Taking Earth S Temperature: Delving Into Climate S Past

Lesson 1: Proxy Climate Records Taking Earth’s Temperature: Delving into Climate’s Past

Summary In this lesson, students work in small groups to research different types of proxy climate records. After, they present their findings to the class. Links to online reference material are provided in the lesson. Students complete a table that lists information about their specific proxy type and share their summary with the class. All students complete the full table using information from the presentations by other groups so they can compare and discuss the different proxy types.

Background information Paleoclimatologists use many techniques to study past climate. They collect and analyze proxy climate indicators that can extend back thousands of years. Proxy records can indicate temperature or precipitation conditions from long ago. Instrumental records of climate based on actual temperature and precipitation measurements only began in the 1880’s. Therefore, proxy climate indicators are critical to determine past climatic conditions. This documentary presents the basic principles used to reconstruct climate based on the proxy records in lake sediment, trees, glacier ice, stalagmites, corals, pollen, biological molecules, and historical documents.

Grade level High school to early college

Time Approximately 3-4 class periods

Student learning objectives Understand some methods paleoclimatologists use to determine past climate conditions.

Materials needed Each group needs access to a computer or tablet for internet resources.

Educator instructions Day 1 Students watch the documentary, “Taking Earth’s Temperature: Delving into Climate’s Past”. If time is limited, play the film through the section on proxy climate records (x minutes).

Day 2 (or beginning after movie segment) 1. Divide students into no more than 8 groups.

2. Each group chooses one proxy type to investigate.

1 3. Distribute the “Proxy Climate Records” table to each person in the group. 4. Direct each group to use the online resources for its proxy type to complete the “Proxy Climate Records” table for their one proxy.

Day 3 - 4 1. Each group presents its findings to the entire class. If possible, the students show segments from the film explaining the climate proxy they studied.

2. The class completes the entire “Proxy Climate Records” table as they listen to the presentations from other groups.

Conclusion The class discusses the following analysis questions: 1. Which proxy type(s) are available when above treeline in the Arctic? 2. Which proxy type(s) are available from ocean sites? 3. Which proxy type(s) are based on biologic indicators? 4. What is the advantage of using multi-proxy records?

Assessment criteria Students can be assessed on:  Contributions to the group project  Completeness of table of Climate Proxy Records  Presentation of group project  Quality of responses to the analysis questions

2 Student instructions Day 1 Watch the documentary, “Taking Earth’s Temperature: Delving into Climate’s Past”. If time is limited, watch the film through the section on proxy climate records (x minutes).

Day 2 (or beginning after movie) 1. Your teacher will divide you into groups. Each group will choose or be assigned one proxy climate record to investigate further.

2. Use the online resources provided for your proxy (or new resources you find) to individually complete the “Proxy Climate Records” table for your proxy.

Day 3 - 4 1. Your group will present your findings to the entire class. If possible, show a segment from the film explaining the climate proxy you investigated.

2. Complete the entire “Proxy Climate Records” table as you listen to the presentations from other groups.

Conclusion Answer the following questions using information from your “Climate Proxy Records” table. Discuss your responses with your class. 1. Which proxy type(s) are available when above treeline in the Arctic? 2. Which proxy type(s) are available from ocean sites? 3. Which proxy type(s) are based on biologic indicators? 4. What is the advantage of using multi-proxy records?

3 Online Resources for Proxy Types

General Paleoclimate Lecture - http://www.globalchange.umich.edu/globalchange1/current/lectures/kling/paleoclimate Wikipedia – http://en.wikipedia.org/wiki/Proxy_(climate) NOAA Paleoclimatology – http://www.ncdc.noaa.gov/paleo/primer_proxy.html

Pollen Wikipedia - http://en.wikipedia.org/wiki/Palynology ResearchGate Discussion - http://www.researchgate.net/post/How_does_study_of_palynology_helps_in_identifyin g_the_climatic_changes Environpedia - http://www.global-climate-change.org.uk/3-3-6.php

