"In 2005 data from NASA's Mars Global Surveyor and Odyssey missions revealedSome of you may have seen this. Interesting that it is on a National Geographic website.
that the carbon dioxide "ice caps" near Mars's south pole had been diminishing
for three summers in a row. Habibullo Abdussamatov, head of space research at
St. Petersburg's Pulkovo Astronomical Observatory in Russia, says the Mars data
is evidence that the current global warming on Earth is being caused by changes
in the sun. "The long-term increase in solar irradiance is heating both Earth
and Mars," he said. Abdussamatov believes that changes in the sun's heat output
can account for almost all the climate changes we see on both planets. "
"The conventional theory is that climate changes on Mars can be explainedThis is just one example of how desperately the National Geographic is trying to spin this story to make the theory look bad. The story is replete with context-dropping, arguments from authority, and links to other Geographic stories that support global warming.
primarily by small alterations in the planet's orbit and tilt, not by changes in
the sun. Mars and Earth wobble in different ways, and most scientists think it
is pure coincidence that both planets are between ice ages right now. "
"Perhaps the biggest stumbling block in Abdussamatov's theory is his dismissalWell, no, I don't think it does. What keeps the Earth warm is 100 miles thick of atmosphere that has been heated up by the sun. Any gas is not a bad insulator, which is why we all have double pane glass. The warm air near the surface of the Earth has a heat capacity, just like a hot iron. It takes awhile for the heat to be radiated through the insulating layers of air between the Earth and space. And every layer stores some heat as well.
of the greenhouse effect, in which atmospheric gases such as carbon dioxide help
keep heat trapped near the planet's surface."
Here's something to consider: "Argon gas filling provides an effective thermal resistance level of R-7 per inch, krypton gas provides R-12.5 per inch, and xenon gas provides R-20 per inch." Air is 5.1. The larger values denote better insulation ability. (http://gfp.lbl.gov/)
These are all noble gases. Is CO2 a noble gas? No. It will have *worse* insulation qualities. Makes one suspicious of whether it “heat traps”.
So what would be the "R" rating of a double-pane window filled with the "heat-trapping" of CO2? Probably not so good. (You could do an experiment pretty easy... get a window filled with CO2, then compare the rate of heat loss to a conventional window.
Without trying to do pure science and claim I’m proving anything, let me do a brief investigation based on my hypothesis, to cast doubt on the CO2 “heat trapping” premise.
Let me start from my idea (I shouldn’t formalize it as a “hypothesis”) that the principal reason the Earth stays warm is that the total mass of the atmosphere has a heat capacity, and the gas of the atmosphere simultaneously acts like an insulator, retarding the rate of heat loss into outer space. That is, during the day, sunlight heats the atmosphere (and the ground under it), and during the night it cools by radiation into space. The heat near the Earth has to radiate up through the layers of atmosphere before escaping into the vacuum, but the atmospheric gas insulates to slow the loss of heat.
One could do a day’s worth of research to calculate this pretty exactly, by getting the values of heat capacity and thermal conductivity (higher conductivity = more rapid heat loss) for air and its constituents (O2, N2, CO2, etc) and admixtures thereof for each pressure and temperature at every altitude, and from that, do a simple numerical integration to arrive at the rate of heat loss after the sun goes down.
That is, if I wanted to prove this, I’d pretend the atmosphere is made of many thin layers of gas-filled double paned glass windows. Each layer insulates the temperature of the atmosphere below it, and passes a little bit of heat to the layer above it at a certain rate.
I could do this, and it’s not a hard calculation, but I don’t want to frighten or bore you.
So just consider this a little more qualitatively, using a little data taken from one website:
We find that the thermal conductivity of air is about 4 times lower than CO2.
We also find that the heat capacity of air is a little less than that of CO2.
Now, if CO2 is really a “heat trapping gas”, causing the temperature of the Earth to rise, shouldn’t the thermal conductivity of CO2 be *lower* than Air? Instead, it’s higher. That is, more CO2 should cause more rapid heat loss, leading to the *opposite* effect of heat trapping...
Even under the most dire global warming scenario, the concentration of CO2 in the atmosphere isn’t more than a percent or so of the total atmosphere, so the extra heat capacity of CO2 will have an inconsequential effect. All the effect is in the insulating properties, which are based on the thermal conductivity. Ergo, CO2 is probably not a heat trapping gas.
Now, you could argue that increased CO2 in the upper atmosphere might increase the transmissivity of solar radiation from lower and higher spectral wavelengths, thereby increasing the heating of the atmosphere during the day, thereby causing global warming.
