The Azolla Event


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Why did the Earth go from a hot, humid planet with forests all the way up to the North Pole and then suddenly convert to a more modern cooler climate around 47 million years ago?

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The Azolla Event

  1. 1. The Azolla Event<br />The Creation of the Modern Earth’s Climate<br />By Jeff Taylor<br />Olympus High School<br />Get You High School Diploma Online!<br />
  2. 2. Today’s Rocks Explain The Past’s Climate<br />
  3. 3. Did you know that the Arctic Circle was a warm swamp 50 million years ago?<br />Then<br />Now<br />
  4. 4. Ellesmere Island Today<br />One of the northernmost pieces of land on Earth<br />Very cold, very dry, very dark in winter<br />Winters average high -30° C (-22° F)<br />Summers average high 6°C (43° F)<br />This is summer where you are lucky if it gets above freezing<br />
  5. 5. Ellesmere Island<br />50 million years ago<br />
  6. 6. South Carolina<br />Today<br />
  7. 7. Fossils of Ellesmere Island<br />On this cold arctic island are preserved stumps and fossils of an ancient temperate forest, which had a climate similar to South Carolina today!<br /><br />
  8. 8. But, How Could That Be?<br />Today<br />50 Million Years Ago<br />
  9. 9. The Position is Similar<br />Sometimes different climates can be explained by movement of continents due to plate tectonics. But, in this case, Ellesmere Island is pretty close to where it was 50 million years ago.<br />North Pole<br />Lomonosov ridge<br />
  10. 10. So, What’s The Deal?<br />
  11. 11. Hothouse Earth<br />For over 200 million years, up to and past the extinction of the dinosaurs, the Earth was much warmer than it is today.<br />How much warmer? About 8-10° F worldwide average temperature.<br />That was enough to have forests in Antarctica and tropical jungles in Seattle. <br />Carbon Dioxide levels were some 6 times higher than today. <br />
  12. 12. The EoceneAbout 50 Million Years Ago<br />Dinosaurs had been extinct for 15 million years<br />Mammals were becoming the dominant animal on Earth<br />It was tropical all the way north to the Pacific Northwest<br />It was temperate all the way to the poles<br />No ice caps at either poles and no glaciers<br />
  13. 13. Evolution of the WhaleEocene Brought About Remarkable Mammalian Evolution<br />
  14. 14. Some Differences Between Now and Then<br /><ul><li> With no ice caps, the sea levels were much higher, flooding lower areas
  15. 15. Antarctica was covered in forests and there were no glaciers
  16. 16. India has not yet hit Asia, so the Himalayas could not block moisture.
  17. 17. South America and North America were not connected, so ocean currents could go right between them and animals could not cross back and forth.
  18. 18. Europe and Africa had not collided, so there were no Alps yet.</li></li></ul><li>But, why so warm?<br />That isn’t completely understood yet. <br />But, here are some theories and evidence.<br /><ul><li> CO2 levels were way higher than today (about 6 times). This greenhouse gas captured more solar energy.
  19. 19. Ocean currents could transport heat better due to the configuration of the continents.
  20. 20. No ice caps meant no white snow to reflect sunlight back into space.</li></li></ul><li>So, why did it get cold?<br />Around 47 million years ago, the “Hothouse Earth” ended and within 800,000 years the temperature dropped dramatically.<br />By 45 million years ago, the temperature began to approach the current conditions.<br /><ul><li> CO2 dropped dramatically
  21. 21. Ice caps formed over Antarctica
  22. 22. “Icehouse Earth Phase” has begun</li></li></ul><li>“Icehouse Earth”What Could Cause Such a Dramatic Change?<br />It is currently theorized that a fern caused a dramatic change in Earth’s climate that has continued for the last 47 million years.<br />Wait a minute….A FERN?<br />
  23. 23. Meet Azolla<br />This is a tiny little aquatic fern found in swamps and bogs today<br />
  24. 24. Azolla Ecology<br /><ul><li> Grows in tropical and subtropical regions
  25. 25. Is intolerant to freezing conditions
  26. 26. Can be a pest that will completely cover waterways</li></li></ul><li>Azolla – The “Super Plant”<br /><ul><li>Azolla has the amazing ability to double its biomass in just 2-3 days.
  27. 27. It can absorb a great deal of carbon dioxide from the air
  28. 28. When it dies, it can form peat layers at the bottom of the lakes
  29. 29. The decomposing masses at the bottom quickly become anoxic (without oxygen), which prevents future decomposition and preserves the dead materials.</li></li></ul><li>The Azolla Event<br />Approximately 50 million years ago, the Arctic Sea was a semi-closed basin with few ocean currents to mix the waters.<br />Freshwater flowed in from the land and temperate swamps.<br />Freshwater is lighter than saltwater and would float on top.<br />Azolla, being a floating fern, could drift into this ocean and continue to grow on the freshwater surface.<br />
  30. 30. Like The Black Sea Today<br />Due to its enclosed nature, the Black Sea is the least salty body of seawater connected to an ocean in the world. <br />The Black Sea is only ½ as salty as the ocean.<br />It is only habitable in the top 10% because the bottom 90% lacks oxygen.<br />The bottom is anoxic, because there is little mixing to bring surface oxygen to the bottom.<br />The bottom is much saltier than the top, since saltwater sinks.<br />
  31. 31. Azolla Event<br />With Azolla doubling its mass every few days, it sucked up huge amounts of Carbon Dioxide from the atmosphere.<br />As layer upon layer of this “superplant” died and sank to the bottom, thick deposits of organic material formed on the sea floor.<br />This permanently stored the CO2 under the ocean.<br />Lower levels of this greenhouse gas meant less solar energy captured and reduced temperatures.<br />Within 800,000 years, the CO2 levels had dropped from 3500 ppm to 650 ppm and ice caps began to form on the poles.<br />Just like that, the Azolla could not grow in this region anymore, but the “damage” was done.<br />Coal Seam<br />
  32. 32. Carbon DioxideAre we inching back up to a Hothouse Earth?<br />When we burn fossil fuels like coal, oil, and natural gas, we are taking the CO2 that was removed from the air by plants millions of years ago and are returning to back to the atmosphere.<br />
  33. 33. Relationship Between CO2 and Temperature<br />Before 1800, we were essentially “carbon neutral”. That is because CO2 came from sources that absorbed it like plants and wood.<br />But, with the Industrial Revolution, we really started pumping extra CO2 from burning coal and then oil to power industry and transportation<br />
  34. 34. Azolla Deposits Means Money?<br />Much of the current energy exploration in the Arctic is to gain access to these ancient Azolla deposits.<br />Of course, that would mean releasing that ancient stored carbon back into the air when it is burned.<br />The ironic thing is that global warming actually makes it easier to access these deposits, because the sea ice will melt faster.<br />