New Paper: Humans Caused Central U.S. To Cool By -0.35°C Since The 1940s As Crop Yields Soared

Climate Depot | 12/29/2017 | Rob Bushway
iVchan (Posted by) Level 3
Post-1940s ‘Agricultural Intensification’ Caused Deep Cooling, 400% Crop Growth In a new paper published in Geophysical Research Letters, three MIT scientists assert that the human influence on the climate of the Central United States is dominated by agricultural activity rather than greenhouse gas (GHG) emissions. Human activity has caused a significant long-term cooling trend (-0.35°C between the 1940s and 2009) and higher rainfall totals via the mechanism of “agricultural intensification” – a photosynthesis-associated increase in the air’s water vapor or humidity levels due to an explosive (400%) increase in crop production and yield since the 1940s. The authors assert that the human-caused post-1940s cooling trend and increase in precipitation dramatically conflict with climate model expectations which project a human-caused warming trend and decreasing rainfall with the advent of increasing GHG emissions. From all appearances, the effects of the human influence on climate is still teeming with inconsistencies and contradictions. Alter et al., 2017 Summary “Observations and numerical simulations both suggest that agricultural intensification has cooled temperatures and enhanced rainfall.” Climate Models Predicated On A Driving Influence For GHG Emissions…Are Wrong “From 1910- 1949 (pre-agricultural development, pre-DEV) to 1970-2009 (full agricultural development, full-DEV), the central United States experienced large-scale increases in rainfall of up to 35% and decreases in surface air temperature of up to 1°C during the boreal summer months of July and August … which conflicts with expectations from climate change projections for the end of the 21st century (i.e., warming and decreasing rainfall) (Melillo et al., 2014).” “The output from this subset of CMIP5 models [climate models predicated on CO2 emissions assumptions] indicates only small changes in rainfall (between -2% and +4%) during the summer in the central United States, which are much smaller than the frequency distributions of rainfall change from both the observational data and the...
(Excerpt) Read more at: Climate Depot
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