Lucas's Wordlist

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.

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.

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.

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.

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.

The findings, published in a recent issue of the journal Science, reveal how carbon dioxide isotopes have reacted to volcanic activity, water and weathering – thus forming a more complete picture of the current martian atmosphere.

A new atmosphere-ocean climate modeling study shows that atmospheric carbon dioxide acts as a thermostat in regulating the temperature of Earth.

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.

Without non-condensing greenhouse gases, water vapor and clouds would be unable to provide the feedback mechanisms that amplify the greenhouse effect.

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.

Revealing More about the Martian Atmosphere

Dr. John Hoffman designed the mass spectrometer through which soil samples collected at the surface of Mars were analyzed.

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.

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.

Revealing More about the Martian Atmosphere

Dr. John Hoffman designed the mass spectrometer through which soil samples collected at the surface of Mars were analyzed.

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.

The NASA mission in which this work was accomplished was the Phoenix Lander, an unmanned spacecraft deployed to Mars in 2008.

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.

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.

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.

"Today we are in uncharted territory as carbon dioxide approaches 390 parts per million in what has been referred to as the 'superinterglacial.'"

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.

Scientists have also studied material from martian meteorites that have landed on Earth.

"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.

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."

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.

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 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.

"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.

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.

Without non-condensing greenhouse gases, water vapor and clouds would be unable to provide the feedback mechanisms that amplify the greenhouse effect.

“Obviously, these geologic and atmospheric changes are slow processes, but we now have a better idea of the earlier planetary atmosphere.”

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.

A new atmosphere-ocean climate modeling study shows that atmospheric carbon dioxide acts as a thermostat in regulating the temperature of Earth.

"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.

“These findings are exciting because they show how the atmosphere of Mars evolved and we can contrast that to our own history here on Earth,” Hoffman added.

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.

By contrasting these isotopes, Hoffman and other researchers could see how the gases were affected by geologic processes on Mars.

The work was conducted in collaboration with researchers at the University of Arizona.

By contrasting these isotopes, Hoffman and other researchers could see how the gases were affected by geologic processes on Mars.

“We examined these carbon dioxide molecules and measured the ratio of the light to heavy atoms of carbon and oxygen.”

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.

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.

Samples of atmospheric gasses were drawn into the instrument during several Martian days, called “sols,” and analyzed to determine the type of gases that comprise the atmosphere.

“We examined these carbon dioxide molecules and measured the ratio of the light to heavy atoms of carbon and oxygen.”

Credit: NASA GISS/ Lilly Del Valle
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.

Credit: NASA GISS/ Lilly Del Valle
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.

Revealing More about the Martian Atmosphere

Dr. John Hoffman designed the mass spectrometer through which soil samples collected at the surface of Mars were analyzed.

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.

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).

The findings, published in a recent issue of the journal Science, reveal how carbon dioxide isotopes have reacted to volcanic activity, water and weathering – thus forming a more complete picture of the current martian atmosphere.

By this accounting, carbon dioxide is responsible for 80 percent of the radiative forcing that sustains the Earth's greenhouse effect.

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.

Credit: UT Dallas
Instruments designed by a UT Dallas professor to measure atmospheric components on the surface of Mars have uncovered important clues about the planet’s atmosphere and climate history.

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.

"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, 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.

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.

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.

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.

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.

The findings, published in a recent issue of the journal Science, reveal how carbon dioxide isotopes have reacted to volcanic activity, water and weathering – thus forming a more complete picture of the current martian atmosphere.

Revealing More about the Martian Atmosphere

Dr. John Hoffman designed the mass spectrometer through which soil samples collected at the surface of Mars were analyzed.

“We examined these carbon dioxide molecules and measured the ratio of the light to heavy atoms of carbon and oxygen.”

Credit: NASA GISS/ Lilly Del Valle
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.

To provide perspective to the nearly 1 C (1.8

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.

"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.

Without non-condensing greenhouse gases, water vapor and clouds would be unable to provide the feedback mechanisms that amplify the greenhouse effect.

“The dominant gas is carbon dioxide,” Hoffman said.

By this accounting, carbon dioxide is responsible for 80 percent of the radiative forcing that sustains the Earth's greenhouse effect.

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."

Credit: NASA GISS/ Lilly Del Valle
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.

The precision of those measurements was limited by the technology available at the time.

“We examined these carbon dioxide molecules and measured the ratio of the light to heavy atoms of carbon and oxygen.”

"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.

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.

Credit: UT Dallas
Instruments designed by a UT Dallas professor to measure atmospheric components on the surface of Mars have uncovered important clues about the planet’s atmosphere and climate history.

