PLEASE COMMENT - SCHOOL PROJECT
Hello everyone! For a school project about advocacy in the climate change realm, I was interested in explaining a bit about HOW we know what we know. I want to talk about the proxies that climate scientists use in order to date and determine what past climates were like!
SED CORES and CORALS
Sediment cores are similar to ice cores, but sediment cores can give us much older data than ice can! Sediment cores are exactly what they sound like: a cylindrical shape of sediment that’s drilled up from earth’s crust, specifically from under the sea. In a similar way to how snow is compacted, all of the oceans dying plankton and sediment falls to the ocean floor and compacts down the plankton and sediment underneath it! Sediment cores like these ones:
Are taken and analyzed for several things, including chemical compounds, but one of the most important parts is the foraminifera! This is a fancy way of saying all of the tiny little microorganisms or fossils that get trapped in the sediment as everything is compacted. The presence (or absence) of these little guys can tell us a lot - like the amount of CO2 in the atmosphere at the time, or the surface temperature of the ocean
CORALS:
The corals that scatter the tropics of our oceans aren’t just beautiful, they’re also very good indicators of past ocean temperature and composition.
Corals are animals just like the fish that live in and around them. They build their skeletons out of a substance called calcium carbonate that they extract from the ocean water that they live in.
Scientists extract small core samples to study the life of the coral. They then fill in the hole with cement, which the corals grow around so that the animal isn’t harmed. Essentially we study the density and the composition of what the coral absorbs. The growth and structure of the coral is influenced by ocean temperature, pH, nutrients in the water, and many more things; this means that scientists can identify summer growth from winter growth. These changes in growth, sometimes visible to the naked eye:
(you can see the bands on the coral in the front of the picture) but more often at a much smaller level:
can tell us about the climate at the time that the coral was created! Not only can scientists use this data to reconstruct climate records for when the coral was living, it can also help them predict possible future trends in the climate systems, like El Niño events!
Any questions? PLEASE PLEASE ask!
Sources:
1. Grothe, Pamela. “Cretaceous Greenhouse.” Icehouse-Greenhouse Earth. Class lecture, 2021, University of Mary Washington.
2 .Grothe, Pamela. “Last Glacial Maximum.” Icehouse-Greenhouse Earth. Class lecture, 2021, University of Mary Washington.
3. “Picture Climate: How We Can Learn from Corals.” National Climatic Data Center, www.ncdc.noaa.gov/news/picture-climate-how-we-can-learn-corals.
Images (in order):
1. https://www.wgtn.ac.nz/antarctic/outreach/image-gallery/andrill
2. https://oceanservice.noaa.gov/facts/coral.html
3. https://ccoc.stanford.edu/
4. https://eos.org/meeting-reports/reconstructing-climate-and-environment-from-coral-archives
