"Our results show that the amount of carbon that drove the PETM warming was about the same amount as the current 'easily accessible' fossil fuel reserves of about 4,000 billion tons. But the warming that would result from adding such large amounts of carbon to the climate system would be much greater today than during the PETM and could reach up to 10 degrees.
Speaking at the Tencent WE Summit Sunday, Hawking warned that overpopulation and extreme energy consumption will turn Earth into a fire ball by the year 2600.
Why would anyone using Fahrenheit?? ???to confuse foreigners. ;D
The problem with this question is that it involves the value for ECS but it also has to take into account whether we will take effective action to curb CO2 emissions. I do not think we will act quickly enough to eliminate anthropogenic emissions and expect us to blow past a doubling of ppm from preindustrial (560 ppm) by shortly after mid century at the latest. My uneducated guess is 4C to 5C.Indeed. And it's not uneducated at all.
A temperature increase that has been described as incompatible with human civilization.
This will cause an unprecedented destabilization of tectonic plates and degassing of the mantle.
... which will cause volcano eruptions all around the world, which will reduce the temperatures again. At least, this is my layman understanding. Correct me if i'm wrong.
A plus 10-degree scenario is a scenario where humans most likely can't exist, right?
The question is, when will tectonics kick in and cause these disruptions? We can't possibly know, or can we?
Which leads to the question, for how long humanity manages to make this planet uninhabitable for higher life?
Unfortunately, long-term cooling does not work. Sulfur sprays precipitate much faster than carbon dioxide. After the volcanoes calm down, the temperature will rise to huge values.
5-6 C. Feedback loops tend to be forgotten often. Tons of people think we just have to stop emitting co2 and then we will be fine, but that is false.
This 5-6 C rise in temp is likely going to wipe out most life on the planet as well as our species.... or at least a large percent of us. Civilization probably has till mid century
Assuming the current rate of rise for CO2 continues unabated, we will hit a doubling of pre-industrial levels around 2100.
At 10 degrees, the average temperature of the planet will be about 24 degrees Celsius. It will be more tolerable for people. But if this value is exceeded, the planet will turn into a total desert.
Assuming the current rate of rise for CO2 continues unabated, we will hit a doubling of pre-industrial levels around 2100.
How do you figure this? We are currently at nearly 415 ppm and recent annual increases, week over week are > 3 ppm.
https://forum.arctic-sea-ice.net/index.php/topic,2541.100.html
Meanwhile, increases in atmospheric CO2 are accelerating.
https://www.esrl.noaa.gov/gmd/ccgg/trends/full.html
https://www.esrl.noaa.gov/gmd/ccgg/trends/gr.html
A 3 ppm increase year over year is the best we can expect over the next couple of decades and that is only if we first hold and then reduce emissions which we currently are not doing. At 3 ppm increase per year, we will have doubled CO2 concentrations over preindustrial by 2070 and this is assuming that positive feedbacks that reduce natural carbon sinks (drying of rainforests) or increase carbon release (permafrost thawing) do not kick in.
True on both points. Projecting long term trends using short term data is a questionable practice. Using an inappropriate dataset makes it worse.
True on both points. Projecting long term trends using short term data is a questionable practice. Using an inappropriate dataset makes it worse.We have long-term data to show that CO2 emissions have increased.
At 10 degrees, the average temperature of the planet will be about 24 degrees Celsius. It will be more tolerable for people. But if this value is exceeded, the planet will turn into a total desert.
Please tell me I am reading this wrong. You are not suggesting that a 10C rise in average temperature will be more tolerable are you?
True on both points. Projecting long term trends using short term data is a questionable practice. Using an inappropriate dataset makes it worse.
Not sure how the data set collected by the Scripps Institution of Oceanography is inappropriate.
https://www.esrl.noaa.gov/gmd/ccgg/trends/full.html
https://www.esrl.noaa.gov/gmd/ccgg/trends/gr.html
Both of these charts clearly show that the growth rate in atmospheric CO2 is increasing. Between 1960 and 1970, CO2 increased by 1ppm annually. Between 1990 to 2000, it increased by 2ppm annually.
What data set would you use to evaluate the growth rates in atmospheric CO2?
True on both points. Projecting long term trends using short term data is a questionable practice. Using an inappropriate dataset makes it worse.
Not sure how the data set collected by the Scripps Institution of Oceanography is inappropriate.
What data set would you use to evaluate the growth rates in atmospheric CO2?
There was nothing wrong with the dataset. It was your extrapolation of the past decade out to the end of the century that I was criticizing.
True on both points. Projecting long term trends using short term data is a questionable practice. Using an inappropriate dataset makes it worse.
Not sure how the data set collected by the Scripps Institution of Oceanography is inappropriate.
What data set would you use to evaluate the growth rates in atmospheric CO2?
There was nothing wrong with the dataset. It was your extrapolation of the past decade out to the end of the century that I was criticizing.
But, of course, that is not what you said. You pointed out that my extrapolation using only a decade of data was wrong (perhaps you are correct) and then you specifically stated that the data set I drew it from was inappropriate.
The reason I used the last decade is that it suggests this trend that we see over the last 60 years of accelerating growth in CO2 levels is continuing to grow. The growth rate in three of the last four years is very close to 3 ppm.
I would suggest using an arbitrary annual growth rate (say 2.2 ppm per year) that we have already blown past and will never see again in my lifetime to project a doubling of atmospheric CO2 by 2100 is far more inappropriate than my suggesting the acceleration in the growth of atmospheric CO2 will continue into the future.
When CO2 annual growth shows long term acceleration over several decades, and when supporting trends like population growth and rising affluence are continuing, picking a desired constant number for that growth is what I personally consider as cherry-picking.
