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How much warmer on Earth in 2100, compared to mid-19th century?

1-2 degrees
1 (1.5%)
2-3 degrees
8 (12.3%)
3-4 degrees
18 (27.7%)
4-5 degrees
20 (30.8%)
5-6 degrees
5 (7.7%)
6-10 degrees
10 (15.4%)
10-20 degrees
0 (0%)
20-50 degrees
0 (0%)
50-100 degrees
0 (0%)
Not enough information
3 (4.6%)

Total Members Voted: 64

Author Topic: Magnitude of future warming  (Read 3069 times)

Rich

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Re: Magnitude of future warming
« Reply #50 on: July 04, 2019, 01:02:16 PM »
The magnitude of future warming. Interesting question.

The current CO2 level (I know it's not the only GHG) at 415 ppm is the highest it has been in ~3M years. Our trajectory is taking us to perhaps a 10M+year high.

50M years ago, the earth warmed 5-8C during the Paleocene Eocene Thermal Maximum. We need to be concerned that we don't trigger a similar event because that would pretty much end human civilization.

It's very difficult if not impossible to ascertain the degree feedback effects that will be triggered along the way to net zero eimissions. So temperature projection is somewhat guesswork.

If we stopped emitting GHG's immediately, we'd probably get an atmospheric temp bump from forcing inertia if 0.5C and another 0.5C from aerosol removal.

That's 2C +/- unknowns for feedbacks, geoengineering and length of time required to scale down emissions.

Shared Humanity

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Re: Magnitude of future warming
« Reply #51 on: July 04, 2019, 01:50:45 PM »
This forum focuses on arctic sea ice which is obviously a key component, but there are many more pieces to this problem.

This forum focuses on virtually anything related to AGW.

johnm33

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Re: Magnitude of future warming
« Reply #52 on: July 04, 2019, 03:01:46 PM »
I went 2-3 had the question been about the Arctic I'd be about an order of magnitude higher.

magnamentis

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Re: Magnitude of future warming
« Reply #53 on: July 04, 2019, 11:12:07 PM »
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.

petm

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Re: Magnitude of future warming
« Reply #54 on: July 05, 2019, 12:48:49 AM »
6-10 C

IPCC is the best comprehensive summary of the current (very immature) science. Humans won't mitigate their behavior I think, so take RPC 8.5 as the initial guess. Add in known and unknown feedbacks that have been omitted, the conservative nature of science which has consistently underestimated effects, and the politicization of the IPCC report. Result is easily 6 C.

wolfpack513

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Re: Magnitude of future warming
« Reply #55 on: July 05, 2019, 12:56:55 AM »
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.

Yes, Schurer et al. 2017 is specifically about underestimated 19th century warming.  The paper states that 1850-1899 warming may be underestimated by 0.1-0.2°C(mostly due to higher than normal volcanic activity).

If this is true then global mean temperature is closer to 1.3-1.4°C above preindustrial.  That would mean we’ve got 5-10 years until +1.5°C..

kassy

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Re: Magnitude of future warming
« Reply #56 on: July 05, 2019, 02:53:42 PM »
Funny thing is that we found the same for a more recent temperature set:

"The UK’s Met Office recently released “HadSST4”, the largest update since 2011 to its widely used sea surface temperature (SST) record.

The new version provides more accurate estimates of SSTs in the period during and after the second world war, as well as over the past decade. It suggests that the world’s oceans have warmed by around 0.1C more than previously thought since pre-industrial times.

Carbon Brief estimates that the revisions to the Hadley SST record would reduce the global “carbon budget” remaining to limit warming to 1.5C by between 24% and 33%, depending on how the budget is calculated.

This means that instead of having 9-13 years of current emissions before 1.5C is exceeded, the budget only has 6-10 years left.

https://www.carbonbrief.org/analysis-major-update-to-ocean-heat-record-could-shrink-1-5c-carbon-budget

Hat tip ASLR. He also writes: The linked article calculates that due to recent more accurate estimates of SSTs that the IPCC SR15's carbon budget to stay below a 1.5C GMSTA will be spent 3 to 5 years sooner that previously assumed by consensus climate scientists.  However, if climate sensitivity is higher than consensus climate scientists assume, then we may already spent all of our carbon budget and then some.

b_lumenkraft

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Re: Magnitude of future warming
« Reply #57 on: July 05, 2019, 02:57:11 PM »
Another nail in the coffin of the 'carbon budget' myth.

