Good ole CO2, one carbon atom hooked to two oxygens. What’s the problem? Don’t plants love it, and give us life-sustaining oxygen in trade? Shouldn’t we be producing more, not less?
That’s one of the arguments of climate change deniers.
To understand why increased CO2 is a problem, I asked my friend Pieter Tans, an expert climate scientist, for help. Pieter heads the Carbon Cycle Greenhouse Gases Group in the National Oceanic and Atmospheric Administration’s (NOAA) Earth System Research Laboratory in Boulder, Colorado.
In 1987 Pieter and I worked on a project sponsored by National Geographic to remotely probe the interior of a sealed boat-tomb beside the Great Pyramid in Egypt. My job was to drill a three-inch-diameter hole through a five-foot-thick limestone block, while allowing no modern air into the tomb or any ancient air to escape. Pete Petrone of Nat Geo was responsible for photographing the tomb interior. Representing NOAA, it was Pieter’s task to collect air from the tomb.
Pieter is one of the most affable, unpretentious, competent people I have known. He is not prone to exaggeration. When he says we have a dire problem, and future generations will pay for our failure to address it, I believe him. He was happy to provide most of the data, and sense of urgency, for this article. The words are mine.
We must make this problem more visible. Please educate yourself, your friends, and your representatives. There is nothing more important than this, and it is why I have composed this essay.
Now to the problem. It has to do with the Greenhouse Effect.
When it’s cold outside, plants grow better in the warm, moist confines of a greenhouse. A greenhouse has windows that allow sunlight through to warm things inside. Because the warmed air cannot easily escape, the temperature inside stays warmer than outside. That is the familiar greenhouse effect.
The greenhouse effect with regard to our planet is similar but more complicated.
Our atmosphere acts as a blanket that traps heat and insulates us from the cold of space. The average temperature at Earth’s surface (all over Earth, night and day, all year round) is 59 degrees. Without our atmosphere, it would be zero oF, and Earth would be an ice planet, inhospitable to plants and most animals larger than bacteria.
How does greenhouse Earth work? Note the energy balance diagram that Pieter sent me last summer:
In this diagram, W/m2 means watts per square meter, a measure of energy transmitted or absorbed per square meter of area. You can see that the total radiation hitting our planet from the Sun is equal to the total radiation departing our planet and heading back to space. You can also see that the total radiation hitting Earth’s surface is the same as the total energy leaving it. Together, these conditions are called “in balance.”
Now notice on the right side of the diagram that a large portion of the energy leaving Earth’s surface is absorbed by our atmosphere and returned as back radiation. Why? Why doesn’t the radiation departing Earth’s surface pass right through our atmosphere and into space?
The answer is: There are gases in our atmosphere that are good at trapping radiation. These are called greenhouse gases. In the diagram above, all energy interactions are in balance, or equilibrium. However, an increase of greenhouse gases causes an energy imbalance which results in a warmer Earth.
The principal greenhouse gases, in order of energy trapping effectiveness, are:
Clouds and water vapor (H2O) – contribute about 75% of greenhouse effect.
Carbon Dioxide (CO2) – contributes about 20% of greenhouse effect.
Methane (CH4), Nitrous Oxide (N2O), Ozone (O3), and others contribute remaining 5%.
Although greenhouse gases comprise a tiny percentage of our atmosphere, less than a half percent, they are by far the most important gases that keep us warm. The problem is: we don’t want them to keep us too warm!
Carbon dioxide, the main greenhouse gas increasing due to the activities of humans, currently comprises “only” 0.041% (by volume) of our atmosphere. That number is usually spoken of as 410 parts per million (ppm) because ppm units are easier to remember.
Water vapor in our atmosphere is also a greenhouse gas, even more so than carbon dioxide. Increased water vapor in our atmosphere results mainly from higher ocean temperature. But because higher ocean temperature results from higher atmospheric temperature and the higher atmospheric temperature is driven mostly by increased CO2, we come right back to CO2 as the main culprit in global warming.
