Climate Change Basics for the SoutheastClimate 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

IntroductionIntroduction

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

New Emphasis on Climate Change

“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 ConclusionsIPCC 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 globally-averaged 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” 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 ConsensusScientific 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 Natural Causes of Climate ChangeChange

Milankovitch CyclesMilankovitch 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 CyclesSunspot 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 interactionsCoupled 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 ConcentrationsGreenhouse Gas Concentrations

Recent CO2 TrendsRecent CO2 Trends

Historical Greenhouse Gas ConcentrationsHistorical Greenhouse Gas Concentrations

Scientist extract ice cores from up to two miles beneath the surface at Vostok, Antarctica.

Global and Regional Global and Regional TemperatureTemperature

Reconstructed Temperature RecordsReconstructed 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 TemperaturesModern Day Temperatures

Southeast Temperature TrendsSoutheast Temperature Trends

Florida

Georgia

Rural Weather StationRural Weather Station

Town is located to the northeast of Eglin AFB, a large expanse of undeveloped forests.

Surrounding countryside consists of pastures, farmland, and pine forests.

Station located at Showel Farms, 3 miles to the east of the city.

Walton County population is very low at around 40,000.

Small TownSmall 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 MyersA 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 CitrusClimate and Florida CitrusAdapted from: John Attaway, “Adapted from: John Attaway, “A History of Florida Citrus Freezes”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 Global and Regional PrecipitationPrecipitation

Global Precipitation TrendsGlobal Precipitation Trends

Southeast Precipitation TrendsSoutheast Precipitation Trends

Impacts of Land Use ChangesImpacts of Land Use Changes

1973 1989 1994

Modeled differences in convective summer (July – Aug.) rainfall using pre-1900 and 1993 land cover.

Marshall, Pielke, et. al. 2004

Extreme Events and Sea Extreme Events and Sea Level RiseLevel Rise

Climate Change and HurricanesClimate Change and Hurricanes

Hurricanes and Global WarmingHurricanes 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 HurricanesAtlantic 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?Sea Level Rise – Who is Right?

Image courtesy of Environmental Studies Laboratory, University of Arizona

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:

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 RiseCauses 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 riseHistoric 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 measurementsLocal sea level measurements

Pensacola2.14 mm/yr

Key West

2.27 mm/yr

Predictions for the Next Predictions for the Next CenturyCentury

An Uncertain Future

Uncertain FutureUncertain Future

Limitations of Climate Models

•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 RainfallOther 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?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