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Climate change, 55 million years ago

Thu, 10th Oct 2013

Dave Ansell

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About 55million years ago, Earth's temperature suddenly shot up owing to a massive release of carbon dioxide into the atmosphere, new research have revealed. Scientists are warning that we should take note and cut carbon emissions to avoid a Weatherrepeat.

Historically, Earth was much warmer. About 55 million years ago, temperatures were, on average, 8 degrees Celsius higher than they are now. There were crocodiles living off Greenland, and palm forests in Wyoming.

Suddenly, the levels of carbon-dioxide doubled and global temperatures increased by 5 degrees.

Previously, scientists had thought this warming had taken tens of thousands of years.

But now researchers Morgan Schaller and James Wright have been studying offshore clays dating from this period from Maryland and Delaware. They discovered a repeating pattern in the clay, resembling tree-rings, corresponding to a yearly cycle of rivers dropping more and less sediment into the ocean.

By looking at different isotopes of carbon present in each of the clay layers, including carbon-12, which is more easily taken up by living things, and carbon-13, which is more common in inorganic carbon sources, they found evidence for a huge injection of about 3000 billion tonnes of carbon into the atmosphere over a period of a few months.

Over the next 13 years, this dissolved into the shallower parts of the sea causing it to become acidic, killing off more deep sea species than at the end of the cretaceous which killed off the dinosaurs. It then took 150 000 years for things to return to normal.

This, they say, should help us to understand not only an interesting piece of Earth's early history, but also serves as the best model we have of the experiment we are doing to our climate by adding CO2 to the atmosphere by burning fossil fuels.

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For a long time we've known a correlation between CO2 and glacial/interglacial periods.  However, the timing seems to indicate an increase of temperatures preceding the increase in CO2 levels, with the interpretation that the rising temperatures drive the CO2 out of the oceans.

Is there any reason to believe that 55 million years ago the CO2 increase would have preceded the temperature increase?
CliffordK, Mon, 14th Oct 2013

The inherent properties of water lead to a bounded chaotic oscillation of atmospheric temperature if driven by a constant solar input. If we start with a dry atmosphere over a wet planet, evaporation increases the greenhouse effect (since water is the major greenhouse gas), thus raising the air temperature, encouraging more evaporation, and increasing the capacity of the atmosphere to hold water.  This positive feedback produces a rapid rise in temperature up to the point that the planet is covered with cloud which cuts off the surface heating but also reduces radiative loss, so it slowly cools down again. Hence the sawtooth temperature/time profile we find in ice cores.

When the sun shines, plants grow and extract CO2 from the atmosphere. As the temperature rises, the population and activity of coldblooded animals  increases and they live by converting plant material back into CO2. The converse happens as the temperature falls. Hence the CO2 level follows the temperature graph.

All of these mechanisms can be observed in the laboratory and locally on a daily scale, and there's no reason to suspect that the laws of physics and biochemistry have changed over geological time. Water is the thermostat, CO2 is the thermometer. alancalverd, Wed, 16th Oct 2013

As with many systems, proportional variation over a long enough time is not so much the problem.  The rate of change is.

Trees, plants and animals will play a dampening role on the changes but this can't happen instantaneously.  As a result we are entering a mass extinction period.

No one is in doubt that the planet will eventually settle towards a new equilibrium (obviously it's never completely fixed), but it's possible we may not be around to see it as a species. peppercorn, Wed, 16th Oct 2013



Everyone is (or should be) in such doubt! The geological record shows that it has never been in equilibrium, and the laws of physics explain why it never can be. alancalverd, Wed, 16th Oct 2013



Do note I said "settle towards a new equilibrium", meaning it won't actually reach one.
Humans have just introduced a large forcer (think spring/damper) on top of the other natural actors previously in play. We have done this by liberating the CO2 stored in ages past. peppercorn, Wed, 16th Oct 2013

