Joshua trees

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Joshua trees are some of the most iconic plants in the Southwest. They are also some of the oldest. With a lifespan of almost 300, years, Joshua trees have survived in the inhospitable Mojave Dessert for over 2.5 million years. Thanks to climate c change, nearly all of them could be extinct by the year 2070.

The fate of the Joshua tree

In a new study, scientists and researchers surveyed over 4,000 trees in Joshua Tree National Park in Southern California. The purpose of the study was to find out which trees could survive during periods of historic heat and drought. A Joshua tree can live up to 300 years. Because of climate change, temperatures over the next decade are predicted to be record-breaking. Temperatures are shown to be extreme, even for the desert. Joshua trees may only survive until the end of the century if the temperature predictions ring true. If we can curb greenhouse gas emissions, around 19% of the Joshua trees in the Joshua Tree National Park could survive past 2070. Summer temperatures could only rise by 5.4 degrees Fahrenheit for this to happen. If we stay on pace and no action is taken we stand to lose all of the trees habitats by the end of the century. At our current rate of carbon emissions, temperatures in the summer are rising by nine degrees Fahrenheit.

Joshua Tree National Park

The Joshua Tree National Park is located in the desert between Arizona, Las Vegas, and Los Angeles. The park spreads across 1,200 square miles. Joshua trees thrive in the desert because they are able to hold an incredibly large amount of water to help them survive through the worst droughts. Although they’ve survived for millions of years this way, if climate change continues they won’t be able to store enough water to survive. Droughts such as the epic one we saw from December 2011 to March 2019, was 376 weeks long. Parts of the park were too dry for young Joshua trees to live. The area became too try for the trees to grow properly and reproduce. The more our global temperatures rise, the longer the droughts are expected to be. Around the world, this means fewer and fewer Joshua trees. Researchers surveyed the park to find out which areas could support drought and which couldn’t. Thousands of trees were counted throughout the park. The scientists measured the heights of the trees to help determine the tree’s age. They also counted the number of sprouts found in an area. One finding was that more trees survived on a higher elevation.

The outlook

The research team also looked at climate records of years past to see how many Joshua trees could be lost if temperatures rise. As the temperatures rise and rainfall decreases, over the next century, it’s only likely that one in five Joshua trees will survive over the next 50 years. Unfortunately, if we don’t reduce the number of greenhouse gases, even the trees in the best locations could face extinction. Trees that are located in well-hydrated areas could still be in danger due to wildfires. Wildfires have been occurring a lot more frequently. Wildfires have also been a lot more intense. Fewer than 10% of the Joshua trees can survive during a wildfire. Part of the problem during wildfires is that car exhaust coats the plants and desert shrubs in nitrogen. Nitrogen is highly flammable and the plants aren’t able to withstand the fires. If changes aren’t made to our greenhouse gas emissions, we may not be able to save the Joshua trees and other desert wildlife. If we can protect our trees, we can also protect the animals and native insects inhabiting the area.