When CO2 annual growth shows long term acceleration over several decades, and when supporting trends like population growth and rising affluence are continuing, picking a desired constant number for that growth is what I personally consider as cherry-picking.
Agreed.
What is interesting about the NOAA data is that we see a doubling in the growth rate in 4 decades, 1 ppm annually from 1960 to 1970 to 2 ppm annually from 2000 to 2010. Will this trend of accelerating growth result in a doubling in the next 4 decades? If so, we will have an annual increase of 4 ppm in 2040 to 2050. This depends, I think, on the sources of CO2. How much of the current and future growth is and will be due directly to the burning of fossil fuels etc.? How much is and will be due to a shift in the behavior of carbon sinks?
I think we will make significant progress in cutting CO2 emissions by 2050 as the catastrophic nature of climate change becomes more obvious. Not sure about the behavior of carbon sinks. Sure hope we are not at 4 ppm annual increase in 2050. Fairly certain we will not be at 2.2 ppm annually.
I do not think we will see a doubling of CO2 over that timeframe, even if we do absolutely nothing to cut emissions. The main reason is that the global population doubled during the same timeframe that CO2 emissions doubled. The population growth rate has slowed, and will likely continue to do so, possibly reaching s maximum before the end of the century. This will naturally lead to slower emission growth.
Check out the water thread. I would wager that countries like India et al will run out of the most basic essentials well before they reach developed standards of living outside of their 1era. Mass death will be the correction, not willfully sufficient adoption of green tech (IMO).
The nations that have signed agreements to stabilize the global mean temperature by 2050 will fail to meet their goals unless existing fossil fuel-burning infrastructure around the world is retired early, according to a study—published today in Nature - by researchers at the University of California, Irvine and other institutions.
... According to the study, emissions from existing energy infrastructure take up the entire carbon budget to limit mean warming to 1.5 degrees Celsius and close to two-thirds of the budget to keep warming to under 2 C over the next three decades.
The 1.5C target is just a mythical dream based on magic thinking not an achievable goal
QuoteThe 1.5C target is just a mythical dream based on magic thinking not an achievable goal
It will require a miracle. Luckily, miracles do happen, usually to those working hard towards a goal.
+1I expect about 4 C.I voted 3-4, but could just as easily have voted for 4-5.
I change to 2-3 °C, after reading Archimid's comment! ;)QuoteThe 1.5C target is just a mythical dream based on magic thinking not an achievable goal
It will require a miracle. Luckily, miracles do happen, usually to those working hard towards a goal.
Wow! This is one of the most upbeat posts I have ever seen from you Archimid! I hope you are right!
This forum focuses on arctic sea ice which is obviously a key component, but there are many more pieces to this problem.
Re: Magnitude of future warming
Re: Magnitude of future warming
can you for the sake of making sure we're all talking the same thin your definition of 19th century ?
no offense meant but we all know that some people have issues with those terms.
the 19th century covers the years 1800-1899, please confirm that this is the period we talk here, thanks.
In this regard, I think the final warming will be several tens of degrees.
“We are close to the tipping point where global warming becomes irreversible. Trump’s action could push the Earth over the brink, to become like Venus, with a temperature of two hundred and fifty degrees, and raining sulphuric acid,” he told BBC News.
“Climate change is one of the great dangers we face, and it’s one we can prevent if we act now,” he continued. “By denying the evidence for climate change, and pulling out of the Paris climate agreement, Donald Trump will cause avoidable environmental damage to our beautiful planet, endangering the natural world, for us and our children.”
Stephen Hawking is a man of few words, as the device that allows him to communicate limits him to about one per minute. When he does speak, the topic increasingly veers towards doomsday scenarios for humanity. Last year he said the substantial destruction of our species was a near certainty within 10,000 years, a prediction he has since revised to 1,000 and then to 500 years.
Hawking has offered several possible scenarios for the downfall of humans, but in his recent interview he refers specifically to the Venus syndrome, which supposes that if enough greenhouse gases enter Earth’s atmosphere there will be runaway global warming that will not stop until the planet is dead and dry.
In a sense, the Venus syndrome is Earth’s inevitable fate, barring some extraordinary event that pushes this planet out into a farther orbit. On a timescale of billions of years, the sun will grow brighter and hotter until the Earth can no longer let out as much energy as it takes in.
Average surface warming above ~15 C seems unlikely, since that would be hotter than at any time in the last 500 million years.
Average surface warming above ~15 C seems unlikely, since that would be hotter than at any time in the last 500 million years.Past Performance Is No Guarantee of Future Results
Man, did you hear anything about feedbacks?
Past Performance Is No Guarantee of Future ResultsLol. Very true, which is why, as magnamentis pointed out, I said unlikely rather than saying impossible.
The fact that the current warming will be huge directly says that the maximum of the past interglacial was sharp, while the current has a flat top. Why does Holocene have stable temperatures compared to Eem?
The early anthropogenic hypothesis holds that prolonged warmth in the Holocene was caused by early agriculture. Paleoclimatologists have long sought an analog of the current Holocene interglaciation. Here, precession (A) and obliquity (B), which impact solar insolation, and atmospheric carbon dioxide concentrations (C) of previous interglaciations are compared with the Holocene (stage 1). The closest analog to the Holocene is stage 19, which began about 787,000 years ago. Credit: Ruddiman et al., Review of Geophysics, 2016.
Throughout the 20th century the paleoclimate science community regarded the warmth of the current (Holocene) interglaciation — prior to the major anthropogenic intervention of the last 150 years — as overwhelmingly natural in origin. In this view, changes in Earth’s orbit had resulted in increased summer insolation at high latitudes of the Northern Hemisphere, which began melting the North American and Scandinavian ice sheets 17,000 years ago and eventually ushered in interglacial warmth. Although further orbital shifts then led summer insolation to begin decreasing 10,000 years ago, the drop was thought not to have been substantial enough to cause renewed glaciation.