Credit: NASA GISS/ Lilly Del Valle
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.

By contrasting these isotopes, Hoffman and other researchers could see how the gases were affected by geologic processes on Mars.

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.

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.

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.

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.

Credit: NASA
“The accuracy of the current measurements far surpasses the previous information we had,” Hoffman said.

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.

Credit: NASA GISS/ Lilly Del Valle
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.

"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.

Previous samples from the Martian atmosphere were analyzed three decades ago during NASA’s Viking program.

Credit: NASA GISS/ Lilly Del Valle
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.

These data have helped fill in the time scale for the evolution of the atmosphere on Mars.

These data have helped fill in the time scale for the evolution of the atmosphere on Mars.

Credit: NASA
“The accuracy of the current measurements far surpasses the previous information we had,” Hoffman said.

Revealing More about the Martian Atmosphere

Dr. John Hoffman designed the mass spectrometer through which soil samples collected at the surface of Mars were analyzed.

Revealing More about the Martian Atmosphere

Dr. John Hoffman designed the mass spectrometer through which soil samples collected at the surface of Mars were analyzed.

Revealing More about the Martian Atmosphere

Dr. John Hoffman designed the mass spectrometer through which soil samples collected at the surface of Mars were analyzed.

Undestanding the history of Mars' atmosphere and climate is essential in determining the potential for past life on the planet.

"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.

UT Dallas Physics Professor John Hoffman, a member of the William B. Hanson Center for Space Sciences, designed the mass spectrometer through which soil samples collected at the surface of Mars were analyzed.

These data have helped fill in the time scale for the evolution of the atmosphere on Mars.

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 precision of those measurements was limited by the technology available at the time.

The findings, published in a recent issue of the journal Science, reveal how carbon dioxide isotopes have reacted to volcanic activity, water and weathering – thus forming a more complete picture of the current martian atmosphere.

Credit: NASA GISS/ Lilly Del Valle
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.

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.

The findings, published in a recent issue of the journal Science, reveal how carbon dioxide isotopes have reacted to volcanic activity, water and weathering – thus forming a more complete picture of the current martian atmosphere.

The study's results will be published Friday, Oct. 15 in Science.

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.

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.

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.

Scientists have also studied material from martian meteorites that have landed on Earth.

Credit: UT Dallas
Instruments designed by a UT Dallas professor to measure atmospheric components on the surface of Mars have uncovered important clues about the planet’s atmosphere and climate history.

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).

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.

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.

"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, 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.

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.

Previous samples from the Martian atmosphere were analyzed three decades ago during NASA’s Viking program.

Scientists have also studied material from martian meteorites that have landed on Earth.

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."

The precision of those measurements was limited by the technology available at the time.

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.

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.

"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.

By contrasting these isotopes, Hoffman and other researchers could see how the gases were affected by geologic processes on Mars.

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.

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.

Undestanding the history of Mars' atmosphere and climate is essential in determining the potential for past life on the planet.

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.

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.

These data have helped fill in the time scale for the evolution of the atmosphere on Mars.

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.

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."

"Today we are in uncharted territory as carbon dioxide approaches 390 parts per million in what has been referred to as the 'superinterglacial.'"

The NASA mission in which this work was accomplished was the Phoenix Lander, an unmanned spacecraft deployed to Mars in 2008.

The NASA mission in which this work was accomplished was the Phoenix Lander, an unmanned spacecraft deployed to Mars in 2008.

The research was funded by NASA as part of the Mars Scout Program.

The findings, published in a recent issue of the journal Science, reveal how carbon dioxide isotopes have reacted to volcanic activity, water and weathering – thus forming a more complete picture of the current martian atmosphere.

Different mass atoms of an element are called isotopes.

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.

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.

By contrasting these isotopes, Hoffman and other researchers could see how the gases were affected by geologic processes on Mars.

The findings, published in a recent issue of the journal Science, reveal how carbon dioxide isotopes have reacted to volcanic activity, water and weathering – thus forming a more complete picture of the current martian atmosphere.

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."

The precision of those measurements was limited by the technology available at the time.

The findings, published in a recent issue of the journal Science, reveal how carbon dioxide isotopes have reacted to volcanic activity, water and weathering – thus forming a more complete picture of the current martian atmosphere.

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.

The work was conducted in collaboration with researchers at the University of Arizona.

"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 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.

"Today we are in uncharted territory as carbon dioxide approaches 390 parts per million in what has been referred to as the 'superinterglacial.'"

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.

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).