There's a significant difference between an asymptotic equilibrium and an inherently unstable and chaotic oscillator. CO2 is irrelevant. alancalverd, Wed, 16th Oct 2013

1. Do you accept that humans have released a significant volume of CO2 into the atmosphere?
2. If so, in what way do you think this is not independent of the CO2 present as a consequence of the processes you describe?
3. Do you deny the greenhouse effects of CO2? Ophiolite, Thu, 17th Oct 2013

The infrared absorption spectrum of carbon dioxide is negligible compared with that of water vapor, and the albedo of clouds is the principal determinant of heat input and output. Unfortunately all we know about these drivers of climate is that they are overwhelmingly large and very variable, as the IPCC admitted in its very first report.

Because CO2 concentration varies with temperature, it is easy to assume that it has a causative effect, so you can construct a model that somehow links the two parameters as cause and effect. Huge efforts have gone into this, because anthropogenic CO2 is in principle controllable and can be taxed, so it would be nice if the theory had some predictive value. Alas, the models have so far failed to predict what actually happened, because they are based on a false assumption. Correlation is not proof of causation, and no such model can explain the geological history of temperature fluctuation without invoking sudden, mysterious and spontaneous appearances of vast amounts of CO2 about every 500,000 years. Which would be fine, if a little puzzling,  if the geological record showed CO2 increasing before temperature. But alas, it's the other way around. Not by a lot, but in my book, if the light comes on even a nanosecond after I press the switch, the light isn't causing the switch to close. 

It's interesting to apply the supposed CO2 forcing function to the atmosphere of Mars, knowing he solar inoput and the concentration of CO2 in its almost water-free atmosphere. It turns out that Mars is a lot colder than predicted, so the forcing function must be wrong. alancalverd, Thu, 17th Oct 2013




I seem to have overlooked the data showing that temperatures rose prior to any CO2 being released 55m years ago. peppercorn, Thu, 17th Oct 2013


In the glacial records, the temperature rise tends to occur before the CO2 rise.  However, I'm not sure if they have the data in the clay records to make the same determination. 

That doesn't remove the possibility of a positive feedback in which a small temperature rise could be amplified by a CO2 rise, causing a further temperature increase and greater CO2 release. CliffordK, Fri, 18th Oct 2013

Please provide peer reviewed citations to substantiate this. It would also be nice, for background understanding of your position, if you would answer the first of my three questions. Ophiolite, Fri, 18th Oct 2013

As far as water vs CO2 vs Methane & etc.

Each compound has a slightly different IR absorption spectrum, and it may even vary with the physical state (solid, liquid, vapor). 

So, while water vapor does have a broad IR absorption spectrum, there are "windows" in the spectrum.


http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png

Much of the IR absorption by CO2 occurs in one of the "windows" of the water absorption spectrum, around 15 microns.  Apparently, while it looks rather saturated, the peaks do widen with increasing atmospheric CO2.  So, the low absorption window is closed further with greater CO2 concentration.

The methane peak at about 8 microns may have a greater masking by the water absorption spectrum.

Altitude may also be important.  CO2 is a heavy molecule, and may cause the IR to be absorbed at lower altitudes, and thus would be more likely to impact the surface temperatures. CliffordK, Fri, 18th Oct 2013

I note that the y-axes of the component graphs are not scaled, and the range of upgoing transmission is 2:1. Since the CO2 concentration doesn't vary much, that must all be due to water.

And of course water doesn't only occur as vapor in the atmosphere - it's present as liquid, solid (in several forms, some with over 90% albedo) , and umpteen gaseous forms as transient polymers. Dominant, chaotic, and unmeasurable. So the IPCC ignores it. alancalverd, Fri, 18th Oct 2013



Measurable, or at least calculable, yes. Significant? I think not. And I hope not! 10% of all anthropogenic CO2 comes from humans breathing, and another 25% from farm animals. If our emissions are significant and significantly damaging to the ecosystem, we must kill ourselves and stop eating meat. 

