From melting polar icecaps to rising sea levels, the effects of global climate change are impacting our planet on a large scale.

Researchers at the UA Ecology and Evolutionary Biology department, successfully isolated the impact of increasing temperature on the pinon pine, one of North America’s most abundant species of pine tree, and the experiment produced some worrisome results.

“”Widespread die-off of pinon pine throughout the southwest will occur five times faster in future droughts if the climate warms by four degrees Celsius,”” said Henry Adams, the lead researcher of the experiment.

This equates to a 28 percent higher die-off rate than trees that were used as a control at cooler temperatures.

“”The increased mortality rate of pinon pines due to higher temperatures will increase the release of carbon into the atmosphere, affect erosion rates and increase the likelihood of forest fires in the southwestern United States,”” Adams said.

Furthermore, because the climate is warming, shorter duration droughts will have a more detrimental effect upon tree mortality rates than they did during cooler temperatures.

The experiment was conducted at the UA’s Biosphere 2 facility where researchers had the unique opportunity to isolate the effects of temperature on the pinon pine.

“”We used all the controls of the Biosphere facility which included moisture, relative humidity, overall temperature cycle and precipitation,”” said professor David D. Breshears of the UA’s School of Natural Resources.

The Biosphere provided researchers with the scale needed to perform the experiment on fully grown pinon pines rather than seedlings.

The main cause of draught-stressed tree mortality was identified as being carbon starvation. As the temperature increases, the pinon pines close off the tiny pores in their needles and are unable to absorb carbon in the atmosphere.

“”Intensifying the mechanism of carbon starvation showed us that warmer temperatures make pinon pines use carbon faster,”” Biosphere 2 Director Travis Huxman said.

While the experiment answered many questions, it raises new issues that Breshears, Adams, Huxman and other researchers will attempt to address.

“”Our next step will be a bridging study, conducted in Flagstaff, where we will compare trees that aren’t transplanted from their original environment to those that are in order to determine whether transplanting the trees affected our results,”” Breshears said.

While the experiment did use fully-grown pines, there still remains some doubt as to whether pinon pines, in their natural environment, have more fully developed root systems and are therefore able to absorb more nutrients and survive longer.

Breshears compared the adverse effects of temperature on pinon pines to a “”canary in the coal mine.””

“”It’s our role as scientists to highlight how big of a problem we are dealing with, hopefully our work will influence policy changes,”” Breshears said.