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NASA – Water Vapor Confirmed as Major Player in Climate Change

Water Vapor Confirmed as Major Player in Climate Change


Still from animation showing global distribution of atmospheric water vapor

The distribution of atmospheric water vapor, a significant greenhouse gas, varies across the globe. During the summer and fall of 2005, this visualization shows that most vapor collects at tropical latitudes, particularly over south Asia, where monsoon thunderstorms swept the gas some 2 miles above the land.
Credit: NASA
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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.
Graph showing that the energy trapped by water peaks near the equator
Based on climate variations between 2003 and 2008, the energy trapped by water vapor is shown from southern to northern latitudes, peaking near the equator.
Credit: Andrew Dessler
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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.”

Related Links:

> Will Runaway Water Warm the World?
> Atmospheric Infrared Sounder (AIRS) Web page

Kathryn Hansen
NASA’s Goddard Space Flight Center

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Global warming – What role does water vapor really play?


Global warming – What role does water vapor really play?

Scientists say man-made CO2 causes global warming; climate skeptics insist that water vapor is responsible. Here’s why both assumptions are true.

Water vapor rises from a river in Siberia / Credits: Reuters

Here are the perfect ingredients for a conspiracy theory: water vapor is the most important factor influencing the greenhouse effect but doesn’t feature on the UN’s list of greenhouse gases responsible for anthropogenic global warming.

Critics of the idea of man-made global warming love this simple fact and have turned it into one of their most potent arguments to sabotage decisive climate action.

So why doesn’t the UN’s climate body the International Panel on Climate Change (IPCC) list water vapor as a greenhouse gas? It’s because water vapor does not by itself increase temperatures. It amplifies already occurring warming.

Water vapor’s role in the Earth’s climate system is defined by the very short time it remains in the atmosphere and actively traps heat. While additional CO2 from factories or airplanes can remain in the atmosphere for centuries, extra water vapor will only remain a few days before raining down as water.

The concentration of water vapor in the atmosphere is in equilibrium. The atmosphere can only hold more water vapor if overall temperatures increase. So a small warming effect caused by human CO2 emissions will increase the amount of water vapor in the atmosphere.

The added water vapor leads to even more warming, thus amplifying the CO2 warming effect. Water vapor follows temperature changes, it doesn’t cause or, as climatologists say, ‘force’ them. As a feedback effect, water vapor is comparable to a car’s turbo charger that increases a motor’s power.

However, the amount of water vapor in the atmosphere changes regionally. While there is virtually no water vapor above deserts or the Arctic and Antarctic regions, the air above the equator can consist of up to four percent water vapor.

In humid equatorial regions, where there is already a strong natural greenhouse effect, additional CO2 and water vapor have little impact on local climate. The opposite is true in cold, dry places, which is one reason why warming is much more pronounced in Polar regions.


CO2: Endless warming

Carbon dioxide is the number one reason for man-made climate change. But what is carbon dioxide, and why is it harmful?


Concentration matters

Regional differences aside, the atmosphere contains on average only 0.4 percent of water vapor and ten times less CO2. This relatively small concentration is another argument often cited to refute the idea of man-made global warming. How can CO2 cause rising temperatures, skeptics demand, if it only accounts for 0.04 percent of the atmosphere?

Again the riddle is solved easily.

Oxygen and nitrogen are the most abundant elements in the Earth’s atmosphere and make up 99 percent of it. But neither of the two gases traps or emits heat.

This is why water vapor is responsible for most of the natural greenhouse effect. Scientists estimate that without water vapor average temperatures would be up to 30 degrees Celsius lower. CO2, on the other hand, is responsible for a much smaller but still substantial amount of the natural warming effect.

If things remain like this, we could continue living on a cozy, warm planet. But too much of a good thing is often bad. CO2 levels have increased from 0.028 percent of the atmosphere to about 0.04 percent since the Industrial Revolution. This has led to a temperature increase of about 0.7 degrees Celsius so far.

About half of this warming could be due to feedback warming from water vapor, estimates the IPCC. But it would not have happened without the added CO2 pumped into the atmosphere. CO2 is the guy robbing the bank, water vapor is just the getaway driver.


