Whitebark pine is a rugged, tough, resilient, beautiful tree that inhabits the high country of the Northern Rockies. Whitebark pine is typically the last tree one sees before going above timberline. Whitebark pine seeds - or pine nuts - feed Clark's nutcracker birds, red squirrels, and grizzly bears.

In the Greater Yellowstone Ecosystem (GYE), whitebark pine seeds are the primary food source for grizzly bears during late summer and fall when the bears are trying to fatten up for their winter hibernation. Bears in Alaska have salmon, bears in Glacier National Park have berries, and bears in the GYE have whitebark pine seeds.

But the whitebark pine population is being rapidly decimated by global warming.

The main killer is the mountain pine beetle, which bores through the tree's bark, cuts off its supply of water and nutrients, and starves it to death. A second killer is blister rust, a fungus accidentally introduced from Europe in the late 1800s.

While mountain pine beetles are native to the West, the high-altitude environment that whitebark pine trees inhabit has typically been too cold and harsh for the beetles to do any damage. Prolonged cold snaps (i.e., 40 below zero for several days) in whitebark country previously prevented major beetle infestations.

But global warming has changed that.

Milder temperatures have allowed the beetles to move to higher altitudes and prey on whitebark pine. And while other trees evolved with the beetles and have natural defenses (e.g., lodgepole pine), whitebark pine have none. As such, the beetles are literally destroying the whitebark pine ecosystem in the Northern Rockies.

And it's happening alarmingly fast.

Earlier this week, I had the opportunity to see this devastation up close. I was in Jackson, Wyoming, for an event on whitebark pine and grizzly bears. NRDC and the Jackson Hole Conservation Alliance sponsored the event, which was held at the Teton Science School's Jackson Campus. The event featured presentations by legendary grizzly expert Doug Peacock, renowned entomologist Dr. Jesse Logan, talented guide/writer/musician Thomas Turiano, and the delightful musicians Beth McIntosh and Phil Round.

The next morning, Bruce Gordon of EcoFlight flew a few of us over the Teton Wilderness, which is east of Grand Teton National Park and south of Yellowstone National Park, to see some of the damage from the air. What I saw was shocking: hundreds and hundreds of acres of red (dying) and gray (dead) whitebark pine forests. Dr. Logan has seen such devastation all over the GYE and predicts that whitebark pine will be functionally gone from the GYE in less than ten years.

The decimation of whitebark pine in the Northern Rockies is a tangible manifestation of the harmful effects wreaked by global warming. And the loss of whitebark pine will be catastrophic for grizzly bears and the Greater Yellowstone Ecosystem, which is why NRDC filed a petition with the U.S. Fish and Wildlife Service in December 2008 to list whitebark pine as an endangered species.

Because whitebark pine is found at high elevations, it keeps grizzly bears in the high country in late summer and fall - and away from people. Without whitebark pine, the bears will be forced to go to lower elevations to find food, and more human conflicts will occur, which often end badly for the bear involved. (There were 37 human-caused bear mortalities in the GYE in 2008, the highest number ever recorded.)

The dismal scenario I've described is very real, but there is some good news. Whitebark pine is doing well in the Wind River Range in Wyoming and on the Beartooth Plateau in Montana. Both still have the requisite prolonged cold snaps (thanks to glaciers in the Winds and high elevation on the Plateau) needed to kill the beetles. This points to one conclusion: we need to curtail global warming - quickly.

Yesterday, progress was made when the House Energy and Commerce Committee passed the most ambitious energy and global warming legislation ever debated in Congress, which NRDC helped shape. But this bill still has a long way to go before it can be signed into law by President Obama. And all of us still have a long way to go to curb our greenhouse gas emissions and reverse the warming trend.

Whitebark pine and Yellowstone's grizzlies are two more reasons to care about global warming.