It has been around eight years since the Intergovernmental Panel on Climate Change (IPCC) summarized the state of our climate and its forecasts in a world climate report. Now the update is here. The current, sixth assessment report confirms that mankind has already changed the earth’s climate in an unprecedented manner – and that extreme weather conditions are also increasing significantly. The data also show more clearly than ever before that humans are the main cause of climate change and the extent to which greenhouse gas emissions influence the various climate factors. The report also reiterates that the window of opportunity for action is rapidly closing.
The status reports of the Intergovernmental Panel on Climate Change (IPCC) are not the work of individual governments, research institutions or interest groups, but are based on the research work of thousands of scientists from all over the world. For the world climate reports, several hundred climate researchers named as lead authors evaluate tens of thousands of specialist publications and summarize them in a balance sheet of current climate knowledge. The last, fifth assessment report of the IPCC was published in 2013/2014. Even then, he predicted a significant increase in extreme weather conditions, further thawing glaciers and rising sea levels if greenhouse gas emissions are not reduced drastically and quickly. Since then, hardly anything has happened in terms of climate protection.
“Unprecedented changes in the climate”
The Intergovernmental Panel on Climate Change (IPCC) has now published the first volume of its sixth assessment report (AR6). The data summarized in it illuminate the current state of the earth’s climate in order to then present new, more precise forecasts for the further course of the climate. The report confirms that global warming is around 1.1 degrees compared to pre-industrial values. Land areas have already warmed up by 1.6 degrees, while the seas react with a delay of 0.99 degrees. “The magnitude of recent changes throughout the climate system and the current state of many aspects of the climate system have been unprecedented for many centuries to millennia,” the IPCC report said. “The global surface temperature has increased faster since the 1970s than in any other 50-year period in the last 2,000 years.” The sea level has risen faster since 1900 than in any previous century in the last 3,000 years.
The new climate report also confirms that the observed changes in the earth’s climate cannot be explained by natural fluctuations alone: According to the current data, natural variability only accounts for around 0.2 degrees of the changes, the rest is due to anthropogenic influences, according to the IPCC. This is made clear, among other things, by the fact that the climate models cannot reproduce the current observations if the anthropogenic influence is not included. These statements are supported by a specification of the climate sensitivity – the dependence of warming on the CO2 content of the atmosphere. In the 2013 report, the range for the warming effect of a doubled CO2 content was 1.5 to 4.5 degrees, but the range has now been narrowed to 2.5 to four degrees. This means that it is now easier to assess what specific consequences an increase in greenhouse gas values will have on the climate system. “An additional 1,000 gigatons of CO2 from the cumulative CO2 emissions cause global surface temperatures to rise by 0.27 to 0.63 degrees, on average by 0.45 degrees,” the report says.
Extreme weather and gloomy forecasts
The current world climate report also confirms that extreme weather conditions have increased significantly worldwide. It is almost certain that heat extremes, including heat waves, have become more frequent and intense over most land areas since the 1950s. According to the report, the same applies to heavy rain events. The frequency of particularly devastating combinations of several weather extremes at the same time, for example of heat and drought, of weather conditions that favor strong fires or floods, has also increased sharply. “With every additional ounce of global warming, the changes in extreme weather conditions are also increasing. Every half a degree more causes a noticeable increase in the frequency and intensity of heat waves, heavy rain and droughts in some regions, ”the authors report. Even with a warming of 1.5 degrees there will also be extreme events that are unprecedented in the history of observation.
In terms of forecasts, the sixth World Climate Report shows that by 2040, warming will definitely have reached 1.5 degrees – no matter how well our climate protection efforts work. The threshold of two degrees warming would also be exceeded in the course of this century with moderate and hardly any climate protection. If emissions are not drastically reduced in the short term, the two-degree target could even be broken as early as 2050. “Unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to 1.5 or two degrees will be unattainable,” according to the IPCC. The report also quantifies the CO2 budget that will remain for mankind if the climate protection targets are to be met. According to this, humanity should only release 300 gigatons of CO2 if the 1.5 degree target is to be met with an 83 percent probability. We still have 900 gigatons of CO2 left for the two-degree target.
“This report is a reality check. We now have a much clearer picture of the past, present and future climate, “states Valérie Masson-Delmotte, co-head of Working Group I, which is in charge of the report.” That is essential to understand where we are going and what is being done can and how we can prepare. “
Source: Intergovernmental Panel on Climate Change (IPCC), World Meteorological Organization (WMO)