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I don't think current models are going to be anywhere close to accurate. They don't account for recently published research. U of M recently found that polar ice has lost 25% of its cooling reflectivity. The ice melt slush on top absorbs rather than reflects sunlight/heat. The authors expect current model's predictions of warming to increase a couple of degrees C by 2100 as soon as their data is incorporated into the models. Other research which projects higher warming include studies of ocean stratification, drought/heat stricken trees not absorbing CO2 as much as they used to (not growing), and landfills emitting huge amounts of unreported CH4. My best guess is that if we incorporate these study's data into models, they will predict 3 degrees C warming by 2050.

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Hi David,

Current CMIP models include robust albedo responses already, and have taken strides (relative to CMIP5) to incorporate more realistic sea ice climatologies. That being said, we recently published an estimate of temperature impacts of full summer Arctic sea ice loss in our review on climate tipping points that might be of interest: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2021RG000757

I would note that none of the CMIP6 models (even those with an ECS of 5.7C per doubling CO2) see 3C by 2050 as a plausible outcome under a current-policy-type scenario (e.g. SSP2-4.5). I have a recent update of projections normalized to observations here: https://www.carbonbrief.org/analysis-what-record-global-heat-means-for-breaching-the-1-5c-warming-limit/

-Zeke

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If one incorporated all the data from recent research (polar ice reflectivity, ocean stratification, tree leaf pores closing, drought stricken ground fissures emitting CO2, unreported landfill CH4 emissions, increased CH4 emissions from swamps, bogs, and wetlands as warming acts as a catalyst to microbes, and added it into the models, how much warming would you expect? I admit I don't know, but it sounds like a lot to me. It sounds like a better explanation than low sulfur fuels for our current temperatures being higher than models said was possible.

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While ECS may be turn out to be on the high side of the CMIP6 range, saying current models of global heat accumulation aren't accurate isn't really relevant here. Zeke is talking about how the amount of future warming depends critically on emissions from now on. The decadal trajectory of global emissions, and therefore of climate forcing, is largely or entirely controlled by collective human agency. Although the trend of global decarbonization is uneven, by now it looks IMHO unstoppable no matter who's in power in the US.

IOW, doomism is no better supported than denialism is.

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I don't see doom at 3 degrees C warming. Australopithecus flourished nicely in that climate 3-4 million years ago. Even in the PETM life didn't go extinct. I expect the 2-3 billion people living in the tropics will have to move or die. I don't see that as doomism (unless you live in the tropics, of course). I expect summers to be comfortable in mountain valleys above 6,000 feet elevation, for some time to come. But, if we were to incorporate all of the research which has identified newly discovered sources of warming into current models, how much warming would you expect? None of the articles on fissures in the Earth's crust in drought stricken areas, for example, gave an estimate of how much sequestered CO2 will be released. None of the articles on ocean stratification estimated how much warming it will cause. Does anybody have a realistic estimate of all of this?

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I agree with you. So would Dr. James Hansen et al. Geologic and cryospheric records show that you bake in +2.5C to +3.0C at 450 PPM [which we're likely to hit by or before 2035] and if you measure against CO2eq you're probably in the range of +4C - +4.5C by end of this century - as if our moral responsibility ends at the end of the century. Look, we've set in motion accelerating feedback loops lowering albedo, reducing low-level oceanic cloud cover, permafrost melt [with the axiomatic increasing CO2 & CH4 releases, and northern Boreal forest and Amazon Rainforest are shifting to net CO2 producers. And, that doesn't include the unknown unknowns that keep emerging and shaking up the system - not to mention the 2nd & 3rd order effects and feedbacks.

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While waiting for an expert to respond: AFAIK, current coupled GCMs can hindcast pleistocene climates pretty accurately, so they appear to account for the major forcings already. See Schmidt et al. "Using paleo-climate comparisons to constrain future projections in CMIP5" (ntrs.nasa.gov/api/citations/20140011351/downloads/20140011351.pdf)

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It is hard to please some people....

"The assumptions for adoption of renewable energy are too optimistic."