ArcticMelt2

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Re: Magnitude of future warming
« Reply #58 on: July 05, 2019, 05:32:21 PM »
The current warming should be huge.

During the past interglacial period 130 thousand years ago, the temperature over 8 thousand years after the maximum of the Milankovich cycle fell by about 5 degrees:



The development of agriculture over the past 8 thousand years with a minimum increase in the concentration of greenhouse gases (carbon dioxide and methane) has made it possible in fact to stabilize the temperature without multi-degree cooling.

If the development of agriculture allowed to increase the concentration of CO2 by 20 ppm, then today's industrial civilization did it at least 140 ppm.

This means that the contribution of industrial civilization to the present time is at least 7 times greater than the agricultural civilization.

In this regard, I think the final warming will be several tens of degrees.

magnamentis

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Re: Magnitude of future warming
« Reply #59 on: July 05, 2019, 05:59:40 PM »

In this regard, I think the final warming will be several tens of degrees.

30+(at least 2 tens to make it several) is 50C and since twice is more twice but several that wold make it at least 30C + 30C = 60C  / 40C + 30C = 70C ?

perhaps you reconsider such extreme statement.

i repeat that if anyone comes to read what we have to say and is reading obvious exaggerations he feels confirmed in his doubts and further spread the news that GW is a hoax.

credibility is everything ot make things happen fast, at the end what counts is are the facts and the real events but in case of prediction it is  "crime" to the cause to torbedize it with easily to falsify extreme exaggerations.

there is too much profiling and belonging to the winning group energy in this forum, best seen in the  electric car / tesla threads. black or white instead of thinking about the best and fastest and most sustainable solutions which ALWAYS will be a MIX.

ArcticMelt2

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Re: Magnitude of future warming
« Reply #60 on: July 05, 2019, 06:10:26 PM »
Man, did you hear anything about feedbacks?

The main warming does not occur immediately, but over several decades, centuries, millennia. For example, the simulations say that Greenland will melt from one to ten thousand years.

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?

Or maybe you think Stephen Hawking is an idiot?

https://www.inverse.com/article/33729-stephen-hawking-trump-climate-change-venus-syndrome

Quote
“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.


petm

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Re: Magnitude of future warming
« Reply #61 on: July 05, 2019, 06:37:45 PM »
Average surface warming above ~15 C (vs. pre-industrial) seems unlikely, since that would be hotter than at any time in the last 500 million years.

Anyways, it's somewhat moot since anything above ~4 C could make Earth uninhabitable and cause global ecosystem collapse, especially if that change occurs as quickly as by 2100. That would be many orders of magnitude faster than any previous warming event and leave not nearly enough time for ecosystems to migrate, let alone for species to adapt.

https://en.wikipedia.org/wiki/Geologic_temperature_record#Overall_view
https://skepticalscience.com/Can-animals-and-plants-adapt-to-global-warming.htm.
« Last Edit: July 05, 2019, 07:16:56 PM by petm »

b_lumenkraft

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Re: Magnitude of future warming
« Reply #62 on: July 05, 2019, 06:40:51 PM »
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

magnamentis

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Re: Magnitude of future warming
« Reply #63 on: July 05, 2019, 07:03:20 PM »
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

yes but there are the laws of physics and even if it will be 19C it won't be several tens as he said. nothing to add to that read below what i have to say and that will be it.

and he said "unlikely" not impossble while this IS TOTALLY IMPOSSIBLE indeed

magnamentis

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Re: Magnitude of future warming
« Reply #64 on: July 05, 2019, 07:04:15 PM »
Man, did you hear anything about feedbacks?

don't get picky man, especially when you don't read and your reply has nothing to do with my point.

several tens of degrees, no matter how long, due to man made carbon emission, will not happen, it will happen once when the sun starts the process to become a red giant, even more then.

it will never be 80C (for example) at the equator due to man made global warming as we discuss it here and before this happen we really get extinct and the process will start to reverse upon next opportunity (negative feedback) lock at the curve during WW1 and WW2. if we say it's man made we can assume that the process slows down and eventually will reverse once we stop to contibute.
and at 60C air temps over large areas we will not be able to contribute, cooling will be impossible be it ICEs or nuclear power plants or anything, animals will day and stop farting etc. etc.

