Climate change and uncertainty

Harold Brown's picture

Hurricane Sandy has been described as a harbinger of what comes with rising seas: the inundation of coastal cities, devastating storm surges, destruction of coastal wetlands and abandonment of land. The story is simple: Glaciers melt and oceans warm, causing seas to rise.

The reality, however, is anything but simple. The sea has been rising since the last ice age, but at a variable and poorly known rate. Long-term measurements are necessary to establish an accurate trend, but measurements were few in the 19th and early 20th centuries, especially in the Southern Hemisphere.

More than two thirds of the 322 world sea level records listed on the National Oceanic and Atmospheric Administration (NOAA) website are 50 years or less. Only 11 percent are more than 100 years, none of those south of the equator.

Sea rise is complicated because it is uneven and relative. It is uneven in time, space and certainty. All sea level measurements based on the shore are relative to that shore. Some shores are rising, some are sinking. As a 1986 editorial in the Journal of Coastal Research noted, “Many of the world’s great cities, including London, New Orleans, Tokyo, Houston, and Mexico City, are sinking.”

All news sources know that New Orleans has the most to fear from rising seas. They apparently don’t know that the concern is not new. Civil engineer E.L. Corthell reported in National Geographic in 1897 that a Spanish magazine built 200 years earlier below New Orleans was standing in 10 feet of water by 1877. He concluded from this information and an 1894 Mississippi River Commission report that the Mississippi Delta was sinking at about 0.6 inches) per year (about five feet per century).

More than a century later, not much has changed. Some sections of the lower Mississippi Delta are sinking at rates of 0.8 inches or more per year; some parts of New Orleans are already eight feet below sea level. The average sea rise of 1 to 2 mm per year (4-8 inches per 100 years, which the Intergovernmental Panel on Climate Change estimates for the 20th century) is hardly New Orleans’ biggest problem. It is sinking several times as fast.

The threats of wetland loss and coastal flooding caused by climate change are considered something new and devastating. But, as Corthell wrote in that century-old report, “It is a fact well-known to people living in the delta of the Mississippi that large tracts of land were long ago abandoned in consequence of overflow by Gulf waters, due to the sinking of the lands.”

The south Mississippi Delta was built over many centuries by sediment brought down from mid-continent by the river and deposited in the salt marsh. The sediment is loose or uncompacted and mixed with vegetation, but over the centuries it settles, compacts and sinks.

A similar process occurs in estuaries all over the earth where land subsidence complicates sea-level rise. Subsidence on the Gulf Coast extends from the Panhandle of Florida to the south Texas coast. In the Chesapeake Bay, subsidence accounts for about half of the observed sea level rise.

An opposite complication of sea level measurement occurs over extensive areas of the earth where land is rising. This can occur along geologic faults, but also over large areas covered by thick ice during the last ice age. The earth’s crust is not completely immovable; it floats on a molten core. As the ice age ended, tremendous weight was removed from the surface. The land rebounded and still is rebounding.

Coasts of some countries are losing land to the sea, others are gaining. The town of Churchill on Hudson Bay, large portions of Scandinavia and Finland coasts, and the southeast coast of Alaska have falling sea levels, relative to land surface. Skagway, Alaska, is rising as fast as the Mississippi Delta is sinking. The North Ireland coast has slightly falling seas. Twelve of 32 stations in China showed falling seas over the 20 to 80 years preceding 1993.

NOAA knows the variability. On its website it warns: “Over the next century, sea level rise within the United States is expected to vary between -6 to +4 feet, depending on location.”

The causes and variability of sea level rise are so complicated that hundreds of scientific papers are written every year to clarify it.

Unfortunately, as the discussion after Hurricane Sandy revealed, too often, “experts” and activists try to simplify the process to float their own agendas.

[University of Georgia Professor Emeritus R. Harold Brown is a Senior Fellow with the Georgia Public Policy Foundation and author of “The Greening of Georgia: The Improvement of the Environment in the Twentieth Century.” The Georgia Public Policy Foundation (www.georgiapolicy.org) is an independent think tank that proposes market-oriented approaches to public policy to improve the lives of Georgians.]

conditon55
conditon55's picture
Offline
Joined: 03/12/2010
The Green Revolution

The earth does not care about environmental policy.
It knows nothing of oil companies or coal companies.
It knows nothing of profits or loss.

The bible mentions that man has dominion over nature, but it does not say that man has free license to treat the earth like a cesspool and an ash tray.

The implication is dominion in the form of stewardship. That is the part that is missing.

Al Gore got his CO2 statistic correct. On an Earth with a population of 7 billion people, humans can quickly and easily overwhelm a zone, area or region, and now, even the entire planet.

One point to remember is that the world is a system. Every thing it had or will even have is here on it right now. What is the option to add to it or subtract from it ? That is why the Globe at Disney Epoch it called Spaceship Earth.

So what we say think and do matters. The hand of man makes a difference. But since the system is huge, it will absorb an insult for a long time and then the pendulum of change will swing. There is a lag time between what I do today and the effect that is seen in the environment. And that is what is happening now. The effects of our actions today will be felt for another 100 years. So the effect we feel today are from action from the early 1900s. If this is correct, and how could it not be? What will the world be like in another 100 years.

The earth cares not for profits from fossil fuels but If you pump in CO2, it is going to get hotter. And that is what is happening. As there is no technical barrier to transition to wind and solar, best to ramp up that effort now. Because there is no external saving grace that will materialize from some unknown external place to save us from stupid management of our home, Plant Earth.

Davids mom
Davids mom's picture
Offline
Joined: 10/30/2005
Quote: The earth cares not
Quote:

The earth cares not for profits from fossil fuels but If you pump in CO2, it is going to get hotter. And that is what is happening. As there is no technical barrier to transition to wind and solar, best to ramp up that effort now. Because there is no external saving grace that will materialize from some unknown external place to save us from stupid management of our home, Plant Earth

Amen. This was being taught in science classes in the 50's. Oh well.

ptc87
ptc87's picture
Offline
Joined: 06/19/2011
Professo Brown wrote,

"Unfortunately, as the discussion after Hurricane Sandy revealed, too often, “experts” and activists try to simplify the process to float their own agendas."
I wonder which category Prof. Brown considers himself to be: an expert with an agenda or an activist with an agenda?

Davids mom
Davids mom's picture
Offline
Joined: 10/30/2005
No matter activist or expert

We, the people, need to know the TRUTH!! (Not political expedient sayings that get votes/sympathy, etc.)

Recent Comments