"RCP8.5 is unrealistic, misleading, and politically motivated."

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At least they're not usually the same people.

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I can think of one in particular...

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I don't believe we have "baked in warming", as is often claimed, for hundreds or thousands of years. The statistically significant strong trend is that the natural carbon sinks (ocean and land biomass) have continued to remove CO2 from the atmosphere at rates directly proportional to atmospheric CO2, with at most only very slight degradation in recent years.

If we successfully decrease worldwide anthropogenic CO2 emissions at about the same rate that has been achieved in the USA and the UK over the last two decades, then we can expect to reach a balance between emissions and removals within 2-3 decades, followed by gradual but significant reductions in atmospheric CO2 after that.

The IEA has noted that we are "bending the emissions curve" thanks to the commercialization of modular, low-carbon technologies (heat pumps, solar photovoltaics, wind turbines, etc) that, when mass-produced, become economically-competitive with conventional, fossil energy technologies. We aren't on the "business-as-usual" trajectory realization, and the natural sinks continue to help out by drawing down atmospheric CO2 at high rates. But together we have a substantial opportunity to make excellent progress in additional deployments of low-carbon, carbon-neutral and even carbon-negative technologies by mid-Century.

This is certainly an optimistic prognosis but, as Michael Mann has said, the truth is bad enough, so reducing emissions is still critically important.

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Phys.org's article, "The Overshoot Myth," takes a different view. They don't think natural systems are likely to pull significant amounts of carbon from the air very quickly. At 2 degrees C warming tree's react to heat and drought stress by closing the pores on the undersides of their leaves. They don't absorb CO2 as much as they used to. They don't grow during stress conditions. Which changes the carbon cycle, keeping increasingly larger amounts more CO2 in the air. Also, above 2 degrees C warming the heat acts as a catalyst, increasing the speed at which microbes decay carbon in the soil, again adding increasingly more CO2 into the air. The heat catalyst also drives microbes to release increasing amounts of CH4 from bogs, swamps, and wetlands. In past warming events, nobody was burning fossil fuels. These natural positive feedback loops overwhelmed natural carbon sinks, and the amount of carbon in the air did in fact increase for periods of thousands of years.

And, as we go above 2 degrees C warming, nobody knows how much of the Amazon will be pushed into savanna, or how quickly. I've heard the PETM described as 10,000 years of El Nino. Where does that put us?

But to address the land and ocean carbon sinks directly, Muller et al, 2023 found that 1994-2004 the oceans absorbed 29 billion tons of CO2, but 2004-2014 (as the amount of carbon in the air skyrocketed) the oceans only absorbed 27 billion tons. They think the ocean is hitting its saturation point.

As far as land as a sink, the amount of land experiencing extreme drought is rapidly increasing. It doesn't act as a sink in that condition. Studies show that todays wild fires are so hot that they prevent the burned from acting as a sink for decades.

You may know of more positive research studies, but what I'm reading doesn't offer much optimism in the forseeable future.

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So, Zeke and Andrew. Some questions I would like to ask you as someone who is kind of in a downward spiral of emotions due to climate change.

Considering Hansen's quite accurate predictions for these past 2 years (he got the range of 2024 and 2023 warming above pre-industrials exactly right), do the past models (especially CMIP6 and the one the CAT, IEA and others uses) still hold water? I ask this out of curiosity and anxiety due to the growing evidence of warming accelerating (and potentially proving the "Warming in the Pipeline" article right).

I do agree with your point of not being in the high-end emissions currently, but I am skepctical of not being in high-end temperature ranges. Do you still stand by the models having a too-hot problem after the past 2 years events?

I find even SSP2-4.5 way too optimistic these days due to the quite high possibility that there could very well have been a change in the earth's systems + feedback loops, climate sensitivity, lower sinks, aerosols and forcings coming in stronger and earlier than previously thought.

I am aware of the points of the revolution in energy that we are having (good thing, but what if it's not enough to prevent doomsday?) and "solving" climate change + net zero being more of a political problem then a scientific one and that is what scares me.

