“It’s kind of a double whammy,” said Todd Dawson, a plant ecophysiologist at the University of California Berkeley, who also didn’t participate in the study. “They’re running out of water and also getting this heat stress,” he said. “They’re used to living in a very narrow temperature range of 8 to 27 degrees Celsius (about 46 to 80 degrees Fahrenheit). California, like everywhere, has been getting long periods of much warmer days than we’ve ever experienced, and now the fog, which is normally kind of like an air conditioner, has also declined between 30 and 40 percent.”

These temperature swings also impact the organisms living high up in the trees. “If they experience really excessive heat throughout the summer,” Ambrose said, “then the soil mats and ferns will probably dry out much faster. And then those salamanders and birds might not be able to live there. So we’ll see cascading effects through the whole ecosystem at that point.”

Klinek said, the trees seem to be doing okay after the heat passes; while the leaves she and her team looked at over their two-year study didn’t acclimate to the heat, they also didn’t lose their capacity to photosynthesize after the heat passed. While that’s a bit of hopeful news, it doesn’t reduce the urgency of the need to better understand the impact of climate change on these trees, and to reduce the warming itself.

“Right now the temperatures are coming back to normal in the fall and winter and letting the trees recover,” Klinek said. “But in five or 10 years, if temperatures are even hotter and heat waves are even more frequent, we don’t really know if there would be a recovery.”

For now, the salamanders and seabirds still have their homes high atop the coast redwoods. But we’re a part of the redwoods’ larger ecosystem too, even if we don’t live near them—they, like all trees, are key to keeping our planet hospitable. The trees Klinek studied have the potential to live for more than a thousand years. The question is if we’ll let them.