(Translated by P. Gosselin)
June 7, 2020
Dear ladies and gentlemen
First, the global mean temperature of satellite based measurements was surprisingly much higher in May 2020 than in April. In contrast, the global temperatures of the series of measurements on land and sea decreased. The difference can be explained by the fact that under warm El-Nino conditions the satellite measurements lag about 2-3 months behind the earth-based measurements.
From November 2019 to March 2020 a moderate El-Nino was observed, which has now been replaced by neutral conditions in the Pacific. Therefore, it is to be expected that also the satellite based measurements, which we use at this point, will show a decrease in temperatures within 2-3 months.
The average temperature increase since 1981 remained unchanged at 0.14 degrees Celsius per decade. The sunspot number of 0.2 corresponded to the expectations of the solar minimum.
The earth is greening
In August 2019, I reported on a remarkable publication by the Max Planck Institute for Meteorology in Hamburg: “Our main finding,” said Aexander Winkler’s researchers at the time, “is that the effect of CO2 concentration on terrestrial photosynthesis is greater than previously thought and therefore has important implications for the future carbon cycle.
According to this, the CO2 attenuation effect of plants is 60% higher than the average of climate models had assumed.
“In the last two decades, an average of 310,000 km² of additional leaf and needle area – roughly the size of Poland or Germany – has been created every year,” the researchers say. I had shared this important finding with the members of the German Bundestag at the time, which led Stefan Rahmstorf to conclude that I was “trying to fool the German Bundestag“. This assessment was taken up by some media such as the TAZ and ultimately led to my dismissal as sole director of the German Wildlife Foundation.
New confirmation: CO2 uptake by plants is increasing
In April ,2020, a research group led by the Australian scientist Vanessa Haverd published a paper in Global Change Biology which more than confirmed the findings of the Max Planck Institute. The researchers describe that plants have absorbed 30% more CO2 since 1900. The previous estimates were 17%. In their calculation for a mild increase in CO2 in this century (IPCC scenario 2.6), the researchers led by Vanessa Haverd arrived at a net uptake of 528 billion tonnes of CO2 by plants by 2100, compared to the 238 billion tonnes of CO2 previously calculated by climate models.
According to Adam Riese, this is more than twice as much. By way of comparison: In scenario 2.6, a total of 1000 billion tonnes of CO2 (IPCC, Chapter 6, p. 468) will be emitted in this century. Today the plant world absorbs about 30% of the anthropogenic CO2 annually, the oceans another 24%.
In contrast, the statement of the IPCC in its last report from 2013 (p.26 of the Summary for Policymakers) is diametrically different: “Based on Earth system models, there is a high confidence that the feedback between climate development and the carbon cycle in the 21st century is positive. As a result, more of the anthropogenic CO2 emitted will remain in the atmosphere. Maybe I need to write to the German Bundestag again.