In the “early anthropogenic hypothesis,” first published in 2003, I proposed a different interpretation: that greenhouse gas emissions from early agriculture were the main reason for prolonged warmth lasting into modern times. I noted that in three previous interglaciations observed in ice-core records, concentrations of both carbon dioxide and methane decreased through the first 10,000 years, resulting in cooling trends that led to renewed glaciation. But the equivalent part of the current interglaciation has been different: Carbon dioxide concentrations rose during the last 7,000 years, and methane concentrations rose during the last 5,000 years. I proposed that these anomalous greenhouse gas increases were anthropogenic in origin and kept global climate warmer than it would have been in a world controlled only by nature.
I attributed the anomalous rise in carbon dioxide since 7,000 years ago to early deforestation, and the rising methane trend since 5,000 years ago to the spread of rice irrigation and livestock tending. Back in 2003, quantitative information about early agriculture was scarce, except for one very interesting data point: The 1086 Domesday Book, a survey ordered by William the Conqueror, reported that forests covered just 15 percent of Britain, indicative of early deforestation, with forest cover already similar, in fact, to levels today.
The early anthropogenic hypothesis was received with acclaim by some scientists, but with deep skepticism by others. From 2004 to 2009, several prominent climate scientists published papers criticizing it. The most prevalent argument was that far too few people were living thousands of years ago to have caused land-use changes sufficient to alter greenhouse gas levels.
Another criticism centered on a previous interglaciation that was proposed as the closest orbital analog to the current interglacial — stage 11, which began about 424,000 years ago. That interglaciation was thought to have lasted 26,000 years, compared to just 11,000 years (to date) for the present one, suggesting that some 15,000 years of interglacial warmth potentially still remain ahead of us now before the next glaciation.
In addition, ratios of carbon-13 to carbon-12 in ice-core carbon dioxide, an index of net global terrestrial emissions, showed only a weak decrease since early in the current interglaciation. This implied very low deforestation emissions during the last 7,000 years, equivalent to an addition of just 2 to 3 parts per million (ppm) carbon dioxide to the atmosphere.
Since 2010, however, a surge of new evidence converging from a wide range of geoscience-related disciplines has refuted these criticisms and lent support to the early anthropogenic hypothesis. Surveys of historical records by ecological modeler Jed Kaplan, myself and landscape ecologist Erle Ellis found that farmers in both Europe and China 2,000 years ago used at least four times as much land per person as those in the centuries just before the industrial era (the 1700s). Early slash-and-burn farming practices that rotated from plot to plot were highly inefficient and cleared large amounts of land. In contrast, modern farmers plant one or more crops on the same land every year.
This evidence of early farmers clearing more land per capita suggests, for example, that the 200 million to 250 million people living 2,000 years ago were using an area of land for agriculture equivalent to that used by almost a billion people in more recent times. Based on this evidence, Kaplan ran a land-use simulation that found that preindustrial anthropogenic carbon dioxide emissions would have added 24 ppm to the atmospheric concentration, five times the amount estimated by modelers who had assumed that early farmers used relatively small amounts of land through the millennia.
Work by geologist and palynologist Chronis Tzedakis and others showed that interglacial stage 11 is not a good orbital analog for the current interglaciation after all. While both interglaciations were characterized by similar low-amplitude changes in the eccentricity-modulated precession of Earth’s orbit, the obliquity of the orbit during stage 11 was far offset from the one in the current interglaciation (see figure parts A and B).
The optimal orbital analog to the Holocene turns out to be interglacial stage 19, which began about 787,000 years ago. Comparison shows that the orbital indices of each are almost exactly in phase (see figure parts A and B). Yet, during the first 10,000 years of stage 19, atmospheric carbon dioxide concentrations fell steadily to between 240 and 245 ppm. This is identical to the range predicted by the early anthropogenic hypothesis (see figure part C) for a Holocene interglaciation free of an early anthropogenic overprint.
Archaeobotanist Dorian Fuller and his colleagues mapped the spread of irrigated rice across southern Asia from 5,000 to 1,000 years ago. He found that emissions from methane-producing rice paddies accounted for 70 parts per billion (ppb) out of the 100-ppb methane increase observed in ice cores during that interval. He also mapped the spread of methane-emitting livestock, but has not estimated their methane emissions.
Paleoecologists Ralph Fyfe, Jessie Woodbridge and Neil Roberts and their colleagues recently published results of a comprehensive synthesis of pollen data from hundreds of cores across north-central Europe. They showed that deforestation was nearly complete before the industrial era, as I had claimed in the early anthropogenic hypothesis. In Britain, deforestation was already extensive by 2,000 years ago, consistent with the evidence from the Domesday Book. No other continent has been analyzed in comparable detail, but planning for such studies is underway.
The problem of the weak carbon-13 isotopic signal turns out to have a plausible explanation also: a coincidental offsetting of the anthropogenic emissions by natural burial of carbon in boreal peats. Ecologist Zicheng Yu has shown that the amount of carbon stored in peats during the last 7,000 years is equivalent to a 21-ppm reduction of carbon dioxide in the atmosphere. Similar increases in carbon storage in peats during previous interglaciations must have contributed to the decreases in atmospheric carbon dioxide observed in ice cores at those times, with resulting cooling effects on climate. During the current interglaciation, however, anthropogenic emissions from deforestation offset that natural trend. The 24-ppm anthropogenic carbon dioxide release due to deforestation estimated by Kaplan slightly outweighs the 21-ppm carbon dioxide withdrawal Yu estimated for carbon burial in peats and satisfies the carbon-isotopic constraint.
Another factor in the global carbon budget of the last 7,000 years is carbon dioxide feedback from the ocean. Direct emissions of carbon dioxide from deforestation represent an anthropogenic anomaly compared to previous interglaciations. These emissions would have prevented both the atmosphere and oceans from cooling, keeping them anomalously warm.
