Global Climate Report: It’s Dangerous – Wissenschaft.de

It has been eight years since the Intergovernmental Panel on Climate Change (IPCC) summarized the state and prospects of our climate in its Global Climate Report. Now the update is here. The current Sixth Assessment Report confirms that humanity has already changed the Earth’s climate in an unprecedented way – and that extreme weather conditions are also increasing exponentially. The data also shows more clearly than ever that humans are the main cause of climate change and how much greenhouse gas emissions influence different climatic factors. The report also reiterates that the window for business is rapidly closing.

The status reports from 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 around the world. For the Global Climate Reports, several hundred climate researchers appointed as lead authors have evaluated tens of thousands of specialized publications and summarized them in the balance sheet of current climate knowledge. The latest Fifth Assessment Report of the Intergovernmental Panel on Climate Change was published in 2013/2014. Even then, expect a significant increase in extreme weather conditions, increased glacier melting and rising sea levels if greenhouse gas emissions are not reduced dramatically and rapidly. Since then, almost nothing has happened regarding climate protection.

‘Unprecedented changes in climate’

The Intergovernmental Panel on Climate Change (IPCC) has now published the first volume of the Sixth Assessment Report (AR6). The data summarized in it illuminates the current state of Earth’s climate in order to provide new, more accurate predictions for the next climate path. The report asserts that global warming is about 1.1 degrees Celsius compared to pre-industrial values. The land areas have already warmed by 1.6 degrees, while the oceans react with a delay of 0.99 degrees. “The magnitude of recent changes across the climate system and the current state of many aspects of the climate system are unprecedented for centuries to millennia,” the IPCC report said. “The Earth’s surface temperature has increased faster since the 1970s than in any other 50-year period in the past two thousand years.” Sea level has risen faster since 1900 than in any previous century in the past 3,000 years.

The new Climate Report also stresses that the observed changes in Earth’s climate cannot be explained by natural variability alone: ​​According to current data, natural variance accounts for only about 0.2 degrees of changes, and the rest is due to human influences, according to the Intergovernmental Panel on Climate Change. This is evidenced, among other things, by the fact that climate models cannot reproduce current observations if human influence is not included. These data are supported by a specification of climate sensitivity – the dependence of warming on the carbon dioxide content of the atmosphere. In a 2013 report, the range for the warming effect of a doubling of the carbon dioxide 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 estimate the specific consequences that increased greenhouse gas values ​​will have on the climate system. “An additional 1,000 gigatonnes of carbon dioxide from cumulative carbon dioxide emissions causes global surface temperatures to rise 0.27 to 0.63 degrees, on average by 0.45 degrees,” the report says.

Severe weather and gloomy forecasts

The current Global Climate Report also confirms that extreme weather conditions have increased dramatically around the world. Temperature extremes, including heat waves, have almost certainly become more frequent and intense over most land areas since the 1950s. According to the report, the same is true for heavy rain events. The frequency of particularly destructive combinations of several extreme weather events has also risen sharply, for example heat and drought, and weather conditions favoring strong fires or floods. “With each additional ounce of global warming, changes in extreme weather conditions are also increasing. Each additional half-degree leads to a marked increase in the frequency and intensity of heat waves, heavy rains and droughts in some areas,” the authors stated. Even as the temperature rises by 1.5 degrees, there will also be extreme events unprecedented in the history of observation.

In terms of forecasts, the Sixth Global Climate Report shows: by 2040, warming will certainly have reached 1.5 degrees – no matter how successful our climate protection efforts are. The threshold of two degrees warming will also be exceeded during 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. According to the Intergovernmental Panel on Climate Change, “unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, the reduction A warming to 1.5 degrees or two would be out of reach.” The report also outlines the carbon dioxide budget that humanity will still have if climate protection goals are met. According to this, humanity should release 300 gigatons of carbon dioxide only if the 1.5-degree target is to be achieved with a probability of 83 percent. We still have 900 gigatonnes of CO2 remaining for the two-degree target.

“This report is a reality check. We now have a much clearer picture of past, present and future climate,” said Valerie Mason-Delmott, Co-Chair of Working Group I, which is responsible for the report. “This is essential to understanding where we are going, what is being done and how. We can prepare.”

Coyle: Intergovernmental Panel on Climate Change (IPCC), World Meteorological Organization (WMO)

© wissenschaft.de – Nadia Podebrigar