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May 30, 2003 You've been at sea for a day now - what is it that your team is most excited about, now that your journey is finally underway? Thanks, Hi Sheila, Well, honestly, we are most excited about finding some good weather so that the Alvin dives can continue. However, we did get on the bottom yesterday and finding 33 Desmophyllum cristagalli was just fantastic. The fossil corals have really energized everyone on board. We can't wait to find more. Thanks for writing, Jess Adkins Dear Scientists on RV Atlantis, I have a question with regard to deep-sea corals. What element of coral fossils are you going to examine in order to understand the temperature, salinity, and current speed of the sea at certain points in long span of time? What features/ characteristics of deep sea coral will tell you about temperature, salinity, and current speed of the sea where they lived? I learned that the excavation of the North Pole ice indicated the change in salinity in the sea, and changes in design of plankton fund in the ice column (whether its outer shell is swirled clock-wise or anti-clock-wise). Can tell you temperature change of the sea over a very long period of time. This time, what are the key signs to be examine to predict the change in cold deep water flow? I am very excited about the expedition: the cold deep water mass and climate change is the area where I am most interested in! Good luck with your trip! Michiko Katagami Hi Michiko, Thanks for your question. For some general information on these topics, please see the Introduction to Expedition 7, on the Dive and Discover web site. Some more detailed explanation is below. We are going to measure the Uranium age, the radiocarbon age and the Cadmium/Calcium ratio of the fossil corals. Together these three will tell us the age of the coral, the relative ratio of northern source and southern source deep water at the coral growth site and the average rate of overturning of the deep ocean at this site and at the time in the past. We hope to combine these results with the ice core data you mentioned to better understand how the ocean and atmosphere work to transfer heat from the equator to the pole in the past. Hopefully this will give us a better understanding of the mechanisms of climate change. Thanks for tuning in, Jess Adkins Dear Dive and Discover, How can coral affect the climate? Sincerely, Hi Sammy, The corals growing in the deep sea that we are looking at cannot affect climate. We are trying to use them as little "tape recorders" of what climate did in the past. The climate system is too massive for our corals to have much effect on it directly, but their skeletons are affected by climate shifts. Reading this information from their skeletons is what we hope to do back in the lab at Caltech. That being said, the large coral reefs in the surface ocean can affect climate by changing atmospheric carbon dioxide concentrations. When a coral grows, it takes up one unit of carbon to make its skeleton. However it also takes up two units of base (called "alkalinity" by oceanographers) at the same time. This change in the acid-base balance of the ocean slightly shifts the sea surface to being more acidic. A more acidic ocean will give off more of its carbon dioxide to the atmosphere, kind of like opening a can of Coca-Cola which is also acidic. The changes are small, but the coral reefs are large and there is a lot of carbon in the ocean. So ironically, even though growing coral takes up carbon, it causes there to be more carbon dioxide in the atmosphere. This is only true because the ocean contains about 60 times more carbon than the atmosphere. It is some pretty cool chemistry. Thanks for writing, Jess Adkins Hello to all. Your website is so exciting. Having an avid interest in exotic Zoology, I wonder if you expect to see any extraordinary sea creatures. Patricia Quit U.S. Department of Energy - Brrokhaven
National Laboratory Hello Patricia, I expect we will see many exotic creatures. The photos and video from the first Alvin dive already showed a surprising number of filter-feeding sea stars perched on the lava rock and waving their arms in the passing current. There have also been a few individuals of a rarely-seen soft coral, which has a long stalk and branches that make it look like a feathery umbrella. As we proceed with further dives, I am sure we will see many more exciting animals. The deep sea is filled with many unusual and undiscovered animals. Cheers, Jon Moore My question is regarding methane hydrates. I was talking with a geologist about the effects of a large earthquake off the Southern California coast. I was telling him of my worries about a tsunami. He said I should be more worried about methane hydrates, but didn't elaborate why. Could someone help me to understand what he meant, or was he just trying to scare me? Thanks, Linda Hi Linda, I am not sure he was trying to scare you, but there is something to the methane hydrate story. There are large amounts of carbon stored in the ocean sediments as a hydrated mineral called methane clathrates. At the right temperature and pressure the gas methane will be trapped in a solid lattice of water molecules. During a large coastal slump event, or other "mass wasting" process that happens quickly, the pressure in the sediments can change enough to release the methane from its water prison and let it out as gas. This methane will, theoretically, rise quickly to the surface and get into the water column and atmosphere and then possibly be converted to CO2 and cause climate change. There is much debate in the paleoclimate community about whether these sorts of large methane releases have even happened. I personally am very skeptical about this process for the last glacial cycle, but for millions of years ago it might have happened. As far as our immediate future I am not too worried. Hope this helps, Jess Adkins
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