Experiments by climate modelers John Kutzbach, Steve Vavrus and Feng He suggest whole-ocean warming of 0.8 to 0.9 degrees Celsius or more, sufficient to cause two kinds of feedbacks that would have released stored carbon dioxide from the oceans. Reduced carbon dioxide solubility in the warm ocean would have emitted 6 ppm or more carbon dioxide to the atmosphere. Additionally, anomalous warmth in the Southern Ocean would have reduced sea-ice cover and prompted carbon dioxide exchange with overlying air masses, again increasing carbon dioxide in the atmosphere. These feedbacks count as anthropogenic because they are the result of direct emissions from deforestation.
One indication of the expanding impact of the early anthropogenic hypothesis on the larger scientific community is the evolving agenda of the Past Global Changes (PAGES) program, a core project of the International Geosphere-Biosphere Program. In the 1980s, PAGES began a major initiative called the “2K” project, with the goal of measuring paleoclimatic responses during the last 2,000 years in order to construct a natural baseline against which to assess the anthropogenic effects of the last 150 years.
Last year, however, PAGES began a new effort called the “Land Cover 6K” project, motivated by the growing realization that humans have been altering land cover, greenhouse gas concentrations and global climate in a substantial way for at least 6,000 years.
In this regard, I think the final warming will be several tens of degrees.
This is far out of earths historical bounds:
During the PETM, the global mean temperature appears to have risen by as much as 5-8°C (9-14°F) to an average temperature as high as 73°F. (Again, today’s global average is shy of 60°F.)
*their inconsistent editing* Max was 23 C (22,77) current is 15,55 C.
The limit is set by incoming solar radiation. The greenhouse gasses keep outgoing radiation in and warm the planet that way. In the PETM there was no ice at the poles so 23C is about the max we can get until someone blows up the sun.
https://www.climate.gov/news-features/climate-qa/whats-hottest-earths-ever-been
PS: Speaking of that a freebie. It is not currently possible for Earth to reach a venus like atmosphere but we will get there. As the sun swells up at the end of its life it will become much warmer here. When ocean surface temperatures reach 66C the climate flips to a venus type one.
The limit is set by incoming solar radiation. The greenhouse gasses keep outgoing radiation in and warm the planet that way. In the PETM there was no ice at the poles so 23C is about the max we can get until someone blows up the sun.
https://www.climate.gov/news-features/climate-qa/whats-hottest-earths-ever-been
PS: Speaking of that a freebie. It is not currently possible for Earth to reach a venus like atmosphere but we will get there. As the sun swells up at the end of its life it will become much warmer here. When ocean surface temperatures reach 66C the climate flips to a venus type one.
... "Higher warming would allow less time to adapt and mean a greater likelihood of passing climate 'tipping points' such as thawing of permafrost, which would further accelerate warming."
... "It is a scary finding because it indicates that the temperature response to an increase in carbon dioxide in the future might be larger than the response to the same increase in CO2 now. This is not good news for us."
Yes, i do, except for TCS. Maybe you can explain that one?
1 Do you now the difference between TCS, ECS and ESS ?
2 Climate = 30 years. Less than that you are looking at internal variably "weather" not the accuracy of "climate" models. The talk of a pause in warming was based on the same idiocy.I didn't bring up any 'pause in warming' as it is indeed idiocy. The oceans are continously warming, as more than 90% of warming goes there, whereas the atmosphere has more variability.
3 The keeling curve is still a curve. We have not yet halted the acceleration in CO2 levels.True, but we're getting there. FF are being phased out, and the out-phasing will only get stronger in the coming two decades.
4 What has happened in the past has no relevance to what is happening now. Never has the earth experienced such a quick rise in CO2 . ESS will take millenia to resolve before we will really know. We may already have emitted enough to be outside of an ice age .I think you should read the wikipedia pages on ice age. We are currently in an ace age called the Quaternary glaciation, it has lasted 2.58 million years. To claim that "we have emitted enough to be outside of an ice age" is a collossal statement. We have emitted for some 150 years, and we can de-emit in the coming centuries.
5. Relying on an as yet unknown future CCS technology is magical thinking.There is nothing magic with CCS technology, as there are already several viable techniques being developed and deployed as full scale experimental facilities. CCS can be applied, and it will be applied. That's what IPCC says in AR5. You think that IPCC also divulge in 'magical thinking'? Carbon capture and storage (CCS) is necessary in almost all scenarios to mitigate climate change.
6 You should be banned from this forum for denial.I'm grateful to all in this forum for their valuable contributions, even from high priests wanting to ban me. I'm here primarily to learn, and I have learnt a lot over the years of lurking.
(KiwiGriff posted just before me but I have different points)Nanning, I hope I answered most of your points in my answer to KiwiG, so I'll keep this brief.
Sorry Hefaistos but I strongly disagree with your post.
You probably don't mean it like that but to me your list smells of soft denial.
1. If any progress has been made, it has accellerated the Keeling curve. The system of capitalism can't solve this. How long do you want GDP growth?
2. We are not in an iceage anymore. The increasing amount of GHG in the atmosphere prohibits that. We have changed the sensitive Earth systems. All the ice is going.Sure, if nothing is done all the ice will be going. However, the time scale is millennia. Capitalist mankind will not let it happen. I'm sure there will be many problems with the consequenses of AGW but we haven't passed any no-reversal tipping points yet. Read AR5 from IPCC.
3. And here I was thinking that a lot of AGW related observations of reality suprise us time and again because they happen much sooner than expected. If I understand correctly, many more realistic CMIP6 models have a higher climate sensitivity i.e. are predicting even higher temperature increases.
