The giant sequoia is so enormous that it was once believed to be indestructible. High in California’s southern Sierra Nevada mountains, the oldest trees – known as monarchs – have stood for more than 2,000 years. Today, however, in Sequoia national park, huge trunks lie sprawled on the forest floor, like blue whale carcasses stranded on a beach. Many of these trees were felled by a combination of drought and fire. But among the factors responsible for the rising toll is a tiny new suspect: the bark beetle. Along with wildfires and rising temperatures, scientists fear that the insects could contribute to the breakdown of Earth’s northern conifer forests, including the potential dieback of the taiga, the vast ecosystem that stretches across Canada, Scandinavia, Siberia and Alaska.

Related wildfire and watershed article: 

• San Francisco Chronicle: Photos - How California’s dramatically transformed landscape increases wildfire risk
• Sierra Nevada Conservancy: Proposition 68 delivers a nature-based solution to Amador County wildfire risk