It's a battle in my head of "IPCC vs Hansen and Rockström" of figuring out who has the more credible approach to the current situation. Dang, just in my time of being an adult, society as we know it might as well collapse, goodbye my dreams of kids, dogs and travelling, who's to say getting old.

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I won’t speak for Zeke, but my perspective is that the models are doing a pretty good job. It’s a classic mistake to confuse short-term variability with long-term climate change, which happened with “the pause”. I wrote about that here: https://www.theclimatebrink.com/p/the-pause-vs-the-surge

So 2023/24 should not disprove the models. Rather, comparisons between the models and observations over a few decades do look good; Zeke had a thread on that: https://bsky.app/profile/hausfath.bsky.social/post/3lfkxicwzdg2h

In the next few years, we’ll see if something has changed that the models do not predict. My money remains on the models.

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To add to Andrew's reply, Hansen's prediction of acceleration is actually more or less identical to the CMIP6 multimodel mean (though a bit above the IPCC assessed warming projections that exclude hot models). That being said, its hard to draw too firm a conclusion from two years about the magnitude of long-term acceleration. See this article I wrote on the topic last year: https://www.carbonbrief.org/factcheck-why-the-recent-acceleration-in-global-warming-is-what-scientists-expect/

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Thanks to both of you for answering my question. I think I asked this for the most part because of bad anxiety related to climate change as a whole. I'm pretty young so I hope I learn how to manage it eventually.

It's just that it's hard not to fall into the sort of doom cycle (literally lost nights of sleep) I fell these last months. It's the sort of feeling like "at my time of being an adult and make a name for myself, society as we know it will collapse" or, borrowing from a sub-celebrity from where I live "too young to explore space, too old to explore the earth". It's a mix of anger, sadness, fear but maybe some immaturity as well.

Your posts help me cut some of those feelings but I think you both, living in academia for a good portion of your lives know about the uncertainty in science in general, but earth sciences especially, where everything is so dynamic and fast-changing (just like my field of study where computers and coding in general are always striving for better efficiency, even more so in the age of AI). And it's this uncertainty in climate science that is could very well be a salvation but has equal or more chances of being a curse which kept me awake more than once.

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It is I believe this rapidly changing world and anxiety about the future that has helped stoke a worldwide renewed interest in Stoicism over the last decade or so as reflected by a proliferation of contemporary articles, books and blogs on the subject.

And for good reason I think. People really do find that it provides some helpful ways of thinking about how to navigate the uncertainties of life with a bit more ease.

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Stoicism, Buddhism, or fatalism aside, dispair is not a viable option. We must all do whatever we are able to provide the best world we can for our descendents and all other species on this planet. We must not don sackcloth and sprinkle ashes or contemplate eternal truths. We must just put our shoulders to the wheel.

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Thank you, Michael. I share your conviction, though now mostly in a rhetorical way. Other than living mindfully, I've aged out of accessible wheels: SIWOTI (xkcd.com/386) is pretty much all I've got left. Yet I've consistently done the most impactful thing I can all along: vote Democratic, for better or worse the defacto US party of collective action for public good; and exhort others to vote likewise. We were in a 48.4% minority last fall, and that can easily turn around again in four years of worsening weather. I'll be nattering away through the interval!

Meanwhile, global and even US decarbonization are advancing. Of course, even alarmists are constrained by economic forces. The grid here is almost all hydro or nuclear; there's even a little landfill methane in the mix. My house is all-electric already, with a good heat pump. I'll keep driving my little old ICE pickup (22 mpg) once or twice a week for groceries until it's no longer reliable, by which time BEVs will be cheaper. The landscape of my little nature preserve is self-maintaining, but for annual mowing with a large, exhaust-belching, walk-behind ICE mower, to keep the invasive shrubs down; I'd prefer to burn it biennially, but that's illegal. So I enjoy exquisite native spring wildflowers now, while big battery-powered mowers are coming down in price. I may install solar PV, with a battery backup; a BEV will make even more sense then. Much depends on how my 401k, which has to last as long as I do, performs in the next couple of years. I'm as alarmed as ever, but I'm not dead yet!

