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Studying Climate Change

AP Environmental Science

Mr. GrantLesson 49

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Objectives:

• Define the term proxy indicators.• Summarize how researchers study climate.• TED - At TED2009, Al Gore presents updated slides

from around the globe to make the case that worrying climate trends are even worse than scientists predicted, and to make clear his stance on "clean coal."

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Proxy Indicators: A type of indirect evidence that serves as a proxy, or substitute, for direct measurement, and that sheds light on conditions of the past. For example, pollen from sediment cores and air bubbles from ice cores provide data on the past climate.

Define the term proxy indicators.

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Summarize how researchers study climate.

• Proxy indicators such as data from ice cores, sediment cores, tree rings, packrat middens, and coral reefs, reveal information about past climate.

• Direct measurements of temperature, precipitation and other conditions tell us about current climate.

• Climate models serve to predict future changes in climate.

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Direct measurements tell us about the present• We document daily fluctuations in weather

- Precise thermometer measurements over the past 100 years

• Measuring of ocean and atmospheric chemistry began in 1958

• Precise records of historical events- Droughts, etc.

Atmospheric CO2 concentrations have increased from 315 ppm to 389 ppm

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• Paleoclimate = climate of the geological past• Gives a baseline to compare to today’s climate

• Proxy indicators = indirect evidence that serve as substitutes for direct measurements - Shed light on past climate

- Ice caps, ice sheets, and glaciers hold clues to Earth’s climate history

- Trapped bubbles in ice cores provide a timescale of:- Atmospheric composition, greenhouse gas concentrations,

temperature trends- Snowfall, solar activity, and frequency of fires

Proxy indicators tell us about the past

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Ice cores from Antarctica• Ice cores let us go back in time 800,000 years

- Reading Earth’s history across eight glacial cycles

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More proxy indicators• Cores in sediment beds preserve pollen grains and

other plant remnants • Tree rings indicate age, precipitation, droughts, and fire

history• In arid regions, packrats carry seeds and plants to their

middens (dens)- Plant parts can be preserved for centuries

• Researchers gather data on past ocean conditions from coral reefs

• Scientists combine multiple records to get a global perspective

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Models help us predict the future

• Climate models = programs combine what is known about:- Atmospheric and ocean

circulation - Atmosphere–ocean

interactions- Feedback mechanisms

Models simulate climate processes to accurately predict climate change

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Results from three simulations

• Figure (a) shows natural climate factors only- Volcanoes

• Figure (b) shows only human factors- Greenhouse gas emissions

• Figure (c) shows both factors

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Current and future trends and impacts

• Evidence that climate conditions have changed since industrialization is everywhere- Fishermen in the Maldives, ranchers in Texas,

homeowners in Florida, etc.• Scientific evidence that climate has changed is

overwhelming and indisputable• Intergovernmental Panel on Climate Change (IPCC)

was established in 1988- Composed of hundreds of international scientists and

government officials

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TED Video

Al Gore warns on latest climate trends (7:48)

Once the US Vice President, then star of An Inconvenient Truth, now Nobel Peace Prize winner, Al Gore found a way to focus the world's attention on climate change. In doing so, he has invented a new medium -- the Keynote movie -- and reinvented himself.

At TED2009, Al Gore presents updated slides from around the globe to make the case that worrying climate trends are even worse than scientists predicted, and to make clear his stance on "clean coal."