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Can the Azolla Fern That Cooled the Planet Do It Again?

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Some scientists are exploring the use of carbon dioxide hungry plants like Azolla...

Fifty-five million years ago, when scientists believe the Earth was in a near-runaway state, dangerously overheated by greenhouse gases, the Arctic Ocean was also a very different place. It was a large lake, connected to the greater oceans by one primary opening: the Turgay Sea.

When this channel closed or was blocked nearly 50 million years ago, the enclosed body of water became the perfect habitat for a small-leaved fern called Azolla. Imagine the Arctic like the Dead Sea of today: It was a hot lake that had become stratified, suffering from a lack of exchange with outside waters. That meant its waters were loaded with excess nutrients.

Azolla took advantage of the abundant nitrogen and carbon dioxide, two of its favorite foods, and flourished. Large populations formed thick mats that covered the body of the lake. When rainfall increased from the changing climate, flooding provided a thin layer of fresh water for Azolla to creep outward, over parts of the surrounding continents.

Azolla bloomed and died like this in cycles for roughly 1 million years, each time laying down an additional layer of the thick blanket of sediment that was finally found in 2004 by the Arctic Coring Expedition.

The fact that the fern only needs a little over an inch of water under it to grow makes the whole scenario seem just within reason—that is, until you learn how much carbon this carbon dioxide-hungry plant sucked up over the course of those million years.

"Around half of the CO2 available at the time," said Jonathan Bujak, who studies dust and fine plant particles as a palynologist. "Levels dropped from between 2500 and 3500 [parts per million] to between 1500 and 1600 ppm."*

While what ended the Azolla age remains unclear, the next 49 million years saw the Earth fall into a cycle that brought even more drastic drops in CO2 levels.

The southern continents broke up, and, as South America and India migrated north, the Antarctic become isolated and increasingly cold, absorbing more CO2 and creating a conveyor-belt-like effect of cold air that perpetuated ice. A succession of ice ages was triggered once the atmosphere's CO2 dropped below 600 ppm around 2.6 million years ago, just 200 ppm shy of the Earth's current estimate.

Cyclical glacial ages began, rotating between 100,000 years of massive glaciers, followed by 10,000-year breaks. By the mid-18th century, CO2 levels were at 280 ppm.

Finding modern uses for a heroic plant

"What's really incomprehensible," Bujak said, "is that the previous process of our planet cooling and CO2 dropping took 50 million years to unfold. Now, we may be reversing this process in a matter of centuries."

What is known about Azolla's true inner workings may still only skim the surface, but people all over the world, like Kathleen Pryer, a Duke professor who is crowdfunding the fern's genome, have continued to find creative ways to explore its possibilities. Alan Marshall, a former radiologist living in Tasmania, Australia, is just one example of a citizen scientist who believes Azolla can help the planet reach a better balance.

Eat your Azolla. It's good for you.

Others have taken to experimenting with the edible aspect of Azolla, including Andrew Bujak, a chef and son of Jonathan Bujak. Andrew Bujak has been growing it at his home in Canada. Initially interested in the slow food concept, an Italian movement spawned in opposition to the growing influence of fast-food chains like McDonald's Corp., Bujak saw a personal use for Azolla.

"I realized this was not only a good food source, being nutritious and virtually tasteless, but it could be grown by anyone pretty much anywhere in the world. It's easy enough to find, either online or at stores selling aquariums. Just add water, literally," Bujak said with a laugh. When asked to describe the taste of the fern, Bujak compared it to a blade of grass.

Azolla has grown not only in Canada but nearly everywhere in the world, Bujak said, so it's adapted to many different regions and climates naturally. This makes it easy for people to simply pick it up and put it to use.

"Maybe you're a small-time farmer in Alberta and you want to cut costs and leave less of a carbon footprint," Bujak said. "Grow Azolla, and boom, you now have a valuable fertilizer, food source for livestock and something to eat yourself."

He added that Azolla could also be a superfood of the future, both because of its nutrition and because of how little land it requires.

"Even if we grew it as crops, it wouldn't be wasting other cropland. It would simply be added to existing systems, such as it is now used in rich paddy crops," Bujak said. "In conditions when space for food growth is extremely limited, Azolla offers a lot of nutrition for a small amount of space. They have even been working on its use in outer space!"

Bujak said his next project is to recreate nori, pressed dried seaweed sheets, using the fern. Currently, Azolla can be sold as a nutraceutical in Canada, in capsules and powder claiming antioxidant and general health benefits, but it has yet to be approved in the United States. Bujak suggested it likely won't be long before Azolla is approved across the border, given the fern's track record.

"This plant is so incredible at every level," he said. "I wouldn't be surprised by just about anything we found out it was capable of."

China becomes fern-happy

Two weeks ago, the Beijing Genomics Institute, or BGI, owner of the most sophisticated sequencing platforms in the world, agreed to take on Pryer's project to fund the mapping of the Azolla genome. In as little as a year, the mysteries of the fern's past and full applications for the future could become open-access data.


A fortune ahead for a weed?

"This knowledge will give us control over Azolla in a way we didn't have before," said Francisco Carrapico at the University of Lisbon. "We can increase carbon sequestering and nitrogen fixation, or give Azolla's properties to other plants. We've even found chemicals in Azolla that stop cell division. The question is almost what will we find that Azolla cannot do."

The fern does have one drawback, which has gained it a nasty reputation in parts of Europe and a designation as a weed in North America. Azolla, like most algae, can form massive blooms, as it did 49 million years ago in the Arctic, choking out life below.

Yet even in these cases, Jonathan Bujak argued, "the bloom is a symptom," usually due to high levels of nitrogen.

While Pryer said her motivations to pursue Azolla were mostly academic, she certainly sees the potential for venture capitalism to grow up around Azolla in the future.

"We wanted a genome for the people, by the people," Pryer said with a chuckle. Yet others think something beyond academic learning, environmental applications or industrial uses is to be gained from Pryer's work.

"Azolla has made me realize things in life are very different than what we are taught they are," Carrapico said. "Life is like the Internet: Everything is invisibly connected, but we forget this so often. We don't see how we impact one another. We can look to these connections and, through biology, invest in changes that will improve the world we leave behind."

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