Historical CO2 Data

[Alpha5]

Hey guys, I'm looking curious about historical CO2 levels. I was interested in comparing CO2 levels today to ancient times, but Ive found a lot of conflicting ice core data.

Some show the highest CO2 levels in modern day, while others show CO2 levels thousands of years ago dwarfing today's.

If anyone can clear up this issue it would be greatly appreciated.

[BethesdaWX]

Geocarb is probably the best proxy we have. Keep in mind CO2 and Temp are on the same resolution, so there is no "missing" data.

[WeatherRusty]

NASA Link source

[BethesdaWX]

http://www.geocraft.com/WVFossils/Reference_Docs/Holocene_CO2_stomata_Wagner_etal_2004.pdf

[Clifford]

Interesting paper.

On the "short-term", I think we can say that the CO₂ has likely been less than 300 ppm for the last million years or so, with today's values being around 380 or 390 ppm.

On the "long term", the levels have been dropping over the last few hundred and fifty million years, and we are likely still very close to the minimum over the last 150 million years, and of course there has been significant variability throughout the history of Earth. The oxygen concentration has also varied significantly over time, at least during the last 600 million years.

Humans likely would not have been able to survive in the atmosphere 700 million years ago.

[The_Global_Warmer]

The Current ppm is 393.4 or so.

It was 380 a decade ago.

It will be over 400 by 2014.

The amount of rise per year has more than quadrupled since the 60s.

It is still going up.

[BethesdaWX]

The Current ppm is 393.4 or so.

It was 380 a decade ago.

It will be over 400 by 2014.

The amount of rise per year has more than quadrupled since the 60s.

It is still going up.

True. But Again you should feel better looking at the data when correlating to temperature.

[The_Global_Warmer]

I agree to some extent. However I also believe in terms of historical co2 ppm to temps it is hard to take the correlations serious because of all of the unknown factors.

I also have a hard time believing the doubling of the Co2 PPM causes a rise of 2.5-4C. Globally by itself.

If that is the case then we are in deep trouble the next few decades. Ppm will be over 500 by 2050. That would rise temps by 1-1.5C. Which would melt the arctic out for sure.

[BethesdaWX]

Well I think much better of you now Correct there are obviously other factors long term such as plate tectonics that alter circulations/heat gain/release in the oceans & thus the global air temperature, but this cannot explain most of the temperature variation. There may be other things, we just don't know.

Still, just over 250 million years ago CO2 was at 400-450ppm and the temp was about 10C warmer than today's for a time. Yet in the Ordovician Ice age, one of the coldest all time, CO2 was over 4000ppm, while much of the planet was covered in ice. Both temp and CO2 are on the same resolution, so there is no missing data.

And just to put into perspective...we are right now in the middle of the Neogene Ice Age with CO2 at the same PPM value it was when temps were over 8C warmer.

Obviously plate tectonics can explain away a small part of the variation/base value in temps, but not much.

[Clifford]

There is a lot of evidence that over the last million or so years, temperatures have driven the CO₂ levels.

Often with data lags, with temperatures seemingly increasing before the CO₂ increases, and then later the temperatures dropping significantly before the CO₂ levels drop.

CO₂ levels changing due to the gas being driven into or out of the oceans due to partial pressure changes based on ocean temperatures.

For the Antarctic to melt, it will need much more than a few degree shift. Noting, of course, that there has been essentially no significant changes to the Antarctic temperatures over the last few decades.

For the Arctic to melt... well, to a large part it does every year. Yet, on those dark, sunless winter nights, it also refreezes.

What was the original question? CO₂, and not Temperatures? Anyway, I can imagine this topic will lead to a mud-slinging contest.

[BethesdaWX]

I can imagine this topic will lead to a mud-slinging contest.

I'm surprised it hasn't started yet, but I'm ready for it It is amazing how complicated the AGW thing actually is... I had no idea really until I started my education in the field.

Anyhow the last interglacial is the best example Global temperature's independance from CO2, we lost almost 8C with no change in CO2...if additional CO2 in the air supposedly added to the warming on the way up, why did we lose the entire 8C before CO2 concentration even changed?

