By Anders Lorenzen

CO2 is a long-lived greenhouse gas and the main culprit of climate change. But even if we stopped all emissions tomorrow, the CO2 we have emitted already would still stay in the atmosphere for a long time, between 300 to 1,000 years, continuing to cause damage.

But still, we continue to emit CO2 and other greenhouse gasses (GHG) unabated and, as a result, the CO2 in the atmosphere continues to build up. 

Records continue to be set

The National Oceanic and Atmospheric Administration’s (NOAA), a US government agency, Mauna Loa Observatory in Hawaii has announced that annual readings stood at 414.4 parts per million (ppm) during 2020. This represents a rise of over 2% compared to 2019 and was it not for global lockdowns due to the COVID-19 pandemic that amount would have been even higher. In addition, in March this year, it averaged 417.14 PPM, a new record high. 

This year, atmospheric CO2 will spend several weeks at levels more than 50% higher than when humanity began large-scale burning of fossil fuels in the industrial revolution in the late 18th Century. In addition, a 50% increase on this (417 ppm) is predicted to be exceeded by the monthly average values in April, May and June. Daily concentrations above this level were measured at Mauna Loa during May 2020, but 2021 will be the first year with these levels are exceeded consecutively for longer than a few days.

Pieter Tans, a senior scientist at NOAA’s Global Monitoring Laboratory, said that without the economic slowdown, the 2020 increase would have been the highest on record. 

As high as 3.6 million years ago

It is important to understand just how much our planet has warmed since the beginning of the industrial age. The atmospheric burden of CO2 is now comparable to where it was during the Mid-Pliocene Warm Period around 3.6 million years ago when concentrations of carbon dioxide ranged from about 380 to 450 ppm. During that time sea level was about 23 metres higher than today.

Colm Sweeney, assistant deputy director of the Global Monitoring Lab, said no matter how fast we reduce emissions we still need to deal with CO2 concentration in the atmosphere: “Human activity is driving climate change. If we want to mitigate the worst impacts, it’s going to take a deliberate focus on reducing fossil fuels emissions to near zero – and even then we’ll need to look for ways to further remove greenhouse gasses from the atmosphere.”

Prof Simon Lewis, from University College London, explained that the speed at which humanity is affecting the atmosphere is staggering.  It took over 200 years to increase the amount of CO2 in the atmosphere by 25%, and just 30 years to reach 50% above pre-industrial levels. 

But experts say there is still time to change course if we act now, but it will require ambition on a scale never before seen.