Global Warming and Climate Change

David M. BushRisk Assessment

GEOL 4093

What’s going on?

or

Two big questions:

Is Earth warming?Are we to blame?

What is climate?

• “Climate is what you expect, weather is what you get”–100-year average state of the

atmosphere–Excludes variations occurring within

a human lifespan

This is weather, not climate

cartoonaday.com

The Greenhouse Effect

NASA graphic

NASA

Greenhouse Effect: Good or Bad?

Average surface temperatures

NASA photos and data

Earth“Just

Right” Atmospher

e

15 oC59 oF

Venus“Too

Thick” Atmosphere

464 oC867 oF

Mars“Too Thin”

Atmosphere

-63 oC-81 oF

First Big Question

Is Earth Warming?

Two billion years of temperature change

http://www.scotese.com/climate.htm

Big picture: cycles of warm and cool periods. Warm conditions often called “Hothouse” like age of dinosaurs. Cool periods called “Icehouse” like now.

What caused all these changes?

• Tectonic forcing– Change in size and location of continents– Opening and closing of oceanic gateways– Uplift and erosion of mountain belts– Volcanism

• Astronomical forcing– Change in solar output – Change in Earth’s orbit (Milankovich Cycles)

• Humans obviously not to blame for these

Ron Blakely, NAU, http://www2.nau.edu/rcb7/

Plate tectonics moves landmasses which affects Earth’s reflectivities, temperatures of land versus ocean, and global atmospheric circulation. DeConto (2009).

On long time scales, plate tectonics plays major role in climate change

90 Ma

Today

Decreased sunspot activity correlates with lower solar luminosity.

Change in solar output, though small, may account for 25% of global warming.

May be responsible for Little Ice Age

It is now commonly believed that ice ages are caused by variations in the amount of solar energy hitting Earth which is controlled by predictable astronomic variations called Milankovich Cycles.

Work over 90,000 to 100,000 year scale

"Image created by Robert A. Rohde / Global Warming Art"

2 thousand years Black line =

Instrumented data

"Image created by Robert A. Rohde / Global Warming Art"

1880-2004

Image created by Robert A. Rohde / Global Warming Art

Second Big Question

Are we to blame?

How do you take Earth’s temperature?

Where do you stick the thermometer?

Global observations show trends!

Robert A. Rohde, Global Warming Art

Photograph by Ulysses S. Grant

Photograph by Bruce F. Molnia, USGS

Northwestern Glacier in Kenai Fjords National Park, Alaska

The Evolution of the Rhone glacier from 1850 until today. Swiss Institute of Technology.

Robert A. Rohde, Global Warming Art

95% of alpine glaciers are retreating

2007 was record-breaking Arctic sea ice minimum

Image created by Robert A. Rohde / Global Warming Art

photo by Martha de Jong-Lantink on Flickr

Richard Waring,Oregon State University College of Forestry

Species combined current, historical, and stressed range models based on current climate for Douglas-fir. From Richard Waring, Oregon State University College of Forestry website: http://www.pnwspecieschange.info/linked/df.pdf.

Ocean Acidification• CO2 causes oceans to become more acidic,

reducing calcification rate of marine organisms

(A)Healthy coral (B) Degraded coral and water quality. USGS photos

homepage.ufp.pt

Earth sea-level change history

Story similar to temperature.

We care most about what’s happening now, and what will happen in the next 100 years and beyond.

Sea-

leve

l

fall

Sea-level

rise

Vandenberg (2011)

(Above) Source: Stan Riggs(Left) Source: Marten Vandenberg

Here come the beaches!

How did the Georgia coast end up looking like this?

Jekyll Island Erosion--The topography of Jekyll Island illustrates the process of erosion occurring on most of Georgia's barrier islands. Many of the islands consist of a Pleistocene-era core to which a Holocene-era barrier island became attached around 5,000 years ago. Subsequent erosion by the rising sea has removed most of the Holocene barrier sands. Courtesy of V. J. Henry

The Anthropocene

• Term introduced by Nobel Laureate Paul Crutzen– Reasoning: global

environmental effects of humans

– Geological Society of America supports formalization of term

– Exact starting date being debated

See: Crutzen, P. J., 2002, Geology of mankind: Nature, v. 415, p. 23.

