California wildfires aren’t the only thing killing the state’s majestic giant sequoia trees. So is a little-known bark beetle. Researchers in the Sierra Nevada, the only place where the giant sequoia naturally grows, have found several of the world’s largest trees unexpectedly infested with beetles, some dying from the attacks. While the mortality numbers are small, especially when compared to the toll of the wildfires that wiped out as many as 20% of all mature sequoias in 2020 and 2021, the emergence of another lethal threat to the titans — this one also tied to the warming climate — is hugely worrisome. That’s why research teams at Sequoia and Kings Canyon National Parks are climbing into the towering canopy of the Giant Forest this week and assessing the condition of the biggest tree on Earth, the 275-foot General Sherman Tree.