Climate Change May Reduce Ability of Soil to Absorb Water—a Key Store of Carbon Dioxide

Climate change is degrading the ability of soils to absorb water, according to a study published in the journal Science Advances.

This could have implications for global warming, because water in the soil plays an important role in storing carbon dioxide—the most important greenhouse gas. Increases in CO2 in the atmosphere are helping to warm the planet due to its heat-trapping effect.

Climate change is expected to bring increased rainfall to certain regions of the world, which, along with other environmental changes, could lead to less infiltration of water into the soil, the researchers say.

"Since rainfall patterns and other environmental conditions are shifting globally as a result of climate change, our results suggest that how water interacts with soil could change appreciably in many parts of the world, and do so fairly rapidly," said co-author Daniel Giménez, a soil scientist from Rutgers University, said in a statement.

The latest study is the result of a field experiment conducted over a quarter of a century. Giménez and his colleagues used a sprinkler irrigation system on a grass prairie in Kansas to artificially increase the average annual amount of rainfall that the soil received by 35 percent over the 25 years.

This increase in rainfall led to between a 21 and 33 percent reduction in how much water infiltrated into the soil, according to the scientists.

"The key finding of this work is that the architecture of soil pore systems changes with shifts in precipitation, and that the changes happen within a decade or so—more rapidly than previously assumed," Giménez told Newsweek.

"With increased precipitation, more, and presumably thicker, roots alter the soil by 'drilling' new pores and colonizing existing ones," he said. "We also suspect that the process of contraction and expansion of the soil is less intense with increased precipitation because the water content in the soil fluctuates less. The combination of at least these two processes resulted in less water absorbed by the soil receiving supplemental irrigation."

The researchers say that the impact on soils from climate change could have significant implications for groundwater supplies, food production, the behavior of water run-off from storms, and the functioning of ecosystems.

"Water that is absorbed in the soil can be used for plants to grow. A fraction of the remaining water tends to percolate down and recharge shallow aquifers," Giménez said. "In many parts of the world, crop production depends entirely on rainfall. Food production is then threatened if the rainfall pattern shifts and/or the soil cannot absorb as much water as before. This would lead to food insecurity when food production is not enough to satisfy the needs of the population."

"Additionally, water that is not absorbed by the soil becomes stormwater runoff, which typically has a negative impact on water quality," he said. "The amount of water in soil can also limit plant biodiversity and ecosystem health by influencing the composition of the plant community."

The next step, they say, is to look at what is behind the trends that they observed so that the findings can be applied to other parts of the world.

The Earth's soil has a surprisingly big part to play when it comes to global warming, thanks to its ability to store carbon. For example, rapidly thawing permafrost in the Arctic could double the warming effect produced by greenhouse gases that are being released from the soil there, potentially exacerbating climate change, some researchers argue.

Climate change has been linked to a host of worrying outcomes for Earth, including an increase in extreme weather events, mass extinctions and rising sea levels.

Soil
Local farmers prepare the soil to sow Guaimaro (Brosimum alicastrum) tree seeds at a small farm in Dibulla, La Guajira department, Colombia on February 28, 2018. LUIS ACOSTA/AFP/Getty Images
Climate Change May Reduce Ability of Soil to Absorb Water—a Key Store of Carbon Dioxide | Tech & Science