© 2011 Pearson Education, Inc. Studying Climate Change AP Environmental Science Mr. Grant Lesson 49

© 2011 Pearson Education, Inc. 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."

© 2011 Pearson Education, Inc. 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.

© 2011 Pearson Education, Inc. 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.

© 2011 Pearson Education, Inc. 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 CO 2 concentrations have increased from 315 ppm to 389 ppm

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. Ice cores from Antarctica Ice cores let us go back in time 800,000 years -Reading Earth’s history across eight glacial cycles

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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 Composed of hundreds of international scientists and government officials

© 2011 Pearson Education, Inc. 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."