global warming and climate change
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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
e15 oC59 oF
Venus“Too
Thick” Atmosphere464 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-l
evel
fallSea-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 CurveNamed 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 levelLast 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
Gas Formula
Atmospheric concentration
Water vapor H2O 0-4 % (deserts to tropics)
Carbon Dioxide CO2 0.033 %
Methane CH42 parts per million (0.02 %)
Nitrous Oxide N2O 0.5 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
CLIMATEGATE!
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
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