1 of 21

U.S. Ice Drilling Program

School of Ice

Decoding Ice Cores

Making Proxy Temperature Measurements

Using Isotopes

​

www.icedrill-education.org

2 of 21

Today’s Agenda…

  • Supply and set-up check
  • Background on proxy isotope measurement
  • Data collection
  • Graphing & process data/lab questions

3 of 21

Making Proxy

Temperature Measurements

Using Isotopes

Set-up Check

Ocean

Standard

4 of 21

Page #

Developing Mathematical Proxies. Bill G. 6/29

Tree Ring = (0.33 SGI * Precipitation) + 0.99 SGI

Growth rainfall deviation

Index

Precipitation = Tree Ring Index - 0.99 SGI rainfall

0.33 sgi/rainfall deviation

5 of 21

Proxy Mathematical Models to Reveal Ancient Climates

The goal of this analysis was to develop a proxy mathematical model to estimate the temperature in Northwestern Canada back to the year 1780. Temperatures would be estimated based on the relationship between direct measurements of Oxygen-18 in tree ring cellulose and temperatures taken between 1927 and 2003.

O-18 Deviation

6 of 21

7 of 21

Your Classroom Ideas

Isotopic Deviation Bill G.

Proxy Temp. Estimates Using Isotopes

DV:

IV:

Proxy

Temperature

Estimate

How far back in time

Temperature

Investigable Question:

How did the temperature of the planet

change when you go back into the Earth’s

past?

8 of 21

We need a “proxy” for temperature.

There is a measurable relationship between temperature and the ISOTOPIC DEVIATION of oxygen atoms in snow compared to an ocean standard.

How has the temperature of the planet changed when you look back into the Earth’s past?

9 of 21

Using snowfall isotopic deviation as a “proxy” for temperature… Facts

    • The ocean always contains a higher percent of heavy water than snow.
    • The freezing/condensation point heavy water (O-18) is slightly higher (warmer) than O-16 water.
    • Warmer temperatures favor snow containing higher percentages of heavy water (O-18) since it has a slightly higher condensation point.
    • When temperatures are colder, more O-16 water molecules are condensing causing the relative amount of heavy water in the snow/ice to decrease.

How has the temperature of the planet changed when you look back into the Earth’s past?

There is a measurable relationship between temperature and the ISOTOPIC DEVIATION of oxygen atoms in snow compared to an ocean standard.

10 of 21

Your Classroom Ideas

Isotopic Deviation Bill G.

Proxy Temp. Estimates Using Isotopes

DV:

IV:

Proxy

Temperature

Estimate

How far back in time

Temperature

Investigable Question:

  • How has the temperature of the planet changed when you go back into the Earth’s past?
  • How has the average isotopic mass of ice/water molecules from the past deviated from the ocean standard?

(isotopic deviation)

11 of 21

Calculating

ISOTOPIC MASS DEVIATION.

How much does the average isotopic mass of the water in an ice sample deviate from the ocean standard?

Average Mass of Ocean standard “molecules”

(washers). =

Ocean

Standard

Avg. mass of water molecules from ice core

Avg. mass of water molecules from the ocean standard

Isotopic Mass. =

Deviation

H2O16

H2O18

12 of 21

Calculating

ISOTOPIC MASS DEVIATION.

How much does the average isotopic mass of the water in an ice sample deviate from the ocean standard?

= —

- 4.51 g

Average mass of ice core

water “molecules”

(washers) =

Ice Core #3

Age of Ice

20,000 years BP

Avg. mass of ice core water molecules

Avg. mass of ocean standard water molecules

Isotopic Mass. =

Deviation

H2O16

H2O18

Ocean

Standard

13 of 21

Your Classroom Ideas

DV:

IV:

Investigable Question (s):

How far back in time

Temperature

(isotopic deviation)

​

Mass Dev. = Avg. Mass Water - Avg. Mass Ocean Standard

Ice Core Molecules Water Molecules

Proxy Temp. Measurements Using Isotopes

Isotopic Deviation Bill G.

Age of

Ice

(yrs BP)

​

Isotopic Mass Deviation (g) (grams)

Avg. Mass of ice core “molecules” (g)

Core

#

Avg. Mass of Ocean Standard “molecules”(g)

​

  • How has the temperature of the planet changed when you go back into the Earth’s past?
  • How has the average isotopic mass of ice/water molecules from the past deviated from the ocean standard?

1

​

2

​

3

​

4

20,000 6.22 10.73 -4.51

14 of 21

Your Classroom Ideas

-500 -400 -300 -200 -100 0

Mass Deviation (g)

Age of Ice (thousands of years before present)

Isotopic Mass Deviation (grams) vs. Age of Ice

Isotopic Deviation Bill G.

10.75 g

15 of 21

Your Classroom Ideas

-500 -400 -300 -200 -100 0

Mass Deviation (g)

Age of Ice (thousands of years before present)

Isotopic Mass Deviation (grams) vs. Age of Ice

Isotopic Deviation Bill G.

Warm

Cold

16 of 21

Your Classroom Ideas

Page #

Isotopic Deviation Bill G.

3-2-1 Inquiry Questions

​

3 things I noticed about the graph are…

1.

​

2.

​

3.

​

2 things I wonder about based on the data collected in this lab are…

1.

​

2.

​

The one most important thing I think the data suggest is…

17 of 21

Age of Ice (thousands of years before present)

Age of Ice (thousands of years before present)

-500 -400 -300 -200 -100 0

-500 -400 -300 -200 -100 0

Conductivity (uS/cm)

Lab #2: Conductivity vs. Age of Ice Sample

Lab #3: Isotopic Deviation vs. Age of Ice Sample

Isotopic Deviation (g)

-.25 -.20 -.15 -.10 0.0

US Ice Drilling Program icedrill.org icedrill-education.org

18 of 21

US Ice Drilling Program icedrill.org icedrill-education.org

Age of Ice (thousands of years before present)

Age of Ice (thousands of years before present)

-500 -400 -300 -200 -100 0

-500 -400 -300 -200 -100 0

Conductivity (uS/cm)

Lab #2: Conductivity vs. Age of Ice Sample

Lab #3: Isotopic Deviation vs. Age of Ice Sample

Isotopic Deviation (g)

-.25 -.20 -.15 -.10 0.0

19 of 21

US Ice Drilling Program icedrill.org icedrill-education.org

20 of 21

US Ice Drilling Program icedrill.org icedrill-education.org

21 of 21

U.S. Ice Drilling Program

School of Ice

Decoding Ice Cores

Making Proxy Temperature Measurements

Using Isotopes

​

www.icedrill-education.org