Near Term Human Extinction

[WXheights]

This will definitely fall in the "alarmist camp" anything less would not be "human" to not be "alarmed" by the very prospect that we as humans who have benefited in our history from the use of fossil fuels will also come to destroy us. 

 

In Paul Beckwith's video, he lays out others predictions, conclusions and then his own.

 

It is within this backdrop that many discuss climate change on this blog. Thought this would be thought provoking, enlightening and scary. Those who want to out right dismiss need to explain why -

 

 

[Jonger]

Paul Beckwith predicted an arctic melt out last summer. I'll take a look at the link, but he was considered a joke by alarmists and skeptics.

When the melt season was looking very tame, he vanished for almost 6 months.

[skierinvermont]

Paul Beckwith predicted an arctic melt out last summer. I'll take a look at the link, but he was considered a joke by alarmists and skeptics.

When the melt season was looking very tame, he vanished for almost 6 months.

 

Someone else posted a video from him in another thread. I forgot it was the same guy who until mid August last year was insisting on a complete melt out of ice by September.

I didn't look at this link. But what he said about methane in the other video was completely unsupported by peer-reviewed literature. He appears to be some sort of self-proclaimed expert and not a real part of the scientific community. 

[Msalgado]

Someone else posted a video from him in another thread. I forgot it was the same guy who until mid August last year was insisting on a complete melt out of ice by September.

I didn't look at this link. But what he said about methane in the other video was completely unsupported by peer-reviewed literature. He appears to be some sort of self-proclaimed expert and not a real part of the scientific community. 

 

I've seen him attack well known and respected climate scientists on twitter.  Combine his attitude with his ridiculous prediction then I can't really say I'm all that interested in devoting time to what he has to say.

[WXheights]

Paul Beckwith predicted an arctic melt out last summer. I'll take a look at the link, but he was considered a joke by alarmists and skeptics.

When the melt season was looking very tame, he vanished for almost 6 months.

 

 

Someone else posted a video from him in another thread. I forgot it was the same guy who until mid August last year was insisting on a complete melt out of ice by September.

I didn't look at this link. But what he said about methane in the other video was completely unsupported by peer-reviewed literature. He appears to be some sort of self-proclaimed expert and not a real part of the scientific community. 

Paul Beckwith is part-time professor with the laboratory for paleoclimatology and climatology, department of geography, University of Ottawa. Paul teaches climatology/meteorology and does PhD research on 'Abrupt climate change in the past and present'. Paul holds an M.Sc. in laser physics and a B.Eng. in engineering physics. 

 

I pulled this off the Arctic blog. What was interesting the is the various predictions of near term human extinction which I thought as he described it seems reasonable. I guess that was my main point with consensus toward a 2100 ending of humanity with for me seemed plausible-reasonable with feed backs primarily methane. There are earlier predictions 2030-2050 time frame which seems more unreasonable. 

 

All I can say is that the trajectory with BAU is unsustainable and the two lines intersect unless there are negative feedback's.

[Jonger]

Paul Beckwith is part-time professor with the laboratory for paleoclimatology and climatology, department of geography, University of Ottawa. Paul teaches climatology/meteorology and does PhD research on 'Abrupt climate change in the past and present'. Paul holds an M.Sc. in laser physics and a B.Eng. in engineering physics. 

 

I pulled this off the Arctic blog. What was interesting the is the various predictions of near term human extinction which I thought as he described it seems reasonable. I guess that was my main point with consensus toward a 2100 ending of humanity with for me seemed plausible-reasonable with feed backs primarily methane. There are earlier predictions 2030-2050 time frame which seems more unreasonable. 

 

All I can say is that the trajectory with BAU is unsustainable and the two lines intersect unless there are negative feedback's.

 

Barring an asteroid strike, nuclear holocaust or some type of super virus, the odds of a human extinction in the next 50,000 years is almost zero. We have already survived ice ages and this is without modern technology. As long as there is oxygen, water and plant/animals to feed off of.... no chance.

 

If warming even got a fraction of that, we could engineering a solution and avoid the entire ordeal all together.

 

 

Edit: Add the threat of AI slaughtering us off someday. I honestly think this one is a real possibility too.

[StudentOfClimatology]

Beckwith's heart is in the right place. He's legitimately concerned about our future.

