What if the climate situation was even more dramatic than we thought? What if the +1.5°C mark had in fact already been crossed a decade ago and warming had started much earlier than we thought? Here are the findings of a new study that, while controversial, reinforces that it is high time to act.
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Here is a new study that is causing a stir within the community of climatologistsclimatologists. Published in review Nature climate change, an article suggests that we have in fact already exceeded +1.5°C compared to the pre-industrial era. And for good reason: the climate of the pre-industrial era would have been colder and global warming associated with human activities would have started much earlier than we thought!
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Needless to say, this hypothesis is not unanimous. However, it is necessary to consider it, as it could have strong implications. The most important would be that we would actually have even less time than expected to try to turn things around.
Sponges: formidable climatic archives
It was by studying marine sponges from the Caribbean that a team of researchers came to this conclusion. Sponges are in fact sensitive to several environmental parameters, such as water temperature, acidity or even the CO level.2 atmospheric, variations of which influence their growth. These marine organisms have lived for a very long time, several hundred years, which makes them real climatic archives for studying the period of the revolutionperiod of the revolution industrial.
The analysis of the sponges thus made it possible to reconstruct the evolution of the climate for the 1800s. And the results turned out to be very different from what is currently accepted by the scientific community. The study reveals that temperatures around the middle of the 19th centurye century would have been 1°C lower than previously thought and that the start of global warming linked to broadcastsbroadcasts of greenhouse gases would have started around 80 years earlier than current models suggest! And that makes a huge difference.
Warming from 1860, the +1.5°C mark already crossed 10 years ago?
The models accepted by the IPCC (Intergovernmental Panel on Climate ChangeTHE Intergovernmental Panel on Climate ChangeIntergovernmental Panel on Climate Change) indeed propose that human activity began to impact the earth’s climate after the year 1900. They base this on measurements of ocean temperatures acquired by boat at the end of the 19th century.e century. Values which, according to the authors of the study, could be biased by the methodology used at the time, and would therefore be much less precise than the set of data obtained by the study of sponges. To support their observations of an earlier start to global warming, the researchers also point out that greenhouse gas emissions began well before 1900, from the industrial revolution which took place in the early 1800s.
In detail, scientists studied the fine deposits of calciumcalcium and of strontiumstrontium marking the skeleton of sponges, based on the principle that warming water leads to an increase in strontium deposition compared to calcium, and vice versa for cooling. And their results show that global warming would have started as early as 1860. Adding to this the fact that temperatures at the start of the 1800s would have been lower than previously thought, the researchers deduce that we would in fact have passed the stage of +1.5°C for a decade, and that we are currently at an increase of +1.7°C compared to the pre-industrial era. We would therefore be late in our effort to limit global warming, which could therefore accelerate even more than we had predicted in the future.
A study that sparks debate
As said above, however, these results are far from consensus. The first argument to be made against this study is the fact that it is not based on data acquired equally distributed across the globe, unlike temperature recordings made by boat. Indeed, the sponges only come from a very specific region and it remains possible that the deduced temperature values could in reality only represent cyclical variations linked to the El Niño and La Nina phenomena. In short, the debate remains open.
It therefore seems wise to remain cautious regarding the results provided by this new study. But all scientists agree on one point: whatever happens, action is urgently needed.