As we now know all too well, parts of New Orleans were built below sea level -- the result of dredging and dike construction

Earth System Science studies the interactions among the earth's 'spheres' such as the atmosphere, hydrosphere, biosphere, lithosphere and anthrosphere. The anthrosphere is that part of the environment that is made or modified by humans for use in human activities. As human technology develops, so do the impacts of human activities on the environment. Humans have impacted the biosphere by altering the distribution of species; the atmosphere by creating large amounts of greenhouse gases; and the lithosphere by building cities.

New Orleans was first built on natural levees along the Mississippi River, making flooding a concern. In the 1830s an ambitious system of underground drainage canals beneath the streets were developed, and used to drain water by gravity into the low lying swamps. By the 1980s, the city was protected by a system of 20 pumping stations with 89 pumps, with a combined capacity of 15,642,000 gallons per minute, 22.5 billion gallons per day, equal to the flow of the Ohio River. This is obviously a dramatic alteration of the hydrosphere, or the natural flow of the water.

Human interaction with the environment has resulted in an increase in the temperature of the ocean. Because of the link between higher ocean temperatures and hurricanes, there is speculation that hurricanes will increase in frequency or intensity in a warmer world, with higher wind speeds and greater precipitation. An MIT study published recently in Nature provides the first data analysis indicating that tropical storms are indeed becoming more powerful over time. In addition the higher temperatures cause an increase in sea levels. This was a critical factor in the damage that resulted from Katrina. It remains a concern as New Orleans is rebuilt.