There’s bad news. But there’s good news, too.

If you haven’t seen this clip of a mother polar bear taking her new baby for baby’s first walk outside their den, you must. The spy-cam that caught it is amazing, as you’ll see, and the footage of Baby that Mama unwittingly helps the spy-cam capture will melt your heart.

Click the image above or below to see the clip, and be sure to watch all the way through. Baby enters at the very end.

The clip comes from the one-hour BBC documentary “Polar Bear: Spy on the Ice,” which isn’t available for viewing anywhere right now, sadly, but may air on Animal Planet in early March. Keep an eye out!

In the meantime, the clip above and four more below are available on Youtube, and they’re all a huge treat to watch — for the astonishing polar bear footage the spy-cams capture, the amazing and hilarious R2D2 type spy-cams the filmmakers used, and the utterly delightful narration by actor David Tennant. Check them out:

To watch a polar bear stage an amazing sneak attack on an unsuspecting seal, click below:

To watch three polar bears take a break from feeding on a kill to paw Snowball Cam, click below:

To watch different polar bears destroy different spy-cams, trying to figure out what they are, click below:

And, finally, to watch a flirtatious female arouse a male’s interest with cheesecake poses and risqué gymnastics, click below:

It’s wonderful to watch these videos and imagine polar bears living wild and free, healthy and unmolested in a cold, vast, blue-and-white universe of sky and water, snow and ice.

But that’s not their world anymore.

The U.S. Fish and Wildlife Service (USFWS) listed polar bears as a threatened species in 2008 due to loss of habitat throughout their range. Translation: There’s no more arguing about whether the Arctic winter sea ice polar bears depend on to hunt prey is disappearing or not. It is.

And if it keeps going the way it’s going, there’s also no more arguing about whether the estimated 20,000 to 25,000 polar bears left on the planet will disappear. They will.  The only question is when.

“Threatened” means “may face extinction.” “Endangered” means “facing it.” Greenpeace, the Natural Resources Defense Council, the Center for Biological Diversity and other conservation groups wanted polar bears listed as endangered in 2008. They still want that. But first the Bush Administration and now the Obama Administration have said, “No, things aren’t that bad yet.”

Oh, yes they are, conservationists argue. The government just doesn’t want to admit it because it doesn’t want to do what it might have to do to help save polar bears if it acknowledged the truth. Like: Ban oil drilling and gas exploration anywhere in polar-bear habitat. And: Significantly reduce the greenhouse gas emissions that scientists say are fueling global warming and melting the Arctic ice.

The two sides go back to court in a few days. Meanwhile, other interest groups have sued to prevent polar bears from getting any protections that could cost or inconvenience them. And the Republican-controlled Congress is pushing to cut EPA funding, dismantle the Clean Air Act and prevent the EPA from using the Act to pressure greenhouse-gas polluters to retool.

And, meanwhile, the ice continues to melt.

According to the National Snow and Ice Data Center, there was less sea ice in the Arctic this past January than in any January since satellites began keeping track in 1979. Almost half a million square miles of water that used to freeze regularly don’t now, and other areas that still do freeze are weeks late.

To put that number in perspective: Almost half a million square miles  — 490,000, to be exact — is an area bigger than Texas. A lot bigger. Almost twice as big.

What does this mean for polar bears? Here’s what it meant for one mother and cub: In late August 2008, researchers in Alaska collared a healthy, 498-pound adult female with a healthy, one-year-old, 350-pound female cub.

Two days later, according to their data, Mama led Daughter into the water off Alaska’s north coast and set out for the pack ice of the Beaufort Sea.

It wasn’t a good year for pack ice. The mother swam and swam. And swam. And swam. By the time she finally reached the ice, she had traveled more than 426 miles and had been swimming — ready for this? — for more than 9½ days straight. Closer to 10.

The sea ice this polar bear finally reached was out over deep water, where prey is scarce. When the researchers tracked her there two months later to retrieve the collar, she had lost more than 100 pounds (22 percent of her body weight), and her cub was gone: perished, the researchers suspect, during the long swim.

