MEDICINE BOW NATIONAL FOREST, Wyoming – From the vantage point of an 80-foot (25 meter) tower rising above the trees, the Wyoming vista seems idyllic: snow-capped peaks in the distance give way to shimmering green spruce.

But this is a forest under siege. Among the green foliage of the healthy spruce are the orange-red needles of the sick and the dead, victims of a beetle infestation closely related to one that has already laid waste to millions of acres (hectares) of pine forest in North America.

“The gravity of the situation is very real,” said Rolf Skar, a forest campaigner with Greenpeace.

The plague has cost billions of dollars in lost timber and land values and may thwart efforts to combat climate change, as forests are major storing houses of carbon, the main greenhouse gas blamed for global warming.

The beetle outbreak, which has taken a lesser, but mounting, toll on spruce trees, could make it that much tougher to meet the ambitious target to reduce U.S. carbon emissions by 17 percent of 2005 levels by 2020 and 83 percent by 2050.