t i n y b u b b l e s

Dr. Ed Brook, Oregon State UniversityUS Ice Drilling Program

T I N Y B U B B L E S

Greenhouse gases and climate information from polar ice cores

Three Messages

Humans have radically altered the amount of atmospheric greenhouse gases.

Greenhouse gases and climate are linked tightly in the record from ice cores.

We should expect warming, and sea level change, as greenhouse gas levels rise in the future.

Greenhouse Effect Greenhouse gases are

like a dam on a river. They increase the amount of heat in the atmosphere.

Major ones are water vapor, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O).

Without them earth would be -18˚C (0˚F)

The greenhouse effect is well understood. It was articulated in the early 1800’s by Joseph Fourier, but influenced by earlier work.

C OO

The Changing Atmosphere“The Keeling Curve”

Modern measurement network is sophisticated and accurate http://www.esrl.noaa.gov/gmd/index.html

Systematic, direct measurements of greenhouse gases since the 1950’s at best.

What happened before that?

Polar Ice Cores

WAIS Divide

Gases in Ice Cores

Gas Extraction and Analysis

Dry ExtractionCrushing under vacuumAnalysis by gas chromatography, laser spectroscopy, mass spectrometry

Wet ExtractionMelting under vacuumAnalysis by gas chromatography, laser spectroscopy, mass spectrometry

Other Climate Information from Ice Cores

Snowfall rate from layer thickness

Temperature from stable isotopes (18O/16O, or 2H/1H) of ice

Dust and aerosol content of atmosphere from chemical measurements

Ice sheet elevation from total air content

Pre-ice sheet history from basal material

WAIS Divide Camp, Antarctica

http://www.waisdivide.unh.edu

Drilling at WAIS Divide

The Human Impact: CO2

40% Increase since 1700s

Industrial Revolution

The Human Impact: Methane

240% Increase since 1700s

The Long View

Preindustrial Methane

Preindustrial Carbon Dioxide

Antarctic Temperature

Dome C Ice Core - Antarctica

*Greenhouse Gases and Climate Change Together in Natural Cycles*No Precedent for Modern Greenhouse Gas Levels in last 800,0000 years

A Good Analogy

What Do These Data Tell us About Climate Change?

The modern atmosphere is very different than the previous 800,000 years.

Can’t explain the warm periods of the past without greenhouse gases. Gases always higher during warm periods.

The climate system works the way we think it does. In detail there are puzzles we spend lots of time on, but we understand that greenhouse gases cause warming. That warming is happening now, and will continue.

Global Temperatures and Sea Level ~1˚C of warming

since 1850. Likely that ~ 50% due to human activity

~ 20 cm sea level change in the same time period

Decreases in snow cover and sea ice, and increases in drought

What about the Future? Need models. They are

good, but not perfect. Models predict the last

century pretty well. Models respond to

greenhouse gases in ways that are similar to what we see in the past.

Models don’t predict small-scale regional climate that well yet, but things are getting better.

What about the Future? To predict the future we need to know how greenhouse

gases will change.

How much will they increase?. A lot in the short run, but the range of “a lot” matters for prediction of climate.

Warming by 2100 is about 2-4˚C (4-7 ˚F) by most predictions.

Ice age to present warming was about 5˚C (9˚F).

Sea level is rising, and will continue to rise. The future amount is uncertain because how ice sheets behave is not known well. More than a meter by 2100 is possible.

Science Communication Lessons You have to know the science! Really well! You have to know the science! Really well! Believe it or not, journalists, and politicians, and the

public, are often really smart. Really. They can, and will, ask very hard questions, and expect answers.

Even when the questions are hard, they expect clear, simple, non-waffling answers. Practice these.

Know what your message is, and stick with it. Know your audience – figure them out beforehand.

Not everything scientists do is interesting to the public. In fact, most of what we think is cool is not interesting. That’s OK.

Science Communication Lessons Is it OK to advocate for policy when talking about

science of climate change?

http://www.youtube.com/watch?v=L2m9SNzxJJA