Following the posts by ASLR in 'his' important science thread, I got the idea that the previous models were too conservative.
Imagination and science. I can imagine many feedbacks kicking in and powerful step-changes with or without an El Niño. Because the climate system will self-amplify and the anthropogenic influence will not be significant anymore.The climate system will certainly not self-amplify and run out of control on a time-scale of decades, and the anthropogenic influence will certainly not be made insignificant. No serious climate scientists believe that, and the IPCC provides us with mitigation scenarios. If they are realistic or not can and will be discussed. But we should never discount capitalist mankind's capacity for problem-solving technological innovation and implementation.
Reading your last paragraph, I think you do have strong imagination. Just not the right kind.
Your very last sentence seems to contradict your second sentence.
CIMP3
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.realclimate.org%2Fimages%2Fcmp_cmip3_sat_ann-1-600x485.png&hash=66f65586c7090c2fd668acb127a74e25)
CIMP5
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.realclimate.org%2Fimages%2Fcmp_cmip5_sat_ann-2-600x484.png&hash=90af28e18b427972f38d1536b37473cd)
http://www.realclimate.org/index.php/climate-model-projections-compared-to-observations/
Annual average for 2019, eight months in, is now second behind 2016 and ahead of 2018 in third place. This year was a very mild El Niño or neutral depending on the metric you use. We are presently above the mean of the model runs in both cmip 3 and 5 . The models have not erred at all let alone strongly.
Referring to the previous two posts by Vox, i don't think they are too relevant for AGW.
It's unimaginable that we will get to 1000 ppm CO2 and a climate like in the Early Eocene given:
1. the fast transition to renewable energy taking place. Capitalism already prefers renewables as they are less costly per energy unit, i.e. more profitable, than fossil fuels. This trend will only become stronger over the coming decades.
2. that we still are in an ice-age, i.e. the basic climate setup for coming millenia is unfavourable for an Early Eocene to develop.
3. that previous CMIP model generations (CMIP 3 and 5) have erred strongly, demonstrating too much warming compared to actual observations.
The time-scale involved for a transition to Early Eocene climate is millenia, and for such long period of time mankind will not only strongly scale back using fossil fuels, we will also start sucking CO2 back.
Thus, it would be irrelevant to use the high-end ECS values coming out of the climate models running Early Eocene climate.
The only thing that might refute this is if we get some strong, positive feedback mechanisms triggered in the coming decades.
It means that if your best personal interest is to solve a problem then you will work very very hard on it and you will likely get a solution. Self-interest drives man. That drives is very basic. That drive created capitalism and technological progress starting from the first stone-axes or before
H wrote: " Capitalist mankind will not let it happen."
WTF?
Klondike Kat
Look at the forcing adjusted result not the original projection for cimp5 .
Climate models are not designed to be economic models or project future solar activity.
I should add that even if we cut emissions to zero today, we have suppressed not just the next glaciation bu the next two.How is that possible if CO2 sticks around only a few centuries?
Abstract
CO2 released from combustion of fossil fuels equilibrates among the various carbon reservoirs of the atmosphere, the ocean, and the terrestrial biosphere on timescales of a few centuries. However, a sizeable fraction of the CO2 remains in the atmosphere, awaiting a return to the solid earth by much slower weathering processes and deposition of CaCO3. Common measures of the atmospheric lifetime of CO2, including the e-folding time scale, disregard the long tail. Its neglect in the calculation of global warming potentials leads many to underestimate the longevity of anthropogenic global warming. Here, we review the past literature on the atmospheric lifetime of fossil fuel CO2 and its impact on climate, and we present initial results from a model intercomparison project on this topic. The models agree that 20–35% of the CO2 remains in the atmosphere after equilibration with the ocean (2–20 centuries). Neutralization by CaCO3 draws the airborne fraction down further on timescales of 3 to 7 kyr.
However, the atmospheric concentration is a function of both the amount present and the amount emitted. Should emissions cease tomorrow (bear with me for a bit), atmospheric concentrations would begin to decline, rapidly at first, until they reach about ~25% of emitted levels. This approximate value is consistent among all three previous references. That equates to about 314 ppm after a century (280 ppm + 25% * (415 ppm - 280 ppm). Hence, global temperatures would begin to fall shortly after atmospheric CO2 levels begin falling.I have no direct expertise here but I suspect the math is not proper. 415 does not represent the emitted amount, but the amount remaining after some equilibration with the ocean. So you are double-counting the equilibration.
Some fractino of carbon dioxide will remain in the atmosphere for centuries, perhaps millenia.I thought some arithmetic was in order, starting with
https://www.yaleclimateconnections.org/2010/12/common-climate-misconceptions-atmospheric-carbon-dioxide/
However, the atmospheric concentration is a function of both the amount present and the amount emitted. Should emissions cease tomorrow (bear with me for a bit), atmospheric concentrations would begin to decline, rapidly at first, until they reach about ~25% of emitted levels. This approximate value is consistent among all three previous references. That equates to about 314 ppm after a century (280 ppm + 25% * (415 ppm - 280 ppm). Hence, global temperatures would begin to fall shortly after atmospheric CO2 levels begin falling.
Obviously, emissions will not cease tomorrow. They do not need to, in order to stabilize atmospheric concentrations at current conditions. While the last 25% of emissions takes centuries to be removed, the first 25% is fast, taking about one decade. Estimates vary widely, but an emissions reduction of about 40% would stabilize concentrations at current levels.
