Warming in a global cool period
By Peter N. Spotts| Staff Writer for The Christian Science Monitor/ September 25, 2008 edition
Graph above added by Anthony – not part of original article
With all the focus on human-triggered global warming, it may be hard to imagine that the world is riding a 50-million-year-long cooling trend.
But it is, and blame the trend on a continental-scale collision, say geophysicists Dennis Kent of Rutgers University and Giovanni Muttoni of the University of Milan in Italy.
Researchers say there is strong evidence that increases in atmospheric CO2 contributed to a warm spell 50 million years ago dubbed the Early Eocene climate optimum – the warmest period in 65 million years. But over the following 15 million years, deep sea temperatures fell by about 10.8 degrees F., reflecting a significant cooling at the surface. This cooling ultimately allowed the cycle of ice ages to emerge.
Drs. Kent and Muttoni have mined paleomagnetic and other data and suggest that atmospheric CO2 dropped because India collided with Eurasia, shutting down a productive, natural CO2 factory.
Some 120 million years ago, the subcontinent that is now India was migrating north from Antarctica. As it moved, it shoved the ocean crust that was ahead of it under an existing crustal plate. As long as this zone off the Eurasian coast was under water, bottom muck enriched by carbon from the biologically-rich ocean plunged under the plate. It got recycled as lava in volcanoes along a geological feature dubbed the Kohistan Arc, as well as in a vast lava-oozing formation called the Deccan Traps. The eruptions released the carbon as CO2, which helped warm the climate. But once India collided with Eurasia 50 million years ago, India rode over the top of the zone and shut off the process. This, plus changes in ocean circulation as continents rearranged themselves, contributed to the long chill, the researchers suggest.
The results appear in the current issue of the Proceedings of the National Academy of Sciences.
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Joel Shore
I linked to your reference: http://www.sciencemag.org/cgi/content/summary/sci;306/5697/821
Their findings on the sensitivity of the climate system I assume is true. The speculative sensitivity of the climate system to climate models is invalid.
“Climate models and efforts to explain global temperature changes over the past century suggest that the average global temperature will rise by between 1.5º and 4.5ºC if the atmospheric CO2 concentration doubles.”
“They conclude that the climate system is very sensitive to small perturbations and that the climate sensitivity may be even higher than suggested by models.”
It should be obvious that Nature is not subject to the control of models. The authors “suggest” and say “if” about facts not in evidence and say “maybe” about “suggestions” made by unverified models.
Spinning speculation does not create scientific fact.
RE: Bruce Hall (14:04:25) :
That is my fear as well. I keep beating the interstellar migration planning drum. We need to start planning now. Unless there is a break through in technology and our understanding of physics, we need to allow a few million years to move everyone, and that is after we actually determine where to move to. We need to assume that the space transport technology will still be way below light speed, when we need to move. If things get easier, then great, icing on the cake. But if they don’t we need to plan and execute multigenerational space emigration on a massive scale.
My understanding of the atmospheric CO2 levels is that there are 2 main physical cycles going on that are going on together. On top of that you have the biological and
One cycle involves the rate of absorption into surface Ocean water of a slug of CO2. To understand this cycle you have to assume an ocean that does not have large scale upwellings and downwellings. Simple diffusion physics combined with wind/wave surface mixing are the mechanisms. This is the cycle that I understand is on the order of 5-10 years.
The other cycle is driven by the longer term Ocean current driven upwellings and downwellings. This can drive CO2 up or down . I understand the simple version of this is that when the older water was at the surface it would have reached close to a an equilibrium concentration of CO2 as influenced by atmospheric CO2 concentration and surface water temperatures at that time. That time is based on the oceanic cycles and I’ve heard 200-800 years. This may actually be represented by several distinct oceanic cycles. Perhaps one for the Atlantic, a couple in the Pacific, etc. So notionally, the Atmospheric Co2 concentration levels may be significantly represented by a 5-10 year equilibrium cycle, on top of 200, 600 and 800 year oceanic cycles.