Tree rings (dendroclimatology) Arizona Laboratory of Tree Ring Research - http://ltrr.arizona.edu/about/treerings Science of Tree Rings - http://web.utk.edu/%7Egrissino/ Wikipedia - http://en.wikipedia.org/wiki/Dendrochronology Bristlecone Pine Site - http://www.sonic.net/bristlecone/dendro.html Earth Observatory - http://earthobservatory.nasa.gov/Features/Paleoclimatology_CloseUp/ Environpedia - http://www.global-climate-change.org.uk/3-3-3.php Climate Data Information - http://www.climatedata.info/Proxy/Proxy/treerings_introduction.html

Corals NOAA Paleoclimatology - http://www.ncdc.noaa.gov/paleo/primer_proxy.html NASA’s Earth Observatory - http://earthobservatory.nasa.gov/Features/Paleoclimatology_CloseUp/paleoclimatology_ closeup_2.php Wikipedia - http://en.wikipedia.org/wiki/Proxy_(climate)#Corals UCAR – Coral for Studying Past Climate Movie - http://spark.ucar.edu/coral-studying- past-climate-movie

Speleothems (cave calcite) NASA Earth Observatory - http://earthobservatory.nasa.gov/Features/Paleoclimatology_Speleothems/ Wikipedia - http://en.wikipedia.org/wiki/Speleothem

Varves (annually banded lake sediment) Wikipedia - http://en.wikipedia.org/wiki/Varve Lake Varves as Natural Calendars - http://hyperphysics.phy- astr.gsu.edu/hbase/varve.html

4 UCAR - http://spark.ucar.edu/lake-bottom-sediments-studying-past-climate-movie Varve image library - http://www.geopolar.uni-bremen.de/varves/

Glacier Ice UCAR Movie - http://spark.ucar.edu/ice-cores-studying-past-climate-movie UCAR Notes - http://eo.ucar.edu/staff/rrussell/climate/paleoclimate/ice_core_proxy_records.html CSA – Ice Core Proxy Methods for Tracking Climate Change - http://www.csa.com/discoveryguides/icecore/review.php Climate Data Information - http://www.climatedata.info/Proxy/Proxy/icecores.html

Alkenones Ice Stories from Billy D’Andrea - http://icestories.exploratorium.edu/dispatches/alkenones-natural-thermometers/ Wikipedia - http://en.wikipedia.org/wiki/Alkenone

Historical archives Global Climate Change - http://www.global-climate-change.org.uk/3-3-1.php NOAA Paleoclimatology - http://www.ncdc.noaa.gov/paleo/primer_proxy.html

5 Proxy Climate Records

From where is the How is the proxy interpreted in terms of How far back do the Climate proxy record obtained? climate? records usually extend? Pollen (palynology)

Tree rings (dendroclimatology) Coral

Speleothems (cave calcite)

Varves (annually banded sediments) Glacier ice

Alkenones (type of biomarker)

Historic records

6 Proxy Climate Records [Answers]

From where is the How is the proxy interpreted in terms of How far back do the Climate proxy record obtained? climate? records usually extend? Pollen Lakes and bogs, often Identify pollen grains to determine plant species. Species types Tens of thousands of years, sampled by coring or in and abundance indicate climate, including precipitation and although pollen can be recovered (palynology) natural exposures; nearly temperature from sediment many millions of world-wide (terrestrial) years old coverage Tree rings Anywhere trees grow or The rate at which trees grow depends on summer temperature Hundreds of years, although recently grew. Trees at and available moisture. Ring width can be interpreted in terms of chronologies can be spliced (dendro- middle to high latitudes the climate variable that limits growth. together to extend a thousand climatology) exhibit strong annual banding years or more Coral Anywhere coral lives or once The thickness of growth bands, and the chemical (elements and Hundreds of years lived, typically tropical isotopes) signatures within the calcium carbonate skeleton, can shallow seas be interpreted as changes in near-surface water temperature, rainfall and nutrients entering the ocean Speleothems Anywhere with caves that The thickness of layers reflects the rate of growth, which can Thousands to hundreds of contain deposits of calcium depend on the amount of soil water that seeps into the cave. The thousands of years; specifically (cave calcite) carbonate (calcite) chemical signatures (isotopes) indicates the temperature under to ~500,000 years using which the calcite precipitated from drip water radiometric (U-Th) dating Varves Deep lakes with low oxygen The thickness of annual layers reflects the amount (discharge) of Thousands of years content, especially where the rivers that carry sediment to the lake. In drainages with (annually seasonality is strong, glaciers, summer temperature can control melt water input. In banded including lakes fed by glacier non-glacial lakes, snowmelt and rainfall are often the primary sediments) melt water control Glacier ice Polar regions, especially the The thickness of annual layers records the amount of snowfall Thousands to hundreds of two largest ice sheets: each year. The chemical (isotope) signature of the ice is thousands of years Greenland and Antarctica interpreted in terms of temperature. The amount of dust trapped in the ice indicates wind strength and general aridity Alkenones (type Lake and ocean sediments Chemical analyses of the proportion of alkenones with of different Thousands to hundreds of that contain these molecules, chain lengths, which represents more-dense fat versus less-dense thousands of years of biomarker) which are produced by fat. This ratio is determined by the temperature of the water in specific algae which the algae grew

