Transcript Zierden-PeaceRiver - Center for Ocean

Climate Change Basics for the Southeast
Peace River Basin Management
Committee Meeting
September 30, 2009
David F. Zierden
Florida State Climatologist
Center for Ocean Atmospheric Prediction
Studies
The Florida State University
Introduction
New Emphasis on Climate Change
Growing interest in climate change
issues:
• IPCC 4 and Al Gore
• New administration in Florida
• Changing markets - biofuels and
ethanol production
• Carbon credits and markets
• Sustainability
“Governor Crist is passionate about government leading by
example… The three Executive Orders represent the Governor’s
commitment to addressing global climate change.”
IPCC 4 Conclusions
“Warming of the climate system is unequivocal, as
is now evident from observations of increases in
global average air and ocean temperatures,
widespread melting of snow and ice, and rising
global average sea level.”
“Global atmospheric concentrations of CO2,
methane (CH4) and nitrous oxide (N2O) have
increased markedly as a result of human activities
since 1750 and now far exceed pre-industrial
values determined from ice cores spanning many
thousands of years.”
“Most of the observed increase in globallyaveraged temperatures since the mid-20th century
is very likely due to the observed increase in
anthropogenic GHG concentrations.”
- IPCC 4 Summary for Policy Makers
Criticisms:
• politicized process
• improper review
• understates the importance of other
natural and man-made forcings
• inadequate communication of
uncertainties
“Climate Change” versus “Global Warming”
Climate change is ongoing and has many causes, both natural and man-made.
Natural causes:
• Changes in solar intensity
• Eccentricity in the earth’s orbit and “wobbles”
• Vegetation, albedo changes
• Volcanic eruptions
• Coupled ocean/atmospheric cycles
Man-made causes:
• Urbanization
• Land use changes
• Aerosols
• Greenhouse gases
“Global warming” specifically refers to a general warming of the planet due the
anthropogenic increase in greenhouses gases.
Unfortunately, “climate change” is now misconstrued as the same as “global warming.”
Is there a consensus?
Scientific Consensus
Synthesis Reports or
Assessments
• IPCC Fourth Assessment
(2007)
• U.S. Global Change
Research Program (2009)
• Arctic Climate Impact
Assessment
Concurring Statements
• National Academy of Science
• National Research Council
• American Geophysical Union
• American Meteorological
Society
• World Meteorological
Organization
Surveys and literature
reviews
• Doran and Zimmerman, 2009
• Oreskes, 2004
Natural Causes of Climate
Change
Milankovitch Cycles
Changes in the
eccentricity of the earth’s
orbit, obliquity, and
precession of the
equinoxes are the main
triggers to the 100,000
year ice age cycles.
Sunspot Cycles
The number of sunspots varies
on an 11-year cycle. High
numbers of sunspots correspond
to increased solar irradiance and
solar winds.
The current inactive period has
been more quiet and long-lasting
than previous minima.
Coupled air-sea interactions
The El Nino/La Nina cycle is the
predominant mode of year to
year climate variability. Other
modes include:
• Pacific decadal oscillation
• North Atlantic oscillation
• Atlantic multidecadal oscillation
Greenhouse Gas Concentrations
Recent CO2 Trends
Historical Greenhouse Gas Concentrations
Scientist extract ice cores
from up to two miles
beneath the surface at
Vostok, Antarctica.
Global and Regional
Temperature
Reconstructed Temperature Records
“the Holocene, which has already lasted
11,000 years, is, by far, the longest stable
warm period recorded in Antarctica during
the past 420,000 years,”
- Petit, et. al., 1999
The famous “hockey stick” graph
of reconstructed temperatures
from Mann, et al.
- Source:
Intergovernmental Panel on
Climate Change 2001
Modern Day Temperatures
Southeast Temperature Trends
Florida
Georgia
Rural Weather Station
Town is located to the northeast of Eglin AFB, a large
expanse of undeveloped forests.
Surrounding countryside consists
farmland, and pine forests.
of
pastures,
Station located at Showel Farms, 3 miles to the east
of the city.
Walton County population is very low at around
40,000.
Small Town
Small Town surrounded by pastures,
citrus groves, pine stands, and
lowlands.
Station located at the water treatment
plant inside the city limits.
