In which region of the world are plants most productive in photosynthesizing water and carbon dioxide into carbohydrates? If you guessed the tropical rain forest, you’d be wrong. The region with the highest gross primary production (GPP) from photosynthesis is the U.S. corn belt.
That is the finding of a new study (Guanter et al. 2014) published in Proceedings of the National Academy of Sciences (PNAS). The team of 20 researchers used satellite-based spectroscopy to monitor sun-induced chlorophyll fluorescence (SIF), an electromagnetic signal emitted as a byproduct of photosynthesis.
Global map of maximum monthly sun-induced chlorophyll fluorescence (SIF) per 0.5° grid box for 2009.
The results of the study really shouldn’t be surprising. The U.S. leads the world in combined private-public R&D spending on agriculture and is the world’s top corn producer and agricultural exporter. Nonetheless — and this too is not surprising — the corn belt GPP reflected in satellite SIF data substantially exceeds the GPP estimated in carbon cycle models. The researchers report:
Our SIF-based crop GPP estimates are 50–75% higher than results from state-of-the-art carbon cycle models over, for example, the US Corn Belt and the Indo-Gangetic Plain, implying that current models severely underestimate the role of management.
Perhaps to appease the political-correctness guardians at PNAS, the study begins with a warning that “past advances” in agriculture are “threatened by climate change,” and the authors say their research is significant because it provides benchmark data for “more reliable projections of climate impact on crop yields.”
Clearly, though, the finding is also significant for another reason. It doesn’t fit into the fear narrative promoted by the recently-released IPCC Working Group II (WG2) report on climate impacts. Current models “severely underestimate the role of management.” That suggests current models underestimate farmers’ ability to adapt to climate change. [click to continue…]