And this is why modeling of ocean currents is much more significant an area of research to understanding and projecting CO2 levels.
Joel Shore:
(1) No serious scientist that I know of is claiming that there is a Venus-like instability and the climate is going to “spiral out-of-control into a life-baking oven” once CO2 levels hit 400ppm.
The name Hansen rings a bell perhaps?
Or perhaps he’s not a ‘serious’ scientist………
Joel Shore,
They can’t have it both ways. You’re suggesting that there is a second “tipping point” (or “blocking point”) somewhere in the future that causes the positive feedback to stop.
But I haven’t seen that anywhere else. I would be happy to learn where the AGW theory says that increasing warming will come to an end, the positive feedbacks will stop, and the atmosphere will stabilize.
To the contrary, we have eminent, award-winning scientists like Jame Lovelock predicting that, “Before this century is over, billions of us will die, and the few breeding pairs of people that survive will be in the Arctic where the climate remains tolerable.”
http://www.independent.co.uk/environment/environment-in-crisis-we-are-past-the-point-of-no-return-523192.html
With a heat source assumed to be steady (the sun), and an increasingly warm, thick and efficient atmospheric blanket to lock that heat in, what is going stop the warming? Especially with all the extra CO2 and soon methane etc. predicted to come pouring in real soon now?
So again, does the AGW hypothesis really say that temperatures will stop spiraling upward at some point? Do you (or does anyone) have a link or a reference? This is the first time I’ve heard of warming being predicted to come to a stop somewhere down the road.
This is basically the same chart Smokey posted, accredited to Scotese, 2001,
a year earlier. It is a bit easier to read, and shows regardless of the CO2 levels,
temperature has never run away. Even at 4000ppm temperatures have been similar to today’s. There simply is no tipping point from CO2 levels. Historically, CO2 levels are about as low as they get, and temperature is too. So ‘normal’ is having both be higher.
http://i35.tinypic.com/2rh4fbb.gif
Joel Shore
You write: “… what is being said is that they are temperatures that have not been experienced in quite some time (probably in the entire history of our species) and that the change will be very rapid relative to past temperature changes…”
It is not what is being said, it is who is saying what the temperatures will be and that the temperature change will be relatively very rapid.
Do you have any scientific facts to back these assertions?
Re Lovelock. Why then is humanity concentrated near the Equator rather than at the poles right now? I mean if warmer is so deadly and all, how come most people live in tropical or semi-tropical environments?
Re rising sea levels. Why not move to higher ground rather than to distant planets? What exactly is the point of building cities below sea level when the continents have plenty of room?
Wouldn’t that be more constructive than economic monkey wrenching and civil disobedience? I’m just saying…
Re the demise of ecosystems. Gimme a break. Most plants and animals evolved on a much warmer planet. The Ice Ages have been the driver of most extinctions in the last few million years. Plant and animal species move around. Yes they do. The harum scarum dire reports of ecosystem collapse are exaggerated foolish nonsense.
A better way to think about CO2 residence time is “how long will the increased CO2 stay in the atmosphere (presumably causing warming)” which is the reason to ask the question in the first place.
How long will it take for CO2 levels to return to normal levels?
Right now, natural processes (oceans and plants) are absorbing about 2 ppm of the additional 4 ppm humans are adding to the atmosphere each year.
If we have increased CO2 about 105 ppm (from 280 to 385), natural processes will return CO2 to its pre-industrial level in about 50 years if current trends continue.
More likely, natural processes will slow down as the CO2 levels drop, so the best estimate would be 50 to 75 years (the same length of time we have been adding CO2 in a serious way.)
Joel Shore
“Your whole argument rests on a number of misconceptions that I will try to clear up:”
A very informative comment.
Hi everyone,
I wonder if any study is exist regard of the heat coming up from the deep, natural decay which would drive the deep ocean temperature?