But that’s not “heat trapping”. That’s “energy absorption”, or whatever you want to call it. Once the energy gets *into* the atmosphere and is stored there in the thermal motion of gas molecules, the heat-trapping effect is supposed to be what’s causing the global temperature rise. And if the data is reasonably representative of actual atmospheric pressure, temperature (it’s based on data from about 80C to -150C at near-atmospheric pressures) I don’t see how to reconcile the higher thermal conductivity of CO2 with heat trapping hypothesis. Ipse dixit. Et cum spiri, two two-oh. De gustibus non est disputandum. Non est ad astra mollis e terris via. Whatever.
Comparison between conventional and advanced insulations (thermal conductivity for a given thickness)
Mars Melt Hints at Solar, Not Human, Cause for Warming, Scientist Says
Kate Raviliousfor National Geographic News
February 28, 2007
Simultaneous warming on Earth and Mars suggests that our planet's recent climate changes have a natural -- and not a human-induced -- cause, according to one scientist's controversial theory.
Earth is currently experiencing rapid warming, which the vast majority of climate scientists says is due to humans pumping huge amounts of greenhouse gases into the atmosphere. (Get an overview: "Global Warming Fast Facts".)
Mars, too, appears to be enjoying more mild and balmy temperatures.
In 2005 data from NASA's Mars Global Surveyor and Odyssey missions revealed that the carbon dioxide "ice caps" near Mars's south pole had been diminishing for three summers in a row.
Habibullo Abdussamatov, head of space research at St. Petersburg's Pulkovo Astronomical Observatory in Russia, says the Mars data is evidence that the current global warming on Earth is being caused by changes in the sun.
"The long-term increase in solar irradiance is heating both Earth and Mars," he said.
Abdussamatov believes that changes in the sun's heat output can account for almost all the climate changes we see on both planets.
Mars and Earth, for instance, have experienced periodic ice ages throughout their histories.
"Man-made greenhouse warming has made a small contribution to the warming seen on Earth in recent years, but it cannot compete with the increase in solar irradiance," Abdussamatov said.
By studying fluctuations in the warmth of the sun, Abdussamatov believes he can see a pattern that fits with the ups and downs in climate we see on Earth and Mars.
Abdussamatov's work, however, has not been well received by other climate scientists.
"His views are completely at odds with the mainstream scientific opinion," said Colin Wilson, a planetary physicist at England's Oxford University.
"And they contradict the extensive evidence presented in the most recent IPCC [Intergovernmental Panel on Climate Change] report." (Related: "Global Warming 'Very Likely' Caused by Humans, World Climate Experts Say" [February 2, 2007].)
Amato Evan, a climate scientist at the University of Wisconsin, Madison, added that "the idea just isn't supported by the theory or by the observations."
The conventional theory is that climate changes on Mars can be explained primarily by small alterations in the planet's orbit and tilt, not by changes in the sun.
"Wobbles in the orbit of Mars are the main cause of its climate change in the current era," Oxford's Wilson explained. (Related: "Don't Blame Sun for Global Warming, Study Says" [September 13, 2006].)
All planets experience a few wobbles as they make their journey around the sun. Earth's wobbles are known as Milankovitch cycles and occur on time scales of between 20,000 and 100,000 years.
These fluctuations change the tilt of Earth's axis and its distance from the sun and are thought to be responsible for the waxing and waning of ice ages on Earth.
Mars and Earth wobble in different ways, and most scientists think it is pure coincidence that both planets are between ice ages right now.
"Mars has no [large] moon, which makes its wobbles much larger, and hence the swings in climate are greater too," Wilson said.
Perhaps the biggest stumbling block in Abdussamatov's theory is his dismissal of the greenhouse effect, in which atmospheric gases such as carbon dioxide help keep heat trapped near the planet's surface.
He claims that carbon dioxide has only a small influence on Earth's climate and virtually no influence on Mars.
But "without the greenhouse effect there would be very little, if any, life on Earth, since our planet would pretty much be a big ball of ice," said Evan, of the University of Wisconsin.
Most scientists now fear that the massive amount of carbon dioxide humans are pumping into the air will lead to a catastrophic rise in Earth's temperatures, dramatically raising sea levels as glaciers melt and leading to extreme weather worldwide.
Abdussamatov remains contrarian, however, suggesting that the sun holds something quite different in store.
"The solar irradiance began to drop in the 1990s, and a minimum will be reached by approximately 2040," Abdussamatov said. "It will cause a steep cooling of the climate on Earth in 15 to 20 years."