Early Snowmelts Dirsupt Subalpine Forest Carbon Dioxide Uptake

A new study revealed that earlier snowmelts caused by global warming are disrupting the ability of subalpine forest to regulate atmospheric carbon dioxide.

The study, published in the journal Geophysical Research Letters, suggests that earlier snowmelts that occur during colder air temperatures reduce the ability of the forest to take carbon dioxide out of the atmosphere.

For the study, the researchers analyzed 15 years worth of snowmelt and atmospheric carbon dioxide data.

The forest ability to take carbon out of the atmosphere is being restrained during winter, but increase to peak capacity in spring when snowmelt provides sustained water input. However, global warming causes the snow to melt during the colder periods of the seasonal temperatures cycle. Due to this, the trees ability to uptake carbon dioxide during snowmelt period is reduced. Snowmelt period is a key period for a seasonal carbon uptake.

"The implications of this research are quite profound as mountains in the western U.S. are an important part of the regional cycling of carbon and water," explained Noah Molotch, the director of the Center for Water Earth Science & Technology (CWEST) and a co-author of the study, in a statement. "In this regard, earlier snowmelt will reduce carbon uptake in mountain forests, weakening the ability of forests to offset increases in CO₂ associated with human burning of fossil fuels."

Another study, also co-authored by Molotch, showed that slower snowmelts might also reduce the amount of streamflow, which could potentially affect agriculture, municipal water supplies and recreational opportunities.

"This analysis suggests that all of the regions studied will experience a decrease in streamflow with a decrease in snowmelt rate, with some regions exhibiting more streamflow sensitivity than others," said Theodore Barnhart, a graduate researcher at INSTAAR and lead author of the study, in a press release.

According to the researchers, the decline of snowmelt-derived streamflow might affect 60 million people in the western United States who depend on snowmelts for their water supply. Additionally, it can also put additional stress on over-allocated water supplies.