Climate crisis – livelihoods at risk

Shortly before this year’s UN climate conference in the Azerbaijani capital Baku, the climate system is sending another loud warning after devastating hurricanes in the Caribbean and the USA and no less destructive typhoons in southern China and Southeast Asia: Spain’s Mediterranean coast was repeatedly attacked last week and at the beginning of this week torrential rainfall and catastrophic flooding. Over 200 deaths and massive destruction of houses and infrastructure have been reported there – one of countless similar disasters that have occurred on almost every continent this year.

The climate crisis is about to fully unfold. It is almost certain that it is already clear two months before the end of the year that 2024 will set another heat record. According to the EU climate program Copernicus, the last twelve months from November 2023 to October 2024 were 1.62 degrees Celsius too warm if the decades at the end of the 19th century are used as a benchmark. According to Copernicus, by 2024 the 1.5 degree limit will almost certainly be completely exceeded throughout the year.

The greenhouse effect has been increasing since 1990
Drive on

In the comparable period at the end of the 19th century, almost no petroleum products were burned and the consumption of coal was minimal compared to today. So humans had the CO₂-Atmosphere content has not yet changed on a large scale. Today things look completely different. Since pre-industrial times, CO₂-Concentration in the atmosphere increased from 280 to 420 millionths of a volume, as the World Meteorological Organization (WMO) announced in Geneva at the end of October. In the last 20 years alone, the increase was around ten percent, making it faster than ever before in the more than 200,000-year history of humanity. At the same time, according to the WMO, the influence of greenhouse gases on the Earth’s radiation balance, i.e. the effect that leads to warming, has increased by 50 percent since 1990.

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Of course, this only refers to the additional gases released by human activities. There are also greenhouse gases from natural processes in the atmosphere that make the global climate an average of 33 degrees Celsius warmer. Without these, life in the form and richness as we know it would hardly be possible. In fact, there was a phase over 600 million years ago when our planet was completely iced over because there was hardly any CO₂ existed in the atmosphere. British researchers have recently succeeded in precisely dating this ice epoch, but that is another story.

Once-in-a-century events are becoming the new normal

We now have the opposite problem. But how do we actually know that the severe storms of the last few months and years are related to climate change? A first indication is that many of them represent events of the century. That is, in the climate we have known for the last 150 years, they are so rare that they would only occur once every 100 years or even less. But the fact that they are occurring more frequently is a sign that things are changing. What was extreme 30 or 40 years ago is becoming the new normal.

In addition, the physical connection between warming on the one hand and increased precipitation and storms on the other is relatively simple: the seas and air are getting warmer. On the one hand, this allows more water to evaporate and, in the subtropics, conditions under which tropical cyclones such as hurricanes and typhoons can arise are more common. On the other hand, the warmer air can absorb more water. Significantly more, because the ratio is exponential. For every degree Celsius, the air’s absorption capacity increases by seven percent. The consequences are greater amounts of precipitation and stronger storms. This is because water vapor condenses into clouds when it rises in eddies or mountains, releasing energy in the process. This in turn heats the surrounding air, increasing its buoyancy. Warmer air is lighter than cooler air and therefore rises – an essential principle that underlies all winds and storms.

Heat waves cause the most deaths

Finally, there is a third way to determine the connection between man-made climate change and severe weather events. So-called attribution research determines how often a certain event would occur in a world without additional greenhouse gases. To do this, climate models are fed with pre-industrial conditions and calculated very often and for a long time, which was only made possible by the enormous computing power available today. By evaluating the weather data simulated in this way and comparing it with real events, it can then be said how much more likely or intense a hurricane or heat wave became.

Heat waves are usually less spectacular than floods and extreme rainfall, which is why they receive less media attention. But according to recent WMO data released earlier this week, they are the leading cause of death as a result of climate disasters. Between early 2020 and the summer of 2024, heat waves accounted for 54 percent of extreme weather deaths reported by national weather services.

Rainforest on the threshold of the savannah

And what are the future prospects? Anything but rosy. The Amazon rainforest is currently experiencing its worst drought in living memory for the second year in a row. In many places, river levels are at record lows. The consequences are devastating for large parts of the continent, because the forest in the Amazon basin acts as a pump that brings moisture and rain to the south, to the Pantanal. This wetland on Brazil’s border with Bolivia and Paraguay is one of the planet’s largest reservoirs of fresh water, but this summer was hit by one of the worst wildfires ever recorded there, fires made far more likely by climate change. An area of ​​around 4,400 square kilometers burned.

A mapping study by Imperial College in London has shown that such fires can only be expected every 161 years in an undisturbed climate, but under current conditions they can be expected three times a century.
But it gets even worse. At the beginning of the year, a team of Brazilian and European researchers came to the conclusion that as early as the middle of the century, up to 47 percent of the rainforest could be at risk of tipping over, i.e. dying off and becoming a savanna. They had not yet taken into account that the Atlantic overturning circulation – best known in this country through the Gulf Stream – is also important for the forest.

At the beginning of November, a similarly international team published in the journal Nature Geoscience based on evidence that was 25,000 to 12,500 years old pointed outthat the north of the Amazon basin in particular will become significantly drier when the circulation weakens.

Warning of Gulf Stream collapse

But this is exactly what can be expected in the next few decades, as just October 43 brought together scientists from all over the world who have been researching in the field for many years Letter to the governments of the Nordic Council of Scandinavian countries warned. Accordingly, Northern Europe’s heat pump, which brings heat from the subtropics beyond the Arctic Tropic to the northern North Atlantic, is more vulnerable than previously thought. Various studies in recent years have shown that with further global warming, a gradual collapse of the circulation becomes increasingly likely.

In addition to the aforementioned effects on the South American rainforest and a southward shift of the tropical rain zones, the immediate consequences for Scandinavia would be a dramatic cooling of several degrees Celsius, despite global warming. In this country, the drastically increased temperature differences would lead to more extreme weather, stronger storms and probably strong climate fluctuations from year to year.

The point at which this humanly irreversible collapse will occur is somewhere between 1.5 and 2 degrees Celsius of global warming above pre-industrial levels, according to the fire letter to Nordic governments. This means that we are only a few tenths of a degree Celsius away from this point. It is not surprising that a group of leading climate researchers such as Johan Rockström and Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research and Michael E. Mann from the University of Pennsylvania at the beginning of October warns: »We are on the brink of an irreversible climate catastrophe. There is no doubt that we now have a global emergency. A large part of the basis of life on earth is in danger. We are entering a critical and unpredictable new phase of the climate crisis. (…) Tragically, we are failing to avoid serious impacts and can only hope to limit the extent of the damage. (…) We have brought the planet into climatic conditions that neither we nor our prehistoric relatives within our genus Homo have ever seen.”

“We can only hope to limit the extent of the damage.”

The 2024 state of the climate report

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