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Analysis of potential for reducing emissions of greenhouse gases in municipal solid waste in Brazil, in the state and city of Rio de Janeiro

New Report: Man-made Global Warming Is a Farce

Thursday, 13 December 2012 13:55

New Report: Man-made Global Warming Is a Farce

Written by Rebecca Terrell

New Report: Man-made Global Warming Is a Farce

The notion of the “new normal” of extreme weather is a farce, according to a recent report by the environmental group Committee for a Constructive Tomorrow (CFACT). Extreme Weather Report 2012 was presented at the latest UN Climate Conference in Doha, Qatar, but the only press this landmark study received was when British politician and author Lord Christopher Monckton was kicked out of the conference for presenting it.

The report is actually a massive compilation of scientific studies and news articles from both public and private sources, including the National Oceanic and Atmospheric Administration (NOAA). Together they indicate claims of “global warming,” “climate change” and “climate disruption” are nothing but a ruse to usher in massive carbon taxes and crippling regulations. Like Pavlov’s dog, politicians are conditioned to react to any harsh weather event by drooling for higher taxes, notes the study. Naturally, delegates at the UN conference were not interested in the conclusions of the CFACT study.

The Pavlov analogy is appropriate, nevertheless, as this small sampling of items from the report illustrates:

• Extreme Weather Events are Killing Fewer People Than Ever Before — Reason Foundation, September 22, 2011.

• Recent historically low global tropical cyclone activity: In the past 5-years, global tropical cyclone activity has decreased markedly — Geophysical Research Letters, 2011.

• Downward trend in strong (F3) to violent (F5) tornadoes in U.S. since 1950s — former NASA scientist Dr. Roy Spencer, May 24, 2011.

• Drought Trends, Estimates Possibly Overstated Due to Inaccurate Science: Study suggests that there has been little change in drought over the past 60 years — CBS reporting on findings published in the journal Nature, November 19, 2012.

• Are US Floods Increasing? The Answer is Still No: A new paper out today shows flooding has not increased in U.S. over records of 85 to 127 years — University of Colorado environmental studies professor Roger Pielke, Jr., October 24, 2011.

• “These recent U.S. ‘extremes’ were exceeded in previous decades…. The expression of ‘worse than we thought’ climate change as documented in [James] Hansen’s OpEd does not stand up to scrutiny.” — Alabama State Climatologist John R. Christy, Ph.D., in testimony before the House Energy and Power Subcommittee, September 20, 2012.

Other citations show the hypocrisy of climate alarmists such as Al Gore, who is on record in 2009 blaming global warming for vanishing snow and ice even at Earth’s poles. A mere two years later he published on his blog “increased heavy snowfalls are completely consistent with what [scientists] have been predicting as a consequence of man-made global warming.” Doha delegates were sure to feel that sting of reproach since the UN’s Intergovernmental Panel on Climate Change (IPCC) published warnings in 2007 in its Fourth Assessment Report (AR4) of “fewer cold outbreaks” and “fewer, shorter, less intense cold spells/cold extremes in winter.” Northern Hemisphere countries have endured unusually harsh winters since AR4 hit the newsstands.

Perhaps the most provocative citation in the report is the November 29 open letter from 125 scientists to UN Secretary-General H.E. Ban Ki-Moon, rebuking the UN for its claims that mankind is responsible for suffering caused by extreme weather events. “The hypothesis that our emissions of CO2 have caused, or will cause, dangerous warming is not supported by the evidence,” noted the authors, who also begged, “We ask that you desist from exploiting the misery of the families of those who lost their lives or properties in tropical storm Sandy by making unsupportable claims that human influences caused that storm. They did not.”

The letter went on to point out NOAA’s State of the Climate in 2008 report declared it would take 15 years of no observed warming to prove climate models and alarmist predictions wrong. Yet the U.K. Met Office recently reported “no statistically significant global warming for almost 16 years,” during a time when NOAA says atmospheric carbon dioxide concentrations rose by nearly nine percent and now make up 0.039 percent of the atmosphere.

Mark Morano of Climate Depot, who compiled the CFACT report, summed up the nature of popular climate science on Fox News (see video below): “Mayor Bloomberg said we need to take immediate action to prevent bad weather. This has now reached the level of the Mayan Calendar and Nostradamus. The New York Times has a picture of the Statue of Liberty under water and warning of the end times. This is not science! This is doomsday stuff of the Mayan calendar, and we have no business masquerading it as science.”


More in this category:« UN Summit Fails to Enact “Complete Transformation” of the World Climate-change Computer Models Fail Again — and Again, and Again »


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