If not the Sun drive the climate (IPCC) this maybe the variable not used for
computer modelling. LOL
How about the continental drift generated heat? Is there are any correlation
of the continental drift and the Solar system barycenter motion?
Sorry about the naive questions…. 🙂
Mick.
Ray, the crib burning is the smelting process Inco used near the turn of the century. Thanks for the link. That shows the superstack that was built in 1972 that ended up sending the smoke farther away. Now a larger area is affected.
By the time the superstack was built, the soil was already eroded and there were few trees left as noted by NASA using our landscape as a test drive for their lunar rover in the 60s once. Some damage was done by Inco and other mining companies after crib burning was abandoned, but it was the cribs that did the bulk of the damage by using the wood. My point is that soil erosion was worse than sulfur dioxide when it came to our vegetation. It is correct that the soil that was left does best now if it is limed first for most garden plants, but it took decades of acid rain to do the damage.
Now a days, Inco monitors the direction of the smoke plume and particulate emissions. They judge when they need to issue certificates for repainting cars that were beneath the plume when the emissions were too high and created pox marks in the paint of vehicles left outside.
I suspect it would be similar with volcanoes. The rain going through the concentrated plume would cause the most devastation, but if the eruptions are not constant, like Sudbury’s plumes of smoke over decades, then the lake would be able to adapt or heal itself. As well, the soil would have the acid washed through when the sulfur was done being washed from the air.
John M Reynolds
(Sound FX) An explosion off set
(Narr: Walks on stage, clears throat) Ladies and gentlemen, our writer has just exploded due to an overdose of Al Gore. We will continue now with the program as written in your programs.
(Narr: Walks off stage)
Just read on ICECAP that Gore asked young people to demonstrate against coal fired plants that don’t sequester CO2. I think I’m going to be sick – using our youth like this. Hate to say it but this is very similar to another situation in a mid-european country in the second third of the last century.
(moderator: Mr Bentley, you’re banished!)
ARGGGG!
Mike
John, I would think that the volcano eruptions was the norm back then and lasted many million years. You’ve seen the damage in Sudbury. How much damage to the plants and soil would million of years of volcanic acitivity do to the earth back then?
I am not suggesting anything but this is something else to add to the equation and not just consider CO2 and global warming.
Need some help. My neighbor has gone back to community college in order to change careers. One of his required courses is Interdiscipinary Sciences (whatever that is). The professor is an AGWer and my neighbor has brought up some points that I have passed on to him from this blog. The professor told him to ask me 3 simple questions, the answers proving AGW:
1) are there more cars than in 1950?
2) are there more aircraft than in 1950?
3) are there more coal electrical plants than in 1950?
I retorted, “And what is that supposed to prove?” but I can guess his drift.
I want to send my neighbor back with a couple of questions to see how much this professor really knows about CO2. I know I have seen this information on this blog but do not have any idea where to look for it so if anyone can provide the answers, or better questions, thank you so much
My questions will be:
1) What is the absorption spectrum of CO2 and at what point does it become saturated? How does that compare to the absortion spectrum of water vapor?
2) What percent of the atmospheric CO2 is man made?
3) What is the lowest level that atmospheric CO2 can drop to before plant life dies?
4) What is the highest level that atmospheric CO2 has risen to where life still existed?
Dan Lee says:
There is still some confusion here. It is not so much that the “positive feedbacks will stop”. It is that they are strong enough to cause amplification of the warming but not an instability.
To give you an idea of the mathematics that comes into play here: Let’s say that for every 1 deg rise we cause in the temperature due to the direct effects of increasing CO2 levels, the feedbacks (e.g., an increase in water vapor) lead to another 1/2 deg rise. Then you will say, “But, wait, then the feedback on that 1/2 deg rise will lead to even a further rise.” And, indeed this is true. But, that additional rise will be only 1/4 deg. Then the feedback on that will lead to another 1/8 deg rise. What you get is an infinite series 1 + 1/2 + 1/4 + 1/8 + 1/16 + … However, even though the series has an infinite number of terms, this sum does not diverge. In fact, it approaches 2. So, in the simple toy model that I have described to you, the effect of the feedbacks is to double the warming.
