In the short term, preventive action could spare many of the model’s predictions from becoming reality. Key Largo and Miami Beach, which act as a buffer zone preventing salinization of interior land and freshwater, are particularly vulnerable. If these regions flood, seawater intrusion may occur, resulting in widespread ecological, agricultural, and ultimately eco-nomical damage. Titus and Narayanan [1995] recommend building sand walls.
In the long term, carbon emissions must be reduced to prevent disasters associated with sea-level rise.
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Fighting the Waves: The Effect of North Polar Ice Cap Melt on Florida
Amy M. Evans Tracy L. Stepien
University at Buffalo, The State University of New York Buffalo, NY
Advisor: John Ringland
Abstract
A consequence of global warming that directly impacts U.S. citizens is the threat of rising sea levels due to melting of the North Polar ice cap.
One of the many states in danger of losing coastal land is Florida. Its low elevations and numerous sandy beaches will lead to higher erosion rates as sea levels increase. The direct effect on sea level of only the North Polar ice cap melting would be minimal, yet the indirect effects of causing other bodies of ice to melt would be crucial. We model individually the contributions of various ice masses to rises in sea level, using ordinary differential equations to predict the rate at which changes would occur.
For small ice caps and glaciers, we propose a model based on global mean temperature. Relaxation time and melt sensitivity to temperature change are included in the model. Our model of the Greenland and Antarc-tica ice sheets incorporates ice mass area, volume, accumulation, and loss rates. Thermal expansion of water also influences sea level, so we include this too. Summing all the contributions, sea levels could rise 11–27 cm in the next half-century.
A rise in sea level of one unit is equivalent to a horizontal loss of coastline of 100 units. We investigate how much coastal land would be lost, by analyzing relief and topographic maps. By 2058, in the worst-case scenario, there is the potential to lose almost 27 m of land. Florida would lose most of its smaller islands and sandy beaches. Moreover, the ports of most major cities, with the exception of Miami, would sustain some damage.
Predictions from the Intergovernmental Panel on Climate Change (IPCC) and from the U.S. Environmental Protection Agency (EPA) and simulations
from the Global Land One-km Base Elevation (GLOBE) digital elevation model (DEM) match our results and validate our models.
While the EPA and the Florida state government have begun to imple-ment plans of action, further measures need to be put into place, because there will be a visible sea-level rise of 3–13 cm in only 10 years (2018).
Introduction
Measurements and observations of Earth’s ice features (e.g., glaciers, ice sheets, and ice packs) indicate changes in the climate [Kluger 2006; NASA Goddard Institute for Space Studies 2003; Natural Resources Defense Coun-cil 2005] and consequent raised ocean levels resulting from their melting.
Over the past 30 years, the amount of ice covering the North Pole has been reduced by 15%–20%. Additionally, the snow season in which ice is restored to the pack has grown shorter. By 2080, it is expected that there will be no sea ice during the summer [Dow and Downing 2007].
Besides the Arctic ice pack, glaciers of around the world are also shrink-ing. Warmer air and ocean waters cause the melting, and most glaciers have retreated at unparalleled rates over the past 60 years [Dow and Downing 2007].
Two other signs of a changing climate have direct impacts on people: in-creased weather-related disasters and a rising sea level. In 2005, the United States experienced 170 floods and 122 windstorms, compared with 8 floods and 20 windstorms in 1960. The statistics are similar for other countries, with 110,000 deaths due to weather-related catastrophes worldwide in 2005.
Sea-level rise results are visible. Small, low-lying islands in the Southern Pacific Ocean have either disappeared (e.g., two of the Kiribati islands in 1999) or had to be abandoned by residents (e.g., Carteret Islands in Papua New Guinea). Over the 20th century, the average sea-level rise was roughly 15 cm. If this trend continues, many more islands as well as the coastline of some countries would be lost [Dow and Downing 2007].
Assumptions
All the documentation that we encountered stated the same basic claim:
The North Polar ice cap melting will on its own affect the global ocean level by only a negligible amount. This claim is simply a matter of the Archimedes Principle: The volume of water that would be introduced to the world’s oceans and seas is already displaced by the North Polar ice pack, since it is comprised of frozen sea water floating in the Arctic Ocean.
However, the disappearing Arctic ice pack will speed up global warm-ing, which encourages the melting of other land ice masses on Earth (e.g.
Greenland, Antarctica, etc.). Thus, ocean levels will rise more as the North
Polar ice cap shrinks, due to indirect effects. In fact, North Polar ice cap melt is used as an “early warning system” for climate change around the world [Arctic Climate Impact Assessment 2004].