Microscopic fossil shells can reveal climatic conditions by the amount and type of calcium carbonate in their shells.

CarbonBrief.org has a great primer on “How ‘proxy’ data reveals the climate of the Earth’s distant past” ¾

You’re familiar with paleoproxies if you’ve ever heard of studying tree rings to understand historic periods of drought, pests, or fire. Evidence of chemical changes in air and water can also be found trapped in layers of ice drilled out of ancient glaciers. 2/4

Today’s answer: By studying “paleoproxies” such as ocean sediments and sedimentary rocks, we can study ocean and atmospheric temperature from as many as tens of millions of years ago. ¼

Sooo… How far back can we measure ocean and atmospheric temperatures? a) Hundreds of years b) Thousands of years c) Hundreds of thousands of years d) Millions of years

Climate.gov has a great dashboard of climate indicators so that you can check out some of this evidence for yourself. Just take a look at some of the trend snapshots. The trends are… not great. https://www.climate.gov/climatedashboard

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… more things you can measure to look for evidence of climate change: 6. Strengthening mid-latitude westerly winds 7. Fewer extreme cold events / more extreme heat events 8. Increased precipitation events 9. Biological and ecological changes

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Things you can measure to look for evidence of climate change include: 1. Surface, oceanic, and atmospheric temperatures 2. Ice melt 3. Sea level rise 4. Storm frequency and intensity 5. Reduced snow cover … 1/3

Next question: What types of physical evidence could you look at to understand whether climate is changing? What could you measure?

Okay, let’s check your answers: Aside from methane and carbon dioxide, natural greenhouse gases include: water vapor, nitrous oxide, ozone

Synthetic greenhouse gases are: chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs)

Okay, next climate question: Carbon dioxide is a greenhouse gas, obvs. Methane is another. Name a third.