Friday, May 17, 2013

How Warm is it?

Carbon dioxide level reach record high
Steffen Schmidt

The news was everywhere on Friday, May 10, 2013. Reuters reported, “The amount of climate-warming carbon dioxide in the atmosphere topped 400 parts per million at a key observing station in Hawaii for the first time since measurement began in 1958, the National Oceanic and Atmospheric Administration said. To many scientists, crossing the 400 ppm threshold” [there are 400 molecules of carbon dioxide for every million molecules in the air] is important mainly as a milestone according to James Butler of NOAA's Earth System Research Laboratory.

Why is this so important?

Carbon dioxide is a heat-trapping greenhouse gas. That’s a problem. It also remains in the atmosphere for hundreds of years. Where does it come from? Largely from coal burning power plants, cars, trucks, trains, and airplanes. These are all processes that have been growing exponentially. Germany is abandoning nuclear power, has built two new coal plants and is now building six more. Japan's Ministry of Environment is ending a ban on construction of new coal-fired power plants largely because of the nuclear power plant disaster following the tsunami of March 11, 2011. The Guardian reported that there are 1,200 coal-fired power plants on the books in 59 countries with about three-quarters in China and India. India is planning to build 455 new plants with 363 on the drawing board in China.

Japan, South Korea, Guatemala, Cambodia, Morocco, Namibia, Senegal, Sri Lanka, Uzbekistan and Taiwan have coal-fired plants but produce almost no coal so they have to import it. That means shipping and we know that the current fleet of ships is extremely dirty in its emissions.

It’s important to note that the Earth's atmosphere hasn't had this much carbon dioxide in it for millions of years. We didn’t have any monitoring until very recently so we have to rely on indirect measures.

Carbon dioxide, a heat-trapping greenhouse gas, remains in the atmosphere for hundreds of years. It is emitted by fossil-fueled vehicles and coal-fired factories and power plants as well as by natural activities such as breathing.

Reuters reports that, “Carbon dioxide concentrations at Mauna Loa, Hawaii are documented in a graph known as the Keeling Curve, named for Charles Keeling, who began measurements there in 1958, when the level was 317 ppm. Information on the Keeling Curve is available at”(Image courtesy of Scripps Oceanography)

According to NOOA scientist Butler, “During the last 800,000 years, the level of atmospheric carbon dioxide fluctuated between 180 ppm and 280 ppm. With the widespread burning of coal and oil during the Industrial Revolution, the concentration of carbon dioxide rose to about 290 ppm by the end of the 19th century …”

NOAA has a terrific animated graph that shows the rise in Carbon Dioxide.

According to the Washington Post, “One of the main concerns with climate change is that it’s causing the oceans to advance. Global sea levels have risen about seven inches over the past century and that pace is accelerating. Not only does this threaten coastal regions, but it also makes storm surges much worse — both for huge hurricanes like Sandy and for smaller storms too.”

There is still a lot of skepticism about all of this, which is surprising given the consistent and repeated evidence that the oceans are warming, rising, and that this will very likely have pretty disastrous consequences for coastal areas. Many conservatives and Republicans reject the idea that such a tiny amount of CO2 in the air, 0.04 percent, can make much of a difference. Others argue that since there was more CO2 millions of years ago the changes we are seeing are not caused by humans but by natural cycles or processes. Thus, there has been vigorous pushback against many policies directed at reducing CO2 emissions.

The coal and other fossil fuel industry is particularly articulate and well funded through lobbying organizations they have created. The absence of fast replacement fuels to drive vehicles and generate electricity has also delayed more vigorous action to contain and drastically reduce human CO2 emissions.

The Post article confirms, “at this point, it’s unlikely that we could stop further rises altogether. That’s the upshot of a recent study from the National Center on Atmospheric Research (NCAR). The study estimated that aggressive steps to cut emissions could reduce the amount of sea-level rise by somewhere between 6 and 20 inches in 2100, compared with our current trajectory. That’s quite a bit. But sea levels will keep rising for centuries no matter what we do. We can’t stop it entirely. We can only slow the pace.”

There is sensational information on what will happen in worst case scenarios which, to be clear, are forward projections by as much as 200 years. That may seem like a long time but in the perspective of the planet Earth and even in the very short history of humans on the planet it is really just a very tiny slice of time.

What might happen then as we project the effects of sea level rise?

According to NCAR models, by 2300 the sea levels could rise as much as 34 feet. has a great interactive map that shows the consequences -  interactive map. Some examples of what this means include South Florida, which would be largely under the ocean. Other major cities that are wet under these levels of sea-rise are New Orleans, Venice, San Francisco, Shanghai, and Bangladesh. Even the Netherlands would be under water and it’s the model of “holding back the sea.” In fact, the Netherlands is often cited as an example of what the US should be doing for example regarding protecting New York City from rising water and storm surge.

Another important consideration is the increasing acidification of the ocenas. NOAA puts it very succinctly.

"Air-sea gas exchange is a physio-chemical process, primarily controlled by the air-sea difference in gas concentrations and the exchange coefficient, which determines how quickly a molecule of gas can move across the ocean-atmosphere boundary. It takes about one year to equilibrate CO2 in the surface ocean with atmospheric CO2, so it is not unusual to observe large air-sea differences in CO2 concentrations. Most of the differences are caused by variability in the oceans due to biology and ocean circulation. The oceans contain a very large reservoir of carbon that can be exchanged with the atmosphere because the CO2 reacts with water to form carbonic acid and its dissociation products. As atmospheric CO2 increases, the interaction with the surface ocean will change the chemistry of the seawater resulting in ocean acidification."

The following figure illustrates the different processes that affect air-sea gas exchange (Courtesy of NOAA.)

Given these very significant factors it's clear that any study of coastal zones MUST begin with a discussion of CO2 levels, sea level rise, and it’s consequences. This is the Holy Grail of coastal science because it has potentially the most profound impact on the world’s coastal zones.

“It feels like the inevitable march toward disaster,” said Maureen E. Raymo, a scientist at the Lamont-Doherty Earth Observatory, a unit of Columbia University quoted in the New York Times.  

That's pretty serious business.  The impact of elevated CO2 levels on coastal zones and on the oceans is of great significance for students of coastal policy and science as well as for policymakers who are expected to consider bold ways of addressing this problem.

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