The Keeling Curve

Named for Charles David Keeling, the first person to document the rise in Carbon Dioxide concentration.

It is the longest continuous record of atmospheric carbon dioxide, taken at Mauna Loa Observatory, Hawaii.

From The Scripps CO2 Program: http://scrippsco2.ucsd.edu/

CO2 – the main greenhouse gas

• Humans produce 8 billion tons annually• Volcanoes produce about 300 million tons• Current rate of increase: 2 ppm per year

(James Hansen, NASA climatologist)

Time CO2 level

Last ice age maximum 180 ppmJust before industrial revolution

280 ppm

Today 390 ppm

Image created by Robert A. Rohde / Global Warming Art.

The Vostok PlotTemperatu

re

Dust

CO2

ice core

Greenhouse Gases

GasFormula

Atmospheric concentration

Water vapor H2O 0-4 % (deserts to tropics)

Carbon Dioxide CO2 0.033 %

Methane CH42 parts per million (0.02 %)

Nitrous Oxide N2O0.5 parts per million (0.005 %)

Water Vapor

• Most important greenhouse gas• Accounts for 60% of greenhouse warming• BUT! • Concentrations vary around the globe• 36% - 66% depending on location and

time• Long-term constant in atmosphere• Not responsible for current warming

Water vapor, atmospheric temperature, and clouds?

• Warm atmosphere holds more water vapor, more water vapor leads to more warming (POSITIVE FEEDBACK)

• More water vapor means more clouds which block sunlight which means cooling (NEGATIVE FEEDBACK)

• Still, water vapor is variable, but a long-term constant

Global Warming Potential (GWP)

• GWP is measure of how much a gas contributes to global warming

• A function of:– Efficiency of a molecule as a greenhouse gas– Lifespan of the molecule

Global Warming Potential (GWP)Greenhouse Gas

Concentration (%)

Lifespan (years) GWP

Carbon dioxide 77 Thousands 1

Methane 14 12 72

Nitrous oxide 8 114 289

CFC’s, etc. 1 Thousands 1,000+

Data from Pilkey and Pilkey (2011)

Carbon dioxide has a low GWP but is so plentiful and has such a long lifespan that it is the most important greenhouse gas.

Methane• EPA estimates over 50% of

methane comes from human activities

IPCC (2007) Figure 2.2

Origin of the “hockey stick”

Image created by Robert A. Rohde / Global Warming Art

350.org• James Hansen believes we need to maintain

a maximum of 350 ppm atmospheric CO2 to:– “Preserve a planet similar to that on which

civilization developed and to which life on Earth is adapted”

• Author and environmentalist Bill McKibben founded 350.org, a group dedicated to building a global grassroots movement to solve the climate crisis

Naysayers

[Global warming] “…the greatest hoax ever perpetrated on the American people.”

Senator James Inhofe (R-Okla)

Inhofe vs realclimate.org

• Inhofe: – “We are also in the midst of a natural warming

trend that began about 1850, as we emerged from a 400 year cold spell known as the Little Ice Age.”

• www.realclimate.org:– Natural factors can’t account for all the warming – Inhofe statement based on Michael Crichton

novel State of Fear

Inhofe vs realclimate.org

• Inhofe: – “the well-known phenomena of the Medieval

Warming [sic] Period–when, by the way, it was warmer than it is today”

• www.realclimate.org:– All quantitative paleoclimate reconstructions

of the past millennium published in the scientific literature have come to the opposite conclusion

Climategate

• November 2009, stolen emails• From East Anglia University Climate

Research Unit• Evidence of scientists fudging data• Unwanted papers blocked from publication• Global warming exposed as a scam

CLIMATEGAT

E!

wwwwakeupamericans-spree.blogspot.com

The Truth about Climategate• Much ado about nothing• Stolen emails show typical communications• Demonstrate scientific method in action• Messages distorted• How much did we hear about true story?• East Anglia Climate Research Unit

http://www.cru.uea.ac.uk

“Balanced Reporting”

• Not what you think• It means both sides of a story are given

equal merit• Legitimizes marginalized views• UWG is a great and growing university. • UWG gave me five parking tickets last

year and lost my financial aid check.

