At this time [~60 million years ago], the Earth was a much warmer place and most of the Arctic was in fact a gigantic freshwater lake. Azolla bloomed in the Arctic mega-lake, covering an astonishing area of 1.5 million square miles (4 million sq km), which is roughly half the size of the United States. It is a truly staggering thought. If you were to visit this Azolla-filled lake 60 million years ago, you could fly in an airplane for about three hours overhead and continue to see this one species covering the top of the water like a green blanket. –
“Ferns: Lessons in survival from Earth’s most adaptable plants” (Ch 6)
That one paragraph might fill your “fern stuff” quota for today; indeed, it might be more fern stuff than you ever wanted in all your days. But I’m going to take a chance here and provide some important context: an individual Azolla-fern plant would fit on the fingernail of your little finger. Yet some Azolla plants, working together in a truly impressive collective effort, managed to cover 1.5 million square miles of lake. But hey, it wasn’t for long, right? If you’d blinked, you’d have missed it, right?
Wrong.
The bloom lasted about 1 million years and is known as the “Azolla event”. Scientists have estimated that over 10 trillion tons of CO2 were sequestered during this period, enough to cool the Earth by 9°F (5°C).
That part about this feat being “known as the Azolla event” strikes me two ways.
- First, that seems more than fair. If I did something that extended for 1.5 million square miles for 1 million years (or thereabouts), I would fully expect it to be known as the “Gibson event”. Or maybe The Gibson Event®, hold the scare quotes and order the commemorative mugs. And speaking of fair, if any of you had a similar achievement I would expect it to be named after you. I would even write a letter of support to the Event-Naming Commission.
- Second, known to or by whom, buddy? Not to this one-time student of high-school biology and ongoing student of natural history. I was this many weeks old when I first heard of the Azolla event. I expect the same is true for you.
This is yet another reminder that high-school or even college need not — nay, should not — be the end of our learning. There is a *ton* of cool stuff out there, even leaving aside the ferns.
Fascinating that something lasting 1 million years would be called an event. Not sure the human species will achieve that, although in terms of spread we are devastating similar. With the one obvious difference that our lifestyled increases the global temperatures – perhaps there is a future for the Azola yet. Love the thought of flying a plane 60 million years ago.
Judith – “Event” does seem like odd usage. As for the airplane, it’s funny the imagery that people reach for to help a reader understand the scale/scope of something.
Isabel – after the Azolla Effect. There are petrified tree trunks about a 30-minute helicopter ride west of CFS Alert and by going a further 15 to 20 minutes to the northwest by chopper and if you land you may find fossilized seashells in the rocks that are now high above water.
John – I’m guessing that Alert is not on my travel itinerary, but it’s good to know the fossils are there. As a side note, it puts “rising sea levels” into a different perspective.
Actually, I expect that those fossilized shells ended up high on dry land due to seismic activity rather than ‘rising sea levels’ that got lower instead of higher.
Also, it may be that the earth as a whole is elastic and when that 1.5 million square mile lake dried up and the weight of all that water disappeared, the earth in the area that was being held down by that weight would have rebounded.
BTW, that the earth is elastic is something you learn in highway design.
John – From my recent reading, I understand that changes in the level of the land account for much or even most of what we think of as changes in sea level from the perspective of the human time-scale. Most of us didn’t learn about the elasticity of the earth, worse luck.
Isabel: One cubic foot of water weights 62.4 lbs or 0.0312 tons
One square mile equals 27,878,400 sq feet.
If that square mile is one foot deep in water, the weight of water is 870,000 tons. One foot of water over 1.5 million square miles would weigh 1,305 billion with a “b” tons.
How deep was that lake?
John – I’m going to guess more than a foot deep . . . 🙂