That said, my primary studies are in paleoclimatology, so we've all heard of him and know to take what he says with a grain of salt.

[TerryM]

Thanks for the link.

 

He doesn't actually say too much in this presentation. The 2016 +_3 for the 1st ice free day in the Arctic has been floated in many contexts for some time & is only marginally sooner than Admiral White's prediction which I believe centered about 2021.

Paul feels that some form of natural negative feedback is possible and also that TPTB will resort to some form of geoengineering as things progress. This also seems reasonable.

After reading the comments I'd expected something akin to tin a foil hat looney & instead heard quite a reasonable monolog that spent most of it's time defining what near term means depending on one's field. He uses a 150 multiplier for CH4 over a 2 year period & I'd never heard that figure used. It may however fit with the more common 102 over a 20 year timeframe.

His understanding of the 35C @ 100% humidity situation is different than my own. He seems to feel that it's survivable if no work is done & my understanding is that it's lethal regardless of activity level. A minor point since it's easy to assume that if no one is capable of doing anything the group dies quite rapidly from starvation.

I can't imagine that anyone watching the piece would be too upset with the conclusions he draws.

Terry

[JC-CT]

Barring an asteroid strike, nuclear holocaust or some type of super virus, the odds of a human extinction in the next 50,000 years is almost zero. We have already survived ice ages and this is without modern technology. As long as there is oxygen, water and plant/animals to feed off of.... no chance.

If warming even got a fraction of that, we could engineering a solution and avoid the entire ordeal all together.

Edit: Add the threat of AI slaughtering us off someday. I honestly think this one is a real possibility too.

Come on man. You can't call out hyberbole by throwing out your own.

You certainly aren't the only person here throwing out numbers, years, probabilities, etc. with absolutely zero factual evidence to back them up, but you certainly do it often enough.

Unless you want to define near-zero probability, and then provide the statistical calculations and underlying support that allow you to arrive at the conclusion that you have stated...then just leave the numbers, years and probabilities out of your posts. People would actually take you more seriously, and would hear you louder when you rightfully call out some of the other BS that gets posted here.

And you probably shouldn't edit your posts to add statements that undeniably contradict the rest of the post, if you are looking to build credibility, in my opinion.

[FPizz]

Barring an asteroid strike, nuclear holocaust or some type of super virus, the odds of a human extinction in the next 50,000 years is almost zero. We have already survived ice ages and this is without modern technology. As long as there is oxygen, water and plant/animals to feed off of.... no chance.

If warming even got a fraction of that, we could engineering a solution and avoid the entire ordeal all together.

Edit: Add the threat of AI slaughtering us off someday. I honestly think this one is a real possibility too.

agreed. We aren't going anywhere anytime soon.

[skierinvermont]

Paul Beckwith is part-time professor with the laboratory for paleoclimatology and climatology, department of geography, University of Ottawa. Paul teaches climatology/meteorology and does PhD research on 'Abrupt climate change in the past and present'. Paul holds an M.Sc. in laser physics and a B.Eng. in engineering physics. 

 

I pulled this off the Arctic blog. What was interesting the is the various predictions of near term human extinction which I thought as he described it seems reasonable. I guess that was my main point with consensus toward a 2100 ending of humanity with for me seemed plausible-reasonable with feed backs primarily methane. There are earlier predictions 2030-2050 time frame which seems more unreasonable. 

 

All I can say is that the trajectory with BAU is unsustainable and the two lines intersect unless there are negative feedback's.

 

Everything he seems to say is based of an absolutely massive arctic methane feedback, which is categorically ruled out in all the literature on the subject.

 

AR5 provides a comprehensive summary of literature and the overall BAU picture is probably an additional 2-3C of warming by 2100. 

[Jonger]

Come on man. You can't call out hyberbole by throwing out your own.

You certainly aren't the only person here throwing out numbers, years, probabilities, etc. with absolutely zero factual evidence to back them up, but you certainly do it often enough.

Unless you want to define near-zero probability, and then provide the statistical calculations and underlying support that allow you to arrive at the conclusion that you have stated...then just leave the numbers, years and probabilities out of your posts. People would actually take you more seriously, and would hear you louder when you rightfully call out some of the other BS that gets posted here.

And you probably shouldn't edit your posts to add statements that undeniably contradict the rest of the post, if you are looking to build credibility, in my opinion.