Before the industrial revolution, carbon dioxide in our atmosphere was about 280 ppm, a figure that had been fairly steady for many thousands of years. Climate scientists know this because they have obtained samples of ancient air from ice core drilling in Greenland and Antarctica. By the year 2000, CO2 had increased to 370 ppm, and was increasing at a rate of 2 ppm per year. Today CO2 is 410 ppm, increasing at 2.3 ppm per year. These figures come from a worldwide network of sensors monitored by folks at NOAA and in other countries. NOAA’s principal CO2 monitoring location is the Mauna Loa Observatory in Hawaii. You can find the following graph, updated daily, at https://www.esrl.noaa.gov/gmd/ccgg/trends/full.html .
Note that CO2 in our atmosphere is increasing at an increasing rate. The saw-tooth pattern is due to periodic (seasonal) changes in vegetation.
Climate scientists are in near-consensus that the vicinity of 450 ppm produces a level of warming that may be irreversible. With CO2 presently at 410 ppm and increasing at 2.3 ppm per year, how many years will it be until we hit 450 ppm? Answer: 17.4 years.
Should we be concerned?
Global average temperature has been steadily rising since 1980, almost one-and-a-half degrees. There have been a few years where the average temperature has dropped, which global-warming deniers happily point out. But those years are exceptional, not the rule. Besides, climate scientists define climate change in terms of multi-year averages (e.g., 10-30 years), not for periods of one to three years. One or two degrees of warming seems hardly alarming, until we realize that global average temperature was only two to five degrees cooler during the last ice age, when a layer of ice one mile thick covered half of North America, and sea level was 400 feet lower.
Today a horrifying scenario is where all continental ice (e.g., Antarctica, Greenland) could melt. If that occurred, sea level would increase, scientists estimate, by 210-250 feet!
Part of the CO2 we release into the atmosphere is absorbed by our oceans, making sea water more acidic. Aside from being detrimental to marine life in general, increased acidity erodes and bleaches the limestone of our coral reefs, home to 25% of all marine species. Acidification of our oceans, in like manner to increasing CO2 in our atmosphere, is increasing at a rate and concentration not evidenced in the last several million years. Further, the CO2 we are producing will remain in our atmosphere and oceans for thousands of years.
Pieter likens our discounting of global warming to playing Russian roulette – with the gun pointed at our grandchildren.
What should we do?
1) We must wean ourselves from fossil-fuel-burning electrical-power production, the largest source of the CO2 increase. The leading contributors worldwide are coal-fired power plants. A better name for “clean coal” is “less-dirty coal.” Leave it in the ground. We must also reduce dependence on oil-fired and natural gas-fired power plants, the second and third greatest contributors of CO2. Obviously, these steps will take time.
2) After energy production, the next largest contributor of CO2 is transportation (planes, trains, automobiles, trucks, ships). If you need a new car, consider buying a more fuel-efficient one, or a hybrid car, or an electric car. Of course, you can’t beat a bicycle or walking as a green way to travel.
3) Promote the use of “renewable” or “green energy” sources such as solar and wind. Hydroelectric power plants are also green. Nuclear power plants are green in the sense that they don’t contribute much to global warming, but they produce dangerous waste products.
4) Beware of deniers with covert agendas. They are like folks in times past who argued that smoking is not harmful to your health. Vote climate-change deniers out of office. Last year I wrote to Andy Harris (R – MD), imploring him to urge our president to stay in the Paris climate accord. He replied that he stood with Trump on that issue.
I’m worried about the future for your grandchildren and mine. How will they judge us? Because of fossil-fuel-burning, we have already committed our planet to long-term effects of warming. These include land loss due to rising sea level, more violent storms, habitat destruction, species loss, and forest fires. The best we can do is slow the progress of warming, so we have a chance of halting it. Pieter makes the point that “We are responsible. It is urgent for each of us to act, as it will take decades to transform our energy systems after we decide to get serious.”
It’s time to get serious indeed!
Bob Moores retired from Black & Decker/DeWalt in 1999 after 36 years. He was the Director of Cordless Product Development at the time. He holds a mechanical engineering degree from Johns Hopkins University.
Storms of my Grandchildren (2009), by James Hansen
High Tide on Main Street (2014), by John Englander
Finding a Pharaoh’s Funeral Bark, National Geographic, vol. 173, No. 4, April 1988