Carbon dioxide controls Earth’s temperature

NEW YORK — Water vapor and clouds are the major contributors to Earth’s greenhouse effect, but a new atmosphere-ocean climate modeling study shows that the planet’s temperature ultimately depends on the atmospheric level of carbon dioxide.

The study, conducted by Andrew Lacis and colleagues at NASA’s Goddard Institute for Space Studies (GISS) in New York, examined the nature of Earth’s greenhouse effect and clarified the role that greenhouse gases and clouds play in absorbing outgoing infrared radiation. Notably, the team identified non-condensing greenhouse gases — such as carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons — as providing the core support for the terrestrial greenhouse effect.

Without non-condensing greenhouse gases, water vapor and clouds would be unable to provide the feedback mechanisms that amplify the greenhouse effect. The study’s results will be published Friday, Oct. 15 in Science.

A companion study led by GISS co-author Gavin Schmidt that has been accepted for publication in the Journal of Geophysical Research shows that carbon dioxide accounts for about 20 percent of the greenhouse effect, water vapor and clouds together account for 75 percent, and minor gases and aerosols make up the remaining five percent. However, it is the 25 percent non-condensing greenhouse gas component, which includes carbon dioxide, that is the key factor in sustaining Earth’s greenhouse effect. By this accounting, carbon dioxide is responsible for 80 percent of the radiative forcing that sustains the Earth’s greenhouse effect.

The climate forcing experiment described in Science was simple in design and concept — all of the non-condensing greenhouse gases and aerosols were zeroed out, and the global climate model was run forward in time to see what would happen to the greenhouse effect.

Without the sustaining support by the non-condensing greenhouse gases, Earth’s greenhouse effect collapsed as water vapor quickly precipitated from the atmosphere, plunging the model Earth into an icebound state — a clear demonstration that water vapor, although contributing 50 percent of the total greenhouse warming, acts as a feedback process, and as such, cannot by itself uphold the Earth’s greenhouse effect.

“Our climate modeling simulation should be viewed as an experiment in atmospheric physics, illustrating a cause and effect problem which allowed us to gain a better understanding of the working mechanics of Earth’s greenhouse effect, and enabled us to demonstrate the direct relationship that exists between rising atmospheric carbon dioxide and rising global temperature,” Lacis said.

The study ties in to the geologic record in which carbon dioxide levels have oscillated between approximately 180 parts per million during ice ages, and about 280 parts per million during warmer interglacial periods. To provide perspective to the nearly 1 C (1.8 F) increase in global temperature over the past century, it is estimated that the global mean temperature difference between the extremes of the ice age and interglacial periods is only about 5 C (9 F).

“When carbon dioxide increases, more water vapor returns to the atmosphere. This is what helped to melt the glaciers that once covered New York City,” said co-author David Rind, of NASA’s Goddard Institute for Space Studies. “Today we are in uncharted territory as carbon dioxide approaches 390 parts per million in what has been referred to as the ‘superinterglacial.'”

“The bottom line is that atmospheric carbon dioxide acts as a thermostat in regulating the temperature of Earth,” Lacis said. “The Intergovernmental Panel on Climate Change has fully documented the fact that industrial activity is responsible for the rapidly increasing levels of atmospheric carbon dioxide and other greenhouse gases. It is not surprising then that global warming can be linked directly to the observed increase in atmospheric carbon dioxide and to human industrial activity in general.”

Written by:

Kathryn Hansen

NASA’s Earth Science News Team

The material in this press release comes from the originating research organization. Content may be edited for style and length. Have a question? Let us know.