 

My response was to a poster calling a 2100AD human extinction a reasonable possibility. Its possible, like the other events I listed, but  unlikely. What a ridiculous thing to call for more detail on, its border line insanity and deserves no better response than a general comparison to other far fetched possibilities. Whether we survive 1,000 years, 10,000 years or 50,000 years... Who cares, the point is made.

[JC-CT]

My response was to a poster calling a 2100AD human extinction a reasonable possibility. Its possible, like the other events I listed, but unlikely. What a ridiculous thing to call for more detail on, its border line insanity and deserves no better response than a general comparison to other far fetched possibilities. Whether we survive 1,000 years, 10,000 years or 50,000 years... Who cares, the point is made.

No argument here on the ridiculousness of this guy's prediction. I am also noticing some over-the-top posts that occur frequently in the other threads in the CC subforum.

As someone who is browsing this subforum to read and learn about a scientific subject, I can't help but notice some of the nonsensical comments spewing from all directions. I understand the urge to fight fire with fire, but I'm just saying it is a losing battle.

I can only say one thing with certainty, and that is that anyone claiming that anything is certain, is certainly wrong. Hmm.

[WXheights]

My response was to a poster calling a 2100AD human extinction a reasonable possibility. Its possible, like the other events I listed, but  unlikely. What a ridiculous thing to call for more detail on, its border line insanity and deserves no better response than a general comparison to other far fetched possibilities. Whether we survive 1,000 years, 10,000 years or 50,000 years... Who cares, the point is made.

Ecologists, biologists pretty much agree something over 5-6C warming lets say achieved, helped along by seismic activity producing large burps of methane is very possible/reasonable,

 

Ramifications pushed along by an unstable climate may include, severe viral diseases, nuclear disaster i.e. Fukushima X 100.

 

Yeah its outlier but would one ignore CH4 releases already starting to happen, should that be omitted for this discussion? who runs the bogus police?

 

And since you mentioned it, Insanity is defined by "doing the same thing over and over and expecting a different result" 

[WXheights]

Everything he seems to say is based of an absolutely massive arctic methane feedback, which is categorically ruled out in all the literature on the subject.

 

AR5 provides a comprehensive summary of literature and the overall BAU picture is probably an additional 2-3C of warming by 2100. 

I'm guessing here but I think he's very big on a PETM style CH4 release or some such which should be at least IMO kept an eye on would you not say?

[WXheights]

Thanks for the link.

 

He doesn't actually say too much in this presentation. The 2016 +_3 for the 1st ice free day in the Arctic has been floated in many contexts for some time & is only marginally sooner than Admiral White's prediction which I believe centered about 2021.

Paul feels that some form of natural negative feedback is possible and also that TPTB will resort to some form of geoengineering as things progress. This also seems reasonable.

After reading the comments I'd expected something akin to tin a foil hat looney & instead heard quite a reasonable monolog that spent most of it's time defining what near term means depending on one's field. He uses a 150 multiplier for CH4 over a 2 year period & I'd never heard that figure used. It may however fit with the more common 102 over a 20 year timeframe.

His understanding of the 35C @ 100% humidity situation is different than my own. He seems to feel that it's survivable if no work is done & my understanding is that it's lethal regardless of activity level. A minor point since it's easy to assume that if no one is capable of doing anything the group dies quite rapidly from starvation.

I can't imagine that anyone watching the piece would be too upset with the conclusions he draws.

Terry

Yes this is "out there" but my, my it really upsets some people huh?, freaked them right out! Holy crap. touched a nerve, insulted, even threatened wooo-hooo.  I've not seen his other posts, baggage, but this one I posted seemed reasonable at the time. Wow I'm waitin for the death threats to start rolling in C'mon WTF already.

[AvantHiatus]

I'm guessing here but I think he's very big on a PETM style CH4 release or some such which should be at least IMO kept an eye on would you not say?

On my understanding, you need at least 6C+ rises for a PETM event to occur. However, you don't need a PETM-like release to do substantial damage in the short and long-term.

 

5-6C+ would be taking us back to the Miocene, when there were warm temperate forests on Greenland and Antarctica ice sheet was 1/3 of its present size. There is really no way around it, other than if such temperature increases come to fruition, ecosystems will not be able to adapt fast enough and coastlines around the world would be flooded eventually with sea levels rising 150 feet in a few centuries.

