Sea Level Rise Small, Steady and Unprecedented

For years scientists and politicians have been saying the sea is rising. And it is. But because the amount of sea level rise each year is measured in millimeters for many it seems insignificant and for some it seems downright laughable.

But new research this week confirms that sea levels have risen faster in the last century than they have in the last 2,000 years. By sifting through North Carolina sediment deposits and studying microfossil evidence and then comparing that data with detailed maps of sea levels and coastlines scientists are making the strongest case yet that sea level rise is something we should all think about.

Scientists link the rapid increase in rate of sea level rise to climate change. As the global average temperature inches up the ocean’s temperature also increases. When water heats up it expands. This thermal expansion explains a good chunk of the sea level rise we’ve witnessed in the last 100 years.

But the actual amount the seas have risen in the last century doesn’t amount to much — around 7 inches. That’s about two millimeters a year.

Geologist Benjamin Horton, one of the authors and director of University of Pennsylvania’s Sea Level Research Laboratory says, “Where the temperature goes up, sea level goes up. Where the temperature stabilizes, so does sea level. Where the temperature picks up in the 20th century, so does sea level.”

In the most detailed look yet at sea-level change along the east coast of the U.S., scientists have discovered that waters have risen far faster over the last century than at any time in the previous 2,000 years.

By studying fossils, they found that temperature and sea level rise were in lock step during that time.

The team found that sea level was relatively stable from 200 BC to 950 AD. But beginning in the 11th century, sea level rose by about half a millimeter each year for 400 years during a warm climate period known as the Medieval Climate Anomaly. Then sea level was stable again during a period, called the Little Ice Age, that persisted until the late 19th century. However since then, sea level has risen more than 2 millimeters per year on average, the steepest rate for more than 2,100 years.

Horton says, “Sea-level rise is a potentially disastrous outcome of climate change, as rising temperatures melt land-based ice and warm ocean waters.”

But are Al Gore’s predictions about an inundated Florida and climate refugees in coastal areas true? The short answer is maybe. And it all depends on several unpredictable factors — the rate of land ice melting and contributing to sea-level rise and catastrophic ice sheet collapse either in Greenland or Antarctica.

From studying the past Horton can’t predict the future but he says, “So for the 21st century when temperatures will rise, so will sea level.”

But as sea levels rise so does the volume of water the ocean can hold. Most scientists consider the glacial isostatic adjustment (GIA) to be insignificant. GIA explains the slight continental rebound that is ongoing since the weight of the ice during the last ice age has diminished. This land rise is about .3 millimeters per year.

Scientists add this to sea level measurements in order to calculate the true rise or adjusted rise. Steve Nerem the director of the Ice told FoxNews, “We have to account for the fact that the ocean basins are actually getting slightly bigger.” That means the water volume is actually expanding.

However a lawyer for the conservative think tank the Heartland Institute decided to make that tiny measurement into a big deal, calling all the science about climate change into question, saying, “There really is no reason to do this other than to advance a political agenda.”

It begs the question, if most people don’t seem concerned that sea level has risen 7 inches in 100 years, why are a few non-scientists quibbling over .3 millimeters (which can be scientifically explained)?

While Al Gore’s picture of a water-world future entices his detractors to call him an alarmist, history has shown that failure to adapt to the climate spells trouble for people. Take the Vikings.

They inhabited a warmer Greenland during a period of climate anomaly when the temperature was much warmer. They failed to prepare for a cold reality and were forced to flee during the Little Ice Age.

Unless a large land-based chunk of ice collapses and melts, adding immediate increase to global sea levels — which would swamp low-lying islands and nations like Bangladesh — those of us around now probably won’t live to see the harsh presence of major sea level rise.

But that doesn’t mean we should ignore it. Future generations will either look back and thank us or curse us for the action we take now.

While scientists can’t foresee the exact amount of sea level rise, many are saying to prepare for about 36 inches this century. That is five times more than was measured in the 20th Century.

The FoxNews story ends with a snarky statement from the lawyer Taylor, who calls Gore’s suggestion of a flooded New York tomfoolery. “If it were going to happen, he wouldn’t have bought his multi-million dollar mansion along the coast in California.”

I’m sure the Vikings said the same thing.

Though the average sea level rise over the last 100 years was about 2 millimeters each year, since 1993 that rate has increased to 3 millimeters per year, caused largely by thermal expansion and increased melting of Greenland’s ice sheet.