Alexander J. Winkler, Ranga B. Myneni, Georgii A. Alexandrov, Victor Brovkin. Earth system models underestimate carbon fixation by plants in the high latitudes. Nature Communications, 10, 885, 2019.
Most Earth system models agree that land will continue to store carbon due to the physiological effects of rising CO2 concentration and climatic changes favoring plant growth in temperature-limited regions. But they largely disagree on the amount of carbon uptake. The historical CO2 increase has resulted in enhanced photosynthetic carbon fixation (Gross Primary Production, GPP), as can be evidenced from atmospheric CO2 concentration and satellite leaf area index measurements. Here, we use leaf area sensitivity to ambient CO2 from the past 36 years of satellite measurements to obtain an Emergent Constraint (EC) estimate of GPP enhancement in the northern high latitudes at two-times the pre-industrial CO2concentration (3.4 ± 0.2 Pg C yr−1). We derive three independent comparable estimates from CO2 measurements and atmospheric inversions. Our EC estimate is 60% larger than the conventionally used multi-model average (44% higher at the global scale). This suggests that most models largely underestimate photosynthetic carbon fixation and therefore likely overestimate future atmospheric CO2 abundance and ensuing climate change, though not proportionately.
“If you liked last summer’s record temperatures, you’re going to love the 1990s, says James Hansen, the NASA scientist who, during congressional hearings on the Midwestern drought, linked greenhouse warming to the heat wave. Last summer was a preview of the average summer 10 years from now, and the hottest summers during the ’90s will be even hotter and drier than the one we just struggled through, he says.” click here
“The IPCC report said “Feedbacks associated with changes in sea ice and snow amplify surface warming near the poles” and gave several supporting references. But the Southern Oceans temperature pattern above shows the exact opposite: the further south you get, the greater the rate of cooling. In fact, at almost the precise latitude where the IPCC expected the most amplified warming there was some of the fastest cooling on the planet! [Note where zero trend is on the Y axis].” click here
“Yesterday we posted on how rainfall across southern Europe has risen over the past couple of decades, thus going in the opposite direction of what was projected by climate models. And once again the models are shown to be woefully faulty and an unreliable tool for policymaking, as the following example shows.” click here
“The new Santer et al. study merely shows that the satellite data have indeed detected warming (not saying how much) that the models can currently only explain with increasing CO2 (since they cannot yet reproduce natural climate variability on multi-decadal time scales).” click here
Climate model forecasts have shown a 100% failure rate. click here
“There are a number of statements in Cheng et al. (2019) ‘How fast are the oceans warming’, (‘the paper’) that appear to be mistaken and/or potentially misleading. My analysis of these issues is followed by a reply from the paper’s authors: Lijing Cheng, John Abraham, Zeke Hausfather and Kevin Trenberth.” click here