 

Possibly we will resort to some geo-engineering when things get that bad, since such results would be utterly unacceptable. Geo-engineering might also disrupt precipitation patterns and does not fix ocean acidification.

[skierinvermont]

I'm guessing here but I think he's very big on a PETM style CH4 release or some such which should be at least IMO kept an eye on would you not say?

 

I won't say a PETM style CH4 release is impossible, but every credible piece of evidence suggests that it is not. We don't even know that the PETM CO2 came from arctic CH4.

 

Arctic methane emissions are very small (3% of global) and there's no evidence that they are related to the current warm period. They are caused by the general warmth of the last 10,000 years gradually penetrating the seafloor. 

[AvantHiatus]

I won't say a PETM style CH4 release is impossible, but every credible piece of evidence suggests that it is not. We don't even know that the PETM CO2 came from arctic CH4.

 

Arctic methane emissions are very small (3% of global) and there's no evidence that they are related to the current warm period. They are caused by the general warmth of the last 10,000 years gradually penetrating the seafloor. 

Deep ocean temperatures have warmed substantially in the past 100 years, the rate has exceeded the 10,000 year background level. Not sure if this means more CH4 releases as well. It seems to be a long-process, even a 500-year long sudden release of CH4 is impressive compared to previous analogs.

 

Prove me wrong sir. The only thing is that we don't know how much of this CH4 came from the Seabed and the Arctic.

 

[skierinvermont]

Deep ocean temperatures have warmed substantially in the past 100 years, the rate has exceeded the 10,000 year level. Not sure if this means more CH4 releases as well. It seems to be a long-process, even a 500-year long sudden release of CH4 is impressive compared to previous analogs.

 

The arctic is still substantially cooler than it was 6000 years ago. The current low rate of arctic methane emissions is likely related to this warming. The current warmth has only begun to warm the top few meters of the sea floor. Those first few meters would have already been warmed to higher temperatures causing the decomposition of methane clathrates 4-7k years ago. 

 

Arctic temperatures sustained at much higher than the early holocene could begin to gradually penetrate deeper into the seafloor and release untapped sources of methane clathrates. 

[AvantHiatus]

The arctic is still substantially cooler than it was 6000 years ago. The current low rate of arctic methane emissions is likely related to this warming. The current warmth has only begun to warm the top few meters of the sea floor. Those first few meters would have already been warmed to higher temperatures causing the decomposition of methane clathrates 4-7k years ago. 

 

Arctic temperatures sustained at much higher than the early holocene could begin to gradually penetrate deeper into the seafloor and release untapped sources of methane clathrates. 

Not sure about that, how can Arctic temperatures be warmer during the Holocene Climate Optimum yet cooler on a global level than currently? This is especially unlikely now that we know how arctic amplification works. Even if we are cooler by 0.1C, we will be approaching Eemian temperatures very soon, relatively speaking.

 

 

 

In terms of the global average, temperatures were probably colder than present day (depending on estimates of latitude dependence and seasonality in response patterns). While temperatures in the Northern Hemisphere were warmer than average during the summers, the tropics and areas of the Southern Hemisphere were colder than average.^[4] 

[StudentOfClimatology]

Skierinvermont is correct about the Holocene climate optimum, it was a brief but very warm period..warmer than today (especially at the poles). Obliquity (axial tilt) was very amplified during the early Holocene, causing both poles to receive a substantially higher amount of summer insolation. This coupled with precession @ perihelion, and eccentricity at its maximum drive the climate out of the last ice age in an abrupt "jump", marking the end of the younger dryas.

This is a good diagram showing the effect of Obliquity on the distribution of insolation:

See how the ice age cycles became more extreme as obliquity amplified over time:

There was likely no multi-year sea ice during the Holocene optimum, with near ice-free conditions for a good 2kyrs. In 50-60yrs we'll probably surpass the warmth of the early Holocene.

Here's a good image from the Sks, illustrating the rapid anthropogenic warming in recent times. We've now surpassed the MWP and are approaching temperatures not seen in over 2000yrs...not good:

[AvantHiatus]

I disagree, only the Arctic was warmer during the HCO due to your reasoning above. It looks like you disagree with the IPCC (which is cited as the most conservative estimate) if you think it will take 60 years. 

