Climate change: The era of bad surprises
Not just a warmer world, but absolute chaos. Two recent reports show how unpredictable climate change is shaping the future, comments Lars Fischer.
© DNY59 / Getty Images / iStock (details)
Global average daily temperatures in 2023 were often well above previous record values, especially in the second half of the year.
There are two new findings that transform the climate crisis from an abstract concept into a tangible and present reality. One of them is of symbolic value: for the first time, according to the European Union's Copernicus Earth Observation Programme The world will be 1.5 degrees warmer for a full year above the reference period in the 19th century – The brand that made history as a Paris climate target. The other explains the dramatic consequences that lie behind these seemingly small numbers. A study in the journal Science Advances suggests thisthat Europe's climate will soon change radically once the large-scale ocean currents in the Atlantic collapse.
Both initially sound like now-common generic warnings about climate change. The reported global temperature anomaly of 1.52° represents only one annual value; On the other hand, the currency of climate change is average values over decades. And the news that the North Atlantic Circulation (AMOC) and the Gulf Stream, which provides us with heat, may overturn every two or three years. But the situation has changed.
One reason for this is the unusual accumulation of extreme weather events in 2023. Unusual heat waves on all continents, floods in the Mediterranean, and devastating hurricanes such as Freddy in East Africa, Otis in Mexico, and Mocha in Myanmar, are just part of the list. long. A disaster that is often overlooked in the global political drama. A warmer world is a more dangerous world, with extreme weather events often exceeding levels for which human infrastructure and society are unprepared.
The other reason is that some experts suspect Current temperature records cannot be explained by a known warming trend and natural fluctuations. It is possible, and this would be a really bad surprise, that there is a previously unknown effect driving global temperatures to rise. This is supported primarily by the extent and duration of the anomaly. Every month since June has been warmer on record, sometimes by a noticeable margin. December was half a degree warmer than the previous record – a massive range relative to the global average.
Chaos is on the horizon
What is particularly astonishing and worrying is that the world's oceans have suddenly become very warm. In the second half of 2023, the average temperature was more than 0.3 degrees higher than in 2022. This record is very worrying because, on the one hand, the oceans react much weaker to short fluctuations, and on the other hand, because She plays a major role in the play The Weather. It also shows that we still understand very little about what is happening in the world's oceans and how quickly they are actually changing.
So it makes sense that a new “Science” study would now make the known scenario of the collapse of the North Atlantic Current system more, above all, clearer. closer Than was usually the case before. This study is the first to reproduce the AMOC collapse in a high-resolution global climate modelHe confirms that the danger of collapse is real. Fresh water from melting glaciers and increased precipitation gradually weakens the AMOC until it suddenly collapses completely within a few decades. According to the study, this would lead to unprecedented climate chaos in Europe – but also around the world.
It is still not entirely clear when this will happen, but observational data from the South Atlantic suggest that the AMOC is currently moving towards this tipping point. Until now, a collapse of the ocean circulation in the 21st century has been highly unlikely. However, this assumption was based on models that do not correctly reflect the critical factor – changes in salinity.
This emerging scenario of an imminent radical transformation of the world's oceans is conclusively confirmed by the unexpectedly strong increase in global temperature above the symbolic threshold of 1.5 degrees. Combined with the devastating sequence of extreme weather events and already visible changes in the ocean over the past 12 months, these two snapshots represent the clearest warning sign yet of an unthinkable future. The era of climate change is not only an era of rising temperatures, but an era of bad surprises.
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