by: J. D. Heyes
Researchers in the "global warming" community once posited that, if they could find a way to reduce the amount of sunlight reaching Earth's surface through geoengineering, they could reverse the allegedly damaging effects of climate change.
Turns out, that's not helpful.
A pair of German researchers used a simple energy balance analysis to describe how Earth's water cycle responds differently to heating by sunlight than it does to warming from a strong greenhouse gas effect.
What's more, they went on to show that this difference implies that reflecting sunlight to reduce Earth temperatures may even have unwanted effects on the planet's rainfall patterns, Science Daily reports.
The results of their research have been published in Earth System Dynamics, an open access journal published by the European Geosciences Union, or EGU.
Reponses are easy to explain, say the researchers
As reported by Science Daily:
Global warming alters Earth's water cycle since more water evaporates to the air as temperatures increase. Increased evaporation can dry out some regions while, at the same time, result in more rain falling in other areas due to the excess moisture in the atmosphere. The more water evaporates per degree of warming, the stronger the influence of increasing temperature on the water cycle. But the new study shows the water cycle does not react the same way to different types of warming.
Researchers Axel Kleidon and Maik Renner, of the Max Planck Institute for Biogeochemistry in Jena, Germany, employed a basic energy balance model to see how sensitive the water cycle is to increases in surface temperature due to a stronger greenhouse effect, as well as an increase in solar radiation.
In predicting the water cycle response for the two cases, the researchers found that, in the former, evaporation increases by 2 percent per degree of warming, while, in the latter, the figure was 3 percent.
The prediction confirmed results of far more complex climate models.
"These different responses to surface heating are easy to explain," Kleidon, who uses a pot on the kitchen stove as an analogy, said.
"The temperature in the pot is increased by putting on a lid or by turning up the heat -- but these two cases differ by how much energy flows through the pot," he said.
A stronger greenhouse effect would, in essence, put a thicker "lid" over Earth's surface, the researchers argued, but - if there is no additional sunlight, extra evaporation occurs "solely due to the increase in temperature."
More from Science Daily:
Turning up the heat by increasing solar radiation, on the other hand, enhances the energy flow through Earth's surface because of the need to balance the greater energy input with stronger cooling fluxes from the surface. As a result, there is more evaporation and a stronger effect on the water cycle.
'Like putting a lid on the pot and turning down the heat'
In the new study for Earth System Dynamics, the authors also demonstrate how their findings can have great consequences for geoengineering. Many geoengineering approaches seek to curb global warming by reducing the level of sunlight reaching Earth's surface. But when Kleidon and Renner applied their results to such a geoengineering scenario, they found that changes in the water cycle and atmosphere occurring at the same time cannot be compensated for simultaneously.
So, reflecting sunlight via geoengineering is really not likely to restore the planet to its original climate - whatever that means.
"It's like putting a lid on the pot and turning down the heat at the same time," Kleidon said. "While in the kitchen you can reduce your energy bill by doing so, in the Earth system this slows down the water cycle with wide-ranging potential consequences."
Evaluators of the study were stunned by its simplicity in producing results. One noted: "It is a stunning result that such a simple analysis yields the same results as the climate models."
Learn more: http://www.naturalnews.com/043278_geoengineering_global_warming_climate_change.html#ixzz2nr3Qnoqt
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