Pieter Tans, a senior scientist at the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory, provides this answer.
The earth¿s surface absorbs visible radiation from the sun, which causes heating. At the same time the surface and the atmosphere emit infrared radiation back to space, which produces cooling. Our eyes cannot see infrared radiation but we can feel how our skin absorbs it when we are standing next to a hot object without touching it. Over a long period the earth¿s surface temperature will remain approximately constant because the amount of heat absorbed as visible light is equal to the amount emitted as infrared light.
Nitrogen, oxygen and argon together comprise more than 99 percent of the atmosphere. None of these three gases absorb either visible or infrared light; both types penetrate the entire atmosphere. It is as though, when it comes to the absorption and emission of light, the atmosphere¿s three main components do not exist!
The next most abundant gases--water vapor and carbon dioxide--do absorb a portion of the infrared heat radiated by the earth's surface, thereby preventing it from reaching space. Instead of dissipating into space, the infrared radiation that is absorbed by atmospheric water vapor or carbon dioxide produces heating, which in turn makes the earth¿s surface warmer. This is known as the greenhouse effect and without it our planet¿s surface would likely be frozen, like Mars. The heat absorbed by water vapor and carbon dioxide is shared with all the nitrogen, oxygen and argon, because the latter molecules are always bumping into water vapor and carbon dioxide as they mix in the atmosphere. This effect makes the atmosphere act somewhat like a blanket that becomes thicker when amounts of water vapor, carbon dioxide and other ¿greenhouse gases,¿ such as methane and nitrous oxide, increase. The top of the blanket remains cold and continues to emit about the same amount of infrared to space but below the blanket it gets warmer because it is more difficult for the heat to rise to the top.
The heating effect of extra carbon dioxide, methane, nitrous oxide and many other minor gases can be calculated with confidence based on the absorption properties that have been measured carefully in the laboratory. Currently, the total heating produced by the increases of all long-lived greenhouse gases (excluding water vapor) since preindustrial times is equal to about 1 percent of all solar radiation absorbed at the surface. The effect would be somewhat similar if the sun had started to shine 1 percent more brightly during the 20th century.
Water vapor is excluded from the above calculation because it is an intimate and highly variable part of the climate system itself in the form of clouds, rain, snow and other weather. The long-lived greenhouse gases, however, can be considered an external forcing clearly influenced by human action. Most climatologists expect that on average the atmosphere¿s water vapor content will increase in response to surface warming caused by the long-lived greenhouse gases, further accelerating the overall warming trend.
It will be difficult to slow or stop this global warming, thanks to the oceans, which are warming as well. Currently, the amount of infrared heat radiated back to space is slightly less than what we absorb from the sun due to the increase in greenhouse gases. This excess energy slowly warms the oceans. Although it takes them a very long time to heat up, once they have they will release more infrared radiation and the Earth will emit as much back to space as it receives from the sun. But the planet¿s surface will be warmer, because a larger fraction of that infrared will be blocked by the blanket of greenhouse gases. Thus, we can expect about another 0.5 degree Celsius of warming even if the amount of carbon dioxide in the atmosphere were to stop increasing today, which is unlikely as we continue to burn coal, oil and natural gas for our increasing energy needs.
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11 Comments
Add CommentWater vapor yes- green house effect, however no one has ever proven any thermal value to co2. In the earths history there has been 6X the co2 present level, the warming came first followed by the co2 increse. The volume of water vapor compaired to co2 is not even ratioal, however changing economic dynamics and profit from cabon credits, is a motive to lie and pervert data.
Reply | Report Abuse | Link to thisMillions of dollars over twenty years and not one heat island has ever been found over a high concentration of co2, however there are some who would give us 6percent additional unemplyment and 750 to 1300 dollars per household a year to the publics burden. All of this with no scientific proof.
The author glosses over the effects of water vapor when the fact is water vapor accounts for 95% of the greenhouse effect and water vapor is 99.999% natural in origin.
Reply | Report Abuse | Link to this"Of the 186 billion tons of CO2 that enter earth's atmosphere each year from all sources, only 6 billion tons are from human activity. Approximately 90 billion tons come from biologic activity in earth's oceans and another 90 billion tons from such sources as volcanoes and decaying land plants."
"At 368 parts per million CO2 is a minor constituent of earth's atmosphere-- less than 4/100ths of 1% of all gases present."
"CO2 that goes into the atmosphere does not stay there but is continually recycled by terrestrial plant life and earth's oceans"
Excellent points raised here. The Earth's temperature has always been fluctuating and there have been other warm periods in the past, well before industrialized nations.
Reply | Report Abuse | Link to thisAfter 1940, when industry was booming, the global temperature actually decreased for nearly 4 decades. There was even talk about a coming ice age.
The UN is a political entity creating politically motivated organizations such as the IPCC. There are scientists that are named in the IPCC's report on global warming who do not agree with the premise of human created global warming.
The polar bears survived other warm periods and...behold, they are still here.
What about the rest of the solar system? Check this out:
http://www.enterprisemission.com/_articles/05-14-2004_Interplanetary_Part_1/Interplanetary_1.htm
Too many questions for me to blindly follow the beaten CO2 path.
And whatever became of Gore's obsession with the hole in the ozone? I guess it's just not politically viable enough anymore.
