Global warming: water vapor & photosynthesis

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Global warming: water vapor & photosynthesis

Postby Wilberforce » Mon Jun 22, 2009 6:00 pm

As for the claimed "major" water vapor warming effect:

(A) Unlike CO2, the water vapor content of the atmosphere is always fluctuating from saturation down
to the driest desert conditions. This is the effect of precipitation and storms. The warming effects are
variable and highly localized, but not global.

(B) Increasing humidity leading to saturation creates more clouds, which both reflect light back into space,
as well as shield the planet surface from direct sunlight (which in turn reduces radiant warming effect.)

(C) Extremely cold temperatures allow only minute amounts of atmospheric water-holding capacity, due to:
1) Low water vapor pressure at low temperatures
2) Water vapor hydrogen-bonding forces exceeding the inherent momentum of water vapor gas collisions;
hence low atmospheric "carrying capacity" for water vapor at low temperatures

Given (C) why then is the most warming taking effect at the polar regions? There is not very much moisture
there at all. Yet in the tropics, with the highest average humidity levels, why little or no warming effect?
Perhaps mitigated by clouds? Increased plant growth? Considering plant growth, photosynthesis is one of
the most endothermic reactions (actually it is a series of reactions) known to man:

Photosynthesis Gº= + 479.1 kJ/ mol [for 1/6(glucose) CH2O]

Why is photosynthesis interesting? File Format: PDF ... kburda.pdf

"The amount of energy trapped by photosynthesis is immense, approximately 100 terawatts:[3]
which is about six times larger than the power consumption of human civilization.[4]"

The question is: Could it be that good ol' photosynthesis is the reason that warming is "held
in check" at the earth's torrid zone? And seasonally in temperate zones? But what about the polar zones?
NO PHOTOSYNTHESIS taking place there! Hence greatest warming effect there. Same for mountain
tops with their melting glaciers as evidence.

In conclusion:

High latitudes and high altitudes: CO2 is there; H2O vapor is not; black soot is there; plants are not.
We should thus call this polar warming rather than global warming?

Map of the world's forests and grasslands

Image source: NASA
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water vapor vs carbon dioxide

Postby Wilberforce » Mon Jul 06, 2009 10:18 am

Many uninformed folks (amateur "scientists?") out there are using the "water vapor IR absorption"
parameter of the atmosphere to explain global warming. Water vapor does in fact have greater infrared
absorption capacity than carbon dioxide. But there are problems with their hypothesis.

From this reference, note that a comparison of "saturated vapor density: g/m³" amounts to an almost
20-fold increase in the water-carrying-capacity of warm air vs cold air (for temperatures -10ºC vs 35ºC)
(that is ~2 g/m³ vs ~40g/m³) From this, we can conclude that very little actual moisture exists in the
planet's frigid high latitudes. More warming should be occurring at the equator than the poles.
(20 times as much?) Yet, the converse appears to be true: poles are actually warming faster.

The claim that high IR-absorption bands of water vapor somehow "prove" that CO2 is not a major
player in the warming scenario does not take overall geographical locations into account. Some areas
have extremely low absolute humidity content, with (what would seem to be) minimal effect of
H2O vapor. This is why I am highly skeptical of claims of water vapor being the primary impetus
of global warming.

In contrast, carbon dioxide is evenly-distributed around the globe (with temporarily small concentration
increases in large human population centers, as well as the occasional volcanic venting.)

Saturated Vapor Pressure, Density for Water ... atvap.html


A hydrogen bond is a strong inter-molecular attraction between polar molecules. (polar, as in molecular
electrostatic forces, not earth's poles) The attraction force on individual water molecules is almost like
a glue effect, which is essentially the water molecules sticking together and bonding with each other.

If atmospheric temperatures are sufficiently high, the individual water vapor molecules simply bounce
off of one another during normal gas phase collisions, because they possess sufficient kinetic energy
to overcome the "sticky" attractive forces of hydrogen bonding.

As air temperature drops, the h-bonding forces tend to overcome the momentum of the (otherwise)
elastic collision. It's kind of like throwing two pieces of sticky clay at each other: They don't bounce
apart like colliding rubber balls would; they stick together. This is what happens during the process
of condensation of water vapor.

Hydrogen bond


It's as if we should ignore calls to cut CO2, since there is this more powerful "water vapor IR absorption."

The armchair generals attack Al Gore, calling him an "idiot" and everything else. Seems like they want
an excuse to continue to drive their gas-hogging SUV. Interestingly enough, their vehicle's exhaust
contains about as much water vapor as CO2!

