NAS reports: 50 million year cooling trend

I have not read the article concerned but there is another option for the loss of CO2. When India ploughed into Asia the himalayan range and the Tibetan plateau were formed. This major mountain building episode was follwed by rapid erosion. Indeed, erosion and uplift are still actively working in the area.
The theory is that CO2 is involved in the weathering of silicate rocks. The CO2 is incorporated into ocean sediments as carbonates, thereby removing it from the atmosphere. The same effect does not occur with carbonate rocks.
for example, see
American Journal of Science, Vol. 301, February 2001, pp 182-204
Berner & Kothavala

CO2 has been in a general decline over the entirety of geological history. Sure there have been a few attempted renewals, but the long term trend is what it is. It’s disturbing. There may be deadly changes to the Earth’s ability to sustain life, well prior to those owing solely to the life cycle of the Sun.

I always say that the position of the continents and continental drift has a big effect on Earth’s average temperature.
Move North America 200 miles south and there would have been no North American ice ages. The (cooler) summers of the past due to Milakovitch cycles would still have melted all the snow on land over the summer and there would not have been glaciers.
600 million years ago and 300 million years ago, most of the southern continents were locked together over the south pole. Glaciers build up at the poles, move north, spread out over the land and pretty soon all of the near-by land is covered in glaciers. Think Antarctica times ten. We had snow-ball Earth and a long ice age period.
We do know that glaciers do not build up on the oceans. Sea ice freezes, but glaciers cannot spread out very far over the oceans.
Whenever there is land over the poles, there are land-based glaciers and the Earth’s climate cools. The more the continents are weighted toward the poles, the colder Earth’s climate gets.
Over the last 50 million years, North America, Greenland and Eurasia have all moved north due to continental drift. About 2.5 million years ago, they moved just far enough north that we became susceptible to Milakovitch cycles and periodic ice ages occurred.
I don’t buy the Indian continental drift – Himalayan uplift argument since this has occurred throughout Earth’s history dozens of times without the same effects. Continents have always been moving around, moving over oceanic crustal plates and crashing into each other.

What was the CO2 level at the time of the Eocene Optimum?

To be fair, humans have been living in the cool period and at the warmer part of the range so changes from our current comfort level are disconcerting. That being said, there’s no reason to discount the massive natural forces that regulate the climate and in trying to figure out the variability and it’s causes.
BTW, could you add a citation and some explanation of the details of the graph since it supplements the article? Thanks.

Did they look at ANYTHING besides CO2? Doesn’t seem so.
Wouldn’t the same eruptions which released CO2 also release particulates which would cause cooling? And doesn’t such cooling always seem to overpower any other warming factors?

Ray says:

They want you to believe that a volcano just pukes CO2. Well well well, there is also lots of SO2 being ejected in the atmosphere during a volcanic eruption. We know that SO2 has a major cooling effect. Moreover, how come every time there is a major volcanic eruption in our times, it is followed by a global cooling of the temperature? Has atmospheric chemistry changed so much between then and now?

Jeff Alberts says:

Wouldn’t the same eruptions which released CO2 also release particulates which would cause cooling? And doesn’t such cooling always seem to overpower any other warming factors?

I think that the idea that the two of you are missing is that different processes can dominate on different timescales. A given major volcanic eruption releases lots of particulates and not all that much CO2. However, the particulates wash out of the atmosphere relatively quickly (generally within days when they are ejected only into the troposphere and within months to a few years when they are ejected into the stratosphere). CO2, by contrast, stays in the atmosphere a long time.
Hence, if there is a general increase in volcanic activity, this can have a significant effect on determining the level of CO2 over the long term (even though the rise due to any individual eruption will be pretty negligible). However, unless the rate of volcanic activity is so large that you are getting huge eruptions (like Mt. Pinatubo) every several months to a few years, you will probably not affect the average level of particulates in the atmosphere that much.