Seriously, both denialism and defeatism frustrate efforts to muster a voting plurality for collective decarbonization. My quixotic mission is to push back on both kinds of disinformation, whenever I see them in public fora.

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When I type into my search engine, "Is Arctic Sea ice melting faster than climate models are predicting (or 'have predicted')," I get the answer, "Yes, far faster." I get the same result if I ask about Greenlands ice sheets, Antarctic glaciers, thawing permafrost, or ocean temperature. For me, the most striking example is that in 2021 the IPCC published the prediction that we had a 50/50 chance of going above 1.5 degrees C warming in the 2040s. Two years later we went above 1.5 degrees C warming. Correct me if I'm wrong, but what it looks like to me is that climate models always badly underestimate the speed and severity of warming.

I suspect that this is not a problem with the models. It's a 'garbage in-garbage out' problem. A few years ago the Washington Post ran an article called, "Faulty Data." The Post reported that the IPCC allows countries to self report emissions. Naturally, every country's politicians lie. By comparison with independent sources, the IPCC was telling its computers that emissions were 7 billion tons of CO2 less than the number of tons that are actually emitted each year. So, we're looking at 100-150 billion tons (over the last 20 years) more carbon in the air than the gets programed into the models.

In addition we've had multiple studies published in the last year which found that American landfills emit 40% more methane than they report to the IPCC. And, landfills throughout the developing world are far worse than American landfills. Zhang et al, 2024 found that rising temperature has caused CH4 emission from wetlands to increase above what's reported to models over the last 20 years, and they predict a 15%-30% further increase by 2050.

Also, Farshid Vahedifard published in Environmental Research letters that drought stricken land cracks open in deep fissures. Oxygen flows down, bonds with sequestered carbon, and flow up into the air as a new source of CO2 not accounted for in anybody's model. Also, the KIT study published in New Phytologist found that heat and drought stressed trees absorb "far less" CO2 from the air. This is essentially a new source of CO2 in the atmosphere which is not accounted for in anybody's model.

Also, Li et al, 2020 published in Nature Climate Change their research that ocean stratification is increasing, and the warmer water which increasingly stays at the surface will increase air temperature in the years to come. Nobody's model accounts for this.

Given all of this, I don't see how it would be possible for models to accurately predict warming. Warming is going to be far faster and more sever than current models predict. I don't think you need to feel personally threatened by this. Winters are going to be fabulous. Summers will be very comfortable in mountain valleys above 6,000 feet elevation. Climate change looks to me like it will be an inconvenience for the wealthy, and a death sentence to the poor.

I feel like it would be a good idea for people to start taking it seriously and start preparing. For example, if you set the NOAA interactive sea level rise calculator to Boston, 3 feet of sea level rise, high tide, it shows most of the city under water at high tide every day. The Boston Globe reports that city government has applied for all sorts of funding to protect the city, but hasn't actually appropriated any funds for defense against sea level rise. This seems reasonable if one believes the IPCC prediction of 2 feet of sea level rise by 2100. However, Gino Casassa, head of the Chilean Antarctic Institute, at the 11th Scientific Committee on Antarctic Research conference last summer predicted ,"sea levels rising by 4 meters by 2100, more if emissions increase."

I feel like the people of Boston, and really any rational people, would be best served by preparing for what seems inevitable.

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Thanks for posting this as well as for writing the journal article. While, as Michael Mann says, "the truth is bad enough", it's important that people know that we're not on the previously-declared "business as usual scenario".

Additional confirmation: The recent preprint of the "Global Climate Budget 2024" report (Friedlingstein et.al.), by the way, noted that "Total anthropogenic emissions have been stable over the last decade (zero growth rate over the 2014-2023 period)".

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I'm smart enough to know I'm stupid and unable to forecast weather out past three days. Just too blinking many variables and feedback loops recursively playing off each other. I'm stupid enough not to know if anybody is smart enough to have arrived at climate models that are accurate out past three years. We're in "any body's guess/best guess territory.l, but Zeke's is better than most.