 

There is no way it can be warmer globally during the HCO, CO2 is simply too high and the solar forcing would need to be alot more important than we are currently accounting for. Ice-Core Temperatures can only be used regionally.

 

In 60 years, we will be surpassing the Eemian at 0.30C/decade.

 

 

The Eemian climate is believed to have been about as stable as that of the Holocene. Changes in the Earth's orbital parameters from today (greater obliquity and eccentricity, and perihelion), known as Milankovitch cycles, probably led to greater seasonal temperature variations in the Northern Hemisphere, although global annual mean temperatures were probably similar to those of the Holocene. The warmest peak of the Eemian was around 125,000 years ago, when forests reached as far north as North Cape, Norway (which is now tundra) well above the Arctic Circle at71°10′21″N 25°47′40″E. Hardwood trees such as hazel and oak grew as far north as Oulu, Finland.

At the peak of the Eemian, the Northern Hemisphere winters were generally warmer and wetter than now, though some areas were actually slightly cooler than today. The hippopotamus was distributed as far north as the rivers Rhine and Thames.^[1] Trees grew as far north as southern Baffin Islandin the Canadian Arctic Archipelago: currently, the northern limit is further south at Kuujjuaq in northern Quebec. Similarly, the prairie-forest boundary in the Great Plains of the United States lay further west near Lubbock, Texas, whereas the current boundary is near Dallas, Texas. The period closed as temperatures steadily fell to conditions cooler and drier than the present, with 468-year-long aridity pulse in central Europe,^[2] and by 114,000 years ago, a glacial period had returned.

Kaspar et al. (GRL, 2005) performed a comparison of a coupled general circulation model (GCM) with reconstructed Eemian temperatures for Europe. Central Europe (north of the Alps) was found to be 1–2 °C warmer than present; south of the Alps, conditions were 1–2 °C cooler than today. The model (generated using observed GHG concentrations and Eemian orbital parameters) generally reproduces these observations, leading them to conclude that these factors are enough to explain the Eemian temperatures.^[3]

[StudentOfClimatology]

I disagree, only the Arctic was warmer during the HCO due to your reasoning above. It looks like you disagree with the IPCC (which is cited as the most conservative estimate) if you think it will take 60 years.

There is no way it can be warmer globally during the HCO, CO2 is simply too high and the solar forcing would need to be alot more important than we are currently accounting for. Ice-Core Temperatures can only be used regionally.

In 60 years, we will be surpassing the Eemian at 0.30C/decade.

The consensus amongst nearly all credible peer reviewed literature and proxy data suggests the early-Holocene climate was extremely chaotic, and definitely warmer than today's climate, reflecting a system very sensitive to changes in radiative forcing. A stable climate would suggest lower climate sensitivity...we now know that the climate was very unstable, so we can discount the idea of a low climate sensitivity. If we don't stop or reduce our CO2 emissions, we'll probably end up surpassing the early Holocene warm period within 50yrs or less.

My studies are in paleoclimate, so I've read hundreds of papers on this matter. Denying these facts will put you on the fringe. The early Holocene warmth was driven by a weaker equator-to-pole thermal gradient . The Hadley Cells were much broader and tropical convection behaved very differently than it does now. It's the equator-to-pole thermal gradient that controls the "gusto" of the Hadley Cells. Weaken the gradient and you enlarge the cells and amplify the Rossby-wave train..

Here are some good papers on the Holocene climate optimum:

New England:

http://www.sciencedirect.com/science/article/pii/0033589480900514

China:

http://www.sciencedirect.com/science/article/pii/S0277379104000289

Africa:

http://www.sciencedirect.com/science/article/pii/0031018296000764

Antarctica:

http://link.springer.com/article/10.1007/BF00193529

[skierinvermont]

I disagree, only the Arctic was warmer during the HCO due to your reasoning above. It looks like you disagree with the IPCC (which is cited as the most conservative estimate) if you think it will take 60 years. 

 

There is no way it can be warmer globally during the HCO, CO2 is simply too high and the solar forcing would need to be alot more important than we are currently accounting for. Ice-Core Temperatures can only be used regionally.

 

In 60 years, we will be surpassing the Eemian at 0.30C/decade.