Appears CO2 change was not required to equate to the temperature change of 8C...neither on the way up nor on the way down. Same past history repeats itself over the past 700 million years, Temperature does not correlate to CO2 well at all.

[WeatherRusty]

I agree to some extent. However I also believe in terms of historical co2 ppm to temps it is hard to take the correlations serious because of all of the unknown factors.

I also have a hard time believing the doubling of the Co2 PPM causes a rise of 2.5-4C. Globally by itself.

If that is the case then we are in deep trouble the next few decades. Ppm will be over 500 by 2050. That would rise temps by 1-1.5C. Which would melt the arctic out for sure.

By itself a doubling of CO2 produces a surface warming influence of a bit less than 1.2C. Net positive feedback is required to reach the 2.5-4C you cite.

[BethesdaWX]

By itself a doubling of CO2 produces a surface warming influence of a bit less than 1.2C. Net positive feedback is required to reach the 2.5-4C you cite.

A net positive feedback that doesn't exist basd on satellite OLR & Radiative release measurements.

[WeatherRusty]

Well I think much better of you now Correct there are obviously other factors long term such as plate tectonics that alter circulations/heat gain/release in the oceans & thus the global air temperature, but this cannot explain most of the temperature variation. There may be other things, we just don't know.

Still, just over 250 million years ago CO2 was at 400-450ppm and the temp was about 10C warmer than today's for a time. Yet in the Ordovician Ice age, one of the coldest all time, CO2 was over 4000ppm, while much of the planet was covered in ice. Both temp and CO2 are on the same resolution, so there is no missing data.

And just to put into perspective...we are right now in the middle of the Neogene Ice Age with CO2 at the same PPM value it was when temps were over 8C warmer.

Obviously plate tectonics can explain away a small part of the variation/base value in temps, but not much.

And of course science has a counter argument which thwarts this seemingly rational skeptical demonstration that CO2 is irrelevant to geological temperature change.

If you don't trust the article, follow the peer-reviewed links: Skeptical Science

Another example: See Here

[BethesdaWX]

And of course science has a counter argument which thwarts this seemingly rational skeptical demonstration that CO2 is irrelevant to geological temperature change.

If you don't trust the article, follow the peer-reviewed links: Skeptical Science

Another example: See Here

Well there is a double standard...although not surprising in a blog post that is too consumed with refuting an argument that they unknowingly refute their own argument.

Not the Ordovician age...I am more referring to CO2 at 400-450ppm 275 million yrs ago and temps soaring near 10C above those of today on a 1-2 million yr running mean resolution, the variations in temperature even since this time cannot be caused by CO2. And...they can't have it both ways....regarding the faint sun "paradox", CO2 cannot be responsible for temperatures in that timeframe with 30% of solar influence removed, even at 6000ppm or more, we would still freeze, unless the strong solar wind and coinciding lessening of global cloud cover could enofre over 20W/m^2 RF...and that is indeed possible.

So they seemingly thwart their own argument. Yes indeed Solar activity was lower 500million yrs ago...obviously not by 30%, but it is like a scale, so if 4000ppm CO2 does not have the same effect with the reduced incoming solar radiation during the ordovician age, it cannot be responsible for the very high temperatures before or after the Ordovician ice age. Also their calculations of net insolation are off.

[OHSnow]

I'm not sure... I was kind of curious about this myself. I did come across an NCAR study which showed the last time CO2 was at 1000ppm, the world was 16C warmer than it currently is. Palm trees grew at the North Pole and crocodiles lived there. Large tracts of the earth were uninhabitable. And only small mammals lived.

I have no idea where that graph that Bethesda posted came from, but I don't think that's an accepted scientific reconstruction because it sharply disagrees with what NCAR researchers have uncovered.