The current best estimates of the climate sensitivity correspond to the feedbacks magnifying the warming by about a factor of ~1.5 (or a little more) to 4.
As for Lovelock’s scenario, I won’t try to defend it as it seems extreme to me. On the other hand, as disasters like Katrina and economic problems like the current housing crisis show, our societies are not as far from degenerating quite a bit as we may like to believe. So, while I think Lovelock’s climate scenario is extreme, I do think that a milder climate change scenario could still cause enough societal troubles (wars over resources, etc., etc.) to be more serious than we might otherwise expect.
Finally, in my last post when I talked about Hansen’s using the term “tipping points” rather loosely, I may have missed something: I think one important point that Hansen is making is that the positive feedbacks lead to a lot of “hysteresis” and “irreversibility” in the climate system. What I mean is that if we raise the CO2 levels beyond a point where a lot of melting of arctic ice occurs then the positive feedback due to having less ice to reflect the sun will lead to further warming. Also, the way that the ice sheets break up is highly nonlinear and can be much faster than it takes to build them up again.
What this implies is that if we go beyond a certain point and then drop the CO2 levels back down again, temperatures and land and sea ice will not simply go back to the way they were…at least for a long long time. (And, in fact, the ice sheets will continue melting and the sea levels rising.) I think this is the sense in which Hansen is talking about a tipping point…and it is a quite reasonable use of the term. It is not that the temperatures are going to spiral out-of-control but simply that they will likely go to levels that we humans have not experienced and the effects, especially the melting of ice sheets and rises in sea levels, will not be easy to stop even if we are able to stabilize or even start to reduce CO2 levels.
Mick says:
Yes…I have seen some estimates somewhere of a W/m^2 forcing due to heat coming up from the earth and, as I recall, it is down by at least a few orders of magnitude from the forcing due to CO2. (Needless to say, it is even a few more orders of magnitude down from the total energy that we receive from the sun).
Say Tom,
Ask him to name -all- the greenhouse gases and what percentages they are. And then what the human contribution is to CO2, perhaps in comparison…say, to cows.
Show him the Hansen 20 year graph and ask him to point out which end is cooler.
Or get him to critique the Monthly Weather Review from…was it Sept. 1933, that Anthony had here earlier in the year.
….and buy him a copy of “The Chilling Stars”
Tom in Florida: Your friend might also mention that there are more whales than in 1950 (one blue whale breath emits more CO2 than a thousand people would). Those pagophylic (ice-loving) bowheads are many times more numerous than in 1950 despite continued predation by Inupiat Eskimos.
Also mention that the world climate (as measured by eustatic sea level) is about a meter below the Late Holocene Interglacial average, representing about 1°C cooler than the average during the period of human civilization. The maximum sea level during this period was about 3 meters higher than now. We are well within normal climate flux for an interglacial.
Yet another item worthy of mention . . . we have deforested tremendous parcels of rain forests, both tropical and temperate. Make sure the Third World contribution to anthropogenic carbon in the atmosphere is included in any conversation. Third World home fires contribute more than 50% of the anthropogentic CO2. Ocean pollution is also responsible for a double digit percentage of the residual CO2 each year. Cars and aircraft are a relatively small percentage.
Mike:
I am a more naive. Together
If the sun is distant 150000000Km your temperature is 6000 ° C on the surface. The center of the earth is 6000 º C. and your distance to the surface 6500Km.
earthspot number (????)
What is the energy used to move the American continent 1mm by year? (seriously)
Smokey: That’s some graph! There doesn’t seem to be any co-relation between temperature and CO2.
Tom in Florida
As a start, visit: http://www.geocraft.com/WVFossils/ice_ages.html#anchor2108263.
