Indisputable Science: Facts About Climate Change Everyone Should Know

There is less agreement on how to address the problem. 60% of Germans and 58% of Europeans believe that the transition to a green economy must be accelerated. 73% of European citizens estimate that the cost of damage caused by climate change is higher than the investments required for the green transition.

Material for fact-based discussion

It is important that the discussion about how to deal with the climate crisis is based on facts. the German Climate Unionthe German Meteorological Societythe German weather servicethe Extreme Weather Conference Hamburgthe Helmholtz Climate Initiative And klimafacts.de So Publish a paper on the now indisputable knowledge in climate research.

In less than 30 pages”What we know about the climate today“It summarizes the basics in an easy-to-understand way, explains the global significance and consequences of climate change in Germany and identifies possible future developments. The sources are documented and easy to read.

Climate change cannot be explained without greenhouse gases

First of all, there is the argument often made against climate action that climate change is not man-made. According to the authors of the research, warm and cold periods have so far been mostly caused by changes in the Earth’s orbit around the Sun or shifts in the continents or the Earth’s rotation axis. Temperatures have not decreased or increased in decades. For example, the shortest Earth orbit lasted 23,000 years.

Air samples taken from ice fossils up to 800,000 years old showed that historical climate fluctuations cannot be explained unless the concentration of gases in the atmosphere responsible for global warming is taken into account. Since the beginning of industrialization at the end of the eighteenth century, it has increased rapidly. In 2022, it was 50 percent higher than before industrialization began, and 2.5 times higher for methane.

Global warming primarily means that the oceans are warming, with the oceans absorbing 91% of the additional energy available due to climate change. Continents absorb 5% and ice masses 2.7%. Only 1.3 percent remains in our planet’s atmosphere, which is why the temperature of the atmosphere can stagnant or even drop.

The models were right, and they are getting better every day

People often question climate research models based on the slogan “it won’t be that bad.” But they have been in use for more than 30 years, allowing us to judge their accuracy retrospectively. The result is that today’s global temperature rise is exactly within the range of fluctuations predicted by the Intergovernmental Panel on Climate Change (IPCC) in its first study in 1990. Case report is expected.

Climate models that model the consequences of global warming are much more complex. The paper points out that the evolution of precipitation in particular is tricky: where does it get drier? Where does it get wetter? How much? But with today’s computing power and increasingly better measurements, it is becoming increasingly possible to predict what might happen in different scenarios.

Here too a look into the past helps us. Modern climate models can accurately depict developments observed in the past. “Therefore, the conclusions about possible future climate development that we can draw today from the results of model calculations are a reliable basis for policy decisions,” say the authors of the paper.

Since 1980, each decade has been warmer than the previous decade

A cooling of the subarctic Atlantic Ocean has also been correctly predicted, which at first glance is inconsistent with global warming. This appears to be due to the weakness of the Gulfstream system. However, the slight cooling in the Southern Ocean is still unclear.

Otherwise, the Earth’s surface becomes constantly warmer; On average, the global temperature has already risen by more than 1.1 degrees compared to pre-industrial times. Since the 1980s, each decade has been warmer than the previous decade and warmer than any previous decade since 1850.

All 10 of the hottest years on record have occurred since 2005. 2022 is over Data from the US agency NOAA Worldwide, it is the 46th consecutive year that average surface temperatures have been above the 20th century average.

The ice is melting and sea levels are rising

Climate change can also be clearly observed in the Arctic ice. Since satellite measurements began in 1979, its area has been shrinking at a rate of more than ten percent every decade. Also in Greenland, the decline in ice mass is dramatic and occurring at an ever-increasing rate, shrinking by more than 278 billion tons every year.

Water released into the Arctic has increased average global sea level by seven millimeters every decade since 2006. The melting of the Antarctic ice sheet is contributing four millimeters every decade. Between 1880 and 2020, global average sea levels rose by about 20 cm. Mountain glaciers are also melting rapidly; Since 1980, an average layer of ice more than 20 meters thick has disappeared.

It is no longer possible to deny that climate change is causing more extreme weather events around the world and more likely to occur. These include heatwaves and droughts, as well as heavy rains and floods, and the intensity of tropical cyclones is increasing. In addition to direct damage, extreme weather has other serious consequences, including threatening food supplies in some regions of the world.

Germany is already 2.1 degrees warmer

The paper also clearly summarizes the consequences of climate change for Germany, where temperatures have risen more than the global average. According to data from the German Meteorological Service, the past ten years have been about 2.1 degrees warmer than the first three decades (1881-1910) on record.

The pace of global warming has increased significantly in recent years; Since the 1960s, each decade in this country has been noticeably warmer than the previous decade. Nine of Germany’s 10 warmest years since 1881 occurred after 2000. Eight years have already been more than 2 degrees warmer than the long-term average, and even five years have been 2.5 degrees or more warmer.

The number of hot days with temperatures above 30 degrees in Germany has risen from an average of 3.5 to nearly nine days per year since the 1950s. In some years it can be much more. During the same period, the number of snow days accompanied by permafrost decreased from 28 to 19 days. If greenhouse gas emissions remain unchecked, a further increase of five to ten hot days in northern Germany and ten to 15 hot days in southern Germany is expected between 2021 and 2050.

Frequent heavy rains and periods of drought

The data series is still too short to predict this reliably, but it is likely that there will be more heavy rains in Germany, while at the same time there will be more frequent droughts. It is noteworthy that “the drought years from 2018 to 2020 were unprecedented in 250 years,” the paper says. “There has not been a three-year summer drought of this magnitude in Central Europe since 1766.” In 2022, this trend continues in many regions.

According to data from the Leipzig Helmholtz Center for Environmental Research, large parts of Germany have experienced their sixth consecutive year of drought during the growing season. This affects not only agriculture, animals and plants, but also domestic shipping and thus industrial supply chains. Low water also means that power plants have had to reduce their output due to a lack of cooling water.

Every tenth of a degree matters

The authors believe that the Paris Climate Agreement’s goal of limiting global warming to no more than 1.5 degrees, if possible, but certainly well below 2 degrees, is difficult to achieve. They wrote that under current policy guidelines, there would still be an increase of about 3 degrees by the end of the century. If all previous promises are kept, at best two degrees are possible.

However, they point out at the end of the paper that significant emissions reductions are possible, and that every tenth of a degree Celsius counts. For example, a storm surge, which statistically occurs every five hundred years on the North Sea coast near Cuxhaven, would occur once every hundred years at a temperature of 1.5 degrees, and every 33 years at a temperature rise of two degrees.