The UN’s reality check on the climate crisis is grim: The earth is warming much faster than previously predicted. According to the report of the Intergovernmental Panel on Climate Change, this will have devastating consequences – also for Germany.
In its new report, the UN Intergovernmental Panel on Climate Change (IPCC) presents the consequences of man-made global warming more drastically than ever before. According to the latest scientific findings, sea-level rise, ice melt, more heat waves, droughts and heavy rainfall can be predicted much more reliably than before. The facts are alarming. An overview of the most important findings:
Faster temperature rise
In all five scenarios run by the experts, the rise in the Earth’s average surface temperature is already around 1.5 degrees Celsius by 2030 compared with the pre-industrial era. That is a full decade earlier than previously assumed. By mid-century, the 1.5-degree limit formulated in the Paris climate agreement will thus be exceeded everywhere. “We are not far from the 1.5-degree target,” says co-author Veronika Eyring of the German Aerospace Center (DLR). Each of the past four decades has been warmer than any of the previous decades, she said. Moreover, the Earth has been warming much more rapidly since 1970.
There is one glimmer of hope in the distant future: in the most optimistic IPCC scenario, average temperatures fall back to 1.4 degrees above pre-industrial levels by 2100 after rising above 1.5 degrees.
Climate change is man-made
In the very first sentence of the IPCC report, the experts state more clearly than ever the cause of the temperature rise and climate change: “It is beyond doubt that human influence has heated the atmosphere, ocean and land.” In 2019, atmospheric CO2 concentrations were higher than at any other time in at least two million years, the report says. In previous reports, the IPCC put it more cautiously, saying it was “extremely likely” due to industrial activity. But now there is “no uncertainty [left]that global warming is caused by human activity and the burning of fossil fuels,” co-author Friederike Otto writes.
Natural disasters as a direct result
Weather extremes and natural disasters are directly attributable to global warming, according to the Intergovernmental Panel on Climate Change: Severe heat waves, which used to occur about every 50 years, will occur once per decade. Tropical storms will become stronger, and rain and snowfall will increase. Droughts will occur 1.7 times as often as before. Fires will become more intense and last longer.
“The data clearly show that climate extremes are increasing as global warming progresses,” says co-author Sonia Seneviratne of the Swiss Federal Institute of Technology Zurich (ETHZ). The recent heat wave in southern Europe and the western U.S. and Canada, as well as the heavy rains in Germany, are exactly what climate models predict will happen more and more frequently, she said: more weather extremes that have been unprecedented. “Even very small changes in global warming can have very large impacts.”
Summer will be ice-free in the Arctic
The Arctic is the region that climate experts say is warming the fastest – at least twice as fast as the global average. Ice floes on the Arctic Ocean in summer will disappear by 2050, even under the researchers’ most optimistic scenario. This process has been underway since the 1970s. Melting ice causes a feedback loop: while the ice reflects sunlight, the darker surface of the water absorbs radiation, exacerbating global warming.
Rapidly rising sea level
Even if the 1.5-degree limit is maintained, sea levels will rise by two to three meters, and possibly more, in hundreds or thousands of years, the report says. The levels of the world’s oceans have risen by about 20 centimeters since 1900, and the rate of rise has nearly tripled in the past decade alone. The melting of the polar ice and the warming of the oceans are largely responsible for this.
Coastal flooding on a scale that used to occur only once a century will happen every year by 2100, the experts write. Sea level rises of more than 15 meters by 2300 can’t be ruled out if tipping points occur, such as the loss of the Arctic or forest dieback. “The more we drive the climate system, the more likely we are to cross thresholds that we can barely predict,” warned co-author Bob Kopp, a climate scientist at Rutgers University in New Jersey.
Sea-level rise is fundamentally unstoppable, as a look at the distant past shows: The last time the Earth’s atmosphere was as warm as it is today, about 125,000 years ago, sea levels were five to ten meters higher. But a slower rise can be better responded to near the coast.
Gulf Stream weakens
The Atlantic overturning circulation, to which the Gulf Stream is also due, is weakening, and this trend is “very likely” to continue throughout the 21st century, the IPCC report says. The scientists do not rule out the possibility that ocean currents, which regulate global heat transfer from the tropics to the Northern Hemisphere, will come to a complete standstill. This would make winters in Europe significantly colder.
Natural CO2 sinks reach their limits
In the last 100 years, mankind has blown nearly 2,500 billion tons of CO2 into the air, which retains heat and gradually heats up the world. The global temperature rise is due to these same greenhouse gases, which have entered the air with exhaust gases, reports the UN Intergovernmental Panel on Climate Change. CO2 concentrations are higher than at any time in the past two million years. Forests, soils and oceans, which have so far absorbed 56 percent of the sharp rise in emissions, are reaching their limits, according to IPCC experts. The proportion of greenhouse gases emitted that they absorb is expected to decrease noticeably over the course of the century.