Damage among Yellowstone National Park's crucial white-pine trees is higher than anticipated, according to the Natural Resources Defense Council (NRDC), as beetles wreak havoc on this crucial source of food for the region's grizzlies.

The white pines are being ravaged by beetles; a visual inspection by NRDC folks indicate heavy damage among forests of white pines, sometimes reaching 70 percent losses. The beetles aren't new to Yellowstone, but they're doing more damage now that winters are milder in the Park ecosystem, giving them extended seasons to wreak havoc. It is the most visible sign of global warming in the Park, and one that affects a major species whose survival is already in doubt. There's no easy solution here, no fix that Park Service officials can implement, but it's a clear warning sign in the debate over global warming.

Keep up with the latest in Yellowstone National Park news with our free weekly Yellowstone Insider newsletter, where this article first appeared. Subscribe today! More details here.

Follow Yellowstone Insider on Facebook! Click this link to go to our Facebook page, which features story updates.

We've also set up a free Twitter account so you can receive updates on the device of your choice.