The most significant problems for U. S. national parks.

In 20 years, many of the country's 411 national parks, monuments and historic sites will suffer damage as sea levels rise, wildfires rage, glaciers melt and iconic wildlife, such as grizzly bears in Wyoming and pikas in Colorado's high-altitude tundra face shrinking habitat and scarce food.

Hope this helps you if I am wrong sorry
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Iwould say silver and gold