Study Finds Drought-Stricken Trees Are Less Effective in Cleaning Carbon Dioxide From the Air

Trees affected by drought are not as efficient in taking carbon dioxide out of the atmosphere, which may play a role in accelerated climate change, according to a new study published in Science magazine.

A team of researchers studied tree ring data and found that drought can set back the ability of trees to absorb carbon dioxide by as much as four years.

Trees do serve as the proverbial "canary in the coal mine" for climate change for several reasons, Dr. William Anderegg of Princeton University said.

"First, we've known for a long time that trees' growth and death are sensitive to rainfall and temperature. Because they are rooted to the ground and thus can't move to colder places like a bird could, they experience the climate around them," Anderegg said.

It means that trees are particularly vulnerable to changes in climate because they can't move and their generation times are quite long.

"In addition, we've started to see in the past decade examples of widespread forest die-off triggered by drought and temperature stress all across the world, but with a major hotspot in the western United States," he said. "These forest die-offs are an example of climate change already occurring in our own backyards. And that they've been triggered by the so far relatively moderate climate change portends bad news for the future."

Trees are an important part of the water cycle as they are effective evapotranspirers and help add moisture to the atmosphere, AccuWeather Senior Meteorologist Jason Nicholls said.

"So a lack or absence of trees would limit the amount of water added to the atmosphere through evapotranspiration," Nicholls said.

"Short-term dryness can be first noticed in vegetable and other plants before trees because their root systems are much closer to the surface than established trees," Nicholls said. "Newly planted trees without well-established root systems would also be more susceptible to short-term dryness. As short-term dryness evolves into drought, the drying of the soil works its way deeper so it will stress trees."

Dryness effects photosynthesis for both plants and trees, Nicholls added.

Trees provide immense economic and non-economic services to society.

"We rely on forests for a vast array of things, from timber and heating to storing immense amounts of carbon dioxide from the atmosphere, thereby slowing climate change," Anderegg said. "The economic value of these services from forests has been estimated in the trillions of U.S. dollars. Animals, too, rely on forests for food and habitat. The vast majority of Earth's species are found in forests."

A collapse of forest trees would be devastating to the environment, Anderegg said.

"It would be devastating regionally. In some cases, forests might be able to growth back or different tree species could grow back, but we know this takes decades," he said. "In other cases, we could lose those forests altogether and lose these incredibly valuable services. We've been studying a massive mortality of trembling Aspen in the western United States and we're seeing that most of these places aren't growing back as forests at all."

During drought, trees should be the no. 1 watering priority over lawns, according to Colorado State University. Lawns can be replaced in a matter of months but a 20-year-old tree will take 20 years to replace.