As many as three million people visit Joshua Tree National Park every year to see the twisted, bristled Dr. Seuss-like trees.

But, one day, Joshua Tree National Park might not have very many Joshua trees. In an interview for "LA Times Today," columnist Steve Lopez joined host Lisa McRee to explain why Joshua trees are dying. 

When Lopez visited Joshua Tree National Park five years ago, he says the trees did not look as vibrant and colorful as they used to.

"They were like a yellowish-green, and a lot of the leaf clusters had fallen off under the trees," he said. "So there is some obvious impact from droughts and not just on the trees but on the entire habitat. They are all related pieces of the ecosystem. So it is kind of sad to see the decline, and I had a pretty good guide to help me understand what was going on and why we need to be concerned about this."

Lopez recently visited the park with ecologist James Cornett, who has studied and revisited Joshua Tree National Park for years.

"He takes notes with a tape measurer, with a field computer and with a camera," said Lopez. "Chris is monitoring their health and how their health is changing. Our first stop was at the ocotillo study site. Now, the ocotillo is like a prawn plant, and when it is healthy and gets normal rainfall, the leaves are green, and the flowers are bursting. But now, that is not happening; we saw many dying limbs, and we came upon one ocotillo that had a nest built into the base of it. It looked like a small tumbleweed. Jim stopped and studied it and could not quite figure it out, but he said it was only the second time he had seen a nest like that. Then, James noticed that other plants that wood rats would ordinarily eat and get moisture from were also dead; even the cactus was dead near these ocotillos. So, he suspected that the rats were so desperate that whatever moisture they did get, they were trying to preserve within their bodies by building shade for themselves. So his theory was that they built a nest, they climb in there, and try to stay out of the sun."

Regarding climate change in California, Lopez says there is not enough focus on how deserts are impacted..

"I think we expect that if we go to the desert, it will be hot and dry, and that is how it is supposed to be, but there are things that live there that struggle to survive. And, that struggle has become a bigger hardship. Everything is connected, like the migrating hummingbirds from Mexico, which feed on the ocotillo do not have a place to eat. It means that because ocotillo and other plants are blooming a little bit sooner due to increased heat, it is throwing off the body clock for animals of all sorts. Because there are no wildflowers, there are no seeds, which means the rats do not have anything to eat, and the snakes do not have the rats to eat, and the hawks are impacted. It is a cascading effect."

Cornett has been writing about the desert for about 60 years, and he thinks climate change is one of the most significant factors. But he told Lopez that there is still hope for the future.

"The ocotillos and Joshua trees are doing just fine at higher elevations, and we ended our time together at a higher elevation in the Mojave Desert at a place called Lee Flat," Lopez said. "Even though there has been less moisture than there has been in decades past, it does not evaporate because it is not quite as hot. And, so those trees are flourishing. The other thing that gave me a little bit of hope is that Jim reminded me that we all have a role in this; we are all partly responsible as humans for lifestyles. We can all play a role in being more conservation-minded regarding how we drive, how we build and how we cool and heat our homes. The way climate change affects the deserts is another alarm being sounded, in this case by James Cornett. We have to take care of how we take care of our planet."

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