Comment on Recent Record-Breaking CO2 Concentrations

Robert MonroeMeasurement Notes


Levels exceeded 409 parts per million for the first time in recorded history this month

We are now witnessing the fastest growth rates of the entire record of CO2 measurements. This record-breaking growth is an expected consequence of the near record-breaking fossil fuel usage combined with the largest El Niño event in several decades.

The very recent bump up in CO2 levels recorded at Mauna Loa Observatory is not entirely unexpected because there is often significant uptick in CO2 near the beginning of April before concentrations peak in May. This bump presumably reflects the fact that soils start to warm well before vegetation greens up in spring. The soil warming allows CO2 to be emitted as organic matter such as compost decomposes. In a matter of weeks this soil emission will be offset by photosynthetic uptake, as the vegetation starts to turn on.

The bump is also getting a boost from the El Niño phenomenon, which is causing additional anomalous emissions from tropical forests through drought and fires.

Still, the levels last week were a bit higher, maybe by a part per million or two, than I would have projected even taking El Niño into account.  I’m frankly not sure what is causing this, but I would not expect it reflects anything other than an unusual blob of air that temporarily settled over the central Pacific. It is clear that other sites around the world where CO2 is meansured are showing the El Niño boost, but I haven’t consulted the most recent data to see if they show anything special over the last few weeks.  The bump last week was seen on both the NOAA and Scripps analyzers at Mauna Loa.

The larger story remains that Earth hasn’t seen levels this high in at least several million years.  Unless fossil fuel emissions soon drop significantly below current levels, I expect CO2 levels will surpass the 450 mark by around 2035 and the 500 mark around 2065.

Barring some major breakthrough that allows excess CO2 to be scrubbed from the air, it is currently an impossibility for us to reach the target of 350 ppm that many consider the threshold of dangerous climate change effects.  I expect it will take at least 1,000 years before CO2 drops again below 350 ppm.

– Ralph Keeling, director of Scripps CO2 Group