A duster scenario of no longer remillable climate change with all its destructive consequences is the management and climate strategist jørgen randers together with a research colleague in a journal on thursday "scientific reports" published study. Even if humanity was stopping all the greenhouse gas emissions on their account again this year, the temperature increase would therefore no longer or hardly limit themselves.
Temperature rise for centuries
Vital ice compounds outside of gronlands and the antarctic melt according to the analysis of the co-author of several reports of the club of rome in the afterseth, the permafrostboden in polar regions taut completely. The norwegian future researcher and his colleague emphasize: regardless of whether the zero-emission target has been hypothetically reached this year or at the end of the century, climbing the global average temperature for centuries.
2500 location, then at about about three degrees compared to pre-industrial time, during which it should be limited to 1.5 or 2 degrees according to the paris climate agreement. Only the increase in the sea level was reflected by the phrases by about half a meter, if the world community immediately the emergency brake tits.
The experts conclude that the "point of no return" is already significantly reduced. According to their calculations, the exit of the greenhouse exhibition had already been completed between 1960 and 1970 to avoid the impending strong temperature rise. The designed cycle "by a global embrocation of only plus 0.5 degrees celsius to be drawn to the pre-industrial level".
Hearing the earth in time lapse (source: NASA climate change)
Follow effects of climate change
As a cause for the even centuries-on-wreak emphasis, the duo calls three factors. They refer to massive CO2 and methane entries in the atmosphere because permafrostboden continues to thwart. To do this, the further decline in the albedo, so the jerk steel of solar energy, because the arctic ice still melt. In parallel, the water vapor, which also fueled the greenhouse effect, increased in the atmosphere due to high temperatures.
To stop this development, according to the authors, when technicians were starting to stop CO2 from the atmosphere. Needily, there are reductions in a magnitude of 33 gigatons per year. For comparison: in 2019, 36.7 gigatons of the greenhouse gas were emitted to the atmosphere.
Their findings have won the scientists with a greatly simplified climate model. You already wrote in 2016: "we have developed a simple system dynamics model, escimo, which is on a desktop computer in seconds and is able to reproduce the most important results of more complex climate models".
Gentle change is not enough
As the wisdom last end, the author does not denote its result. They are planning that they are above all about questioning existing thinking processes and to stop further studies with complex earth system models. Randers is known after decades of declining work on the limits of growth for its view that the value of the earth’s savings can not be achieved on the gentle tour.
German researchers consider the analysis mostly skeptical, even if they do not find the co-vibrant alarmism completely unjustified. The nearby "runaway"-greenhouse effect has previously been shown by any earth system model, stefan hagemann gives concerns about the helmholtz center for material and custodian research. This also applies to simulations with a high climate sensitivity.
"I am sure that there is so-called tilting points in the climate system", emphasizes the scientist. But there has been no evidence that these thresholds have already been achieved with a degree of 0.5 degrees. Furthermore, the authors also go to obvious weakness of their model. This leaves 175 gigatonna carbon from the thawing of the permafrost until the year 2300, "what much more is compared to plus 66 to minus 70 gigatons in other models". Nevertheless, it is "interesting results", the other examinations suggested.
Realistic models need more computing power
"Significant doubts about methodological properties" the study has helge goessling from the alfred wegener institute for polar and marine research. Other striking analyzes so far provided no evidence that the emission budgets could already be more than exploited. Also the statements about negative effects due to water vapor and surfenalbedo awakened doubts. For goessling is so clear: "we should continue to cut to reduce human-made greenhouse gas emissions as quickly as possible to keep the global emphasis."
For particularly long, as here to 500 years in the future, so-called earth system models of medium complexity (EMICS) are useful, says holger kantz from the max planck institute for physics complex systems. This also loves "include other components of the earth system beyond atmosphere and oceans. A halfway realistic model but "not in seconds on a desktop computer", but on a supercomputer rather a day long.
In this respect, it is plausible for the dresdner professor, "that this model simplifies too much". The fact that it has been developed by only two persons, confirm this. Due to the discrepancy to the multimodel result of the world climate IPCC and the statements of the authors for the calculation time of their model kantz it "probably", that the approach used here "is inadequate and therefore the future does not correct correctly". Nevertheless, the study became "certainly lead to a checking of the more complex models and is therefore not worthless".
For the head of the suddeutsch klimaburos, hans schipper, the analysis shows against it "in an impressive way that backup couplings in the climate system can lead to unexpected effects". The embassy is: "if we do not seriously act in climate protection, scenarios will be launched, which drove to significant impacts of our society." for the researcher at the karlsruhe institute for technology (KIT), it is the highest time to continue to promote controversial technologies such as climate engineering. These were able to play a crucial role in involving the consequences of climate change.