you are a pessimistic sensationalist who got hurt because i speak a clear language. poeple who only want to profile themselves, stick out, be right, belong to the winners, seek exitement etc. a larger part of the problem, hence of the causes the brought us to this point.

if only farmers and truckers drove trucks and if everyone would spend on ICE vehicles what he can buy instead of lease and borrow, the problem would be manifold smaller. most things are based on ego driven mechanisms and whether an extremist is a climate change denier, a inquisitor, a jihadist or a follower of any other extremist group, is a sheer coincidence hence for me all extremist are evil, dangerous and counterproductive.

as stephen, yes he was overrated. had he been a healthy, sporty and attractive man he never would have gotten the attention and since i study astrophysics myself for the last few years and
even have my own therries, i.e. about dark matter/energy (probably wrong but interesting LOL)

i'm much farther off my own fields of work and interest in this forum than from stephan's.

fame is only important for fanboys who need someone to follow ( cling to the skirts seem ) else it's often more of a disqualifications with a few exceptions who did not seek public fame but got it through their achievements and until now, that man either howled with the pack and where he did not not much of what he predicted has happened.

buzz words is a known term, buzz names less so haha... can't impress me with names, not at all.

last but not least this will be the last time we talk, no time and energy for this.

several tens of degrees due to carbon emission (manmade) what a joke.

and don't come with venus now, she's much closer to the sun and many other factors play a role but as i said, not longer in a mood for this useless task. KF it will be. so long.


petm

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Re: Magnitude of future warming
« Reply #65 on: July 05, 2019, 07:18:18 PM »
Past Performance Is No Guarantee of Future Results
Lol. Very true, which is why, as magnamentis pointed out, I said unlikely rather than saying impossible.

But gentle people, there's no need to argue. Even 10 C is far, far too much. Stay on target...

ArcticMelt2

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Re: Magnitude of future warming
« Reply #66 on: July 05, 2019, 08:28:32 PM »
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?

On the same topic, an excellent review of 2016.

https://www.earthmagazine.org/article/comment-how-long-have-humans-been-altering-earths-climate



Quote
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.

Quote
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.

kassy

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Re: Magnitude of future warming
« Reply #67 on: July 06, 2019, 05:51:48 PM »
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.


ArcticMelt2

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Re: Magnitude of future warming
« Reply #68 on: July 06, 2019, 06:32:22 PM »
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.

Even during PEMT, the rate of increase in greenhouse gases was less by an order of magnitude:

https://desdemonadespair.net/2016/03/what-were-doing-to-earth-has-no.html



Compared with the past glacial periods, the difference reaches 100 times.

We are heating the planet with unprecedented speed in the geological history of the Earth. This will cause the unprecedented destruction of the biosphere, ice sheets and permafrost, destabilization of tectonic plates.

ArcticMelt2

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Re: Magnitude of future warming
« Reply #69 on: July 06, 2019, 07:28:37 PM »
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.

In addition to ice there are huge reserves of carbon in the earth’s crust and biosphere:





There is no limit for warming.

kassy

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Re: Magnitude of future warming
« Reply #70 on: July 06, 2019, 10:19:26 PM »
We know that.

I will repeat:

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.

All the other stuff is true but the important point is that we can reach into territory where feedbacks overwhelm any possible policy or tech dreams. This is the only point that matters.


wolfpack513

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Re: Magnitude of future warming
« Reply #71 on: July 08, 2019, 01:06:42 AM »
This PETM occurred over 1000s of years so the comparison is silly.  We have a close handle on radiative forcing changes and we’re at 3.1 W/m² above preindustrial.  We’re not sniffing those numbers by 2100 even with some acceleration.  Emissions are going to drop off long before we get above 3°C due economic constraints. 

Tom_Mazanec

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Re: Magnitude of future warming
« Reply #72 on: July 08, 2019, 02:13:50 PM »
I thought they would drop off by now due to Peak Oil but I was wrong. Don't overestimate "economic constraints" or underestimate feedbacks. We could go well over three degrees.
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS