2017 - The highest CO2 for millions of years

As 2017 draws to a close it is set to be 2nd hottest year on record.  With an annual average of around 407 ppm, the concentration of CO2 in the atmosphere was also a record breaker - in fact its the highest its been since the Pliocene around 2.5 to 3 million years ago (see figure below)

Atmospheric CO2 from AD 1000 to AD 2017 (right) from a mix of ice core records and measuresments of the astmosphere from Mauna Lao.  On the left is a compilation of ice core CO2 (red) and boron isotope based estimates (blue).  Note the age scales are different but y-axis is the same. See this document for references.

Here @theFosterlab we use the boron pH proxy to reconstruct CO2 in the geological past beyond the reach of the ice core record (the last 800 thousand years, kyr). What the figure above shows is a compilation of the latest boron data including some data we published this year compared to actual measuresments of the atmosphere and bubbles of ancient atmosphere trapped in the ice cores.  The first time we made a plot like this was a couple of years ago when CO2 was still just below 400 ppm.  Given the relentless rise in atmospheric CO2 it looks like it will be around 20 years or so until even the highest values in the last 3 million years are exceeded.  Pliocene - here we come!

The R-script to make the above figure can be downloaded here, the data here and the relevent references here. If you are interested in coming and working with us to reconstruct CO2 in the past we have several fully funded PhD studentships on offer (see here).