Posted on 04/30/2007 7:57:26 AM PDT by Maelstorm
Science Daily Earth sits between two worlds that have been devastated by climate catastrophes. In the effort to combat global warming, our neighbours can provide valuable insights into the way climate catastrophes affect planets.
Modelling Earths climate to predict its future has assumed tremendous importance in the light of mankinds influence on the atmosphere. The climate of our two neighbours is in stark contrast to that of our home planet, making data from ESAs Venus Express and Mars Express invaluable to climate scientists.
Venus is a cloudy inferno whilst Mars is a frigid desert. As current concerns about global warming have now achieved widespread acceptance, pressure has increased on scientists to propose solutions.
The key weapon in a climate scientists arsenal is the climate model, a computer programme that uses the equations of physics to investigate the way in which Earths atmosphere works. The programme helps predict how the atmosphere might change in the future. To members of the public it must seem like climate models are crystal balls, but they are actually just complex equations says David Grinspoon, Denver Museum of Nature and Science, and one of Venus Expresss interdisciplinary scientists.
The more scientists look at those equations, the more they realise just how complicated Earths climate system is. Grinspoon puts the predicament like this: In fifty or a hundred years, we will know whether todays climate models were right but if they are wrong, by then it will be too late.
To help increase confidence in the computer models, Grinspoon believes that scientists should look at our neighbouring planets. It seems that both Mars and Venus started out much more like Earth and then changed. They both hold priceless climate information for Earth, says Grinspoon.
The atmosphere of Venus is much thicker than Earths. Nevertheless, current climate models can reproduce its present temperature structure well. Now planetary scientists want to turn the clock back to understand why and how Venus changed from its former Earth-like conditions into the inferno of today.
They believe that the planet experienced a runaway greenhouse effect as the Sun gradually heated up. Astronomers believe that the young Sun was dimmer than the present-day Sun by 30 percent. Over the last 4 thousand million years, it has gradually brightened. During this increase, Venuss surface water evaporated and entered the atmosphere. Water vapour is a powerful greenhouse gas and it caused the planet to heat-up even more. This is turn caused more water to evaporate and led to a powerful positive feedback response known as the runaway greenhouse effect, says Grinspoon.
As Earth warms in response to manmade pollution, it risks the same fate. Reconstructing the climate of the past on Venus can give scientists a better understanding of how close our planet is to such a catastrophe. However, determining when Venus passed the point of no return is not easy. Thats where ESAs Venus Express comes in.
The spacecraft is in orbit around Venus collecting data that will help unlock the planets past. Venus is losing gas from its atmosphere, so Venus Express is measuring the rate of this loss and the composition of the gas being lost. It also watches the movement of clouds in the planets atmosphere. This reveals the way Venus responds to the absorption of sunlight, because the energy from the Sun provides the power that allows the atmosphere to move.
In addition, Venus Express is charting the amount and location of sulphur dioxide in the planets atmosphere. Sulphur dioxide is a greenhouse gas and is released by volcanoes on Venus.
Understanding all of this will help us pin down when Venus lost its water, says Grinspoon. That knowledge can feed into the interpretation of climate models on the Earth because although both planets seem very different now, the same laws of physics govern both worlds.
Understanding Mars past is equally important. ESAs Mars Express is currently investigating the fate of the Red Planet. Smaller than the Earth, Mars is thought to have lost its atmosphere to space. When Martian volcanoes became extinct, so did the planets means of replenishing its atmosphere turning it into an almost-airless desert.
What happened on these two worlds is very different but either would be equally disastrous for Earth. We are banking on our ability to accurately predict Earths future climate, says Grinspoon. Anything that can shed light on our own future is valuable. That is why the study of our neighbouring worlds is vital.
So, when planetary scientists talk of exploring other worlds, they are also increasing their ability to understand our own planet.
Note: This story has been adapted from a news release issued by European Space Agency.
In fifty or a hundred years, we will know whether taking today's climate models to make political decisions restricting freedoms were right; -- but if they are wrong, by then it may be too late to restore our liberties.
Mars has a much thinner atmosphere because it is smaller and has less gravity as well. I wonder if terraforming Mars would be feasible given the lack of a magnetic field to deflect the solar wind.