How the oceans absorb carbon dioxide is critical for predicting climate changehttps://www.pmel.noaa.gov/co2/story/Ocean+Carbon+Uptake (https://www.pmel.noaa.gov/co2/story/Ocean+Carbon+Uptake)
Air-sea gas exchange is a physio-chemical process, primarily controlled by the air-sea difference in gas concentrations and the exchange coefficient, which determines how quickly a molecule of gas can move across the ocean-atmosphere boundary. It takes about one year to equilibrate CO2 in the surface ocean with atmospheric CO2, so it is not unusual to observe large air-sea differences in CO2 concentrations. Most of the differences are caused by variability in the oceans due to biology and ocean circulation. The oceans contain a very large reservoir of carbon that can be exchanged with the atmosphere because the CO2 reacts with water to form carbonic acid and its dissociation products. As atmospheric CO2 increases, the interaction with the surface ocean will change the chemistry of the seawater resulting in ocean acidification.
Evidence suggests that the past and current ocean uptake of human-derived (anthropogenic) CO2 is primarily a physical response to rising atmospheric CO2 concentrations. Whenever the partial pressure of a gas is increased in the atmosphere over a body of water, the gas will diffuse into that water until the partial pressures across the air-water interface are equilibrated. However, because the global carbon cycle is intimately embedded in the physical climate system there exist several feedback loops between the two systems. For example, increasing CO2 modifies the climate which in turn impacts ocean circulation and therefore ocean CO2 uptake. Changes in marine ecosystems resulting from rising CO2 and/or changing climate can also result in changes in air-sea CO2 exchange. These feedbacks can change the role of the oceans in taking up atmospheric CO2 making it very difficult to predict how the ocean carbon cycle will operate in the future.
Ocean Acidification: The Other Carbon Dioxide Problemhttps://www.pmel.noaa.gov/co2/story/Ocean+Acidification (https://www.pmel.noaa.gov/co2/story/Ocean+Acidification)
Fundamental changes in seawater chemistry are occurring throughout the world's oceans. Since the beginning of the industrial revolution, the release of carbon dioxide (CO2) from humankind's industrial and agricultural activities has increased the amount of CO2 in the atmosphere. The ocean absorbs about a quarter of the CO2 we release into the atmosphere every year, so as atmospheric CO2 levels increase, so do the levels in the ocean. Initially, many scientists focused on the benefits of the ocean removing this greenhouse gas from the atmosphere. However, decades of ocean observations now show that there is also a downside — the CO2 absorbed by the ocean is changing the chemistry of the seawater, a process called OCEAN ACIDIFICATION.
I would guess sequestration is also dependent on ocean CO2 level.Yes. The other elephant in the room.
Again, I am far from knowledgeable on this subject, but I would guess sequestration is also dependent on ocean CO2 level, which has probably risen since the 1970s. Hope someone with more credentials can pitch in.
A new study, published in Nature, finds that recent changes in circulation patterns in the world’s oceans are playing a key role in how much CO2 they take up.
Weakening circulation patterns have boosted how much CO2 the oceans absorb since the 2000s, the researchers say, but there’s no guarantee that this will continue into the future.
the amount of CO2 that the oceans absorb isn’t constant. In the 1990s, ocean CO2 uptake dropped off, before increasing again in the 2000s. Recent research shows that the Southern Ocean was central to these changes.
The Southern Ocean is the most prolific of the oceans for carbon storage – accounting for approximately 40% of the global ocean CO2 uptake. In the 1990s, strengthening winds circulating around Antarctica affected ocean currents and brought carbon-rich water to the surface. This meant the ocean was less able to absorb CO2 from the atmosphere.
In the 2000s, the winds continued to strengthen, yet the CO2 uptake in the Southern Ocean rebounded. This, combined with increasing CO2 uptake in other oceans, suggested to scientists that there was, ultimately, another factor affecting the ocean carbon sink.
The new study says the reason lies in circulation patterns in the top 1,000m of the world’s oceans.
‘Missing piece of the puzzle’
The water in our oceans is constantly on the move. In the upper layers of the ocean there are several driving forces responsible, explains lead author Dr Tim DeVries, an assistant professor in oceanography at the University of California. He tells Carbon Brief:
“The [circulation patterns] are driven by winds and by ‘buoyancy forcing’ – which means changes in the density of surface waters due to changes in their temperature (heating/cooling) or salinity (adding/removing freshwater).”
Using observed data, the researchers built a computer model to simulate these circulation patterns in the upper ocean. They ran their model to analyse the exchange of CO2 between the ocean and atmosphere over recent decades.
They found that in the 1990s, the ocean circulation patterns were “more vigorous” and coincided with a big dip in CO2 uptake. From around 2000, the circulation patterns then weakened, bringing a rebound in CO2 uptake.
The simplified diagram below illustrates the effect these “overturning” circulation patterns have.
Stronger ocean overturning – as seen during the 1990s – brings more carbon-rich water up from the deeper ocean, the researchers say. When this water reaches the surface it releases CO2 into the atmosphere (see a). More vigorous overturning also means the ocean takes up more CO2 from the atmosphere (b), but not as much as the extra CO2 released.
As the bottom half of the diagram shows, weaker overturning in the 2000s reduces both the amount of CO2 released to the atmosphere (c), and what is absorbed again (d). Overall, this increases how much CO2 the ocean takes up.
Models project that when net CO2 emissions are positive, but start to decline, the land and ocean carbon sinks will begin to weaken and take up less CO2 . Note that these responses may not be driven entirely by CO2 forcing as other factors such as a changing climate also affect the strength of these sinks. At some point, as net CO2 emissions decline, carbon sink uptake will exceed emissions input and the atmospheric CO2 concentration will begin to decline.
So my question remains the same - will CO2 captured by the sinks decrease as emissions decrease? (or in another way- how sensitive is the chemical process that exchanges CO2 from air to ocean to small changes in CO2 ppm?)
As long as atmospheric CO2 concentrations continue to rise, the oceans will continue to take up CO2 .
