The latest climate forecasts made by several French scientific bodies reveal a rather alarming situation: current forecasts are a little too optimistic in relation to the reality of global warming.
According to models from the Pierre-Simon Laplace Institute (IPSL) and France’s National Meteorological Research Centre, our planet, in the worst-case scenario, could warm up to 6 or even 7°C by 2100.
However, at best, the situation is also alarming. If the planet achieves carbon neutrality by 2060, which is far from certain, then global warming will reach 1.9°C, as opposed to less than 1.5°C.
In an intermediate scenario, where the planet would reach carbon neutrality by 2080, the increase would be 2.6°C.
“None of our models allow us to consider an increase of temperature limited to 1.5°C, but other models predict this,” said Olivier Boucher, head of the climate modelling centre at CNRS, the French National Centre for Scientific Research.
In the scientific community, the 1.5°C target appears increasingly unattainable. And climatologists are now increasingly reluctant to mention a “business as usual” scenario, simply because it no longer exists.
But are those forecasts more reliable than previous ones?
The researchers answer in the affirmative: the data comes from a mixture of several models, meaning the number of variables is high. In total, these forecasts are the results of 500 million hours’ worth of calculations and 3,000 terabytes (TB) of data.
These include interactions between oceans and land, atmosphere, precipitation, anthropogenic and non-anthropogenic emissions, ice cycles, aerosols and more.
“We are trying to make the results more complex in order to achieve more realistic results,” explained David Salas y Melio, a climatologist at Meteo France.
The climatologist explained how the models work, highlighting that each model tries to translate anthropogenic events into climate data.
Emissions coming from greenhouse gases, aerosols and atmospheric particles, as well as land-use change have consequences on the energy received and lost by the planet, and must, therefore, be included in the calculations in accordance with socio-economic projections.
The more concrete consequences of these forecasts may seem complicated to imagine.
“We will have more heatwaves in France, to the point that these will be systematic from 2060 onwards; for rainfall, there is a severe decrease in precipitation for the Mediterranean basin, with an increase in instances of violent rainfall,” said Meteo France’s climatologist.
For Pascale Braconnot, paleoclimatologist, it is above all the speed induced by current climate change that makes its consequences difficult to understand.
The last time such a high concentration of CO2 was found in the atmosphere (now reaching 400 ppm), was during the Pliocene, 400 million years ago. However, as the expert pointed out, the temperature had only changed by 3°C and over several thousand years back then.
“We’ve never explored this so quickly before, and now we’re losing track. But what is quite certain is that soon, we may have 47°C every year, with everything burning,” Braconnot added.
In a recent 2040 weather report, Meteo France considered longer droughts, lower rainfall in France that would make certain agricultural practices impossible, an increase in forest fires and more violent rainfall like the ones in Cévennes region in the south of France.
First published by EURACTIV, 18 September 2019