[OHSnow]

Actually, now that I look a little closer at the Bethesda graph, it does show a good correlation between CO2 and temp in the recent eras. It's tougher to discern when you go back hundreds of millions of years like that graph does, because the lay of the continents, the orbit of the earth, the angle of the earth's axis, etc. also have varied markedly during that time. Bethesda's graph shows the last time CO2 was 1000 ppm was about 75 MYA and shows temps more than 8C above an "arbitrary 0" point. I call the zero point on the graph arbitrary, because if you look, it shows current temps are around 3C BELOW that zero point -- which means the graph shows temps were about 11C warmer than today when CO2 was last at 1000 ppm.

The NCAR study shows CO2 was at 1000 ppm around 30-40 million years ago and temps were 16C (29F) warmer than today. It was a peer-reviewed study and published in the journal Science.

http://content.usato...-ahead/1?csp=34

[BethesdaWX]

I'm not sure... I was kind of curious about this myself. I did come across an NCAR study which showed the last time CO2 was at 1000ppm, the world was 16C warmer than it currently is. Palm trees grew at the North Pole and crocodiles lived there. Large tracts of the earth were uninhabitable. And only small mammals lived.

I have no idea where that graph that Bethesda posted came from, but I don't think that's an accepted scientific reconstruction because it sharply disagrees with what NCAR researchers have uncovered.

Geocarb isn't an "accepted" source? lolz... Ok I'll call NASA "unaccepted" then

[WeatherRusty]

Actually, now that I look a little closer at the Bethesda graph, it does show a good correlation between CO2 and temp in the recent eras. It's tougher to discern when you go back hundreds of millions of years like that graph does, because the lay of the continents, the orbit of the earth, the angle of the earth's axis, etc. also have varied markedly during that time. Bethesda's graph shows the last time CO2 was 1000 ppm was about 75 MYA and shows temps more than 8C above an "arbitrary 0" point. I call the zero point on the graph arbitrary, because if you look, it shows current temps are around 3C BELOW that zero point -- which means the graph shows temps were about 11C warmer than today when CO2 was last at 1000 ppm.

The NCAR study shows CO2 was at 1000 ppm around 30-40 million years ago and temps were 16C (29F) warmer than today. It was a peer-reviewed study and published in the journal Science.

http://content.usato...-ahead/1?csp=34

Bethesda's graph is fine, no problem. It can be misused however as in the case of the Ordovician Ice age. The time resolution of the graphic is 10 million years while the ice age in question lasted only about 1 million years. The geological factors such as rock weathering and volcanism discussed in my sourced material above function on time scales of less than 10 million years.

[BethesdaWX]

Both CO2 and temperature are on the same resolution within the greocarb proxy, either 8M or 10M. But we have absolutely no CO2 proxy at a higher resolution to determine on CO2 indeed dropped off, and the "sucking" of CO2 from the atmosphere is barely even hypothesis.

Plate tectonics nor anything else we know of correlates/ can be responsible for the temperature variations in our Past, and even geologically recent future.

My previous post

And of course science has a counter argument which thwarts this seemingly rational skeptical demonstration that CO2 is irrelevant to geological temperature change.

If you don't trust the article, follow the peer-reviewed links: Skeptical Science

Another example: See Here

Well there is a double standard...although not surprising in a blog post that is too consumed with refuting an argument that they unknowingly refute their own argument.

Not the Ordovician age...I am more referring to CO2 at 400-450ppm 275 million yrs ago and temps soaring near 10C above those of today on a 1-2 million yr running

mean resolution, the variations in temperature even since this time cannot be caused by CO2. And...they can't have it both ways....regarding the faint sun "paradox", CO2 cannot be responsible for temperatures in that timeframe with 30% of solar influence removed, even at 6000ppm or more, we would still freeze, unless the strong solar wind and coinciding lessening of global cloud cover could enforce over 20W/m^2 RF...and that is indeed possible.

So they seemingly thwart their own argument. Yes indeed Solar activity was lower 500million yrs ago...obviously not by 30%, but it is like a scale, so if 4000ppm CO2 does not have the same effect with the reduced incoming solar radiation during the ordovician age, it cannot be responsible for the very high temperatures before or after the Ordovician ice age. Also their calculations of net insolation are off.