People Unclear

This is number 40 of a long series

If you’re like me, you wonder where people like this come from:

GOP congressman asks if rocks are causing sea levels to rise

Call me a bleeding heart liberal if you want, but I found it impossible to omit Representative Brooks’ affiliation with the Republican party. It’s not as though when you decide to run for office as a Republican you have to check the “global warming is a hoax” box. But it helps.

But let’s get serious for a moment. Representative Brooks may have a point there. The truth is that the world’s rivers daily deposit tons of soil, scourged from the continents, into the oceans. That has got to account for some sea level rise. Some Skeptical Analysis is in order. Take the Mississippi River as an example. All the stuff that gets washed down from the eastern slope of the Rocky Mountains eventually makes its way to the Mississippi Delta. A similar thing is going on with the Nile. This has been going on for millions of years. We should all be under water by now.

Not quite. Look at Florida. The state is bare inches (many inches) above water. It has an interesting geological history:

Sea levels have had a profound effect on both Florida’s geology and ecology. The fossil record indicates a mass migration of plants and animals occurred between North and South America approximately 2 million years ago, when sea levels were much lower and a land bridge connected North America. During the last ice age, Florida was as much as three times the current land area (red line on Figure 1).

Here is Figure 1:

The map shows what is now Florida and the shape of the coast line 5 million years ago (smaller) and during the previous ice age, when a bunch of the planet’s water was stacked up as ice on the continents (much larger). Melting of the continental ice shrunk Florida to its present day size.

And Florida is much the same shape as it was 500 years ago when Europeans began to explore it. All this while the Mississippi, the Nile, the Amazon, the Indus—all  these great rivers—have been dumping silt into the oceans. Only recently, the past 100 years, has human activity started to make serious changes to the CO2 levels in the atmosphere. And Florida is finally beginning to experience the result:

Map Shows Which Miami Condo Buildings Are Most Threatened by Rising Sea Levels

Even as scientists continue reminding us that Miami is one of the most susceptible cities to the potential damages of sea-level rise, developers continue erecting shiny luxury tower after shiny luxury tower in the areas most threatened by rising tides. So EMiami Condos, a website that tracks condo development in the city, put two and two together to figure out which buildings are at the highest risk. 

The site gathered information from the FIU School of Journalism’s Eyes on the Rise app. The app allows you to key in your address and find out how many feet of sea-level rise it would take for your home to be underwater.

Another source provides additional history:

Although all the details are not well understood, the driving force behind these glacial/interglacial cycles are slow variations in Earth’s orbit as it circles the sun, which slightly decreased/increased the amount of sunlight reaching the planet’s surface. For the current interglacial, the orbitally-driven warming eventually came to an end after the Holocene Climatic Optimum (HCO), and by 4-5000 years ago all the vulnerable land-based ice had disappeared. The volume of the global ocean was static until the arrival of the Industrial Revolution, and by the 19th Century global sea level had begun to rise again. Despite undergoing short-term accelerations, and decelerations, globally-averaged sea level has undergone long-term acceleration up to the present day (Church & White [2006]Merrifield [2009]).

With some 60-70 metres worth of global sea level equivalent locked up in the vast ice sheets of Greenland and Antarctica, and with global warming well underway, it raises the question of how much sea level rise we are likely to see this century (and beyond), and just how fast this might happen. Because the dynamics of ice sheet disintegration are only very crudely known, and ice sheet modelling is in its infancy, there is a large range of estimates of future sea level rise. Many now seem to converge on 1-2 metres of sea level rise by 2100 – much higher than current rates. But is this realistic? A recent paper, examining past ice sheet disintegrations, lends credence to these estimates.

Here is the pertinent graph:

Figure 2 – Global mean sea level from 1870 to 2006 with one standard deviation error estimates (Church 2008).

All records I have seen show the sea level rising since 1870, about the time the Industrial Revolution kicked into high gear, and we started burning fossil fuels in earnest. The rate of increase has, itself, been increasing during the time we have increased the burn rate. Here is what the current activity looks like:

Those measurements are millimeters.

Anyhow, Congressman Brooks lives in Alabama’s 5th District, approximately 600 feet above sea level. He has nothing to worry about regarding sea level rise, which is expected to be as much as 200 feet if all the polar ice melts. In fact, if he could stay around long enough he might be able to cash in on some of Alabama’s beach front property boom.

One thought on “People Unclear

  1. Pingback: People Unclear | Skeptical Analysis

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