New Orleans in the southern US has been devastated by Hurricane Katrina. According to tonights ABC television news, 80% of the city is under water.
I was in Louisiana in February 1999 and remember enjoying a meal of crawfish in Baton Rouge (just north of New Orleans) and hearing about Hurricane Betsy in 1965 and how New Orleans is sinking anyway – how one day it will dissapear into the Gulf of Mexico.
I have found this photo of the Mississippi River at New Orleans taken in 1999. And to put the region in some perspective, the Mississippi drains a catchment of over 1 million square miles, collecting water from 32 US states, before reaching New Orleans and the sea – according to a powerpoint I did in 1999 that I have just found. Check out this old slide: Mississippi drainage basin .
According to my book Roadside Geology of Louisiana:
“Louisiana hosts nearly 40% of the wetlands of the United States, and they are disappearing at a rapid rate. About 35 square miles of wetland in Louisiana slip away each year, an important loss of habitat to innumerable species of birds, animals, fish and plants. Public attention has focused on wetland loss in Louisiana in recent years, and blame flies in many directions. In truth the phenomenon is largely due to natural geological proceses, though human intervention certainly plays a significant role.”
The book by Darwin Spearing (published by Moutain Press Publishing Co, Missoula, Montana, 1995) goes on to explain how 7,000 years of delta construction is being lost to subsidence during the past few thousand years:
“… before humans ever dredged a channel, build a control levee, or cut through a marsh to reach an offshore oil platform. … whether deltas and their wetlands survive or sink benealth the sea hinges on the fine balance between sediment and subsistence. Deltas tend to sink as their soft and watery mud compacts beneath the weight of more mud laid on it. If no new sediment is added to the top of the pile, the top of the delta will sink beneath the waves. If the supply of sediment delivered to the delta exceeds the sinking rate, the delta will continue to grow and wetlands will expand.
…Nevertheless, tinkering human hands have certainly accelerated wetland loss during the last century. Their principle contribution has been construction of continuous levees along the Mississippi River from Baton Rouge to Venice. The levees do contain floods, but they also deprive the marshes of the sediment they need to stay above sea level. Furthermore, the levees force the river to dump all its sediment at the extreme end of the delta, where waves and currents cannot rework it into sandy coastlines as they did before the levees were build. Much of the sediment slides down the continental slope and onto the Mississippi fan on the deep ocean floor.
… The second major human contributor to wetland destruction (and the sinking of New Orleans) through sediment loss is outside Louisiana. Scores of dams were build during the past century upriver in the Mississippi drainage and in its tributories. They were designed to control floods, generate electricity, store fresh water, and provide recreation. They also trap so much sediment that what reaches Louisiana is only about half that of a century ago.”
So this explains why New Orleans is below sealevel.
And for those who want to argue climate change, I received the following from Benny Peiser:
After reading the round-up of German newspaper editorials in Spiegel Online, one can’t be blamed for thinking that global warming is leading to an increase in the number and intensity of hurricanes hitting the US mainland (strangely, Halliburton was not mentioned as the culprit in this present storm). Going back to 1851, what does the actual data from NOAA (http://www.nhc.noaa.gov/pastdec.shtml) say:
Fig 1: The average number of all hurricanes per decade (in red) is 17.7
Fig 2: The average number of major hurricanes per decade (in red) is 6.0
Of course, 2001-2004 is not a complete decade. If you think the increase in the number and intensity of hurricanes is due to global warming, be glad I did not add trend lines. There are plenty of real environmental problems to consider, save the global warming hype.
Knowing the above facts, consider the statement by Germany’s Environmental Minister, Jurgen Trittin, a Green Party member (natch):
“There is only one possible route of action,” he writes. “Greenhouse gases have to be radically reduced and it has to happen worldwide. Until now, the US has kept its eyes shut to this emergency. (Americans) make up a mere 4 percent of the population, but are responsible for close to a quarter of emissions.” He adds that the average American is responsible for double as much carbon dioxide as the average European.
“The Bush government rejects international climate protection goals by insisting that imposing them would negatively impact the American economy. The American president is closing his eyes to the economic and human costs his land and the world economy are suffering under natural catastrophes like Katrina and because of neglected environmental policies.”