Climate change is a phenomenon that has been happening on our planet most likely since it was formed.  Many earth scientists believe the earth was formed some 4.5 billion years ago.  Alternatively, there are those people who calculate the age of the earth based on the Bible. Up front let me say that as a scientist, I believe the former.  Whichever way you believe, it is a fact that climate change is occurring right now.

The earth is warming.    According to an article in this month’s National Geographic, the average global temperature for 2016 was 1.69 degrees Fahrenheit warmer than the 20th-century average.  The icecaps of Greenland and Antarctica are melting at alarming rates and sea levels are rising, slowly, but nevertheless rising.  An interesting fact:  For centuries, European explorers sought a Northwest Passage, a way through the Arctic Ocean to Asia.  Several expeditions met with disaster and safe passage was not found.  The ice was too thick even in summer.  In the early 21st century, as temperatures warm, arctic ice is melting.   icebreakers from several countries have been active in the Arctic Ocean.  In 2016, the first journey through the Northwest Passage was made by a cruise ship.

So the question is, 1) is global warming strictly a natural phenomenon, or 2) is the natural warming exacerbated by human activity vis-à-vis greenhouse gasses released to the atmosphere from fossil fuels?   More than 90 percent of climate scientists believe it is number 2.  There is, however, a vocal minority of a few climate scientists together with non-scientists who vigorously deny that human activities contribute to global warming.  I am not part of this minority.

As a hydrologist, I’m concerned with sea level rise that is one of the results of global warming.  Since 1900, our oceans have risen 8 to 9 inches.  No that doesn’t sound like much but what has happened in recent years is significant increases in flooding in coastal areas around the world.  Couple sea level rise with major storm-related disasters, for example, Superstorm Sandy, together with increasing population densities in coastal areas, and sea level rise seems much more significant.  Sandy itself caused nearly $70 billion in damages.

While predicting sea level rise is an inexact science, enough significant data are available on temperatures and on melting rates of ice sheets and glaciers, that climate scientists have predicted that by the year 2100, sea levels could rise as much as six feet.  If this happens, it would cause dire situations for countries such as Bangladesh, island nations such as the Maldives, and cities such as Shanghai.  In the U. S., barrier islands on the east coast would be threatened or might disappear. New Orleans could become an island surrounded by levees.

Saltwater intrusion from sea level rise already is threatening some aquifer systems, especially in Florida.  The cities of Miami and Miami Beach, Florida are so concerned that they are acting proactively.  They have already embarked jointly on an ambitious program to combat the threat.  In addition to sea walls, they are raising streets and installing pumps to remove encroaching sea water.

I believe that climate change-induced sea level rise will be one of the major environmental problems of the 21st century.  Even in the U. S., it will take careful planning and the judicious expenditure of billions to ensure that millions of residents of low-lying areas near the coasts are not displaced by salt water.