Global warming is the result of somewhat complex atmospheric dynamics which can result in a warmer planet, stronger storms, both floods and droughts, political instability and elevated sea levels. Probably the simplest of these outcomes to understand is sea level rise. If it gets warmer ice melts to water and drains into the oceans, raising the global water level. Additionally as the oceans warm, the warmer water takes up more space and adds to sea level rise.
Those that deny the risks of global warming might say that melting icebergs or the melting of the north polar ice won’t change sea level and if that is all you consider, it is true. But there is much more ice trapped on land in the form of glaciers, the Greenland ice sheet and the vast Antarctic ice sheet. Enough in fact to raise the level of the seas eighty meters, or over two hundred and fifty feet.
A sea level rise of two hundred fifty feet would leave only Lady Liberty’s head above the New York Harbor. Only the tippy-tops of the skyscrapers in most coastal cities will be above water. The Atlantic coastal plain, South Florida, and the state of Louisiana will be fishing grounds.
This level of rising seas is the worst case scenario based on hundreds of years of unabated burning of fossil fuels, according the Intergovernmental Panel on Climate Change. So what about sea level rise in the near term, say within the twenty first century? There are people alive today who will see the turn of the next century. If the combustion of fossil fuels is not reined in, a modest projection is a two meter (over six feet) rise. If anything combustion of fossil fuels is accelerating due to advanced recovery techniques like horizontal drilling and fracturing.
The impact of a two meter rise in sea level varies from a minor nuisance to a catastrophe depending on location. Some islands in the South Pacific are already suffering from the one quarter of a meter rise over the past one hundred years or so. The combination of rising sea level and more severe storm surges due to global warming are causing coastal erosion. Increased salinity of the remaining soils which decreases agricultural productivity is as troublesome as the erosion.
The real catastrophe is the flooding of large coastal cities. Miami, New Orleans, and Tampa are three of those at greatest risk because most exist at sea level already, and are also sensitive to more flooding due to tropical storms and hurricanes. Estimates of fifty billion dollars per city per year may be necessary to prevent or mitigate damage due to flooding.
The most recent experience with severe coastal flooding was due to Hurricane Katrina. Economic losses to Louisiana and Mississippi are estimated to be over one hundred fifty billion dollars.
Our thrust for the cheapest energy up front may very well cost us a lot more when all the costs are accounted for. Solar, wind, and geothermal which don’t drive global warming are looking cheaper every day.