The link “Causes of Global Climate Change” leads to a discussion of the “Greenhouse Effect.” Table 1, from the DOE, October, 2000, gives the pre-industrial base-line and reports the natural and anthropogenic additions separately. I have yet to locate more recent DOE data. If the ratio of natural to man-made CO2 of 5 to 1 holds, then the man-made portion of the CO2 increase of 17 ppm, since 2000, would be about 3.5 ppm
There are references to supporting books, articles and reports.
Fishing the NW Passage!
Damn!!!
Joel Shore,
Good explanation, and good clarifications, thanks.
I like your sequence of diminishing returns on the feedback, that clarifies things a lot. It matches very well with our understanding of the diminishing GHG contribution of CO2 as its level increases, and jives with the idea that we’ve already seen about as much warming from CO2 as we’re going to get.
I’m aware of a .6C/century greenhouse contribution of CO2, and as you say you would still need that positive feedback to get the IPCC’s 1.5C – 4C rise in temps due to water vapor. I guess that’s in tatters at this point, as your example indicates, unless they mean the entire warming that CO2 will ever produce.
I’ve lived in third-world slash-and-burn agriculture economies (with the Cuiba Indians in Colombia) and I know that a group of primitive families can dump more CO2 into the air in one week than my neighborhood full of SUV’s produces in a year. Mankind has been pouring smoke into the atmosphere since we discovered fire, so I also have difficulty with the general assertion that man-made CO2 only started to become relevant since about the 1950’s.
Anyway, if CO2 and water vapor were the only two factors at play, then the IPCC’s take might make sense.
But they’re not the only factors. The warming signal from the ocean oscillations is huge, big enough that you can point at the temp graphs and they jump right out at you. Where’s the positive CO2/water-vapor signal? Buried in the natural warming since the last ice age? Or even since the LIA?
I’m not seeing much room for a positive feedback hypothesis between water vapor and CO2 to explain the trends over the past century. Or the past millenia, to bring this back on topic, and refer the conversation back to the temperature chart at the top.
With such huge natural variations, and if as you say the positive feedback (if it is indeed positive) is minuscule, then what exactly is the point of pushing forward a positive feedback hypothesis in the first place? Especially without accounting for the possible negative feedbacks, such as increases in clouds and rain?
What’s the point of trying to do away with a huge body of historical and scientific work on the Medieval Warm Period and the Little Ice Age by drawing hockey-stick graphs UNLESS one wants to discount natural cycles as an explanation for recent temperature trends?
If all one is willing to accept as an explanation is man-made CO2, then one needs to believe in positive, catastrophic feedbacks and one needs to ignore past variability.
I accept your explanation of the IPCC’s position on the feedbacks, but I find it (the IPCC’s) frustratingly incomplete. They fail to adequately address both natural variability and the effect of negative feedbacks.
Therefore I am skeptical of their pronouncements about future climate. But I feel that I understand them better now, thanks to your explanations. Sincerely appreciated.
Now if only I can get my kids’ science teacher to quit telling them our whole neighborhood will be underwater in 20 years. :-/
Just thought I’d post a longer version of the temperature history of the planet (540 million years) versus the one originally linked to by Peter in the opening of the post. (This version is no longer linked to by Wikipedia but seems to be the best analysis of the paleotemps over the last 540 million years).
http://en.wikipedia.org/wiki/Image:All_palaeotemps.png
This chart is the CO2 history of the planet over the same 540 million years. The yellow orange line from Berner seems to be the most accepted. (earlier in the thread, a CO2 history from Pagani was linked to but Pagani is a rabid warmer and as such should not be viewed as objective.)
http://www.globalwarmingart.com/wiki/Image:Phanerozoic_Carbon_Dioxide_png
One could do their own math on how much doubled CO2 leads to increased temperature in this long paleoclimate history. (Hint: it works out to 1.0C to 1.5C per doubled CO2 ignoring the fact that the Sun was not as energetic in the distant past. One might have to have to raise the climate sensitivity figure to 1.5C taking this into account.)