I don't have a "position", just a vague scientific instinct that causes should precede effects, and the knowledge that it's very easy to draw false inferences from apparent correlations.

Sadly, I can't make head or tail of your second question. Could you rephrase it a bit?  alancalverd, Fri, 18th Oct 2013


Measurable, or at least calculable, yes. Significant? I think not. And I hope not! 10% of all anthropogenic CO2 comes from humans breathing, and another 25% from farm animals. If our emissions are significant and significantly damaging to the ecosystem, we must kill ourselves and stop eating meat. 

99.9% of the food we eat is from consuming plants that convert CO2 into hydrocarbons and carbohydrates. 

Thus you end up with a cycle in which the CO2 is absorbed by plants, eaten, released, and reabsorbed by plants.

And the same goes for cows (except for perhaps some extra cow methane).

The main concern with anthropogenic CO2 is from fossil fuels, I.E.  Carbon that has been sequestered deep under the earth for millions of years, and we're happily releasing back into the atmosphere.

There are, of course, also fossil fuels being used in food production and transport, as well as using fossil fuels to reduce nitrogen for the formation of nitrogen fertilizer.

If we don't change something, eventually we'll reach atmospheric conditions similar to before the dinosaurs roamed the Earth. 

The big question is whether the changes will be acceptable.
CliffordK, Fri, 18th Oct 2013



But the dynamic equilibrium, i.e. the concentration of CO2 in the atmosphere at any time,  obviously depends on the mass ratio of animals to plants. Simple fact is that the over 30% of the CO2 we return to the atmosphere every day is from the exhalations of animals that wouldn't exist if we didn't.

Don't blame cows alone for methane. It's a product of human sewage systems too - and a very useful one! alancalverd, Fri, 18th Oct 2013


In the glacial records, the temperature rise tends to occur before the CO2 rise.  However, I'm not sure if they have the data in the clay records to make the same determination. 

That doesn't remove the possibility of a positive feedback in which a small temperature rise could be amplified by a CO2 rise, causing a further temperature increase and greater CO2 release.


In an effort to return to the original topic...
The glacial record that you speak of, is that one derived from cores taken near the poles?

If that's the case then it would seem to follow that an initial forcer - perhaps ghg release in more temperate zones (continent-wide forest fires, etc) - would, as you imply, create a thermal runaway situation which led to ice melts giving up their stores of CO2.
.... This may be our future too, I imagine! peppercorn, Fri, 18th Oct 2013

If that were the case, there would surely be less CO2 in the "warmer" ice?

Unlike water, CO2 has no inherent positive feedback as its "solubility" in air is not temperature-dependent. alancalverd, Fri, 18th Oct 2013

I would bet the PETM (55 million years ago) had something to do with a nearby supernova or something astronomical. Notice how quickly the temperature returned to previous levels after the spike. Saw a talk by an IPCC scientist and even he admitted that the CO2 data didn't work very well for the PETM (Palaeocene-Eocene Thermal Maximum). Steve Wickson, Mon, 28th Oct 2013

I would say that climate change has definitely affected earth. A lot of typhoons and hurricanes that we are experiencing these days are due to low pressure and warmer water. Global warming is the cause of most of these natural disaster. To learn more about climatic changes go to http://www.researchomatic.com/essay/nature/ . You will see how little changes in the atmosphere can have ahuge impact on its inhabitatnts!
ViolaSheen, Wed, 13th Nov 2013

Not that Wikipedia is particularly trustworthy, but I see no reason for it to lie: 



As with most climate change scare stories, the facts do not support the hypothesis. alancalverd, Wed, 13th Nov 2013


I would hazard to guess that all typhoons and hurricanes are due to low pressure and warm water, both now and in the past.  Global warming is not the cause of these natural disasters. Bass, Thu, 14th Nov 2013

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