What even is a desert?
When you think of a desert, what comes to mind?
- A sweltering endless expanse of sand dunes
- A frozen ice sheet
- A rocky beach
- A dry mountain range home to cacti and venomous snakes
If you any or all of the above popped into your head, you’d be correct. On earth, roughly a third of all land is desert, but deserts are as diverse as the species that inhabit them. We often think of the merciless sun as a desert icon, yet it is in fact rainfall that is generally the only factor used to classify deserts. A desert is simply any place that receives less than 25 cm of rainfall in a year, which means that deserts are found on every continent, including Antarctica.
How do animals and plants survive in deserts?
Contrary to common belief, deserts can actually have an incredible amount of diversity, although they are not without their challenges. The dry conditions, paired with often extreme temperatures, mean that species that live in deserts have developed a variety of special adaptations that allow them to survive in such challenging conditions. That starts right at the base of the food web, with plants. Some desert plants have a waxy coating or unique leaf structure in order to prevent water loss, and species of cactus go the extra mile by not having any leaves at all. Other plants have widespread roots in order to reach as much underground moisture as possible. These adaptations allow the plants to go many months without any rain.
Animals deal with a lack of rainfall in a different way. Desert tortoises can get water from their food, store it in their body, go months without drinking, and have highly concentrated urine in order to decrease the amount of water they lose over that time period. Reptiles such as lizards have a thick layer of skin that prevents water loss. In Antarctica, a cold desert, penguins are able to take in saltwater and then secrete excess salt, avoiding the need to find freshwater.
What happens when deserts get even dryer?
Animals and plants have both developed unique ways to survive in extreme conditions. However, these extremely specific adaptations might not protect every desert species from the impacts of climate change.
One very important impact of climate change is desertification, which is land degradation that takes place in dry areas and turns fertile land into a desert. Desertification makes an area less habitable for animals, plants, and people. Over the next century, climate change is predicted to lead to decreased rainfall in some areas, along with increased drought (and more severe drought) and higher temperatures. This, coupled with our clearance of vegetation that moderates extreme heat and retains water, means that even more of the planet will become desert. Although desert species are adapted to tough conditions, many species are essentially already living on the edge, and even more severe conditions might push them over the edge. For non-desert species, it will have an even bigger impact.
Desertification leads to a decrease in biodiversity (which here means variety/number of different species in an ecosystem), and can lead to extinction for species that can’t relocate or tolerate harsher conditions. For people, it leads to a decrease in usable land.
In these deserts, often the only way humans can survive there is by having a system to bring in water from somewhere else. In the western United States, 40 million people across 7 states and 30 native tribes rely on water from the Colorado River, and have developed detailed agreements to determine how the water is distributed. As populations grow and available water decreases, there will come a time when there isn’t enough water for everyone, and that time might come earlier than people thought. This summer, the US government directed states to find ways to decrease their water use over the next year. If they don’t, the government will make emergency cuts to water allowances in order to ensure that the water reservoirs don’t get too low.
Currently, there are more than a billion people that live in deserts. As deserts become harder to live in, not everyone has the means to relocate to somewhere better. People living in deserts will have to cope with less fresh water, poor sanitation, malnutrition, an increase in diseases, and more.
So what can we do in order to survive in these deserts?
Even though there already isn’t much water in deserts, people living there will have to find ways to use even less water in order to preserve what we have. Indigenous people have been successfully living in deserts for thousands of years, using strategies like moving to cooler areas during the hotter seasons and only growing crops that suit the environment and season. If we want to succeed, we should listen to indigenous communities and adopt these strategies.
We’ll also need to take steps to become more sustainable so that we can share resources like water and ensure that no one has to go without it. We can adapt our infrastructure by taking actions such as installing rainwater harvesting systems and increasing available shade. Living in the desert is incredibly challenging, and it’s not going to get any cooler, but if we learn from those that’ve been here longer than us, we can make the desert our home as well.
Holly Albrecht is currently an educator/zookeeper, and holds a Bachelors degree in Conservation Biology from the University of Arizona. She is passionate about ichthyology, herpetology, and using education/outreach to get people interested in conservation and the natural world.