For more discussion on climate change
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Re: Global warming: water vapor & photosynthesis

Postby Wilberforce » Wed Jul 08, 2009 5:24 pm

Two very important reasons we are not "cooking" yet:

(A) Deep Solar Minimum ... inimum.htm

(B) Much volcanic activity over the past decade spewing cooling-effect particulates

Soufrière Hills Volcano (Montserrat)
Mount Etna (Sicily)
Mount Redoubt (Alaska)
Fourpeaked Mountain (Alaska)
Cleveland Volcano (Alaska)
Others (Archived Volcanic Events of Interest)

Solar radiation reduction from volcanic eruptions

Volcanoes of the world

Solar output variation

A 12-year low in solar "irradiance": Careful measurements by several NASA spacecraft show that the sun's brightness has dropped by 0.02% at visible wavelengths and 6% at extreme UV wavelengths since the solar minimum of 1996. The changes so far are not enough to reverse the course of global warming, but there are some other significant side-effects: Earth's upper atmosphere is heated less by the sun and it is therefore less "puffed up." Satellites in low Earth orbit experience less atmospheric drag, extending their operational lifetimes. Unfortunately, space junk also remains longer in Earth orbit, increasing hazards to spacecraft and satellites.


Above: Space-age measurements of the total solar irradiance (brightness summed across all wavelengths). This plot, which comes from researcher C. Fröhlich, was shown by Dean Pesnell at the Fall 2008 AGU meeting during a lecture entitled "What is Solar Minimum and Why Should We Care?"

Source: NASA
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Re: Global warming: water vapor & photosynthesis

Postby Wilberforce » Sat Aug 01, 2009 8:59 pm

Full impact of global warming masked by air pollution

Air pollution could have been masking the true impact of the effect of global warming on the earth,
a leading scientist stated this week.

Speaking at the 13th World Clean Air and Environmental Protection congress, Professor Meinrat Andreae
of the Max Planck Institute in Germany said that the presence of aerosol gases in the atmosphere could
have actually been protecting the earth from feeling the full force of climate change (see related story).
Research conducted by Professor Andreae shows that a cooling effect caused by aerosols in the air,
which scatter light back to space, could have reduced the acceleration of the warming effect on the earth.
However, this would simply be delaying the catastrophic end results of climate change.

"Warming will be especially fast if large aerosol cooling has hidden a higher climate sensitivity than has
been generally assumed," he said. "Aerosols may have protected us from greenhouse warming, but their
protection will wane while greenhouse gases keep growing."

Professor Andreae warned that even a small probability of such negative outcomes made it vital that there
was a radical and immediate reduction in greenhouse gas emissions worldwide:

"We cannot afford to be complacent. If climate sensitivity is as high as the work on aerosol effects is
suggesting, then climate change in the 21st century may well exceed the current estimates of global warming.
This difference could be as different as that between the Ice Age and today's global climate conditions."

Director of Friends of the Earth, Tony Juniper, was concerned by the report and agreed that action urgently
needed to be taken worldwide to tackle the problem: "Suggestions that climate change may be a bigger
threat than previously thought are deeply disturbing. Unless the world wakes up to the threat, millions of
people across the planet may suffer the consequences."

By Jane Kettle

source ... +pollution
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Re: Global warming: water vapor & photosynthesis

Postby Wilberforce » Wed Dec 16, 2009 9:59 am

Study: Slowdown in Warming Last Year Not Permanent
Comment Posted: December 4, 2009

AP Science Writer

WASHINGTON—Cooler temperatures in North America last year do not mean global warming is
easing, U.S. government and academic scientists said Friday.

Their report comes just days before President Barack Obama heads to Copenhagen, Denmark,
to speak at a United Nations conference on climate change.

Rising temperatures over decades have prompted scientific concern, and the last decade has been
the hottest in thousands of years, according to climate records. However, the warming eased over
North America last year, and groups seeking to deny climate change seized on that in an effort to
challenge the idea of overall warming.

North America was not as warm as expected because of cooler water in the North Pacific — a
condition called La Nina — but the rest of the world continued to warm, researchers said Friday.
The overall warming trend is expected to continue worldwide.

La Nina caused cold air from the Arctic to move south into North America, temporarily overwhelming
the warming influence from climate change in the region, said Judith Perlwitz of the University of
Colorado, lead author of the report being published next week in the journal Geophysical Research Letters.

While temperature readings in North America dropped back to about the level of 1996 last year,
it would have been even colder without the underlying effects of human-induced climate
warming, said co-author Martin Hoerling of the Earth System Research Laboratory of the
government's National Oceanic and Atmospheric Administration.

