CLIMATE CHANGE By ANDREW GARCIA, PhD Coastal Hydraulic Laboratory, - PDF document

The University of the West Indies Organization of American States P ROFESSIONAL D EVELOPMENT P ROGRAMME : C OASTAL I NFRASTRUCTURE D ESIGN , C ONSTRUCTION AND M AINTENANCE A COURSE IN COASTAL ZONE/ISLAND SYSTEMS MANAGEMENT C HAPTER 8 ( A S PRESENTED AT THE WORKSHOP ) CLIMATE CHANGE By ANDREW GARCIA, PhD Coastal Hydraulic Laboratory, US Army Corps of Engineers Vicksbury, MA, USA Organized by Department of Civil Engineering, The University of the West Indies, in conjunction with Old Dominion University, Norfolk, VA, USA and Coastal Engineering Research Centre, US Army, Corps of Engineers, Vicksburg, MS , USA. Antigua, West Indies, June 18-22, 2001

Introduction to Climate Change US Army Engineer Research and Development Center

Course Outline Part I. Indicators of climate change Proposed sources of climate change Attribution of climate change Part II. Effects of climate change Part III. El Nino and tropical cyclones

Principle Material Sources Intergovernmental Panel on Climate Change, Reports of Working Groups I and II Bulletin and journals of the American Meteorological Society NASA reports on Greenland ice cap (Krabill, et al.) and satellite derived atmospheric temperatures (Spencer and Christy) Various text books

Introduction to Climate Change Climate Change Definition… A measurable long-term change in an atmospheric or oceanic physical or chemical variable attributable to natural or anthropogenic effects

Climate Change Indicators • For the period 1901 – 2000, earth’s surface temperature (land and ocean) has increased 0.6 ± 0.2°C • For the Northern Hemisphere, 1990’s was the warmest decade and 1998 was the warmest year • For the Northern Hemisphere, there was ~ 10% decrease in snow cover since the late 1960’s (Continued)

Climate Change Indicators (Concluded) • There has been an overall retreat of mountain glaciers in non-polar regions this century • El Nino (warm episodes) have been more frequent, persistent, and intense since the 1970’s when compared with the previous one-hundred years

Earth’s Surface Temperature

Surface Temperature - 2

Temperature by Hemisphere

NH Proxy Temperature

Northern Hemisphere Temperature

Greenland Ice Cap

NASA Airborne LASER

NASA LASER Close-up

Ice Accumulation - Loss

Southern Greenland

Southeast Greenland

Greenland Close-up

Absent Indicators of Climate Change • Southern Hemisphere oceans and parts of Antarctica have not shown discernable warming • No significant trend observed in the extent of Antarctic sea ice since 1978 using satellite observations (Continued)

Absent Indicators of Climate Change (Concluded) • No discernable trend in tropical or extra-tropical storm activity • No systematic changes in the frequency of tornadoes, hail events, or severe thunderstorms

Attributed Sources of Atmospheric Warming re 1750 “Greenhouse” gases… • Carbon dioxide (CO2) – 31% • Nitrous oxide (N2O) – 17% • Methane (CH4) – 151%

Greenhouse Gas Growth

Nitrous Oxide Increase

Carbon Dioxide Increase

Methane Increase

Sulfate Aerosols in Greenland Ice

What is the “Greenhouse” effect? 1. Incoming solar radiation is strongest in the visible and near UV wavelengths. 2. Outgoing terrestrial radiation is strongest in the IR wavelengths. 3. “Greenhouse gases” (including water vapor) absorb outgoing IR radiation thereby trapping energy.

Incoming Solar Spectrum

Idealized Outgoing Spectrum

Atmospheric Absorption Spectrum

Anthropogenic Sources of “Greenhouse” Gases • Carbon dioxide – burning of fossil fuels, deforestation • Nitrous oxide – use of chemical fertilizers, animal feedlots, chemical industries • Methane – burning of fossil fuels, rice agriculture, deforestation (termites)

Simulated Surface Temperature, Natural

Simulated Surface Temperature, Anthropogenic

Simulated Surface Temperature, Combined

Total Radiative Forcing

Atmospheric Temperature Trend, Troposphere

Atmospheric Temperature Trend, Stratosphere

Big Picture

Summary on Detection and Attribution Recent changes in global climate inferred from near-surface atmospheric temperatures cannot be readily explained by natural climate variability. Greenhouse warming alone is insufficient to explain the observed climate change pattern. Barnett et al., BAMS, 1999 (continued)

Summary on Detection and Attribution The most probable cause of observed warming is a combination of internally and externally forced natural variability and anthropomorphic sources. Barnett et al., BAMS, 1999 (concluded)

Natural Systems at Risk Include - • Glaciers • Coral-reefs and atolls • Mangrove swamps • Tropical and boreal forests • Prairie wetlands

Human Systems Sensitive to Change Include - • Water resources • Agriculture and forestry • Coastal zones and marine fisheries • Human health • Insurance and financial services

Possible Adverse Affects Include - • Reduction in potential crop yields, particularly in tropical and sub-tropical regions • Decreased water availability in present water scarce regions, particularly in the sub-tropics • Increased flooding risk from both more frequent heavy precipitation events and sea-level rise (Continued)

Possible Adverse Affects Include - (Concluded) • Increased energy demand for summertime cooling • Increased geographic range of vector-borne infections

Possible Beneficial Effects Include - • Increased potential crop yields in some mid-latitude regions • Increased potential global timber supply from appropriately managed forests • Increased water availability in some present water- scarce regions, e.g., parts of southeast Asia (Continued)

Possible Beneficial Effects Include - (Concluded) • Reduced human mortality in mid- and high latitudes • Reduced wintertime demand for heating

Observed Climate Trends in Caribbean Islands • Mean annual temperature increase of >0.5°C during the period 1900-1995* • Mean annual precipitation increase of ~250mm* * Based upon data obtained in Cuba?

Predicted Climate Change for Island Basins • Inter-model agreement on climatic effects of CO2 doubling is poor for the Western Atlantic, Caribbean and Mediterranean Seas • There appears to be no clear trend as to frequency, intensity, or distribution of topical cyclones in these basins

El Nino Region Definition

El Nino and Hurricane Seasons

El Nino Damage Estimates

El Nino, La Nina, and Atlantic Hurricanes • La Nina episode means a greater frequency of damaging storms and more damage per storm • El Nino episode does not mean no hurricanes, as several El Nino years have seen large effects • Mid-Pacific equatorial SST anomaly can provide a statistically significant indicator of damage (Continued)

El Nino, La Nina, and Atlantic Hurricanes (Concluded) • Mid-Pacific equatorial SST anomaly is not the only climate factor related to hurricane damage • There appears to be no skill in forecasting Nino SST anomalies other than simple climatology and persistence, which is good only to 8 months

Conditions for Tropical Cyclone Formation 1. Warm ocean surface waters, ~26 degrees C, of sufficient depth, ~50m. 2. Conditionally unstable atmosphere, one that cools with height. 3. Sufficient atmospheric moisture at lower-levels, ~5km. (continued)

Conditions for Tropical Cyclone Formation 4. At least ~5 degrees distance from the equator; sufficient Coriolis force to produce gradient wind balance to maintain low surface pressure. 5. An initiating disturbance, e.g., tropical wave. 6. Low vertical wind shear between the surface and upper troposphere. (concluded)

Hurricane Processes,I

Hurricane Processes, II

Hurricane Processes, III

Hurricane Probability

Intense Hurricane Probability

Closing Quote “Models are what we use when we don’t have data.” R. E. L. Pickett, 1967