Global warming: UN climate conference: Too much energy

Not every extreme weather event makes it into the media anymore. Most people will remember news about the heatwave in the US that lasted up to a month. Or the floods that washed away entire districts of Derna in Libya. Hurricane Otis, which caused death and destruction in Acapulco in late October, was more of a side note, although it presented a whole new threat: It went from a tropical cyclone to a Category 5 hurricane in just one day – an example of excess of energy in the climate system.

Next week, the representatives of the UN member states will meet for the UN Climate Change Conference in Dubai and although the current year is not over yet, there is no doubt that it was a record year: »We can say with some certainty that 2023 will be “It will be the warmest year on record, currently 1.43 degrees Celsius above the pre-industrial average,” said Samantha Burgess, deputy director of the climate change service for the European Earth observation system Copernicus. And even the two-degree limit was broken for the first time for one day on November 17th, according to Copernicus.

Everyone is now affected

If you look not at the calendar year, but at the past twelve months, the global average was around 1.3 degrees Celsius above pre-industrial levels, according to an analysis by the non-profit news organization Climate Central in Princeton. People all over the planet were affected: in 170 countries, temperatures were above the average of the last 30 years, and 99 percent of humanity felt this.

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Higher temperatures and therefore more frequent heat waves are a direct consequence of global warming, which can easily be scientifically attributed to man-made greenhouse gas emissions. The more greenhouse gases there are in the earth’s atmosphere, the greater the greenhouse effect. And greenhouse gas concentrations have increased again in 2022, as the World Meteorological Organization (WMO) announced in mid-November. 417.9 ppm (parts per million) CO₂ On average, the Earth’s atmosphere in 2022 contained 2.2 ppm more than in the previous year and 150 percent of the carbon dioxide content of 1750. But the proportions of the greenhouse gases methane and nitrous oxide also continued to rise.

Carbon dioxide is considered the biggest problem because it breaks down the slowest, meaning the planet would remain at high temperatures for several decades if the goal of net-zero emissions were achieved. In Earth’s history, CO₂Concentrations in the atmosphere were last similar to today three to five million years ago, according to the WMO, and temperatures on Earth were once two to three degrees warmer and sea levels were ten to 20 meters higher.

The heat as a silent killer

»It will be obvious, even to laypeople, that heat extremes will increase in a warming world. But it may be unexpected by how much: Monthly heat extremes that were three standard deviations above average during the baseline period 1951 to 1980 have already increased 90-fold in frequency across the global land area,” write climate researcher Giorgia Di Capua and Stefan Rahmstorf in a paper published in the journal “Environmental Research Letters” in October Contribution. Prolonged heat is a “silent killer”. Unlike the victims of storms and floods, heat deaths are not immediately visible all at once. According to Climate Central, a quarter of the world’s population has been affected by health-threatening heatwaves that lasted at least five days in the past twelve months.

The fact that there is more and more energy in the earth’s system was also shown by the sea temperatures, which have climbed to unprecedented heights since the beginning of May and have remained around 0.2 degrees above previous record values ​​for months. However, this year’s marine heat waves are just the beginning. In a world that is two degrees warmer, they would be 23 times more common than without global warming, according to Di Capua and Rahmstorf.

Increased land and sea temperatures promote evaporation and thus increasingly extreme heavy rain, such as that which fell in the Mediterranean region, particularly in Libya, with the low pressure system “Daniel” in September. “An extreme event like that observed over Libya is up to 50 times more likely and up to 50 percent more intense compared to a climate that is 1.2 degrees Celsius cooler,” found the research association World Weather Attribution, which studies the issue The contribution of climate change to extreme weather events. It seems logical that the amount of rain is increasing, since the atmosphere can absorb seven percent more moisture for every degree of warming. However, the additional amounts of precipitation are not distributed evenly, half of them fall on just six days a year, as climate researchers Angeline Pendergrass and Reto Knutti explained in 2018.

However, there are also regions that are becoming drier. One of these could be the Amazon region, which is suffering from the worst drought since weather records began there 120 years ago. A tipping point could now have been reached, which is not only due to man-made climate change, but also to deforestation. A special feature of the Amazon is that the rain in the western area comes from the forest’s own evaporation in the eastern areas. Scientists suspect that if deforestation reaches 20 to 25 percent, the rainforest could turn into a savanna, with the climate also having a negative impact. The greater the warming, the less deforestation the system can cope with. A recent study by researchers Nils Bochow and Niklas Boers from the Potsdam Institute for Climate Impact Research made it clear that a change in vegetation in the Amazon would change the precipitation patterns of the entire continent.

»We are entering unknown territory«

It is fairly certain that tipping points and feedback effects exist in the climate system, but it remains uncertain exactly when they will occur. In a report on the state of the climate in 2023, international scientists led by lead authors William J. Ripple and Christopher Wolf would like to see a special report from the IPCC on feedbacks and tipping points in the climate system. In that published in “BioScience”. Message it says: “We are entering uncharted territory when it comes to the climate crisis, a situation that no one in the history of humanity has ever experienced first hand.” are shocked.”

Di Capua and Rahmstorf also note that extreme weather events are increasing at a rate that exceeds previous expectations derived from thermodynamic laws. They therefore emphasize how important it is to better research dynamic effects in the climate system. These include changes in the jet stream or the North Atlantic Current. Large bulges in the jet stream can promote heat waves that occur at the same time – and thus endanger crops in several regions. And a weakening of the North Atlantic Current – and thus the Gulf Stream, which ensures a mild climate in Europe – and ultimately its collapse are among the possible climate consequences that are still being intensively researched.

Since 2012, climate change has been evident on every day of weather observation, write Di Capua and Rahmstorf: “There are no longer any days on earth on which the global weather does not differ significantly from what it would be without human influence.”

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