Intergovernmental Panel on Climate Change (IPCC)

• Established in 1988– World Meteorological Organization– United Nations Environment Programme

• Mandate:– Assess scientific information– Evaluate consequences– Formulate responses

• www.ipcc.ch

Climate models have increased in complexity as more variables are added. From IPCC (2007), Third Assessment Report.

IPCC is often attacked because of errors, changes from report to report, and misinformation.

Dealing with very complex and changing science, thousands of researchers, hundreds of agencies, and dozens of countries.

20072001

19951990

cagiecartoons.com

Some sources of doubt:

-Astroturf groups-Carbon lobby-Balanced media -Blogs, 24-hr news-$$$$$

Think tobacco, seat belts, taxes, coal, Dallas Cowboys, etc.

There is no debate among scientists!

Univ. of Illinois poll of 3,146 earth scientists:

Are human activities significantly responsible?Entire group—82% yes; climate scientists—97.4% yes

Entire group—90% yes; climate scientists—96.2% yes

Have global temperatures risen since pre-1800s?

Pew Research Center polls:April 2008—71% Sept/Oct 2009—57%

Americans who say there is solid evidence of global warming:

azhaguboomi.org

IPCC Dire Projections

• Ecosystems• Food• Coasts• Industry• Health• Water• Extreme events

By Mike Nutter from IPCC report 4.

By Mike Nutter from IPCC report 4.

By Mike Nutter from IPCC report 4.

Hurricanes:

No consensus about potential changes in frequency but there is a growing consensus for an increase in intensity of about one-half of a category on average.

Earth’s air and ocean temperatures are rising. Rise was 1.33 oF in 20th century.

Most of the increase occurred in second half of century and was caused by burning of fossil fuels and deforestation.

Natural phenomena (solar radiation and volcanoes) caused most of the warming during preindustrial times.

Most of the current rapid change in magnitude and rate of global temperature has been caused by human impact.

Cnx.org, Figure 7: Correlation of Earth average temperature with carbon dioxide and global population.

American Meteorological SocietyStatement on Climate Change (2007)

• Despite the uncertainties noted above, there is adequate evidence from observations and interpretations of climate simulations to conclude that– the atmosphere, ocean, and land surface are

warming;– that humans have significantly contributed to this

change;– and that further climate change will continue to have

important impacts on human societies, on economies, on ecosystems, and on wildlife

– through the 21st century and beyond.

http://www.ametsoc.org

httpgreenhouseeffectss.com

What can we do?• Wait for next glacial period

– 1,000? 10,000? 100,000? years

• Reduce greenhouse gas production– Reduce creation of greenhouse gases

• Greenhouse gas remediation– Remove greenhouse gases not at source

• Reduce incoming solar radiation– Make Earth more reflective (surface and

atmosphere)

Reduce greenhouse gas production

• Alternative fuels• Hybrid vehicles• Electric cars• More efficient combustion• Solar panels• Turn off the lights• Carpool• Tele-commute

Greenhouse Gas Remediation

• Remove CO2 from atmosphere– Can be done but very expensive

• Seeding oceans– Has worked in experiments

• Reforestation– Easiest

Solar Radiation Management

• Cool roofs– Steven Chu’s big idea, also keeps buildings

cool

• Plant reflective crops and grasses– Danger of exotic species

• Low cloud creation

1991 Mt. Pinatubo ash cloud circled the globe

Aerosols

• Tiny particles in atmosphere– Many natural sources (volcanoes, dust, salt)– 10% from human activity (NASA)

• Pump aerosols into stratosphere– Use long hoses, planes, artillery– Possible negative effects

• Decrease in ozone layer• Regional weather changes• Health considerations

Suggested Reading

Some Internet Resources

• www.ipcc.ch • cires.colorado.edu• www.realclimate.org • www.globalchange.gov • icecap.us• www.climatepolicy.org • www.pewclimate.org • www.noaa.gov • www.nasa.gov

By Joel Pett, Lexington (Ky.) Herald-Leader, Cartoonists and Writers Syndicate, for USA TODAY

Some say the world will end in fire,Some say in ice.From what I've tasted of desireI hold with those who favor fire.But if it had to perish twice,I think I know enough of hate

To say that for destruction iceIs also greatAnd would suffice.

Fire and Ice

Robert Frost