“It gives you a sense of the magnitude” of climate change, President Obama said, as adventure show host Bear Grylls pointed out just how far an Alaskan glacier had receded since Obama was elected to the presidency in 2008.

Scientists estimate that the Arctic region is warming twice as fast as the rest of the world. The president saw this firsthand when he appeared on a recent episode of the television show Running Wild with Bear Grylls.

“It underscores once again why it’s so important for us to pay attention to climate change and understand there’s something we can actually do about it,” the president said.

Nearly 200 countries are doing something about it. They’ve reached a landmark climate agreement to reduce the carbon emissions that drive global warming in Alaska and elsewhere.

What about that grizzly bear? On their hike through Kenai Fjords National Park, Grylls and Obama feasted on a half-eaten salmon left behind by one of the park’s ursine residents.

While it was sobering for the president to see the impact of climate change, he enjoyed his day hiking in the mountains. It was, he said, “one of the best days of my presidency.”

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