However, this reaction is reversible. If atmospheric CO2 were to decrease in the future, the oceans will start releasing the accumulated anthropogenic CO2 back out into the atmosphere. [emphasis mine]
The ultimate storage place for anthropogenic CO2 must be reactions that bind the CO2 in a manner that is not easily reversed. Dissolution of calcium carbonate in the oceans, for example, is a long-term storage place for CO2 . As the oceans continue to take up anthropogenic CO2 , it will penetrate deeper into the water column, lowering the pH and making the waters more corrosive to calcium carbonate. The problem is that carbonate dissolution typically occurs in the deep ocean, well removed from the anthropogenic CO2 taken up in the surface waters. In portions of the North Atlantic and North Pacific Oceans, however, anthropogenic CO2 may have already penetrated deep enough to influence the dissolution of calcium carbonate in the water column.
My answer is not directly. I stand behind my claim that CO2 captured is a function of the concentration in the atmosphere, not the amount emitted. When the captured amount exceeds the emitted amount, then the atmospheric concentration will decrease. That will subsequently lead to decreased capture.KK you insist on ignoring the other factor, ocean surface concentration. The uptake of CO2 by the ocean in the near term is proportional to the atmospheric concentration less the ocean surface concentration (including the slower downward flux from the ocean surface to the deep ocean). But the ocean surface concentration is a function of the past emitted CO2. Thus scrubbing of the CO2 from the atmosphere will be dependent on slower processes (assuming emissions stop at some point).
QuoteMy answer is not directly. I stand behind my claim that CO2 captured is a function of the concentration in the atmosphere, not the amount emitted. When the captured amount exceeds the emitted amount, then the atmospheric concentration will decrease. That will subsequently lead to decreased capture.KK you insist on ignoring the other factor, ocean surface concentration. The uptake of CO2 by the ocean in the near term is proportional to the atmospheric concentration less the ocean surface concentration (including the slower downward flux from the ocean surface to the deep ocean). But the ocean surface concentration is a function of the past emitted CO2. Thus scrubbing of the CO2 from the atmosphere will be dependent on slower processes (assuming emissions stop at some point).
I expect that as a chemist this really should be crystal clear to you. The ocean surface equilibrates fast, and has already swallowed a lot of CO2, so further fast uptake is dependent on further increase in atmospheric partial pressure.
The gas exchange at the surface is but one aspect of the entire planetary sequestration process. The mixing of the surface waters with the deep ocean takes much longer, as does calcification and other terrestrial sinks. We have been operating under the assumption that planetary equilibrium is a slow process, and the atmospheric carbon dioxide lifetime is long. Are you arguing for a fast equilibrium and short lifetime?
<snip>
the imbalance should continue until the ice is gone or almost gone.
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On the causal structure between CO2 and global temperature
by Adolf Stips, Diego Macias, Clare Coughlan, Elisa Garcia-Gorriz & X. San Liang
https://www.nature.com/articles/srep21691
(whole article)
Excellent work by Gerontocrat into carbon sinks. However, I am surprised to find the quantity in gigatonne of carbon sunk being on the same axis as percentage sunk given that total emissions are not constant.It isn't.
Worst-case global heating scenarios may need to be revised upwards in light of a better understanding of the role of clouds, scientists have said.
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“That is a very deep concern,” Johan Rockström, the director of the Potsdam Institute for Climate Impact Research, said. “Climate sensitivity is the holy grail of climate science. It is the prime indicator of climate risk. For 40 years, it has been around 3C. Now, we are suddenly starting to see big climate models on the best supercomputers showing things could be worse than we thought.”
He said climate sensitivity above 5C would reduce the scope for human action to reduce the worst impacts of global heating. “We would have no more space for a soft landing of 1.5C [above preindustrial levels]. The best we could aim for is 2C,” he said.
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Timothy Palmer, a professor in climate physics at Oxford University and a member of the Met Office’s advisory board, said the high figure initially made scientists nervous. “It was way outside previous estimates. People asked whether there was a bug in the code,” he said. “But it boiled down to relatively small changes in the way clouds are represented in the models.”
The role of clouds is one of the most uncertain areas in climate science because they are hard to measure and, depending on altitude, droplet temperature and other factors, can play either a warming or a cooling role. For decades, this has been the focus of fierce academic disputes.
Previous IPCC reports tended to assume that clouds would have a neutral impact because the warming and cooling feedbacks would cancel each other out. But in the past year and a half, a body of evidence has been growing showing that the net effect will be warming. This is based on finer resolution computer models and advanced cloud microphysics.
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The IPCC is expected to include the 5+C climate sensitivity figure in its next report on the range of possible outcomes. Scientists caution that this is a work in progress and that doubts remain because such a high figure does not fit with historical records.
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Previous IPCC reports tended to assume that clouds would have a neutral impact because the warming and cooling feedbacks would cancel each other out. But in the past year and a half, a body of evidence has been growing showing that the net effect will be warming. This is based on finer resolution computer models and advanced cloud microphysics.
So actually doing the maths on clouds shows they have a non neutral impact.
In a recent paper in the journal Nature, Palmer explains how the new Hadley Centre model that produced the 5+C figure on climate sensitivity was tested by assessing its accuracy in forecasting short-term weather.
This seems to be a good test:
https://www.nature.com/articles/d41586-020-01484-5
Pliocene weather is interesting for clouds too.
There is no opposite in magnitude because calculating less then not calculating is not really a magnitude.
GCM models are inherently unable to model convectice processes, as they operate on grid sizes that are about 1000 times bigger than the actual processes. Thus, the GCMs resort to parametrization of these processes. In other words, GIGO modelling.
Regardless, they are claiming that the shortwave radiative effect (SCRE) will be less with future warming, although they state that the clouds will have a higher water content. That seems opposite to established climate science, whereby increased water content leads to increased SCRE.
