John’s Blog/Newsletter: SEA LEVEL RISE NOW

Cape May, New Jersey is a popular seaside destination, particularly in the summer. This week they announced plans to raise a two mile stretch of main road by 5 feet so that it is useable during flooding — which happens increasingly, and is expected to increase with the sea level rise that they expect to continue in future years. The story is in the local Press of Atlantic City at http://tinyurl.com/3nq7uqu

They join a growing list of communities (e.g. Miami, the Florida Keys, Norfolk-Virginia area, etc.) that also are raising streets in the struggle to deal with the increased frequency of flooding. They each have established their own climate change task forces, that have concluded that the warming ocean and melting ice sheets mean that sea levels will just keep getting higher and higher. Most studies now assume that sea level rise (SLR) will reach somewhere between three and five feet (1 – 1.6 meters) this century. That would devastate nearly all coastal communities.

Those estimates have generally been moving higher over the last few years, as the melt rates in Greenland have been accelerating. Just to put things in perspective, when the massive ice sheet on Greenland — now more than two miles thick (3 km) — global sea levels will be approximately 21 feet (6.5 m) higher than today. That will likely take thousands of years however, so there is no need to panic.

Overall, it presents communities with a very difficult, and unprecedented situation. Their efforts are farsighted, yet desperate, and frankly, futile in the longer term. As the sea rises, allowing the odd storm to do the work of erosion from a higher “launch point” the shoreline will move inland. There is no doubt about that. All of the debate and plans about climate change are unable to change that fundamental trend, due to the extremely long “lag time” for increased heat in the atmosphere — mostly transferred to the ocean — which will continue to melt the ice sheets. You can think of the ocean as a giant “heat battery” storing the increased heat trapped in the atmosphere by greenhouse gases. The result is that recent models project that sea level will continue to rise for at least 500 years, even if we stopped all CO₂ emissions today.

So, back to the question of what should communities do? Of course “buying time” likely makes sense even if they realize they may be totally flooded over the next century. But raising a single road — even if it is for an evacuation route — sidesteps the reality of the vast and wide-ranging impacts on coastal communities as sea level rises.

It is not just the “main street.” There are often issues of saltwater intrusion on the underground fresh water table; the storm drain system may not work with higher sea level; the local sewer treatment system may become inoperative with higher sea level. Often there are underground utilities, even power plants, and coastal railroads that will be at risk from even a single incident of flooding at the seasonal lunar high tides.

Property becomes worth much less, if not worthless, in a single instance of flooding, if it is clear that it is part of an ever worsening creeping phenomenon. As properties are affected, and insurance costs rise, the values will start to go down. A smaller community has a lower tax base, which increases the problem of how to pay for the increasing costs of adaptation — a truly vicious cycle.

In my presentations about sea level rise, and upcoming book (you can sign up for notification on my website) I explain that sea level rise is nothing new in Earth’s history. For example, with each ice age, that covered North America and Europe with ice sheets several miles thick, sea level drops almost 400 feet (120 m). This happened most recently only 20,000 years ago. The ice ages are a natural phenomenon that occur in regular cycles every hundred thousand years, for the last few million years. So there is some truth to those that dismiss climate change as a natural cycle, that has occurred before — even if they are confused by timescale.

But now we are changing the cycle. It is a simple connection: more CO₂ (the little graphic on my website shows we are at 394, and climbing) means warmer temperature, and less ice on the planet. Less ice means sea level will rise.

That long term perspective presents all coastal communities with a tough challenge. They can take increasingly expensive short term measures like Cape May is doing, but they have to recognize that it is the ultimate losing battle.

The sooner that we begin what I call Intelligent Adaptation, to plan for inevitable, increasing sea level rise, and changing coastlines, the sooner we can start investing in the future. That means new zoning and setbacks. It means really innovative engineering and large scale civil works to adjust to a new shoreline. Some communities are in a better situation than others. Depending on the slope of the shoreline, and the geologic composition, some communities have a limited future. Surprisingly, rising sea level will not have the same impact everywhere. A simple proof of that is the fact that Alaska presently has dropping sea level in many areas, due to the land uplifting, while Newport News (Virginia) and New Orleans have double the average rate of sea level rise, due to the fact that their land masses are subsiding — moving downward.

Raising roadways is a short term necessity, but limited in the long term. The challenge will keep getting more widespread. There are limits to what can be done, and it will get much more expensive, with no end in sight — well, actually we can foresee the end that will come, but it is a long way off. Yet as sailors and those living on the beach have known for centuries, it is good to “look to the far horizon” to know what is coming, and to prepare.