7 Historic records Libraries and museums with Personal accounts of human-encountered weather can be Hundreds of years, sometimes collections of shipping logs, systematically tabulated to identify trends and to document longer diaries, art, harvest records, extreme events etc.

8 Analysis Questions [answers]

1. Which proxy type(s) are available when above tree-line in the Arctic? Those that accumulate in lakes. Glacier ice and speleothems (where present).

2. Which proxy type(s) are available from ocean sites? Ship records, coral, alkenones.

3. Which proxy type(s) are based on biologic indicators? Palynology (pollen), tree rings, coral, alkenones, and historic records if they include information such as harvest data.

4. What is the advantage of multi-proxy records? Different proxies can be compared to determine if they are yielding similar (reinforcing) or different climate information. Some proxies are available in some areas but not in others. Some proxies are better at sensing some aspects of climate, like temperature, whereas others are better recorders of different climate variables. By combining information from multiple proxies, scientists can gain wider geographic coverage.

9 Alignment to NGSS high school performance objectives Developing an understanding of proxy records used to study past climate changes will lead students toward the following NGSS High School Performance Objectives:

HS-ESS2-4. Use a model to describe how variations in the flow of energy into and out of Earth systems result in changes in climate. Clarification statement: Examples of the causes of climate change differ by timescale, over 1-10 years: large volcanic eruption, ocean circulation; 10-100s of years: changes in human activity, ocean circulation, solar output; 10-100s of thousands of years: changes to Earth's orbit and the orientation of its axis; and 10-100s of millions of years: long-term changes in atmospheric composition. Assessment boundary: Assessment of the results of changes in climate is limited to changes in surface temperatures, precipitation patterns, glacial ice volumes, sea levels, and biosphere distribution.

HS-ESS3-5. Analyze geoscience data and the results from global climate models to make an evidence-based forecast of the current rate of global or regional climate change and associated future impacts to Earth systems. Clarification statement: Examples of evidence, for both data and climate model outputs, are for climate changes (such as precipitation and temperature) and their associated impacts (such as on sea level, glacial ice volumes, or atmosphere and ocean composition). Assessment boundary: Assessment is limited to one example of a climate change and its associated impacts.

Alignment to Common Core ELA/Literacy Standards RST.11-12.1. Cite specific textual evidence to support analysis of science and technical texts, attending to important distinctions the author makes and to any gaps or inconsistencies in the account. (HS-ESS3-5)

RST.11-12.2. Determine the central ideas or conclusions of a text; summarize complex concepts, processes, or information presented in a text by paraphrasing them in simpler but still accurate terms. (HS-ESS3-5)

RST.11-12.7. Integrate and evaluate multiple sources of information presented in diverse formats and media (e.g., quantitative data, video, multimedia) in order to address a question or solve a problem. (HS-ESS3-5)

WHST.9-12.1. Write arguments focused on discipline-specific content. (HS-ESS2-7)

WHST.9-12.7. Conduct short as well as more sustained research projects to answer a question (including a self-generated question) or solve a problem; narrow or broaden the inquiry when appropriate; synthesize multiple sources on the subject, demonstrating understanding of the subject under investigation. (HS-ESS2-5)

SL.11-12.5. Make strategic use of digital media (e.g., textual, graphical, audio, visual, and interactive elements) in presentations to enhance understanding of findings, reasoning, and evidence and to add interest. (HS-ESS2-3)