Everything Everywhere Daily: History, Science, Geography & More - The Dry Valleys of Antarctica

Starting point is 00:00:00 Many places on Earth have extreme climates. However, there is one place on Earth that has a climate so extreme that the closest thing to it might be on another planet. Despite having the most inhospitable and unforgiving climate on Earth, researchers have been shocked at what they found there. Their discoveries may help pave the way to finding life outside of our world. Learn more about the dry valleys of Antarctica, how they came to be, and what makes them so unique on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night.

Starting point is 00:00:55 And how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR. Antarctica is the continent that people most often forget is even there. There's no permanent population. and there's no real economic activity to speak of beyond the small number of tourists it gets. If you envision Antarctica as a land covered in ice and snow, you wouldn't be wrong. 98% of Antarctica is covered with ice. In fact, the ice cap over Antarctica has an average thickness of two kilometers.

Starting point is 00:01:31 That means that most of the surface of Antarctica is pretty uniform and boring. However, there is that 2% that isn't covered with ice. And that is where interesting things can occur. Of the land that isn't covered with ice, there isn't much there either. There are hardly any plants in Antarctica. There are technically two species of flowering plants, and those never get more than a few centimeters off the ground. The remaining plants are nothing more than lichens that cover rock.

Starting point is 00:01:59 There are no land animals that make their home in Antarctica. Some seals may climb onto the rocks, along with some migratory birds and penguins, but that's about it. These few life forms that tenuously exist in Antarctica are not the subject of this episode. These stunted plants with tenuous growing seasons actually have it easy because there's a place in Antarctica that is much worse. Approximately due south of New Zealand is the Ross Sea, which is really just a bay in the southern ocean off of Antarctica. This is home to one place in Antarctica that you might have heard of, McMurdo Station. McMurdo Station is the largest scientific base in Antarctica and is run by the United States National Science Foundation.

Starting point is 00:02:38 It can support a population of up to 1,200 people. and only three kilometers away from there is the much smaller Scott base, which is operated by the New Zealand government. Both of these bases are located on the McMurdo Sound, which is the southernmost part of the Ross Sea and the southernmost body of navigable water in the entire world. The focus of this episode is located directly across McMurdo Sound from these two research stations. Here you will find the largest single section of land in Antarctica that is ice-free, the McMurdo Dry Valleys, also known as. as the Antarctica dry valleys. They were first discovered in 1903 by the explorer Robert Scott. He looked upon them and called them a valley of death.

Starting point is 00:03:20 If you look at Google Earth or some other similar mapping software that uses satellite images, you'll be able to clearly see it because it's a large patch of dark rock surrounded by white ice. There are several of these valleys in close proximity to each other, each of which has mountains with ice on their peaks surrounding them. So what makes these valleys, which are quite literally in the middle of nowhere and don't seem to have anything on them, so special? If you remember back, I previously did an episode on the Atacama Desert in Chile. The Atacama Desert is often called the driest place on earth. There are parts of the Atacama that have never had recorded rainfall, and on average the desert gets only 15 millimeters of rain per year.

Starting point is 00:04:02 Well, the Atacama Desert is a veritable rainforest compared to the McMurdo dry valleys. On average, the dry valleys get zero precipitation. However, just saying they get zero precipitation doesn't really hammer home the point of just how little precipitation they get. Researchers who have studied the dry valleys believe that there has been no precipitation here in the last two million years. If true, it means that there has not been any precipitation in the dry valleys at any point since human beings have existed. So what makes these valleys so especially dry compared to everywhere else on Earth? Well, the first thing is obviously the temperature. Antarctica as a whole is quite dry due to the low temperatures.

Starting point is 00:04:51 Antarctica is the driest continent, and the continent on average only gets 116 millimeters of precipitation per year. It just doesn't seem like that because everything that does fall never melts and just keeps accumulating. The cold temperatures mean that there's very little moisture in the air which can precipitate out. The next thing which causes the unique conditions are the Trans Antarctic Mountains. The Trans Antarctic Mountains are probably one of the lesser-known mountain chains in the world, but they extend across the continent and run right down the coast of the raw sea and include the dry valleys. The mountains, as mountain chains do everywhere in the world, block clouds and precipitation. In the case of Antarctica, it also blocks the flow of the ice sheet, which is why this region

Starting point is 00:05:35 isn't covered in ice like every place else on the continent. The other thing that makes it extremely dry are the catabatic winds. This is really what separates the dry valleys from other arid locations in both Antarctica and on other continents. A catabetic wind is an airflow that results from cold, dense, air flowing down a slope due to gravity. As these winds drop in elevation, they pick up speed as well as temperature. Wind speeds in the dry valley can reach speeds of up to 320 kilometers per hour or 200 miles per hour. Because Antarctica has an enormous ice cap, it also has the highest