QuoteRegardless, they are claiming that the shortwave radiative effect (SCRE) will be less with future warming, although they state that the clouds will have a higher water content. That seems opposite to established climate science, whereby increased water content leads to increased SCRE.
Do you have a quote for that with a link to a paper?
You need to link to where the people in the new research claim that: the shortwave radiative effect (SCRE) will be less with future warming, although they state that the clouds will have a higher water content. That seems opposite to established climate science, whereby increased water content leads to increased SCRE.
Or where you think they do. Not some general background site with Alta Vista vibes.
QuoteGCM models are inherently unable to model convectice processes, as they operate on grid sizes that are about 1000 times bigger than the actual processes. Thus, the GCMs resort to parametrization of these processes. In other words, GIGO modelling.
The Hadley validation test shows that if they use their cloud model parameter in short term weather forecasting it improves the forecasts so that is a hint that it actually works (similar to how they used the method to disprove another model challenge earlier).
And of course there are multiple levels on which we can take this.
You are critical of the model. Fine. But...
Do you think the neutral assumption was more true then what we calculate? Or is it more a problem of magnitudes?
Is the GIGO postulation analysis driven or just because you don´t want it to be true?
I find GIGO kind of harsh. This is complicated stuff which needs tons of computing power.
It's very disturbing that the enormous range of possible ECS's persists between these models. Currently, with AR5 and CMIP5, the range is from 1.5 - 4.5
2. There is a lack of understanding on the radiative forcing of clouds/water vapor. Is there a positive feedback, or a negative feedback between clouds and SST's? No-one knows. Recent research indicates that the feedback is negative in the tropics, but positive elsewhere. Specifically, IPCC doesn't know, and has previously just assumed that the feedback is zero. Yes, maybe better like that, than rely on GIGO models.
Sensitive but unclassified: Part II
— gavin @ 13 June 2020
The discussion and analysis of the latest round of climate models continues – but not always sensibly.
Since then, more model results have been added to the archive, and thanks to Mark Zelinka, we can see some of the analysis as it updates in real time.
By eye, it looks like there are two (or three) groups of models, one within the range of the assessed values (roughly 2 to 4.5ºC), one group with significantly higher values, and one institution/two models with a notably lower ECS. The question everyone has is whether this extended range is credible.
Since my first post, there have been a number of papers have looked at the skill of these models to see whether there are some key observational data that might help in constraining the sensitivity (and by extension, the projections into the future). One set of papers has focused on the global mean trends from 1990 or so onward which is a period of stable or declining aerosol trends and which might therefore be a closer test of the models’ transient sensitivity to CO2 than earlier periods. Notably Tokarska et al. (2020) and Njisse et al. (2020) suggest that many of the high ECS group warm substantially faster than observed over this period and therefore should be downweighted in the constrained projections of the future.
Recently however, writing in Guardian, Jonathan Watts uses results from the UK’s new model (Williams et al., 2020) and a commentary from Tim Palmer to argue that that we nonetheless need to take these high sensitivities more seriously, and indeed that they may indicate that the assessed ECS range has been underestimating potential changes in the future. This is however flawed.
The Williams et al paper demonstrates that updates to the HadGEM3‐GC3.1 model developed by the UK’s Hadley Centre that affect the clouds and aerosols, increase the skill of that model in short-term initialized weather forecasts. This is fine, and indeed, consistent with increases in skill in the newer models across the board when they are compared to a very broad range of observations.
But it is a logical leap to go from an observation of increased skill in one metric to assuming that therefore the overall ECS in this particular model is more likely. To demonstrate that, one would need to show that this particular measure of skill was specifically related to ECS which has not been done (a point Palmer acknowledges). To put in another way, it may be that all models that do well on this task have a range of ECS values, and that the coincidence of this one model doing well and having a high ECS, was just that, a coincidence.
QuoteIt's very disturbing that the enormous range of possible ECS's persists between these models. Currently, with AR5 and CMIP5, the range is from 1.5 - 4.5
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I doubt that a lower bound of 1.5C will hold into AR6 as much work has been published attempting to reconcile the low results of some observational based models with other methods.
https://www.carbonbrief.org/explainer-how-scientists-estimate-climate-sensitivity
At the link, there is a chart that shows very slightly increasing water vapor over the oceans, but only in the tropics.
However, the data is not that straightforward, nor is it simple to interpret. At the NOAA Physical Sciences Laboratory (PSL) you can create charts of humidity.
In my opinion based on following climate change since the 70s is that ECS, like the uncertainty of the preindustrial baseline, is a tool for obfuscation.
Why the doubling of co2, what is magical about that standard ?
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In Climate in the News, Keeling Curve History, Measurement Notes by Rob MonroeJune 4, 2019
Monthly average surpassed 414 parts per million at Mauna Loa Observatory
Atmospheric carbon dioxide continued its rapid rise in 2019, with the average for May peaking at 414.8 parts per million (ppm), according to instruments operated by Scripps Institution of Oceanography at the University of California San Diego at NOAA’s Mauna Loa Atmospheric Baseline Observatory, scientists from NOAA and Scripps announced today.
This is the highest seasonal peak recorded in 61 years of observations on top of Hawaii’s largest volcano, and the seventh consecutive year of steep global increases in concentrations of carbon dioxide, or CO2. The 2019 peak value was 3.5 parts per million higher than the 411.3 ppm peak reached in May 2018; it represents the second-highest annual jump on record.
Monthly CO2 values at Mauna Loa first breached the 400 ppm threshold in 2014.
Care to prove the keeling curve is now linear?
Or is that just your eyeballs?
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2) The data set you get to play with goes from 1950 - 2020. Over that time frame the CO2 and CH4 effects are only present on the end of the range but not in a way they are detectable in your chosen metrics.
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One could look towards data we believe is reasonably accurate rather than relying on that we know is not.