The Earth in a bottle - CO2 games on my kitchen bench

UPDATE 02/09/2016: it has come to my attention (thanks Katharine Hayhoe) that the experiment below was first performed by Mrs. Eunice Foote and reported to the American Association of Science in 1856! here is the report (thanks Gavin Schmidt for the link).  She even foretold the future "An atmospheric of [carbonic acid gas - CO2] would give our earth a high temperature...".

John Tyndall was perhaps the first scientist to recognise the radiative properties of CO2 in 1859. In recent years the study of the role of CO2 and global warming has moved beyond the physics of CO2 and more frequently we hear discussions of record breaking temperatures or equilibrium climate sensitivity in state of the art computer models.  I think it’s quite refreshing though to go back to basics and remember that the theory of global warming is: 1. Over 150 years old; 2. rooted in simple physics (CO2 present in the atmosphere  absorbs long-wave radiation that it later releases warming the air a bit). 

There are quite a few experiments that you can do at home to demonstrate this underlying physics (e.g. here). Over the last couple of weeks I’ve been gathering the necessary equipment to do one of these simple experiments and this weekend I thought I’d give it go.

Here is a picture of my “experimental set-up” on my kitchen bench

It consisted of two Infrared heat lamps (200W), two plastic drinks bottles, to silicone rubber stoppers, two digital fridge thermometers (with some play-doh to seal the hole in the stoppers),  and the all-important CO2 in a can.   

I filled one of the bottles with CO2 (the one on the left in the picture of above) and turned on the lamps.   Entirely consistent with our understanding of the physical properties of CO2, the extra CO2 in this bottle absorbed more of the infrared radiation from the lamp and subsequently released it warming the bottle more than the one with just air in it.

It doesn’t take someone with a Nobel prize to draw parallels between what is happening in this bottle and what is currently happening to the Earth! So remember: the theory of global warming is quite simple and the question should not be “are we warming?” but “how hot is it going to get?”

Decent into the Icehouse Teaser Trailer

Heres a short video introducing a recent project from The Foster Lab that is shortly coming to an end.  Tune in soon to find out more and take a look at some of our recent publictions for some of the latest results:

Lunt, D.J., Farnsworth, A., Loptson, C., Foster, G.L., Markwick, P., O'Brien, C.L., Pancost, R.D., Robinson, S.A., Wrobel, N. (2015) Palaeogeographic controls on climate and proxy interpretation Climate of the Past Discussion 11, 5683-5725,  doi:10.5194/cpd-11-5683-2015

Inglis, Gordon N., Farnsworth, Alexander, Lunt, Daniel, Foster, Gavin L., Hollis, Christopher J., Pagani, Mark, Jardine, Phillip E., Pearson, Paul N., Markwick, Paul, Galsworthy, Amanda M. J., Raynham, Lauren, Taylor, Kyle. W. R. and Pancost, Richard D. (2015) Descent toward the Icehouse: Eocene sea surface cooling inferred from GDGT distributions. Paleoceanography, Early View (doi:10.1002/2014PA002723). click here for data.

 

Is this the last year below 400 ppm?

The average CO2 value for October 2015 was 398.29 ppm.  Ralph Keeling (and he should know) thinks this month (November) may be the last time that CO2 will be below 400 ppm again in his life time (or for that matter, anyone’s lifetime).  His post here discusses why he thinks this is.

CO2 compilation from ice core (in red; Bereiter et al., 2015, GRL, doi: 10.1002/2014GL061957) and boron isotopes in blue (Hoenisch et al., 2009, Science,  doi: 10.1126/science.1171477 and Martinez-Boti et al., 2015, Nature, doi:10.1038/nature14145)

CO2 compilation from ice core (in red; Bereiter et al., 2015, GRL, doi: 10.1002/2014GL061957) and boron isotopes in blue (Hoenisch et al., 2009, Science,  doi: 10.1126/science.1171477 and Martinez-Boti et al., 2015, Nature, doi:10.1038/nature14145)

400 ppm is of course only a symbolic threshold but as the guys at Mountain Beltway suggest it should give us reason to pause and contemplate what a momentous change it is in terms of the planet.  Something we do in thefosterlab is reconstruct CO2 in the geological past using the boron isotope proxy and this allows a little bit more perspective on this issue.  The image above is a plot compiling the state of the art when it comes to CO2 over the last 3 million years or so, including some data for the Pliocene (2.6 to 5.3 Million years ago that we published this year in Nature).  What is clear is that the last time CO2 was 400 ppm was around 2.5 to 3 million years ago.  The world was a different place back then – global temperatures around 3 C warmer than the pre-industrial and sea-levels were around 20 m higher (due to retreat/collapse of the West Antarctic and Greenland ice sheets).  With global temperatures likely to top 1 C above pre-industrial levels this year and CO2 now likely to stay above 400 pppm it appears we are well on the way to a Pliocene-like future.