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Michael, see Gavin Schmidt's analysis from about two years ago (realclimate.org/index.php/climate-model-projections-compared-to-observations). AFAICT, the CMIP ensemble consulted by the IPCC for each of its periodic Assessment Reports have reproduced, within quantified uncertainty limits, the *trend* of global mean surface temperature (GMST) to date for each AR released, over periods longer than about 20 years. Satellite data, which are computed values over the depth of the atmosphere, not so much.

Three years, however, is too short to overcome the noise by any method. Then the question becomes "how much accuracy do you require?" Your answer may differ from Zeke's. That's the trouble with being a single datum!

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My study of C3S climate change stats, including the quarterly June 5, 2024 "Hottest May on record spurs climate change action", which gives a 0,75 degC ave. for the 4 yrs. since the 1991-2020 baseline, and an annual average of 0.214 degC, points to a 6 degC increase in global surface temps by 2047. So, forgive me for saying so, but you are way, way off and our end is coming way before "the end of the century".

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Dr. Miklashek, what makes you confident you're not the one who is way, way off? Zeke does this for a living, you know. Overestimation of one's own competence, and failure to recognize genuine competence in others, are manifestations of the Dunning-Kruger effect. Science depends on trained empiricism, and mutual discipline by equally trained, skeptical peers. Intersubjective verification, i.e. "peer review", is how you avoid fooling yourself, because you are the easiest person to fool. It's not perfect, but it's the only method of predicting the future that's more successful than divination with entrails!

Anyway, my own end is coming before the end of the century even if I'm really lucky. Do you expect our entire species to become extinct by then? How do you see climate change killing everyone on Earth?

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MA, my own end is coming before the end of the decade, but being somewhat a misanthrope I don't care greatly if our species survives our own folly, except we have done some good things like invent the comb and produced the Muppets shows. Brainy lobsters would likely have done neither.

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You deserve a like just for the Muppet comment! It is not easy being green but it is getting easier and cheaper!

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Never forget my alter-ego, Fozzie Bear! We deserve credit for him as well!

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Data is not accurate and has many interpretation to look a certain way then really is for the government pay for this data. The current models cannot see the future.

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I'm confused. Based on your Substack profile and the blogs you follow, you apparently care about global warming. You need to be clearer about what you think is wrong with Zeke's data or analyses.

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The data analysis is limited on a a few finding over many gaps of time. Data has gap of data. A study was done in the artic cycle for 10 years but no studies for 3 years a gap in data. It was more melting then estimated from the study. Yes, this is the best way to see into the future.

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No data can sample the world down to the smallest detail. That doesn't mean the data we can obtain, don't tell us anything useful. And no, the current physics-based models cannot "see the future". What they can do is project likely futures within quantifiable uncertainties, under specified scenarios for future emissions that are determined by politics and economics. Science isn't perfect, it's merely a better method of seeing the future than anything we've tried since hepatoscopy.

But if by "really is for the government pay for this data" you mean that climate scientists are only in it for the government's money, you're either a paid troll or a useful idiot.

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I , Mary Danoff, am a troll and useful idiot in your opinion. Government can take data and say there is no global warming, which many politicians do say. Government has a military base in artic and pay for studies. The military are scientists, too. I am not saying scientists are in for the money. Many grants come from the military or government. Ask your self where is the money coming from.

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I , Mary Danoff, am a troll and useful idiot in your opinion. Government can take data and say there is no global warming, which many politicians do say. Government has a military base in artic and pay for studies. The military are scientists, too. I am not saying scientists are in for the money. Many grants come from the military or government. Ask your self where is the money coming from.

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I agree with Just Dean: You need to be clearer about what you think is wrong with Zeke's data or analyses.

It sounds like you're distrustful of government funding for science. And of course rulers are willing to invest in new knowledge, that may give them and/or their countries a competitive advantage, whether military, economic, or diplomatic. That's partly what drove the Scientific Revolution in Renaissance Europe. But basic (i.e without immediate payoff) science has come to be seen as a public good, requiring government support, for public benefit. Understanding of climate, especially, benefits everyone!

