Ask the Dust

What the driest place on Earth can tell us about climate change

By Aaron Carnes

December 16, 2018


Photo courtesy of Armando Azua-Bustos

In 2003, Dr. Chris McKay at the NASA Ames Research Center, proposed using the Atacama Desert in Chile as a testing site for robots and instruments bound for Mars. His sights were set on Yungay, a town in Peru that he had determined to be the driest part of the Atacama Desert.

Armando Azua-Bustos—who was working in plant biotechnology in Santiago, Chile, at the time—reached out to McKay. Azua-Bustos was not an expert in space exploration, but he had spent a good chunk of his childhood playing in the Atacama Desert. He grew up in a small mining town, and it was not uncommon for him to be gone for hours at a time on his bicycle exploring, and later, when he could drive, out on a 4WD. As a kid, he remembered driving by Yungay and seeing heavy fog when other parts of the desert remained clear and windy.

He didn’t expect a reply and was surprised when McKay responded with interest. After their conversation, Azua-Bustos traveled to the Atacama and placed a number of sensors in areas where he remembered as saying clear. Several of the areas—Maria Elena South, Cerritos Bayos, and Moctezuma—proved to be drier than Yungay. Impressed, McKay brought him onto the project as a principal investigator, repeating experiments done by Viking Landers but using Atacama soil.

After the experiments were over, Azua-Bustos continued studying the Atacama on his own. In 2009, while conducting his own studies on how certain life-forms had adapted to the harsh terrain, he was surprised to discover new microbial life-forms, which he wasn’t directly searching for. He wasn’t the first scientist to find life out there, but he found the desert was still full of surprises, even at its hyperarid core.

In 2013, Azua-Bustos completed a PhD in molecular genetics and microbiology at the Pontificia Universidad Católica de Chile. Today, he works as an astrobiologist, studying the origin of life on Earth and the possibilities of finding life elsewhere in the universe. Azua-Bustos believes the key to understanding this could very well be in the Atacama Desert, where life-forms have adapted to an environment with virtually no water.

SIERRA: Have you seen changes in the Atacama Desert in your lifetime?

Armando Azua-Bustos: Even this amazing place is being affected by climate change. The north part of Chile, where the Atacama is located, is raining more than ever before, and it's raining less in the south part of Chile, which is more or less similar to Switzerland in the vegetation you have around.

We are now investigating what that means for very ancient ecosystems that have not seen water for several million years. The Atacama is not only the driest place but also the oldest desert on Earth. It has been dry for the last 150 million years, and it has been really really dry for the last 15 million years. In 2015 and 2017, for the first time in recorded history, there has been rain coming into the Atacama from the wrong direction—huge masses of clouds from the Pacific Ocean. People are reporting rainbows in the middle of the hyper-arid corridor of the Atacama.

Life adapts to different situations, but it's not immediate. It takes time for evolution to run its course. If you change the conditions so quickly, maybe life is not able to adapt. It's raining more in the Atacama, and that is not so good for the life-forms that are adapted to the lack of water.

How important is it that we put resources into adapting to climate change as opposed to preventing it?

They’re equally important because we still do not know the full effect of climate change. We should do something about it where we can prevent it, but you can start planning for strategies to adapt.

There was somebody in Latin America that invented this apparatus that was able to collect water from the atmosphere, even in the Atacama. You wouldn't get water on the first day, but after a week you would get water from clean air.

Were you surprised to find life-forms in the driest parts of the Atacama?

Maybe there is a dry limit for life on Earth, but we haven't even been able to find it yet. I'm really close to that limit and I'm still finding life. For this, I have to introduce the concept of water activity. A glass of pure water will have a water activity level of 1.0. In the driest site I found in the Atacama, water activity level was 0.15. Even there we found a number of microorganisms.

Maybe there is no such thing as a dry limit. But we cannot test that until we find a place where water activity level is zero. If we do find a place where water activity level is zero, if it is not inhabited, we will find out there is a limit for life on Earth. If we do find life-forms—and I think that may be the case—it means that we could have life-forms on Earth independent of the amount of water, which would be a huge discovery.

Can you explain how your research is showing ways we can better adapt to our world as we contend with the effects of climate change?

About 70 percent of the continent will get drier over time. That's a problem we will have to solve.

There are several mechanisms on how microorganisms are able to adapt to lack of water. When you forget to irrigate the plants, there is a period of time where you can irrigate the plant and the plant will revive again. But there is a point called the permanent wilting point. If this takes place, it will die anyway. How do we find a way to prevent that? It’s been calculated that you need a layer of at least one molecule of water around important macromolecules inside a cell in order to prevent their unspecific aggregation when desiccation takes place.

Some microorganisms, in order to prevent this, synthetize high amounts of different types of sugars, which fulfill the role of water as a molecular shield. These sugars, like trehalose and sucrose, have been found in some of the bacteria we found in the Atacama, which explain while they are so tolerant to extreme desiccation. The answers, nature already found in really dry places like this one.

Do you think in our lifetime we’ll be faced with a world where there isn’t enough water to nourish the living species without technology fixing it?

We've just seen that in Chile. There are some areas farther south you are seeing many fields being abandoned because people cannot grow anything anymore. I have heard that we are starting to import those things that we are not producing anymore. We have seen a very dramatic example happening in South Africa, that for a whole city of several million, they have less than one month of water available. It’s something that sadly is going to be very common. It’s very unpredictable.

I have heard it was predicted that Spain would get drier from climate change, but now people are starting to see the opposite. It’s raining more. This is getting truly unpredictable. Who will be affected by what kind of strange weather?

What other areas do you see your research impacting?

There are a lot of biomedical applications. We have found 20 or 30 novel new species in these places. Maria Elena South is the driest place on Earth—as dry as Mars. However, even here we found a number of different microorganisms, although the diversity was low. Several of these species belong to the Streptomyces genus of bacteria, and other previously known Streptomyces species have given rise to important antibiotics in the past, like Chloramphenicol and Neomycin. We just sent a proposal to start exploring which kind of antibiotics this might be producing, which is a huge problem we're about to face.

Even that place where it looks like there's nothing, it has life and this life may be useful. Maybe we'll find the cure for cancer in bacteria in amazingly dry places, or we may lose them because someone decides to build a new lithium plant just at the one place you can find it.

There are now many mines all around, enclosing areas where it's not as easy to get in as it was in the past. Other areas have been "given" to local communities due to their touristic potential, and now I have to pay for getting into places that were free before.

There's a lot of places that are seemingly wastelands. I'm trying to get the message out that the desert is not a wasteland where you can just build a plant or dig a new mine anywhere. Most people will say there's nothing to protect in the Atacama, but I'm trying to show that it is the opposite.