Lake El'gygytgyn - evidence of Co2-warming link or evidence against it?

[Papa bull]

For months, now, there has been buzz about Lake El'gygytgyn and the findings of a dig there that indicate the last time the Earth had an atmosphere of 400ppm CO2, the temperature was 16 degrees warmer and the arctic was covered with pine trees instead of ice.

And here we are today with the same Co2 level and vastly different temperatures. I think some very serious consideration needs to be given to why the temperatures are so different if Co2 is the direct link to warming. We also need to ask ourselves how the Co2 level got to 400 ppm without man causing it to happen. Surely, that would be impossible without our 2-3 percent contribution to overall Co2 emissions, right?

 

[rocket88]

I think it definitely points toward some connection of CO2 and warmer temperatures, though it may not be as direct as may have been thought.

The problem with evidence like that is that it can be read either way depending on what you want it to say. If you want it to say that there's a link between CO2 and higher temperatures, you can see it that way. Conversely, if you want it to say that there is no link, it's also possible to see it that way since temps are lower now than they were then.

I usually don't call myself a climate change skeptic, because that would lump me in with people who take it as an article of faith that it's not happening. I don't think that there's enough evidence to say one way or the other. I tend to lean toward doing things that reduce pollution, because whether the climate is warming because of it or not, it's certainly more pleasant to be able to breathe. Flat out denying is the kind of thinking that contributes to the air quality (or lack thereof) in Beijing.

In the end, this is one lake, measuring two variables. Not enough evidence to tip it either way, IMO.

 

[Deuce]

For months, now, there has been buzz about Lake El'gygytgyn and the findings of a dig there that indicate the last time the Earth had an atmosphere of 400ppm CO2, the temperature was 16 degrees warmer and the arctic was covered with pine trees instead of ice.

And here we are today with the same Co2 level and vastly different temperatures. I think some very serious consideration needs to be given to why the temperatures are so different if Co2 is the direct link to warming. We also need to ask ourselves how the Co2 level got to 400 ppm without man causing it to happen. Surely, that would be impossible without our 2-3 percent contribution to overall Co2 emissions, right?

Couple things:

1) There are many different variables involved in temperature. CO2 is just one of them. Treating it as the only variable would lead one to conclude CO2 doesn't affect temperature at all. Of course, someone might conclude the sun doesn't drive temperature either, because way back in the day the earth was warmer despite lower solar output. But of course the sun affects temperature, it's just that other things also affect temperature.

2) "2-3% contribution to overall Co@ emissions" is misleading. We're only a small portion of the total emissions, but we're a very large portion of the net emissions. This is because nature absorbs vast quantities of CO2 every year as plants grow. However, there's no equivalent "CO2 sink" caused by human activity that offsets the majority of our emissions. To put it another way, despite the vast output of CO2 by nature, CO2 concentrations stayed relatively stable for thousands of years prior to our burning fossil fuels. There was a balance between emissions and absorptions, and now it clearly isn't balanced.

CO2 does change naturally for various reasons. This time, however, it was us. This is easily proven. Heck, you can even tell a difference between CO2 from natural sources and CO2 from the burning of fossil fuels - different isotope ratios. CO2 in the atmosphere has shifted its isotope ratio towards the fossil fuel ratio, right about in proportion to what you'd expect from our contribution to the atmosphere.