Climate%20Change:%20Science%20Basics%20and%20Impacts%20Around%20the%20Great%20Lakes

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Climate Change Science Basics and Impacts Around
the Great Lakes

• Jeffrey C. Rogers
• Department of Geography and Atmospheric Science
  Program
• State Climate Office for Ohio
• The Ohio State University
• May 6, 2010
• Ohio State University Climate Change Webinar
  Series
• Climate Change Water Resource Impacts
• in the Great Lakes Region

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Overview

• Scientific basics of climate change associated
  with global warming.
• The gases, their sources, temporal changes, role
  in climate change.
• Currently observed the Predicted changes in
  both air temperature and in rainfall intensity.
• Potential changes in Great Lakes precipitation
  patterns and water levels.

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What are Greenhouse Gases?

• Greenhouse gases
• (i) absorb outward bound infrared radiation from
  the earths surface.
• (ii) Delay the return of infrared radiation to
  space
• (iii) warm the atmosphere.
• The greenhouse effect modulates radiation in
  the earth-atmosphere system.

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Greenhouse Gases (GHGs)(ranked by importance)
Gas Source Residency in air
Water Vapor Evaporation from surface, fut- ure impact poorly understood About 10 days
Carbon Dioxide Fossil fuel consumption, deforestation 100-500 years
Methane Ag byproduct fossil fuel extraction 12 years
Ozone Car combustion it is part of photochemical smog Hours/days
Nitrous Oxide Decay of fertilizers car exhaust 114 years
CFCs Aerosol sprays pre-1990s Up to 3,000 yr
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Increasing GHG Concentrations

• N2O
  Methane

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Earth with Greenhouse Gases

• With Greenhouse gases (CO2 and H2O vapor) the
  planets average temperature fluctuates around
  59ºF.
• This is 60ºF warmer than with no greenhouse
  gases
• 40F is contributed by H2O vapor,
• 20F by CO2
• Our societal debate is whether the observed
  increases in GHGs will increase the air
  temperature beyond 59F, to 60F, 61F, etc.

Carina Van Vliet
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Aerosols Sulfate

• Aerosols Tiny particles liquid droplets from
  burning of fossil fuels that also have radiative
  effects in our atmosphere.

• Sulfates are aerosols from coal oil burning
  they backscatter solar radiation cool the
  climate. Global dimming.

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Attribution of Climate Change to Human Activities

• Modeled climate change (shaded gray) is close to
  observed variability (black line).
• The climate change is the sum of the forcings
  shown at bottom, producing a net warming.
• Natural forcings neutral.
• Modeled climate DOE parallel climate model

Meehl et al (2004 J. Climate)
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Annual Air Temperature Trends 1900-2006
Rogers, 2010 J. Climate (submitted)
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Plants, Crops, Climate Change

• 1990 USDA plant hardiness zones (based on
  1974-1986 data)

• 2006 Natl Arbor Day Foundation (based on weather
  service data 1991-2005)

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The U.S. Climate Change Science Program (6/19/08)

• biggest impacts of global warming will come in
  the form of changes in weather and climate
  extremes.
• More heat waves
• Drought more frequent severe in some regions
• Precipitation will be less frequent but more
  intense, high rainfall events more common.

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Trends in Heavy Precipitation Periods, 1931-1996

• Heavy precipitation events have already
  increased.
• Consistent with increases in atmospheric water
  vapor associated with human-caused greenhouse gas
  increases.
• Precipitation has become less frequent but more
  intense.

(Kunkel, Andsager and Easterling, 1999)
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(No Transcript)
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One Inch Rain Days per Year Ohio

• 1900-1910
• Dayton 6 days
• Columbus 4.5 days
• Cleveland under 4 days

• 2000s
• Dayton Over 9 days
• Columbus 8 days
• Cleveland 7 days

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Alternating rainfall extremes

• Consequences flooding, property damage,
  increased fertilizer runoff.
• Old community water/sewer systems may not be able
  to handle high rain events.

• Consequences Prolonged dry periods drought
  low soil moisture reduced lake/stream levels,
  reduced community water storage water conflicts.

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Great Lakes Hydrologic Cycle

• Air temperature ( wind) controls Evaporation
  (red arrows) that removes water as does flow out
  to other Lakes and to the Atlantic (purple).

• Water input from precipitation (tan arrows)
  and flow from the basin streams (green) and
  upstream lakes (purple), plus ground water.

EPA http//www.epa.gov/glnpo/atlas/glat-ch2.html
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Changes in Great Lakes Levels

• Will be driven by temperature, and therefore
  evaporation, increases.

• In all models, precipitation changes little,
  within 10.

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A basin-wide Lake-effect snowfall
event illustrating where the lake effect clouds
and precipitation typically occur.
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Warmer winters less lake-effect snow

• Southern Lakes snows become rain more often.
• Northern Lakes Less ice but still cold, lake
  effect snow still common.

HadCM2 model
Reductions in Lake-effect snowfall
Current Lake-effect snowfall
Study conducted by Kunkel, Westcott, Kristovich
Illinois State Water Survey
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Summary

• Earth already has a substantial greenhouse
  environment, keeping the planet warmer than it
  should be.
• Current temperature increases appear to be the
  result of warming by GHGs and cooling by
  sulfates.
• Expectations for the future emphasize increased
  number of extreme events.
• Large variations in precipitation.
• More frequent high rain events, flooding
  infrastructure strain
• Longer dry spells in between, drought,
  agricultural problems
• Future Great Lakes levels may succumb to
  increased evaporation.

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Thank You!
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References

• Kunkel, K.E., K. Andsager, and D.R. Easterling,
  1999 Long-term trends in extreme precipitation
  events over the con-terminous United States and
  Canada. J. Climate, 12, 2515-2527.
• Meehl, G.A., W.M. Washington, C.A. Ammann, J.M.
  Arblaster, T.M.L. Wigleym and C. Tebaldi (2004).
  "Combinations of Natural and Anthropogenic
  Forcings in Twentieth-Century Climate". Journal
  of Climate 17 3721-3727. Wikipedia global
  dimming
• Rogers, J.C., 2010 The 20th century cooling
  trend over the southeastern U.S. Submitted to J.
  Climate.