The atmosphere is like a swimming pool we’ve been pouring CO2 into for the past 200 years.
Speculation abounds as to whether the present confinement can ‘save’ us from global warming.
It is true that, with so much of the economy on hold and so many cars and planes parked up, a lot less CO2 than usual is being emitted. According to the International Energy Agency, emissions for 2020 could drop as much as 10% compared to those in 2019. Could this respite ease global warming?
The atmosphere is like a swimming pool we’ve been pouring CO2 into for the past 200 years. This pool is accumulating more and more CO2 and, therefore, the temperature is rising (1). After 200 years of emissions, 46% of CO2 in the atmosphere is “ours” - a direct result of human activity.
In 2020, after two centuries of an open tap running in more and more CO2, we are barely stopping the flow… and that’s just for this year.
Obviously turning off the tap by 10% for a year is not going to make much difference to the amount of CO2 already in the swimming pool. And it will not get rid of any more CO2, only the rate at which it is filling up will change - marginally(2).
Without going into the technicalities of measurement, it is easy to chart this.
The amount of CO2 in the atmosphere is measured in parts per million (ppm)(3). Nowadays, the concentration of CO2 in the atmosphere is 414 ppm. In 1800 it was 280 ppm. This increase has come from us.
How do we link this with our emissions? In 2019 we produced about 36 billion tonnes of CO2. That pushed the level of CO2 in the atmosphere from 410 ppm to 413 ppm. In a normal year, that number would be 416 ppm by December 2020. With a 10% reduction, by the end of 2020 it will be 415.7 Instead of 416. What a reduction!
In the context of 200 years, this momentary stop is not going to alleviate climate change very much. However, it does allow us an idea of the magnitude of the necessary changes that need to take place to stop the tap completely, to have zero emissions.
Antoine Bret, Professor in Physics at the Castilla-La Mancha Univerity (Spain).
1. To convince ourselves we just need to compare levels of concentration of CO2 from 1,000 years ago with those that were linked just to human action. The results are clear. See A. Bret, The Energy-Climate Continuum: Lessons from Basic Science and History, Springer (2014), chapter 4.
2. To reduce the water in the swimming pool, turning off the tap is not enough. We must pull the plug.
2. It is like a percentage but substituting ‘per cent’ by ‘per million’. When we say that a gas represents ‘1ppm’ of the atmosphere, it means that there is 1 litre of gas per 1 million litres of atmosphere.