Marilyn continued to discuss her work with isotopes. Presentation
Stable Isotope Lesson #3:Photosynthesis: Plants have lighter carbon isotopes because the lighter ones react faster.
Stable Isotope Lesson #4: Two groups of plants: C3 (vegetables, trees, rice) and C4 (corn, sugar, cane, grasses)—they each have a completely different isotope value, because inside the plant there is something different going on. C4 plants have not been around as long.
Global Biogeochemical Carbon Cycle: Everything that you depend on has to come from a biogeochemical cycle.
Chart of past cycles: Every time the biogeochemical cycle goes down, there is an ice age. So why are we worried? This has been going on for hundreds of thousands of years . . . but suddenly, things changed and it went up.
What’s the difference between global change and global warming? Marilyn discussed her research in Australia.
Megafauna were everywhere before humans arrived. Early humans burned the landscape—repeatedly. With burning, eventually the plants die completely. Ecosystem change is apparent over time in Australia 5,000 years after humans arrived. Marilyn and her colleagues gathered eggshells and analyzed the carbon isotopes. Even without fossil fuels, humans wiped out the megafauna. Animals whose vital food sources were eliminated went extinct. Emus survived; Genyornis went extinct (theory—due to burning and hunting). Ecosystem change has been much more rapid due to human activity.
Earth’s carbon cycle changed dramatically over time: when the earth formed, there was no atmospheric oxygen. Where did the Earth’s water come from? Marilyn will be publishing a paper in Science magazine about this. When the Earth formed, asteroids collided that had lots of water, creating the basis for life-supporting conditions.
Where do humans disrupt the water cycle? Light isotopes evaporate up into clouds; heavy ones rain down—“the whole earth breathing.” Humans have disrupted the biogeochemical nitrogen cycle.
Stable Isotope Lesson #4: Two groups of plants: C3 (vegetables, trees, rice) and C4 (corn, sugar, cane, grasses)—they each have a completely different isotope value, because inside the plant there is something different going on. C4 plants have not been around as long.
Global Biogeochemical Carbon Cycle: Everything that you depend on has to come from a biogeochemical cycle.
Chart of past cycles: Every time the biogeochemical cycle goes down, there is an ice age. So why are we worried? This has been going on for hundreds of thousands of years . . . but suddenly, things changed and it went up.
What’s the difference between global change and global warming? Marilyn discussed her research in Australia.
Megafauna were everywhere before humans arrived. Early humans burned the landscape—repeatedly. With burning, eventually the plants die completely. Ecosystem change is apparent over time in Australia 5,000 years after humans arrived. Marilyn and her colleagues gathered eggshells and analyzed the carbon isotopes. Even without fossil fuels, humans wiped out the megafauna. Animals whose vital food sources were eliminated went extinct. Emus survived; Genyornis went extinct (theory—due to burning and hunting). Ecosystem change has been much more rapid due to human activity.
Earth’s carbon cycle changed dramatically over time: when the earth formed, there was no atmospheric oxygen. Where did the Earth’s water come from? Marilyn will be publishing a paper in Science magazine about this. When the Earth formed, asteroids collided that had lots of water, creating the basis for life-supporting conditions.
Where do humans disrupt the water cycle? Light isotopes evaporate up into clouds; heavy ones rain down—“the whole earth breathing.” Humans have disrupted the biogeochemical nitrogen cycle.
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