Starting point is 00:06:13 average elevation of any continent. When catabatic winds blow down in these valleys, they increase in temperature. Still cold in the big scheme of things, but warmer than what it was at the top of the the mountain. The rapidly moving dry air can then sublimate most ice or snow that happens to be in the way, preventing it from melting and turning into a liquid and seeping into the soil. However, it doesn't remove all of the ice necessarily, as we'll see in a bit. So it's a unique set of conditions which doesn't exist anywhere else on Earth, which explains the extreme lack of precipitation in the dry valleys. However, there is a catch. The dry valleys actually do have some water, just not from precipitation. During the very short Antarctica summer, temperatures can get above

Starting point is 00:07:00 freezing for a very short period of time. When this happens, small amounts of ice from glaciers can melt and flow into the valleys. In some of the valleys, this water has actually accumulated in the form of lakes. Now, you might be wondering how it could be possible for water to accumulate in such an environment. That's because over time, what little water has seeped into the area has brought with it minerals, and the water has become incredibly salty. So you wind up with the seeming paradox of the driest place on earth having lakes in the middle of it, albeit extremely salty lakes. Lake Vita, one of the largest lakes, is perpetually covered in ice. The ice cap on the top of the lake is 21 meters or 69 feet thick, making it the deepest ice in the world that isn't

Starting point is 00:07:46 part of a glacier. The briny water beneath the ice has been locked away from any contact from the atmosphere or the rest of the world for thousands of years. The brine is seven times more salty than the ocean, and some of the lakes have higher salinity than the Dead Sea. One pool known as Don Juan Pond has a salinity level of 33.8%, which means that it'll only freeze when temperatures reach minus 50 degrees Celsius or minus 58 degrees Fahrenheit. Everything I've just described from a geologic standpoint is really interesting. Such an extremely dry place with what little water is there locked under 21 meters of ice in the form of a hyper-salin solution is pretty cool. However, there is a lot more to the story. This extremely cold and dry environment seems, at first glance, extremely similar to

Starting point is 00:08:35 someplace else. Another dry, cold environment that scientists are very interested in. Mars. So the big question, is could life exist in this extremely inhospitable place? I should note that life has been found almost everywhere on Earth. Even in the Atacama Desert, it's possible to dig beneath the surface and find some microbial life. In 2013, a team of researchers from the United States and Canada drilled into the permafrost in one of the driest parts of the valleys to test a drill that was considered for use on Mars. And in their sample, they found nothing. It was the first time absolutely no microbial life forms were found in the soil anywhere on Earth.

Starting point is 00:09:20 However, just like the search for life on Mars, you can't just take one sample and call it a day. You have to check again somewhere else. Well, they did actually manage to find life in several places in the dry valleys, although they were places you probably wouldn't expect, and they were forms of life unlike any other found on Earth. One of the places where microbial life was found was inside some of the wrong. rocks. If you remember way back to my episode on the deep biosphere, there have been microbes found in rocks far beneath the surface of the earth. These microbes often live inside tiny pores inside of

Starting point is 00:09:55 rocks and have incredibly slow metabolisms. Such microbes are known as crypto-endolithic life forms, crypto-meeting hidden, endo-meeting inside, and lithic-meeting rock. Anorobic bacteria that survived just on iron and sulfur have been found underneath one of the glaciers, that are near the dry valleys. These microbes are able to use energy without the presence of oxygen. Cyanobacterial mats have been discovered, which use the extremely small window every year where glacial water may melt. They only exhibit metabolism for about eight weeks every year.

Starting point is 00:10:29 In the extremely briny waters of the valley have been found extremophile microorganisms that are adapted to high levels of salt. Some of them have been found dormant in the ice covering the brine lakes and have been revived after being dormant for thousands of years. Despite the researchers who found nothing, which is in and of itself quite a discovery, it turns out that the dry valleys actually have a wide variety of microorganisms that live there. You just have to look for them very closely.

Starting point is 00:10:57 So what does this all mean? Well, for starters, it means that life can find a way to exist in almost any environment. However, it also means that if microbial life can exist in such an extremely arid and cold environment, sometimes only showing signs of life for a few weeks a year or less, then perhaps such life could exist somewhere like Mars. We know that there appears to be briny water on Mars that flows infrequently. That might be very similar to the conditions which exist in the dry valleys along McMurdo Sound. And if life can exist in the dry valleys, then it might be able to exist on Mars.

Starting point is 00:11:34 The dry valleys of Antarctica are an extraordinary and otherworldly landscape characterized by extreme dryness, minimal ice and snow cover and harsh low temperatures. Their geological origins, lack of ice, distinctive geology, and scientific significance makes them a captivating and critical area of study for scientists, seeking to understand both our planet's past and the potential for life beyond Earth. The executive producer of Everything Everywhere Daily is Charles Daniel.

Starting point is 00:12:05 The associate producers are Thor Thompson and Peter Bennett. I just want to thank everyone, including the show's producers, who support the show over on Patreon. If you'd like to support the show, just head over to patreon.com, which is currently the only place where you can get show merchandise. Also, if you want to talk to other listeners about the show, head over to our Facebook group or Discord server, both of which have links in the show notes.

Everything Everywhere Daily: History, Science, Geography & More - The Dry Valleys of Antarctica

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