Reply | Report Abuse | Link to thisDoes anyone here have any real data (the logic and reasoning incredible - literally). When you assume you have proven some part of the opposition's argument false, how does that prove the rest of it false? How does a personal attack on the opposition prove false anything he says? How does proving that he profits - however much - by his argument prove it is false? How does guessing about the temperature of the earth thousands of years ago contribute to the discussion of today's global warming due increased atmospheric corbon dioxide levels (do we really want to live the way life lived 3,000 years ago?). How does employment (or unemployment) prove anything about the fact or falsity of the argument concerning global warming? Does the condition of the air and atmosphere above major cities around the world suggest anything should the entire planet become so polluted? Is global warming debate a red herring covering up the rest of anthropogenic pollution (when we can walk on the plastic - or drive cars on it - in the Pacific Ocean between Hawaii and Japan, it will have made no difference to the atmosphhere? How much carbon dioxide can a human being breathe without gasping for breath? How much carbon dioxide does, and will, 600 million motor vehicles produce? If or when everyone on the planet has a car - the 6.5 billion here now, for instance - how much carbon dioxide will be produced? How much carbon dioxide is required to acidize sea water? How much will kill the sea anemone and other forms of plankton-sized life? How much carbon dioxide is required to kill or alter bacterial or other microscopic life forms (if we don't so much as know how many life forms are extant, how do we know that the effect of carbon dioxide will be?)
Reply | Report Abuse | Link to thisDoes anyone here remember Pascals' Wager? Does anyone consider that its reasoning might apply to any of this?
I must agree with fishman:
Reply | Report Abuse | Link to thisI have no quaulifications in science or otherwise, but I do have common sence and lodgic..if there is a difference.
I have seen really great summers and some bad winters,I have witnessed floods up and down our country.All were extreme yet not unusual over a period of 60 years.Of course were going to get extreme weather occassionally with the usual weather patterns in between it's common sense.
For anyone, scientists included to say we are experiencing unatural weather patterns is nonsense, global warming may be a fact, but it's a natural cycle that has happened before, is there anyone who will dispute global warming has not happened before?
What if interfering with carbon dioxide levels has the opposite effect and drops alarmingly to allow more harmful radiation to bathe our earth...what then?
Years ago in the UK farmland fields were framed with beautiful broadleafed trees and dotted along side roads,not anymore.
The global warming effect of carbon dioxide is constant with time and essentially independent of the density of carbon dioxide. This is because CO2 is an efficient absorber of infrared in the two spectral bands for this gas. It absorbs approximately 50% of the infrared energy for a meter of absorption length at the present 380ppm concentration. Thus all the energy it can absorb it does so in less than 100 meters. Increasing CO2 only shortens the absorption length in direct proportion of the density. With all the turbulence in the atmosphere CO2 increases are benign. CO2 absorbs about 8.3% of Earth's radiated infrared energy. This is constant over a very wide range of CO2 concentration. CO2 is not a problem.
Reply | Report Abuse | Link to thisShame this fool does not know what he is on about, CO2 comprises less than a third of one percent of all the atomosphere. It is impossible to accurately measure the composition on the atmoshpere to this level, as a mouse farting nearby would make the instrument self destruct.
Reply | Report Abuse | Link to thisThe sun has more to do with global warming than burning fossil fuels, but because it is beyond human control and is a hell of a long place to go to work to (and damned hot when you get there), it remains ignored by the scientific community.
The Greenhouse Effect has been invented to keep moronic scientists usefully employed spouting spurious rubbish to anybody who will listen, in order to keep their jobs.
One of the main climate research centres in the UK was caught manipulating data, how many more do this?
It seems strange that this ambiguous piece would appear in a scientific publication. To blame a trace gas that makes up .036% of the atmosphere, CO2, and is one and one half times heavier than air for what something as complex as the what the earth's climate does is a real stretch of the imagination. At 392 parts per million, CO2 is a minor constituent of earth's atmosphere-- less than 4/100ths of 1% of all gases present. Compared to former geologic times, earth's current atmosphere is CO2- impoverished.
Reply | Report Abuse | Link to thisThere are some obsessed with the supposed increase of 280 ppm to 392ppm of CO2 and I hope that this information will help you to sleep better at nights.
This, I hope, will put this into some kind of a perspective that makes one understand just how insignificant this increase is.
A part per million is like 1 drop of ink in a large
kitchen sink.
A large kitchen sink is about 13-14 gallons. There
are 100 drops in one teaspoon, and 768 teaspoons
per gallon.
Some other things that are one part per million are…
One drop in the fuel tank of a mid-sized car
One inch in 16 miles
About one minute in two years
One car in a line of bumper-to-bumper traffic from
Cleveland to San Francisco.
One penny in $10,000.
I know that you understand that these 112 additional ppm are spread out over this 16 miles in different one inch segments and wouldn't it be a task to be told to sort out the 392 pennies from the number that it would take to make up $10,000.
Now another FACT for you to consider. CO2 is one and one half times heavier than "air". This point was sadly proven on Aug, 21, 1986 when Lake Nyor in Cameroon released about 1.6 million tons of CO2 that spilled over the lip of the lake and down into a valley and killed 1,700 people within 16 miles of the lake. "Carbon dioxide, being about 1.5 times as dense as air, caused the cloud to "hug" the ground and descend down the valleys where various
villages were located. The mass was about 50 metres (164 ft) thick and it travelled downward at a rate of 20–50 kilometres (12–31 mi) per hour. For roughly 23 kilometres (14 mi) the cloud remained condensed and dangerous, suffocating many of the people sleeping in Nyos,Kam,Cha,andSubum.
"http://en.wikipedia.org/wiki/L...
Dear Leak,
Reply | Report Abuse | Link to thisI think your math is a little off. That would be 4/10ths of one percent (not 4/100ths) which still small. However, it used to be closer to 3/10ths, so it is indeed increasing. The point of the article is that this is a significant change in CO2 and it WILL cause the planet to warm, even though it such a small part of the total mixture of gases that make up our atmosphere.
Meanwhile, back on Earth...
Reply | Report Abuse | Link to thishttp://www.youtube.com/watch?v=SIP0O1NJVZA