Nonetheless, scientists who take the government's money to do the research have their own agendas. How do I know? I grew up in international scientific culture, as the son of a Biochemistry professor in a college town. I was further acculturated by a prolonged graduate education from world-class Ecologists and Evolutionary Biologists, before finding an easier way to make a living. Although I was never paid for peer-reviewed research, I spent my next 31 years working in close contact with professional scientists, in a NASA Earth Sciences laboratory, an EPA Ecology lab, and a couple of DOE National Laboratories.

I tell you all that so you'll understand why I'm confident Andrew, Zeke, and the vast majority of their specialist peers who review each other's work, haven't promised the US government any particular results; nor does the government censor their publications. It's hard to explain to people who aren't well acquainted with scientific culture.

OTOH, there are a few mercenary charlatans with scientific credentials, who are skilled at producing specious, sciencey bullshit for anyone who pays them enough money. Their clients are government or private parties seeking to discredit the inconvenient findings of legitimate climate scientists. That's why lay people need "scientific metaliteracy", to know genuine science from propaganda. Unfortunately, the best way to acquire metaliteracy is to put the time in! Failing that, there's really no choice but to accept the formal specialist peer consensus, albeit provisionally, as scientists themselves do. Because without science, we know nothing at all.

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Look... lets agree we don’t have a climate emergency and also that any mitigation of CO2 is impractical anyway..

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Jake the Rake, with a contrarian take,

How does your misguidance grow?

May I suggest you go find a home,

Where deniers and skeptics roam.

For here at The Climate Brink,

They do good science, I think.

I have noticed your comments are often deleted,

Because their science content is mostly depleted.

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Climate alarmists are in the dump as now we have Trump 😊

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No.

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Thank you again for an excellent review of the published scenarios of the expected temperature rise by 2100. It seems that much of the moving away from the high-end emission scenarios is based on the plateauing of the reported CO2 emissions over the last few years. I think this plateauing was mostly due to the pandemic and emission indeed started to rise again last year. Also, I am not sure I trust countries to accurately report their emissions especially since they pledged to reduce them in the Paris agreement and are nowhere close to reaching their pledges.

I do trust the measurements of the CO2 concentration in the atmosphere and it has been going up faster and faster. 2024 has a record growth of more the 3 ppm. As I understand it there is substantial natural variation of the yearly CO2 concentration increase, but the overall trend doesn't show any plateauing. So, what is the reason for this discrepancy between CO2 emissions and CO2 concentration increase in the atmosphere? Maybe it is just the brazen lies of countries about their emissions or, more likely, a signal of the carbon cycle feedback. You mention in your paper that a strong positive carbon cycle feedback is one possible reason for higher projected temperatures in 2100. I wonder whether the difference between CO2 emissions and CO2 concentration increases can be used to measure the carbon cycle feedback. This could be helped by also measuring the fraction of C-14 of the CO2 concentration increase, which would identify the fraction of the CO2 increase that comes from natural sources with C-14 and the fraction that comes from burning of fossil fuels that contains no C-14.

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This came across my radar this morning from the folks at heatmap.news, https://heatmap.news/climate/co2-levels-2024-mauna-loa. It points to a more comprehensive article at carbonbrief.org https://www.carbonbrief.org/met-office-atmospheric-co2-rise-now-exceeding-ipcc-1-5c-pathways/ that explores possible answers to your question.

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Thank you for the links. Yes, indeed, it addresses some of the questions I had. But they are also left with the puzzle of why CO2 concentration is accelerating while emissions are slowing down. I still think that underreporting of emissions is part of the answer. They also point to reduced land uptake of CO2 partly from increased temperature. I think this could also be called carbon cycle feedback and is therefore a measurement of this very important quantity for projections.

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“As I understand it there is substantial natural variation of the yearly CO2 concentration increase, but the overall trend doesn't show any plateauing. So, what is the reason for this discrepancy between CO2 emissions and CO2 concentration increase in the atmosphere?”