Arcadia has grown very little in the last
40 years and only has a population of
around 10,000.
USHCN station (unadjusted data)
A Closer Look – Fort Myers
Station located at Page Field near downtown
Fort Myers.
The city of Fort Myers has experienced
tremendous urban sprawl in the last 40 years.
Lee county population has ballooned from
60,000 to over a half million in the last 40 years.
Climate and Florida Citrus
Adapted from: John Attaway, “A History of Florida Citrus Freezes”
Impact Freezes:
February 7-9, 1835
December 29, 1894
February 8, 1895
February 13-14, 1899
December 12-13, 1934
January 27-19, 1940
December 12-13, 1962
January 18-20, 1977
January 12-14, 1981
December 24-25, 1983
January 20-22, 1985
December 24-25, 1989
January 19, 1997
Freeze damaged orange trees in 1895
Global and Regional
Precipitation
Global Precipitation Trends
Southeast Precipitation Trends
Impacts of Land Use Changes
Modeled differences in convective summer (July – Aug.)
rainfall using pre-1900 and 1993 land cover.
1973
1989
Marshall, Pielke, et. al. 2004
1994
Extreme Events and Sea
Level Rise
Climate Change and Hurricanes
Hurricanes and Global Warming
Emanuel (Nature, 2005) –
Hurricane power has increased in
recent decades due warmer sea
surface temperatures part to global
warming
Webster, et al. (Science, 2005) –
The number of category 4 and 5
hurricanes have doubled in the last
30 years, due to global warming.
Atlantic Hurricanes
“Over
the long term the effects of
changes in society dwarf the effects
of any projected changes in tropical
cyclones…”
“…claims of linkages between global
warming and hurricane impacts are
premature…”
- Pielke, et. al., 2005
“Thus large, long-term ‘trends’ in
tropical cyclone frequency are
primarily manifestations of increased
monitoring capabilities and likely not
related to any real change in the
climate in which they develop.”
- Landsea, 2007
Sea Level Rise – Who is Right?
Some Well-known predicitons:
James Hansen (NASA) – 20 ft. or
more, past the “tipping point”
Harold Wanless (Miami) – 3.3 to 5.0 ft
Harrington and Walton (FSU) – 0.83
to 1.13 ft by 2080
IPCC 4 – 10 to 23 inches
Recent Studies:
Image courtesy of Environmental Studies Laboratory,
University of Arizona
Mitrovica, et al., University of Toronto –
uneven effects of melting Antarctica
Skaarup, et al., University of Copenhagan
– correlation of proxy data with past sea
level measurements
Causes of Sea Level Rise
Global sea level can rise
from two primary
causes:
1)
Warming of the oceans
(thermal expansion)
2)
Melting of ice caps and
glaciers
Historic sea level rise
• Sea level measurements from
23 highest quality tidal stations
around the world.
• Estimates of sea level rise from
1 mm/yr to 2 mm/yr.
• Satellite measurements
(altimeters) since 1992 indicate
a rise of around 3mm/yr.
• IPCC third assessment report
stated "No significant
acceleration in the rate of sea
level rise during the 20th century
has been detected."
Local sea level measurements
Key West
2.27 mm/yr
Pensacola
2.14 mm/yr
Predictions for the Next
Century
An Uncertain Future
Uncertain Future
Limitations
Models
of
Climate
•The physics of water vapor, clouds, and
precipitation are poorly represented.
• Limited spatial resolution
• Climate models have not demonstrated
the ability to reproduce the modes of
variability seen in the 20th century.
• Cannot accurately predict regional
shifts in temperature or precipitation.
• Coupling between the atmosphere and
the ocean, land surface, and ice
surfaces is limited.
Other Possible Outcomes with Rainfall
• Rainfall has become more extreme (larger
events) in the last 50 years (Karl, et al.)
• As temperatures warm, warm air holds more
moisture and rainfall should increase.
• We don’t know exactly when, where, how
much this increase will be.
• Warmer climate may also lead to more
extreme rainfall and extended droughts.
• How a changing climate will effect lakes,
rivers, and water resources is uncertain.
Where do we go from here?
“…climate change that takes
place due to increases in
carbon dioxide concentration is
largely irreversible for 1,000
years after emissions stop.”
- Soloman, et al, 2009