 

GISP2 is a global source not a polar one. It reflects global temperatures not temperatures at the site of the sample. Do some research on the methodology.

 

All sources agree the HCO was warmer globally, and especially at the arctic where trees grew to the north shore of Siberia.

 

Yes CO2 was much higher, but you are forgetting that much of the warming that would have occurred has been cancelled by human aerosol emissions. You are also forgetting that we are not at equilibrium and an additional maybe .~.5C of warming would likely occur even if CO2 were held constant. Also, orbital parameters favored higher global temperatures during the HCO.

You can't just say that CO2 is higher now so temperature must be higher. That's a pretty stupid statement. Temperatures are lower globally, but this is especially true in the arctic where forcing was concentrated during the HCO.

[AvantHiatus]

GISP2 is a global source not a polar one. It reflects global temperatures not temperatures at the site of the sample. Do some research on the methodology.

 

All sources agree the HCO was warmer globally, and especially at the arctic where trees grew to the north shore of Siberia.

 

Yes CO2 was much higher, but you are forgetting that much of the warming that would have occurred has been cancelled by human aerosol emissions. You are also forgetting that we are not at equilibrium and an additional maybe .~.5C of warming would likely occur even if CO2 were held constant. Also, orbital parameters favored higher global temperatures during the HCO.

You can't just say that CO2 is higher now so temperature must be higher. That's a pretty stupid statement. Temperatures are lower globally, but this is especially true in the arctic where forcing was concentrated during the HCO.

CO2 has been elevated above 300 PPM for 50+ years now, that should be more than enough time to outpace the HCO equilibrium globally. Something does not add up here, and Wikipedia explicitly states HCO was colder than currently in the mid-laditudes and tropics. I'll have to go and edit that article since apparently this is not true.

 

What were CO2 levels during HCO? Surely not higher than 250 PPM. The aerosol forcing is either insanely effective or the solar forcing is more important than we thought. I still think the deep ocean warming is absorbing 50% of the heat that would otherwise exist on the surface. The Holocene continental configuration and Drake Passage are also more effective at cooling the Earth.

 

Temperatures during the HCO were warmer in the arctic simply because of the extremely elevated solar insolation as a result of the northward movement of the Tropic of Cancer. This may of also directed more heat away from the equator.

 

I agree the Arctic was warmer during the HCO but the clmate was colder south of 50N, relative to average. Overall, averaged together, temperatures during the HCO are about the same or somewhat colder than modern temperatures.

 

Going from 200PPM to 400PPM CO2 is a massive change for climate sensitivity.

 

 

 

In summary, the mid-Holocene, roughly 6,000 years ago, was generally warmer than today, but only in summer and only in the northern hemisphere. More over, we clearly know the cause of this natural warming, and know without doubt that this proven “astronomical” climate forcing mechanism cannot be responsible for the warming over the last 100 years.

http://grist.org/article/it-was-warmer-during-the-holocene-climatic-optimum/

[skierinvermont]

CO2 has been elevated above 300 PPM for 50+ years now, that should be more than enough time to outpace the HCO globally. Something does not add up here, and Wikipedia explicitly states HCO was colder than currently in the mid-laditudes and tropics. I'll have to go and edit that article since apparently this is not true.

 

What were CO2 levels during HCO? Surely not higher than 250 PPM. The aerosol forcing is either insanely effective or the solar forcing is more important than we thought. I still think the deep ocean warming is absorbing 50% of the heat that would otherwise exist on the surface. The Holocene continental configuration and Drake Passage are also more effective at cooling the Earth.

 

Temperatures during the HCO were warmer in the arctic simply because of the extremely elevated solar insolation as a result of the northward movement of the Tropic of Cancer. This may of also directed more heat away from the equator.

 

I agree the Arctic was warmer during the HCO but the clmate was colder south of 50N, relative to average. Overall, averaged together, temperatures during the HCO are about the same or somewhat colder than modern temperatures.

 

Going from 200PPM to 400PPM CO2 is a massive change for climate sensitivity.

 

http://grist.org/article/it-was-warmer-during-the-holocene-climatic-optimum/

 

CO2 levels were higher than 250ppm during the HCO. They were 260ppm. We've thus far experienced a 1.5X increase in CO2. Almost half of that forcing has been cancelled by human aerosol emissions. And much of the net forcing has yet to fully express itself given the ocean lag effect. 

