2023-05-22 17:19:43
In biology it’s quite simple: Living things always settle where they find good conditions, where there is enough food and pleasant temperatures prevail. Humans are no exception here, at least to a large extent: That is why most people live in regions with an annual average temperature of between six and 28 degrees Celsius – in their climatic niche. But with climate change, these so-called niches will become fewer. People will have to live where it’s far too hot and too dry, in zones considered “almost uninhabitable.” Exactly: outside the climate niche.
Scientists now want to use this concept of the climate niche to show the general public the consequences of global warming more vividly than has been the case with previous presentations that put the economic costs in the foreground.
In a now in the journal “Nature Sustainability” published study An international research team led by Timothy M. Lenton from the University of Exeter and Marten Scheffer from the University of Wageningen has calculated how many people’s living space will fall out of the climate niche by the end of the century. “So far, nine percent and thus more than 600 million people live outside this niche,” write the authors. By the end of the century it could be a third of humanity. At least if the current climate policy did not change drastically – and thus global warming of 2.7 degrees Celsius would be achieved. If it were possible to limit warming to just 1.5 degrees Celsius, only 14 percent of all people would have to live outside the climate niche by the end of the century.
The scientists assume a worldwide demographic increase to up to 9.5 billion people in 2070 with a subsequent decline. You are moving in a medium scenario. According to the calculation, many people will slip out of the climate niche in Nigeria, India and Indonesia. In Burkina Faso, Mali and Qatar, particularly large areas would become almost uninhabitable.
Lenton’s team also emphasized in the study that for every 0.3 degrees Celsius temperature increase avoided, 350 million fewer people would have to live in regions beyond the climate niche.
Lisa Schipper, who researches developmental geography at the University of Bonn and was not involved in the study, tells the Science Media Center that the concept of the human climate niche is “extremely useful”. No metric, not even that of the current study, will accurately reflect reality. “The notion that fewer and fewer people will be able to lead decent lives is directly related to the IPCC’s warning that the window of opportunity for ensuring a sustainable and livable life for all people is closing,” she says . “Even with 1.5 degrees of warming, this is probably not possible, as the authors of the current study show.”
Christian Franzke from the IBS Center for Climate Physics at the Pusan National University in South Korea also thinks the concept of the climate niche makes sense. “The ‘human climate niche’ is of course an oversimplification of the complexity of the problem, but it is illustrative and indicates the implications for poor countries, which in economic terms will suffer less damage because they are poor. That is the benefit of this approach.”
How much migration will be necessary?
Previous studies have either focused primarily on the economic costs of climate change or on mortality. The current study uses demographic projections that assume a growing population, especially in areas that are already warm. These regions in particular are badly affected, but have fewer opportunities to adapt. “Adaptation is possible, but it will cost money that poor countries and poor people don’t have.” For example, in developed countries like Germany most of the work takes place in buildings that can be cooled, but in many developing countries this is not the case the case. There was a lot of work done outside. “You could change the working hours and introduce a siesta at lunchtime like in Spain, but that probably won’t maintain all the productivity of the workforce.”
Richard JT Klein from the International Climate Risk and Adaptation team at the Stockholm Environment Institute (SEI) in Sweden complains that the study does not take into account that habitats could become uninhabitable even though the temperatures are still tolerable. “For example, drought and desertification can already occur within the climate niche, making agriculture almost impossible and making the region uninhabitable. The same applies to low-lying areas threatened by flooding and sea level rise. In other words, there are regions within the human climate niche that could become uninhabitable for other reasons.”
However, he also emphasizes positively that the concept of the climate niche makes it clear how differently global warming affects rich and poor countries. People can adapt to many things, but only if there are enough resources. “However, for many of the people and countries affected, this is not an option,” says Klein. “So the question is what these people are going to do. Moving to cooler places? What are these places and what opportunities will they have there? Could this lead to conflicts over scarce resources?
However, the study is not a cause for panic, says Klein. Rising temperatures increase the risk for a growing number of climate refugees. “However, we should not forget that the vast majority of climate refugees have moved within their own country or to neighboring countries.” It is becoming increasingly important “to support local people and urgently limit further warming”.
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