First, I hope you know that the "Greenhouse Effect” is not “bad.” Without it, Earth probably would not be the very hospitable environment for all the life we see around us.
The atmosphere is a mixture of gases that are transparent to visible light energy, but a bit opaque to infrared heat energy. So the Sun warms Earth, but our wonderful atmosphere and the "Greenhouse Effect” retain some of the heat/infrared energy heading out into cold space and help keep Earth relatively warm and capable of supporting life. It is something not possible on the Moon or, as far as we know, Mars.
Venus also has a greenhouse atmosphere, but it’s an over-the-top greenhouse effect. Where our atmosphere is only 0.04 percent carbon dioxide, Venus’ atmosphere is about 97 percent carbon dioxide with some sulfuric acid clouds to boot. With an almost pure atmosphere of CO2, the pressure of the atmosphere at the surface of Venus is 90 times greater than the surface pressure of Earth’s atmosphere and the surface temperature of Venus is more than 800° F. Scientists say that Venus’ atmosphere is a “Greenhouse Effect gone wild.”
The gas that contributes the most to Earth’s Greenhouse Effect (which many scientists correctly refer to as “The Atmospheric Effect”) is not carbon dioxide but water vapor, the gaseous phase of water. Think about how rapidly a warm spring day will cool after sunset if there is low humidity, versus how warm the nights stay during the humid days of July and August. Water vapor and water droplets in clouds contribute about 80 percent of the greenhouse effect. Carbon dioxide, methane and ozone contribute about around 20 percent to Earth’s Greenhouse Effect. For more about this and why I say “about,” you might want to read this.
The critical questions and observations about carbon dioxide, greenhouse effect and global warming are how much is it increasing, how much warming is due to human activity, what are the effects so far, and what can we forecast or anticipate in the future?
First, let’s go back to some observations. Remember science starts with observations. I know, “Oh no, not another observation and graph.” But this is really important ... and historic. Thanks to one of the most dedicated scientists of recent time, we have this graph.
By the way, place a ruler along the black (average) line and see if you think the line is increasing along a straight line (linear or constant rate) or is a bit of a curve showing some acceleration in the rate of increase?
Charles David Keeling (1928-2005) was the first scientist to confirm the rise of atmospheric carbon dioxide by very precise measurements that produced a data set now known widely as the “Keeling Curve” (shown above). Keeling kept up his meticulous observations even when some funding for his work was withdrawn.
“There are three occasions when dedication to scientific measurements has changed all of science. Tycho Brahe’s observations of planets laid the foundation for Sir Isaac Newton’s theory of gravitation. Albert Michelson’s measurements of the speed of light laid the foundation for Albert Einstein’s theory of relativity. Charles David Keeling’s measurements of the global accumulation of carbon dioxide in the atmosphere set the stage for today’s profound concerns about climate change. They are the single most important environmental data set taken in the 20th century.”
Here is the observation of CO2over the last few years. During northern hemisphere summer, the concentration decreases, as plants take up carbon dioxide. The concentration increases in northern hemisphere winter but the long-term trend is very apparent and we now know (thank you David Keeling) that the concentration of CO2 has increased by almost 40 percent in the last 200 years.
So if the atmosphere is changing, the concentration of carbon dioxide is increasing every year due primarily to human activity (look at the graph below) and we know carbon dioxide is a component of the "Greenhouse Effect.” Why don’t we see a more direct pattern in the observations of CO2 and global temperature?
Courtesy Oak Ridge National Laboratory USDE
Indeed as shown in recent monthly global temperature measurements from NOAA’s National Climatic Data Center (10 years is “recent” in climate), there seems to be little global warming over the last 10 years, although the concentration of CO2 increased by about 5 percent during that time. Why is this? There must be other factors affecting the climate than just the concentration of CO2.
Courtesy climate4you.com
The Atmosphere, Oceans and Climate Aren't That Simple
But you know that. And I know you don’t really think forecasting our weather and climate are simple? How about some more observations and thoughts about this tomorrow?
Scarlett, ready for a break?