The point, to put it plainly: If the sea ice goes, the polar bears go, and the ice is going. But it’s not gone yet! That’s the good news. And a new study in Nature says we can still save enough ice to keep polar bears around for a while if we can cut greenhouse gas emissions enough to hold Co₂ levels below 450 parts per million (ppm).

We’re at 391 now — we, meaning the planet. That’s 41 ppm above the 350 mark many scientists consider the cap for preventing major climate change. And we’re still climbing — faster than before. So it’s good that still have time to prevent total sea-ice melt. But we don’t have a lot of it. If we want to put the brakes on fast enough, we have to act now.

And guess what?  Here’s more good news: There’s a glimmer of evidence, a shred of hope, that we we may actually be starting to do it — that enough of us are changing our energy-producing and consuming ways now to begin slowing things down.

Not all of us yet by any means. But enough to be having an impact.

Consider this: Although China (the world’s biggest greenhouse-gas producer) and India (much smaller but growing) keep pumping more and more Co₂ into the atmosphere every year…

… U.S. Co₂ emissions have actually declined since 2007. And that plus cuts made by other industrialized nations were enough to cancel out China’s and India’s increases and bring global Co₂ emissions down in 2009.

That’s right: down. Not a lot. Just a little. But it’s a start.

If you want to see some really cool things some really cool people are doing to keep emissions moving in that direction — and, trust me, you do….

….You have to see “Carbon Nation,” the new can-do, solutions-oriented, it’s-not-over-until-it’s-over documentary  now playing or soon opening in cities across the U.S.

To watch the trailer, click any of the images above or below.

It’s a short, sweet, wonderfully upbeat and entertaining film that will leave you feeling surprisingly hopeful about our chances of saving this fragile planet of ours….

….and newly fired up to want to do something to contribute to the effort yourself: Turn off a light. Change a light bulb. Unplug an appliance. Something.

We can all do something.

Imagine if we did.

Find Out More:

• To learn more about the making of “Polar Bear: Spy on the Ice,” visit director John Downer’s Web site here. Visit actor and narrator David Tennant’s blog here. Visit the BBC Web site here. Listen to or read a transcript of an interview with director John Downer here.

• Watch other great BBC polar bear videos here.

• Download the U.S. Fish and Wildlife Service’s 2008 ruling adding polar bears to the list of threatened species here.

• Learn more about continuing efforts to get polar bears listed as an endangered species here and here.

• Read Los Angeles Times and SF Appeal Online articles about efforts to get polar bears listed as endangered here and here.

• Visit the U.S. Fish and Wildlife Service’s polar bear Web site here.

• Read the National Snow and Ice Data Center’s February report on low January Arctic sea ice levels here.

• Read a summary of the epic-polar-bear-swim study or order the full study here.

• Read Los Angeles Times, Alaska Dispatch, Discovery News and JuneauEmpire.com/AP stories about the polar-bear-swim study here, here, here and here.

• Learn more about what George Durner, lead author of the polar-bear-swim study, and his colleagues at the U.S. Geological Survey Alaska Science Center are discovering about polar bears here.

• Learn more about what Steven Amstrup, co-author of the polar-bear-swim study, and his colleagues at Polar Bears International are finding out about polar bears here.

• Read the Nature study that says we can still save enough Arctic sea ice to give polar bears a fighting chance to survive here.

• Read a good sciencedaily.com article about the sea-ice study here.

• Watch the trailer for “Carbon Nation” and learn more about the film, how to arrange a screening and how to help fight global warming here.

• Get more tips on “How to Live Greener” from Polar Bears International here.

• See images from photographer Steven Kazlowski’s 2008 book The Last Polar Bear: Facing the Truth of a Warming World here.

• See more of photographer Thomas D. Mangelsen’s gorgeous images of polar bears and other wildlife here.