According to the Intergovernmental Panel on Climate Change (IPCC), the risks of global warming can be reduced to some extent by limiting it to 1.5 degrees. However, this goal can only be achieved through rapid change in all fields. Two months before the next UN climate summit, the researchers warned in a report of what can happen if the temperature increases by 1.5 degrees Celsius – and even more so at 2 degrees.
“Limiting global warming to 1.5 degrees requires rapid, far-reaching and unprecedented changes in all areas of society,” said the IPCC on Monday following a multi-day meeting in the South Korean coastal city of Incheon. It is about changes in the areas of energy, industry, buildings, transport, in cities and in rural areas. Observers described the special report as a political wake-up call.
“One of the key messages of the report is: We are currently already seeing the consequences of one degree of global warming such as more extreme weather, rising sea levels, dwindling Arctic sea ice and other changes,” said the co-chair of an IPCC working group Panmao Zhai.
“The special report sends a clear signal to politicians: act now, it is almost too late,” commented Niklas Höhne from the Dutch University of Wageningen. “Many in politics may not have realized what they were getting into when they agreed in Paris in 2015 to the goal of limiting global temperature increases to 1.5 degrees Celsius as far as possible.”
The paper shows some clear differences between a warming of 1.5 and one of 2 degrees. By the end of this century, global sea levels would rise 10 centimeters less at 1.5 degrees than at 2 degrees. “That would mean that 10 million fewer people would be exposed to risks such as the salinisation of fields or flooding caused by storms in coastal areas,” says IPCC author Wolfgang Cramer. “The Nile Delta and other river deltas are already experiencing loss of land due to the ingress of seawater.”
According to the IPCC, there is an ice-free Arctic Ocean in summer at 1.5 degrees probably once per century, at 2 degrees probably “at least once per decade”. The authors also warn that around 70 to 90 percent of coral reefs will disappear when it gets 1.5 degrees warmer than before industrialization. “At 2 degrees, practically all would be lost.” At 2 degrees warming, significantly fewer fish could be caught.
Most researchers agree that the world is heading for 3 to 4 degrees warming without additional effort. In the Paris climate agreement, the countries decided to set an upper limit of well below two degrees warming. At the insistence of small island states, attempts should also be made to stop them at 1.5 degrees.
The Intergovernmental Panel on Climate Change was commissioned to prepare a special report on the 1.5 degree target. He then analyzed over 6000 studies. The executive summary of the new report was voted on with representatives from 195 countries last week, so that it now has political weight. The data are also the basis for the World Climate Conference in December in Katowice, Poland. According to the IPCC report, global emissions of carbon dioxide (CO2) would have to fall by 45 percent for the 1.5 degree target from 2010 to 2030 and reach zero in 2050.
According to the new IPCC report, humans may be able to emit a little more CO2 compared to older reports in order to still achieve the 1.5 degree target. For the director of the Potsdam Institute for Climate Impact Research, Ottmar Edenhofer, this is no reason to relax. “Compared to earlier estimates by the IPCC, we have at most a time gain of seven years.” But that was “long gone,” in view of the planned and existing coal-fired power plants, which often emit CO2 for decades. “There is no reason for fatalism, but there is enormous pressure to act. If we don’t get out of coal soon, we will slam the door to the 1.5-degree target once and for all. “
The report mainly shows scenarios that do not lead to a so-called overshoot, a short-term exceeding of the 1.5 degree target. With overshoot, humans would later have to pull more CO2 from the atmosphere than they produce. This can be done through what is known as geoengineering. However, the techniques for doing this have not yet been tested on a large scale. Some of them could also harbor great risks, warn the IPCC authors.
“Fortunately, the topic of geoengineering was clearly rejected in the IPCC report,” said Linda Schneider, who took part in the debate in Incheon, for international climate policy at the Heinrich Böll Foundation. On the other hand, there are possibilities of binding CO2 through the restoration of natural ecosystems, “especially forests, which the report assesses as very positive because of their benefits for biodiversity, soil quality and local food security”, emphasized Lindner.