Unabated fossil fuel use has the potential to push the Earth's climate into a state not seen in at least half a billion years, according to a study published in Nature Communications this week. The new long-term atmospheric CO2 compilation shows that future potential atmospheric CO2 concentrations could be higher than anything witnessed in the geological record.
The strength of the Sun and the amount of radiation it emits has increased quite considerably over time, yet our planet's climate has remained relatively stable, supporting life for millions of years. To reconcile this enigma, it is assumed that over geological timescales, greenhouse gases, which have warming effects, must have gradually decreased in line with the Sun's increasing output.
In order to better understand the role of the greenhouse effect in Earth’s long-term climate evolution, Gavin Foster and colleagues compile approximately 1,500 discrete estimates of atmospheric CO2 from 112 published studies covering the past 420 million years. The new compilation shows that the climate stability was indeed the result of a long-term decline in atmospheric CO2 that approximately cancelled out the increase in solar radiation output. However, the authors show that, based on current business-as-usual CO2 emission scenarios, CO2 levels by the end of this century could reach values not experienced for 50 million years. According to this new dataset, should fossil fuels be exhausted under such a scenario, by the year 2400 atmospheric CO2 could rise to levels not witnessed within at least the past 420 million years.