"Our work shows that there can be cold periods, but that does not mean the end of global
warming," Perlwitz said.

Last year "was not an extremely cold year; it was not an extreme event," Hoerling said, but it did
"raise a considerable stir."

The scientists launched their study of conditions last year and compared them with complex
computer climate models, leading to the conclusion that it was a case of natural variability rather
than any change in global warming.

The work was funded by the NOAA Climate Program Office, and other co-authors were from
NOAA's National Weather Service and National Climatic Data Service.


On the Net:


source ... anent.html
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Re: Global warming: water vapor & photosynthesis

Postby Wilberforce » Fri Mar 01, 2013 10:54 pm

Volcanic Aerosols, Not Pollutants, Tamped Down Recent Earth Warming

Mar. 1, 2013 — A team led by the University of Colorado Boulder looking for clues about why Earth did not warm as much as scientists expected between 2000 and 2010 now thinks the culprits are hiding in plain sight -- dozens of volcanoes spewing sulfur dioxide.

The study results essentially exonerate Asia, including India and China, two countries that are estimated to have increased their industrial sulfur dioxide emissions by about 60 percent from 2000 to 2010 through coal burning, said lead study author Ryan Neely, who led the research as part of his CU-Boulder doctoral thesis. Small amounts of sulfur dioxide emissions from Earth's surface eventually rise 12 to 20 miles into the stratospheric aerosol layer of the atmosphere, where chemical reactions create sulfuric acid and water particles that reflect sunlight back to space, cooling the planet.

Neely said previous observations suggest that increases in stratospheric aerosols since 2000 have counterbalanced as much as 25 percent of the warming scientists blame on human greenhouse gas emissions. "This new study indicates it is emissions from small to moderate volcanoes that have been slowing the warming of the planet," said Neely, a researcher at the Cooperative Institute for Research in Environmental Sciences, a joint venture of CU-Boulder and the National Oceanic and Atmospheric Administration.

A paper on the subject was published online in Geophysical Research Letters, a publication of the American Geophysical Union. Co-authors include Professors Brian Toon and Jeffrey Thayer from CU-Boulder; Susan Solomon, a former NOAA scientist now at the Massachusetts Institute of Technology; Jean Paul Vernier from NASA's Langley Research Center in Hampton, Va.; Catherine Alvarez, Karen Rosenlof and John Daniel from NOAA; and Jason English, Michael Mills and Charles Bardeen from the National Center for Atmospheric Research in Boulder.

The new project was undertaken in part to resolve conflicting results of two recent studies on the origins of the sulfur dioxide in the stratosphere, including a 2009 study led by the late David Hoffman of NOAA indicating aerosol increases in the stratosphere may have come from rising emissions of sulfur dioxide from India and China. In contrast, a 2011 study led by Vernier -- who also provided essential observation data for the new GRL study -- showed moderate volcanic eruptions play a role in increasing particulates in the stratosphere, Neely said.

The new GRL study also builds on a 2011 study led by Solomon showing stratospheric aerosols offset about a quarter of the greenhouse effect warming on Earth during the past decade, said Neely, also a postdoctoral fellow in NCAR's Advanced Study Program.

The new study relies on long-term measurements of changes in the stratospheric aerosol layer's "optical depth," which is a measure of transparency, said Neely. Since 2000, the optical depth in the stratospheric aerosol layer has increased by about 4 to 7 percent, meaning it is slightly more opaque now than in previous years.

"The biggest implication here is that scientists need to pay more attention to small and moderate volcanic eruptions when trying to understand changes in Earth's climate," said Toon of CU-Boulder's Department of Atmospheric and Oceanic Sciences. "But overall these eruptions are not going to counter the greenhouse effect. Emissions of volcanic gases go up and down, helping to cool or heat the planet, while greenhouse gas emissions from human activity just continue to go up."

The key to the new results was the combined use of two sophisticated computer models, including the Whole Atmosphere Community Climate Model, or WACCM, Version 3, developed by NCAR and which is widely used around the world by scientists to study the atmosphere. The team coupled WACCM with a second model, the Community Aerosol and Radiation Model for Atmosphere, or CARMA, which allows researchers to calculate properties of specific aerosols and which has been under development by a team led by Toon for the past several decades.

Neely said the team used the Janus supercomputer on campus to conduct seven computer "runs," each simulating 10 years of atmospheric activity tied to both coal-burning activities in Asia and to emissions by volcanoes around the world. Each run took about a week of computer time using 192 processors, allowing the team to separate coal-burning pollution in Asia from aerosol contributions from moderate, global volcanic eruptions. The project would have taken a single computer processor roughly 25 years to complete, said Neely.

