now. So saying that it will be considerably worse than the current projections isn't unreasonable. Certainly when not when you include an additional feedback loop. But there are likely to be others that will act as dampers. Their argument against it is that "last time this is what happened", but "last time" isn't a close match against current conditions, so there may be other effects.
All that said, the conservative approach would be to consider that they might be right.
I think we've pushed this "anyone can grow up to be president" thing too far.
How does that work ? What is actually causing the up- and downturns in these cycles ?
If it is an external force, it would have to be huge; something on the order of magnitude of the sun.
Yep. And we measure the output of the sun from satellites, and it's not changing . So we rule that out.
No, that's the good thing about hundreds of independent research groups on six continents making measurements and running models: they don't all use the same set of assumptions and the same data.
That could do it - except that our measurements show no sufficient long-term increases in solar output.
The measurements do show sufficient long-term increases in gases that trap more of that solar output, though
Why would anyone engrave "Elbereth"?
Yes that's why it's called reductio ad absurdum
Seven puppies were harmed during the making of this post.