John Harte is an ecologist at the University of California at Berkeley.

He and his colleagues wanted to know how an increase in air temperature would affect plants and soils in a sub-alpine meadow in rural Colorado. For the past 14 years, they’ve used heaters to artificially warm several plots of land in the meadow by two degrees Celsius.

In the heated plots, flowering plants are being replaced by sagebrush – a woody shrub that can tolerate more heat and dryness. Sagebrush doesn’t store carbon in the soil as well as flowering plants. So that leaves more carbon in the air in the form of the greenhouse gas carbon dioxide.

So an increase in sagebrush could ultimately lead to more heat trapped by Earth’s atmosphere – and a further temperature rise. Also, sagebrush leaves absorb more sunlight than the leaves of flowering plants. According to Dr. Harte, both of these feedbacks can make Earth warmer.

John Harte: My current belief – based not just on my experiments now but other people’s as well – is that our current global warming models are probably underestimating the magnitude of future warming because they ignore these ecological feedbacks.

Our thanks to the National Science Foundation – where discoveries begin.