We wouldn’t expect these trends to match because they’re measuring two different things. CO2 emissions are the *flow* into the system while the CO2 concentration is the *level*. Like the water coming out of a tap versus the level of water in the tub.

It is exactly when emissions plateau (a flat line) that the rate of increase in the concentration will be at its highest (a steeply upwards line).

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Yes, exactly. I am comparing the CO2 emissions with the CO2 concentration INCREASE, not the level. If the emissions plateau then I would expect the CO2 concentration to continue to increase linearly or the CO2 concentration increase to be constant or plateau.

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Right. I would use “rate of change” in place of “increase” for a bit more clarity. So you’re saying the rate of change in the concentration is still increasing.

I would think that when we’re near the emissions plateau that it would be difficult to separate out the secular rate of change from the variability but I haven’t looked into this whole issue and don’t really know what’s possible.

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Thanks for the suggestion. I have also used "annual increase" in the past, but still get confused responses often. It is not an easy concept, but since CO2 in the atmosphere is at the core of Global Warming how fast we are changing it is probably the most important number for us to judge in how much trouble we are.

As an experimental physicist I much prefer measurements over pronouncements, but I am also aware of the uncertainties in measurements. Keeling's measurements of CO2 concentrations in the atmosphere, starting in the 1950s, are fundamental to our understanding of the changes of earth's climate. The statistical accuracy of the measurements are quite good and sufficient to also accurately measure the annual increase, especially if all of today's measuring stations are included. Also, CO2 emissions are distributed around the northern hemisphere in a few months and to the southern hemisphere in a couple of years. The main issue for correlating emissions with concentration increases is the natural variability, which can be up to 1 ppm. But, I think this actually could be used to learn about carbon cycle feedbacks because hot years during an El Niño event also have higher CO2 concentration increases.

As I mentioned in my post Carbon-14 isotope measurements could add additional information about origin of the CO2. The present measurements of CO2 concentration with a C-14 isotope are not accurate enough to be very useful but that could be improved.

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Remember that to first order the concentration level is proportional to the integral of the CO2 emission rate. The rate is plateauing but it still hasn't stopped increasing, that gets reflected as an increasing rate of concentration levels. If the emission rate truly leveled off, then one might expect the rate of increase in the concentration level to equal a constant, i.e., X ppm / year. However, this does not account for natural sinks.

I basically posed this question to chatgpt4, "To first order, isn't the concentration level proportional to the integral of the co2 rate of emissions?" Here is the first part of the response.

-------------

Yes, to first order, the atmospheric CO₂ concentration is indeed proportional to the integral of the CO₂ emissions rate over time. This relationship arises because CO₂ emissions add to the total stock of CO₂ in the atmosphere, and the concentration is effectively the cumulative result of those emissions, adjusted for natural sinks like oceans and forests.

Breaking it Down:

Rate of Emissions vs. Concentration:

CO₂ emissions are measured as a flow rate (e.g., gigatons of CO₂ per year).

Atmospheric CO₂ concentration (e.g., parts per million, ppm) is a stock, which represents the accumulated CO₂ in the atmosphere over time.

Mathematically:

Concentration (ppm)∼∫Emissions Rate (GtCO₂/yr)dt−Absorptions (natural sinks)

In simple terms: the atmospheric CO₂ concentration increases when emissions occur and decreases when CO₂ is absorbed by natural sinks like oceans, forests, and soils.

--------------

I hope that helps.

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Thank you, but I think I understand this quite well. I was careful to compare CO2 emissions with CO2 concentration INCREASE in my post.

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I guess if you use all caps that makes it clear. Since when does an increase in concentration of CO2 (ppm) mean the same thing as an increase in the growth rate of CO2 concentration (ppm/year), which is what you are really asking about.

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Sorry for not being clear.

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“Every prediction is an operation on the past.”

― Norbert Wiener (1894-1964)

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Just want to make sure I understand the values here -- it's growing consensus of a ~3C rise from a pre-industrial baseline by the end of the century, of which we've seen roughly half of that already. So another ~1.5C from current temperatures in the next 75 years. Is that correct?

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