Tuesday, December 11

Deforestation and global greenhouse effect

It was all there, clearly spelled out in the Mongabay interview in 2012. It's just taking years for climate scientists to catch up. Going back years and quite recently I've posted excerpts from the interview; here I focus on the biotic pump's relation to global warming.    

New meteorological theory argues that the world’s forests are rainmakers
by Jeremy Hance

1 February 2012

Mongabay: Does the biotic pump theory [to be precise, hypothesis] modify our current understanding of global climate change?

Victor Gorshkov and Anastassia Makarieva: The widespread view is that global climate change is largely due to anthropogenic pollution of the global environment. The main anthropogenic pollutant is carbon dioxide, which is emitted by burning fossil fuels. CO2 is the second most important greenhouse substance in the atmosphere of Earth, therefore its accumulation in the atmosphere is believed to be the main cause of the observed warming and other climatic changes. The main proposed strategy to combat climate change is by reducing carbon emissions.
However, the greenhouse effect on Earth is mostly determined by water vapor and clouds, i.e., by atmospheric moisture, which is the main greenhouse substance. The absorption interval of CO2 molecules covers less than 20 percent of the spectrum of thermal radiation of the Earth’s surface, while atmospheric moisture absorbs thermal radiation rather uniformly over the entire spectrum. Therefore, the impact of increasing CO2 concentrations on the greenhouse effect can be completely compensated by a relatively minor change in the hydrological cycle over land. Such climate stabilization can be performed by natural forests that control the hydrological cycle on land and the adjacent ocean, provided they are allowed to occupy a significant area. 
Conversely, destruction of forests leads to disruption of the hydrological cycle, which expectedly causes significant fluctuations of the magnitude of the global greenhouse effect, up to complete loss of climate stability and transition of Earth’s climate to a state incompatible with life.
Most modern climate researchers have grown up on computer models of climate and are used to believing in the model output. As illustrated by the discussion of our work, it is rarely appreciated that by artificially setting the needed numerical parameters it is possible to simulate a very broad range of climate scenarios, including those that will agree with observations of the past. The existence of simulations that mimic the past and present reality does not mean that the physics included in the models is correct or that the model can generate a trustworthy prediction.

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