 

Marcott et al 2013 is the premier reconstruction of Holocene temperatures and they conclude in their abstract:

 

Current global temperatures of the past decade have not yet exceeded peak interglacial values but are warmer than during ~75% of the Holocene temperature history

 

Claiming that global temperatures are now warmer than the entire Holocene is to snub your nose at the best, most comprehensive data available on the question.

[StudentOfClimatology]

CO2 has been elevated above 300 PPM for 50+ years now, that should be more than enough time to outpace the HCO equilibrium globally. Something does not add up here, and Wikipedia explicitly states HCO was colder than currently in the mid-laditudes and tropics. I'll have to go and edit that article since apparently this is not true.

What were CO2 levels during HCO? Surely not higher than 250 PPM. The aerosol forcing is either insanely effective or the solar forcing is more important than we thought. I still think the deep ocean warming is absorbing 50% of the heat that would otherwise exist on the surface. The Holocene continental configuration and Drake Passage are also more effective at cooling the Earth.

Temperatures during the HCO were warmer in the arctic simply because of the extremely elevated solar insolation as a result of the northward movement of the Tropic of Cancer. This may of also directed more heat away from the equator.

I agree the Arctic was warmer during the HCO but the clmate was colder south of 50N, relative to average. Overall, averaged together, temperatures during the HCO are about the same or somewhat colder than modern temperatures.

Going from 200PPM to 400PPM CO2 is a massive change for climate sensitivity.

http://grist.org/article/it-was-warmer-during-the-holocene-climatic-optimum/

The problem is that anyone can go in and edit Wikipedia, regardless of their qualifications. Many climate deniers have already been banned from editing climate-related pages..

The Wiki article is correct correct that warmth was most concentrated in the NH, and maximized during boreal summer, but temperatures were still clearly warmer than they are now across most of the globe.

That said, we're probably going to surpass the HCO fairly soon unless we get our act together.

[AvantHiatus]

CO2 levels were higher than 250ppm during the HCO. They were 260ppm. We've thus far experienced a 1.5X increase in CO2. Almost half of that forcing has been cancelled by human aerosol emissions. And much of the net forcing has yet to fully express itself given the ocean lag effect. 

 

Marcott et al 2013 is the premier reconstruction of Holocene temperatures and they conclude in their abstract:

 

Current global temperatures of the past decade have not yet exceeded peak interglacial values but are warmer than during ~75% of the Holocene temperature history

 

Claiming that global temperatures are now warmer than the entire Holocene is to snub your nose at the best, most comprehensive data available on the question.

Fair enough, you can't win them all. In retrospect, the range of variation between HCO, Eemian Interglacial, and Pliocene is only 1-3C. Suggesting the Earth is very sensitive, considering the diverse flora and arctic ice state present in these periods.

 

These are the 3 most important climate benchmarks for anyone alive today, we can learn volumes by studying these time periods.

 

The Marcott paper was a good read, thanks for mentioning it.

[TerryM]

Just to finish the quote from Marcott et al

 

Current global temperatures of the past decade have not yet exceeded peak interglacial values

but are warmer than during ~75% of the Holocene temperature history. Intergovernmental Panel

on Climate Change model projections for 2100 exceed the full distribution of Holocene

temperature under all plausible greenhouse gas emission scenarios.

All plausible greenhouse gas emission scenarios include some in which temperatures don't rise very much in comparison to the most likely scenarios.

 

While Ellesmere Island driftwood carbon dating is usually referenced to show that the ice shelves have been in place for the past 5,500 years they can also give evidence that the Arctic Ocean was perennially frozen from as early as 9,900 BP Calendar yrs.

If the Arctic had not been frozen the trees would have become waterlogged and would have sunk. Perennial ice was required for rafting them across from the Siberian rivers. If the ice had only frozen seasonally they could not have made the voyage.

Since we appear to be nearing a period when seasonal ice will become the new norm it's fair to say that we're rapidly approaching a time when the Arctic Ocean will be provably warmer than at any time in the last 9,900 years.

It is feasible that seasonal ice could have occurred for short periods between 9,900 & 5,500 yrs.ago, but any extended period would show as a clear break in the deposition of the wood.

http://dro.dur.ac.uk/6877/1/6877.pdf

Terry