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Global Warming and Climate Change. David M. Bush Risk 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

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global warming and climate change

Global Warming and Climate Change

David M. Bush

Risk Assessment

GEOL 4093

two big questions
Two big questions:

Is Earth warming?

Are we to blame?

what is climate
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
greenhouse effect good or bad
Greenhouse Effect: Good or Bad?


“Just Right” Atmosphere

15 oC



“Too Thin” Atmosphere

-63 oC



“Too Thick” Atmosphere

464 oC

867 oF

Average surface temperatures

NASA photos and data

first big question
First Big Question

Is Earth Warming?

two billion years of temperature change
Two billion years of temperature change

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
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

90 Ma

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

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


Ron Blakely, NAU,


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

Decreased sunspot activity correlates with lower solar luminosity.

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


2 thousand years

Black line = Instrumented data

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



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

second big question
Second Big Question

Are we to blame?

how do you take earth s temperature
How do you take Earth’s temperature?

Where do you stick the thermometer?

Global observations show trends!


Northwestern Glacier in Kenai Fjords National Park, Alaska

Photograph by Bruce F. Molnia, USGS

Photograph by Ulysses S. Grant

Robert A. Rohde, Global Warming Art


95% of alpine glaciers are retreating

Robert A. Rohde, Global Warming Art


2007 was record-breaking Arctic sea ice minimum

Image created by Robert A. Rohde / Global Warming Art


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:

Richard Waring,

Oregon State University College of Forestry

ocean acidification
Ocean Acidification
  • CO2 causes oceans to become more acidic, reducing calcification rate of marine organisms

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


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-level fall

Sea-level rise


Here come the beaches!

(Above) Source: Stan Riggs

(Left) Source: Marten Vandenberg

Vandenberg (2011)


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
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
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:

co 2 the main greenhouse gas
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)

The Vostok Plot




ice core

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

water vapor
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
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
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 gwp1
Global Warming Potential (GWP)

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

Data from Pilkey and Pilkey (2011)

  • EPA estimates over 50% of methane comes from human activities

Origin of the “hockey stick”

IPCC (2007) Figure 2.2

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, a group dedicated to building a global grassroots movement to solve the climate crisis

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

Senator James Inhofe (R-Okla)

inhofe vs realclimate org
Inhofe vs
  • 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.”
    • Natural factors can’t account for all the warming
    • Inhofe statement based on Michael Crichton novel State of Fear
inhofe vs realclimate org1
Inhofe vs
  • Inhofe:
    • “the well-known phenomena of the Medieval Warming [sic] Period–when, by the way, it was warmer than it is today”
    • All quantitative paleoclimate reconstructions of the past millennium published in the scientific literature have come to the opposite conclusion
  • 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
the truth about climategate
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
balanced reporting
“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
Intergovernmental Panel on Climate Change (IPCC)
  • Established in 1988
    • World Meteorological Organization
    • United Nations Environment Programme
  • Mandate:
    • Assess scientific information
    • Evaluate consequences
    • Formulate responses

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.






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!

Pew Research Center polls:

  • Americans who say there is solid evidence of global warming:

April 2008—71% Sept/Oct 2009—57%

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

  • Have global temperatures risen since pre-1800s?
  • Entire group—90% yes; climate scientists—96.2% yes
  • Are human activities significantly responsible?
  • Entire group—82% yes; climate scientists—97.4% yes
ipcc dire projections
IPCC Dire Projections
  • Ecosystems
  • Food
  • Coasts
  • Industry
  • Health
  • Water
  • Extreme events


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

american meteorological society statement on climate change 2007
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.

what can we do
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
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
Greenhouse Gas Remediation
  • Remove CO2 from atmosphere
    • Can be done but very expensive
  • Seeding oceans
    • Has worked in experiments
  • Reforestation
    • Easiest
solar radiation management
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
  • 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
some internet resources
Some Internet Resources

Fire and Ice

Robert Frost

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.