This article is another example of “revisionist geology” where all temperature changes are presumed to be due to CO2 in spite of evidence to the contrary. According to multiple sources (e.g.Geocarb 3, Rothman, Kilmafakten) CO2 levels were higher than the time of the PET all through the the late Triassic, the icy times of the Jurassic and early Cretaceous and were close to PET levels of CO2 during the warmer late Cretaceous. Through out the geologic record there has been a poor correlation between CO2 and Sea surface temperatures. Also the Deccan Trap volcanism was active before the KT event 65mya and there was extensive sea floor spreading between Greenland and Europe 55mya with little effect on CO2 for almost 30million years with SSTs being both lower and higher than the PET.
Except for in the world of climate models with their high sensitivity due to positive feedback from water vapor, CO2 appears to be very limited in its ability to cause significant warming with a ceiling imposed by saturation of the wavelengths absorbed by CO2 and the negative feedbacks from watervapor and clouds ( e.g. Hu, Christy and Spencer, Lindzen). In absence of a significant correlation between CO2 and temperature in the Geologic record and no non-modeled evidence for a strong amplifier of the modest warming effect of CO2, papers like this are pure speculation. (Unlike the Svensmark Hypothesis which was developed based on real world observations and is now being tested by the CLOUD project at CERN and by the drop in solar activity.)

If CO2 is such a great warmer it should be something that could be duplicated in a lab. Has anyone built a tall enclosed aquarium and simulated the impact of various levels of CO2, water vapor and other elements of the atmosphere? I mean really, what was the amount of water vapor like 50 million years ago? How strong was the Sun? What about volcanic activity? Shouldn’t we look at the major sources of warming / cooling before jumping on the CO2 bandwagon?

Finally, some perspective. An atmosphere that has remained stable enough to support the 3+ billion year evolution of life, through all these extremes, isn’t going suddenly spiral out-of-control into a life-baking oven when it hits 400 ppm of CO2.
Yet another crack in the positive-reinforcement, CO2 tipping point argument.
And that, as I understand it, is what the whole AGW edifice is based on.
The positive feedback at the very core of the AGW case seems to be: CO2 warming enables more water vapor warming, which releases more CO2, which enables more wam-blanketing by water vapor, etc. in a positive feedback that spirals out of control after it reaches some tipping point.
That’s why they had to get rid of the Medieval Warming Period, and other past climate optimums. Positive feedbacks weren’t triggered back then.
That whole thing falls apart when either of the following are shown to be true:
(1) there was more warmth in the past; (which didn’t trigger any positive feedback b/n CO2 and water vapor),
(2) there was more CO2 in the past (which didn’t trigger any positive feedback either.)
If you take away atmospheric positive feedback, aren’t we done? End of show? Nothing left for AGW to stand on?
Are we giving them life by not shining the spotlight more on the core of their argument?

Joel Shore — “CO2, by contrast, stays in the atmosphere a long time.”
Really? How long? I’ve seen estimates that range from 10 years to 200 years, and these are from the alarmist crowd. The IPCC certainly doesn’t have a reliable and solid answer. There not only doesn’t appear to be a standard answer, implying that nobody knows *anything* about this that can be reliable, but the answers that come seem rather plastic. Depends on what the question was.
I think I rather like the longer answer, because 200+ years suggests that what is in the atmosphere today, if attributable solely to mankind, is the cumulative output of man since the dawn of the industrial revolution. In that case, no big shakes. We can continue to drive all we like.
Meanwhile those who downplay the longevity and stress shorter times point to the oceans as absorbers and emitters of the CO2. In which case, cool — CO2 seems to be emitted in the LIFO (last in first out) fashion, meaning that what’s being emitted today was (again) added from earlier times to the present emissions. (This results in the same answer as in the above paragraph, just in case you need assistance.)
Seems to me that either answer gives the same result, so the contention that “CO2 lives a long time in the atmosphere” as an attempt to explain **anything** is specious at best.
The truth is NOBODY knows how long CO2 stays in the atmosphere, and you, sir, sound like a parrot.