Will the Ice Age Return?
The world is cooling — helped by man
Some scientists are convinced that the world’s climate is getting colder every year, threatening a return to the conditions of the last ice age, which reached its peak about 18,000 years ago.
[...]
From 1890 to 1940 worldwide temperatures rose about 0.18F every 10 years. Some animals extended their ranges northward, the sea was less frozen than before, and icebergs from Greenland did not penetrate as far south.
Since 1940 temperature has been dropping. According to a survey by the National Oceanic and Atmospheric Administration, the average ground readings for the northern hemisphere have, in the years from 1945 to 1968, fallen by one-half degree F. In the United States, east of the Continenal Divide, temperatures in the last decade averaged one to four degrees cooler than in the past 30 years.
-—page 69. Strange Stories, Amazing Facts
Published 1976, The Readers Digest Association
Library of Congress Catalog Card No. 76-2966
[The notion that cooling is being helped by man appears only in the subtitle of the article. Nothing in the article suggests how man might be accomplishing planetary cooling.]
The Holocrust? Is that an episode of Itchy and Scratchy?
What does life have to do with evaporation and rainfall?
Plants pull moisture out of the soil and put it in the atmosphere.
The cooling trend during the middle of the 20th Century was caused by high levels of particulate emissions (smoke) from factories and powerplants. Now that we’ve “cleaned up” the emissions, there is no counterbalance to the greenhouse gasses, and the warming accelerates.
What is the warming situation at Gliese 581?
We need a “Global Alarmist” superhero much like “Captain Obvious” to post with every “the sky is falling” article as they seem to be increasing in frequency during the latest media push on global warming.
What did in Mars and Venus....were Ford SUVs....which are the worst C02 types out there. If these dudes had stayed with Chevy or Honda...things would have been alot different.
“What is the warming situation at Gliese 581?”
Dunno...but the whole planet is a red light district...
The atmosphere of a planet is aways being lost into space as atoms in the upper atmosphere are excited by sunlight or some other form of energy and drift away. The stronger the gravity that a planet has, the harder it is for the atoms to gain enough energy to escape.
If a planet has low gravity, as is the case with Mars, and the atmosphere is not renewed by volcanic activity or some other means, then eventually, the atmosphere will diminish. Even if we terraformed Mars and gave it a heftier atmosphere, it would lose it unless we continually renewed its atmosphere.
TM
“The atmosphere of a planet is aways being lost into space as atoms in the upper atmosphere are excited by sunlight or some other form of energy and drift away. The stronger the gravity that a planet has, the harder it is for the atoms to gain enough energy to escape.
If a planet has low gravity, as is the case with Mars, and the atmosphere is not renewed by volcanic activity or some other means, then eventually, the atmosphere will diminish. Even if we terraformed Mars and gave it a heftier atmosphere, it would lose it unless we continually renewed its atmosphere.”
Yeah...that’s what I figured...oh, well...
Catastrophe?
On worlds like Venus and Mars?
OH PLEASE.
Why stop there? Titan and Europa too!
Jeez man. They are extreme worlds because that is their natural state. It is not a “catastrophe” that Mars is Mars.
That was the theory of Global cooling.
Guess those Venusians and Martians didnt buy enough carbon offset credits. Bet they wish they had had their own Gorical!
You are right that it isn’t directly testable and we don’t know for sure how they started out. All information we have is based on inferences. I think the best thing to come out of this is how complex the climate and how little we really understand the full dynamics of it.
The point though of the article is that we need to look at Venus and Mars and get hysterical and even if the models aren’t good “if they are right” the climate is going to be shot in 50 years. Just long enough so we can waste billions of dollars trying to fix it. And anyway who wants beaches in Greenland? Such a horrible thing to have longer growing seasons and bigger crop yields and how messed up the dessert ecosystem of the Sahara if it reverted back to the lush climate it had several thousand years ago. I think real global warming would be a very good thing politically. It would totally dilute the large coastal liberal city populations much like New Orleans. (Just wait till the left starts talking about that one)
I think Titan would be a great place to get enough hydrocarbons to keep planet Earth fueled for a million years. ;-)
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