Water Vapor Confirmed as Major Player in Climate Change

[C1ay]

Water vapor is known to be Earth's most abundant greenhouse gas, but the extent of its contribution to global warming has been debated. Using recent NASA satellite data, researchers have estimated more precisely than ever the heat-trapping effect of water in the air, validating the role of the gas as a critical component of climate change.

 

Andrew Dessler and colleagues from Texas A&M University in College Station confirmed that the heat-amplifying effect of water vapor is potent enough to double the climate warming caused by increased levels of carbon dioxide in the atmosphere.

 

With new observations, the scientists confirmed experimentally what existing climate models had anticipated theoretically. The research team used novel data from the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite to measure precisely the humidity throughout the lowest 10 miles of the atmosphere. That information was combined with global observations of shifts in temperature, allowing researchers to build a comprehensive picture of the interplay between water vapor, carbon dioxide, and other atmosphere-warming gases. The NASA-funded research was published recently in the American Geophysical Union's Geophysical Research Letters.

 

"Everyone agrees that if you add carbon dioxide to the atmosphere, then warming will result," Dessler said. "So the real question is, how much warming?"

 

The answer can be found by estimating the magnitude of water vapor feedback. Increasing water vapor leads to warmer temperatures, which causes more water vapor to be absorbed into the air. Warming and water absorption increase in a spiraling cycle.

 

Water vapor feedback can also amplify the warming effect of other greenhouse gases, such that the warming brought about by increased carbon dioxide allows more water vapor to enter the atmosphere.

 

"The difference in an atmosphere with a strong water vapor feedback and one with a weak feedback is enormous," Dessler said.

 

Climate models have estimated the strength of water vapor feedback, but until now the record of water vapor data was not sophisticated enough to provide a comprehensive view of at how water vapor responds to changes in Earth's surface temperature. That's because instruments on the ground and previous space-based could not measure water vapor at all altitudes in Earth's troposphere -- the layer of the atmosphere that extends from Earth's surface to about 10 miles in altitude.

 

AIRS is the first instrument to distinguish differences in the amount of water vapor at all altitudes within the troposphere. Using data from AIRS, the team observed how atmospheric water vapor reacted to shifts in surface temperatures between 2003 and 2008. By determining how humidity changed with surface temperature, the team could compute the average global strength of the water vapor feedback.

 

"This new data set shows that as surface temperature increases, so does atmospheric humidity," Dessler said. "Dumping greenhouse gases into the atmosphere makes the atmosphere more humid. And since water vapor is itself a greenhouse gas, the increase in humidity amplifies the warming from carbon dioxide."

 

Specifically, the team found that if Earth warms 1.8 degrees Fahrenheit, the associated increase in water vapor will trap an extra 2 Watts of energy per square meter (about 11 square feet).

 

"That number may not sound like much, but add up all of that energy over the entire Earth surface and you find that water vapor is trapping a lot of energy," Dessler said. "We now think the water vapor feedback is extraordinarily strong, capable of doubling the warming due to carbon dioxide alone."

 

Because the new precise observations agree with existing assessments of water vapor's impact, researchers are more confident than ever in model predictions that Earth's leading greenhouse gas will contribute to a temperature rise of a few degrees by the end of the century.

 

"This study confirms that what was predicted by the models is really happening in the atmosphere," said Eric Fetzer, an atmospheric scientist who works with AIRS data at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Water vapor is the big player in the atmosphere as far as climate is concerned."

 

Source: NASA

[Flying Binghi]

  Quote

This study confirms that what was predicted by the models is really happening in the atmosphere

 

errr, seems a little cooler this year to me :doh:

 

Wheres a link to that cartoon of the customer pointing to the product on the shelf, but the brain wave shop keep saying none in stock because the computer record shows "none in stock" - stupid customers......

[C1ay]

You've taken that out of context by not quoting all of what Mr. Fetzer said, i.e.

 

  \ said:

"This study confirms that what was predicted by the models is really happening in the atmosphere," said Eric Fetzer, an atmospheric scientist who works with AIRS data at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Water vapor is the big player in the atmosphere as far as climate is concerned."

 

Water vapor amplifies global climate effects. Yes, this year is a little cooler compared to recent years and we've just come out of a solar minimum where the sun has exhibited minimal sunspot activity. Global warming is happening and will continue. Just look at the Earth's climate history:

 

 

We're still coming out of the last ice age heading for the historical average temperature of 17°C. We may be contributing to how fast this occurs with CO2 but it's really water vapor that's the leading greenhouse gas.

[HydrogenBond]

There is a subtle affect connected to water and weather patterns. Salt water is harder to evaporate than pure water since the ions lower the vapor pressure. What that means is if weather patterns have more water falling on the land and evaporating, we will get more water in the atmosphere at any temperature. This may seem small but it is huge compared to CO2.

 

There are about 26 billions tons of CO2 each year added by all sources. One ton of water is 35 cubic feet. One cubic mile of water is 127 billion cubic feet. So one cubic mile of water is about 4 billion tons. So the CO2 amounts to about 7 cubic miles of water weight added per year.

 

Collectively, the total continental evapotranspiration (both evaporation and plants transpiration) is estimated at about 71,000 cubic kilometers per day, or about 18,000 cubic miles per day. If we increased this 1% about seven times the weight of water is added per day compared to all the CO2 in a year. The same temperature, by simply shifting more water to the land causes more global warming.