# "You are Here." Perspective on 400 ppm CO2 in the Atmosphere

Just to provide a little perspective, here are the latest data and a graph on atmospheric carbon dioxide, with information going back 800,000 years. Present day is on the far right ("You are here"). The data come from the atmospheric monitoring program of the Scripps Institution of Oceanography, La Jolla, California and can be found here.

I've also noted the approximate period when homo sapiens first appeared -- thought to be around 150,000 to 200,000 years ago. During all human existence, pre-industrial levels of CO2 never exceeded around 275 parts per million (ppm). They touched 400 ppm this year.

As this graph so vividly depicts, humans have now increased the atmospheric concentration of carbon dioxide (and other greenhouse gases) to levels we've never before experienced.

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"... graph so vividly depicts ..."

It looks much nicer if you let the graph start at zero not at 150 ppm C02.

Yes, that is always preferable, graphically. Thanks. This image was taken from the Scripps (Keeling Curve) site and I could not rescale the axes.

If I read that chart correctly, it would seem that there is about .02% more CO2 in the atmosphere than their used to be.

No. There is 50% more CO2 in the atmosphere than in the past. CO2 is a small overall fraction (400 parts per million), but this is irrelevant -- the question is its influence on the climate, and we now understand that even small changes in the total amount (like small changes in the concentration of arsenic in your drinking water, as another example) can have a BIG effect. Don't focus on the "small fraction" -- focus on its effect.

Possibly add a squiggle (denoting discontinuity) near the bottom of left- and right-hand y-axes & block out the 15 in 150?

By Paul Hawley (not verified) on 05 Dec 2013 #permalink

The graph is fine as it is. Re-scaling to show the 0ppm line would compress the graph and make the detail of the line much mor difficult to examine. As well, it would simply add more featureless blue below 150ppm which would not add any information.

By Paul Andreassen (not verified) on 05 Dec 2013 #permalink

I'm curious what the accuracy is between the multiple datasets used. The peak at the end is from the current monitoring which is far more specific and accurate than the ice core samples. I'm curious if this is accurately comparing apples to apples.

You can go to the original research analyses for these data (ice cores from Antarctica), which include error bars, but the estimate range of errors is tiny compared to the 50% increase from industrial activities over the past 130 years or so. Climatologists consider this apples to apples... with appropriate caveats.

Sorry to bother you and thank you for responding. Do you have a specific link or study that you are referring too?

Also, if you don't mind. Would you say that rather than focusing on things like the oil and gas industry we, as a society, should be focusing on getting rid of coal as a power generation source, or at least mandating so-called "clean coal". Wouldn't it be better to go after the low hanging fruit (so to speak) first?

You can search for the research papers on the Antarctic ice cores at Google Scholar -- there are many papers there and I'm not sure (without looking them up) which have the best information on the variance and error bars associated with their estimates.

As for the policy question, I don't raise specific policy issues in this post -- I was hoping just to highlight the data and information on atmospheric CO2 in context. I guess one could safely argue (without much controversy) for "low-hanging fruit" as a priority for just about any policy!

Really appreciate your response. Thank you very much!

Andrew mentioned low hanging fruit. Thats exactly what france did. Now they only have 10% or so of their electricity generated by fossil fuels. 75% or so of electricity in france is nuclear.

they did it with older nuclear plant designs, what more if we use much much safer and cleaner 2013 designs like thorium and standing wave reactors. Is nuclear power dangerous? Considering that 3 mile island melted down and it was contained, what more for newer designs that could not melt down even if you wanted to.

Regarding Hans's comment about the graph and starting at 0 ppm - might I suggest getting around the limitation of rescaling that graph, by embedding it within a vertically larger 'frame', where the bottom of the frame represents 0ppm, then properly space the graph in the top portion of the frame.

That way the original graph doesn't need to be fiddled with and you can still represent the 0 line.

By citizenschallenge (not verified) on 06 Dec 2013 #permalink

Nuclear fission is another fossil-fuel analogue. If it replaced all other non-renewables, we'd run out of fissible material in less than 100 years. Plus have an enormous waste problem. And since a rich uranium ore has a tonne of tailings for a gram of U, the mining makes a huge mess.

Why start 800k years ago? Is ice core data less reliable before then? This chart implies CO2 has not been at 400ppm before, which is not the case. It seems like a rather arbitrary date. If that question worries me think what the denialists will say.

Good questions: first, ice core data are reliable to 800k years, but not much beyond. There are other paleoclimatic data that give us insights into earlier atmospheric composition, and yes, CO2 levels millions of years ago were higher. But those conditions were so different from today that they provide no guidance for humans. Furthermore, since humanity developed only in the last 100,000 years or so, this 800,000 year record is certainly sufficient to help us understand the most relevant part of our climate history. As for what "denialists" will say -- there is nothing that convinces them of anything. That is why they are "denialists" rather than real skeptics.