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7 thoughts on “Carbon dioxide controls Earth’s temperature”

  1. You gotta be kidding.
    The computer model makes no sense whatsoever.
    First you MUST add extra energy to warm the world. CO2 and Water Vapor do not add energy.
    Second, Adding CO2 constantly does NOT allow the temperature to go down. I have news for you . It goes DOWN every night and every winter etc. The CO2 model is absurd idiocy. Arrhenius blew it in his 1896 paper. see “Arrhenius Mis-Applied Basic Physics in 1896 Greenhouse Effect Paper” in He said more GHGs means more Warming. IT JUST AIN’T TRUE. Man adds CO2 at night, when the temperature goes down. When it rains more GHG WV does NOT result in warming.
    CO2 and water vapor, neither of them add energy to the world. It is flat impossible for them to cause warming without adding more energy.
    Now when you add an extra energy photon to either you get imcreased Greenhouse Effect warming, but since there is excess GHGs in the air & lots more left over in the ocean, then the amount of warming is limited by the amount of energy photons.
    See “Gravity cause Climate Cjange” for an explanation of where the photons come form. The temperature and the GHE goes down cyclically when ever the number of photons decreases. Nightly, seasonally, 12 years …
    Third, there is excess CO2 and WV in the air, let alone the rest available in the ocean. Whenever the temperature decreases daily more GHGs that were causing the GHE warming are no longer in use, and they become even more excess GHGs in the air.
    When the supposed feedback model adds CO2 that CO2 just becomes more excess CO2 in the air. There is no warming because ALL of the photons are already maximized in use. There are NO MORE photons available to cause more CO2 warming, or feedback effects. In fact there is so much excess WV in the air that any photon that is added will use one of those airborne GHGs instead of waiting for man to generate CO2 to then generate more feedback. Mankind has nothing to do with the GHE warming. There is no feedback effect.
    See “Gravity cause Climate Change” for more info. This explains why the eccentricity of the planets results in variable potential energy as a source of photons and this causes the Earth’s temperature variations.
    GISS claims that there is no identified source of added energy to account for the real increased warming since the 70s, as the Solar insolation has been essentially constant. WELL there iit is. Gravitational Potential Energy. It dwarfs the solar insolation and actually controls the warming cooling cycles.
    Please withdraw your paper and return the funding. It is a fraud.

  2. I appreciate the link!

    I want to let ScienceBlog know that I appreciated having the link to the actual article, without having to search it out myself.


  3. The evidence for the correlation between global climate change and carbon dioxide is overwhelming. Even as our climate becomes increasingly unstable now (this year is shaping up to be the warmest in recorded history, with significant flooding and drought, forest fires, etc. world-wide), we continue to increase our use of fossil fuels. Added to that, it takes time for gases produced by us through the use of fossil fuels to reach the atmosphere and have an effect on our climate. Even if humans were wiped off the face of the planet today, CO2 levels would continue to increase in the atmosphere for decades to come. As more and more evidence comes out about our impact on the climate, the more pressing it becomes that we need to act on it. We already know that our actions can manipulate our climate. We need to shift our focus to manipulating it in a way that most benefits human existence.

  4. A Denier Manifesto:

    I refuse to sell my soul on the CO2 issue. The new energy we need now is love, not windmills. I am a progressive-liberal and a former CO2 theory believer and now a part of the rising wave of GREEN “CO2 fear mongering” deniers. I suggest you faded doomers do the same. The Carbon issue was our Iraq War of WMD lies and obviously, as we see now, wasn’t sustainable with the consensus that counts, with the voters.. So were we the new neocons. We told our kids they wouldn’t have children because there was a climate emergency that “they” needed to fight it to survive. We acted like fear mongering climate cowards condemning our children’s future to a “Death by CO2“. Climate change has done to us what Bush did to the Republican neocons. Are you embarrassed yet? Good. Now it’s safe to say that climatologists and journalists were to science and journalism what abusive priests were to the Catholic Church. Worse still, the Green movement hated “ANYONE” with money, wealth and waste. Not just Jews, as the “you know who’s” did.
    Preserve, protect and respect the planet, not save and rescue it from a false war.
    We should have stopped spreading fear and lies like we were Bush Jr. babies and instead lead by example for our kids by facing the future with courage, not fear!
    Lets’ be REAL liberals again: SYSTEM CHANGE, NOT CLIMATE CHANGE.
    Birth Control, not Climate Control.


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