The scientists said 10-year climate data sets like the one gathered for the new study are not long enough to determine climate change trends. "This paper addresses a question of immediate relevance to our understanding of the human impact on climate," said Neely. "It should interest those examining the sources of decadal climate variability, the global impact of local pollution and the role of volcanoes."

While small and moderate volcanoes mask some of the human-caused warming of the planet, larger volcanoes can have a much bigger effect, said Toon. When Mount Pinatubo in the Philippines erupted in 1991, it emitted millions of tons of sulfur dioxide into the atmosphere that cooled Earth slightly for the next several years.

The research for the new study was funded in part through a NOAA/ ESRL-CIRES Graduate Fellowship to Neely. The National Science Foundation and NASA also provided funding for the research project. The Janus supercomputer is supported by NSF and CU-Boulder and is a joint effort of CU-Boulder, CU Denver and NCAR.

source ... 123048.htm
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Re: Global warming: water vapor & photosynthesis

Postby Wilberforce » Wed Oct 16, 2013 8:02 pm

Without Plants, Earth Would Cook Under Billions of Tons of Additional Carbon

Oct. 16, 2013 — Enhanced growth of Earth's leafy greens during the 20th century has significantly slowed the planet's transition to being red-hot, according to the first study to specify the extent to which plants have prevented climate change since pre-industrial times. Researchers based at Princeton University found that land ecosystems have kept the planet cooler by absorbing billions of tons of carbon, especially during the past 60 years.

The planet's land-based carbon "sink" -- or carbon-storage capacity -- has kept 186 billion to 192 billion tons of carbon out of the atmosphere since the mid-20th century, the researchers report in the Proceedings of the National Academy of Sciences. From the 1860s to the 1950s, land use by humans was a substantial source of the carbon entering the atmosphere because of deforestation and logging. After the 1950s, however, humans began to use land differently, such as by restoring forests and adopting agriculture that, while larger scale, is higher yield. At the same time, industries and automobiles continued to steadily emit carbon dioxide that contributed to a botanical boom. Although a greenhouse gas and pollutant, carbon dioxide also is a plant nutrient.

Had Earth's terrestrial ecosystems remained a carbon source they would have instead generated 65 billion to 82 billion tons of carbon in addition to the carbon that it would not have absorbed, the researchers found. That means a total of 251 billion to 274 billion additional tons of carbon would currently be in the atmosphere. That much carbon would have pushed the atmosphere's current carbon dioxide concentration to 485 parts-per-million (ppm), the researchers report -- well past the scientifically accepted threshold of 450 (ppm) at which Earth's climate could drastically and irreversibly change. The current concentration is 400 ppm.

Those "carbon savings" amount to a current average global temperature that is cooler by one-third of a degree Celsius (or a half-degree Fahrenheit), which would have been a sizeable jump, the researchers report. The planet has warmed by only 0.74 degrees Celsius (1.3 degrees Fahrenheit) since the early 1900s, and the point at which scientists calculate the global temperature would be dangerously high is a mere 2 degrees Celsius (3.6 degrees Fahrenheit) more than pre-industrial levels.

The study is the most comprehensive look at the historical role of terrestrial ecosystems in controlling atmospheric carbon, explained first author Elena Shevliakova, a senior climate modeler in Princeton's Department of Ecology and Evolutionary Biology. Previous research has focused on how plants might offset carbon in the future, but overlooked the importance of increased vegetation uptake in the past, she said.

"People always say we know carbon sinks are important for the climate," Shevliakova said. "We actually for the first time have a number and we can say what that sink means for us now in terms of carbon savings."

"Changes in carbon dioxide emissions from land-use activities need to be carefully considered. Until recently, most studies would just take fossil-fuel emissions and land-use emissions from simple models, plug them in and not consider how managed lands such as recovering forests take up carbon," she said. "It's not just climate -- it's people. On land, people are major drivers of changes in land carbon. They're not just taking carbon out of the land, they're actually changing the land's capacity to take up carbon."

Scott Saleska, an associate professor of ecology and evolutionary biology at the University of Arizona who studies interactions between vegetation and climate, said that the researchers provide a potentially compelling argument for continued forest restoration and preservation by specifying the "climate impact" of vegetation. Saleska is familiar with the research but had no role in it.

"I think this does have implications for policies that try to value the carbon saved when you restore or preserve a forest," Saleska said. "This modeling approach could be used to state the complete 'climate impact' of preserving large forested areas, whereas most current approaches just account for the 'carbon impact.' Work like this could help forest-preservation programs more accurately consider the climate impacts of policy measures related to forest preservation."

Although the researchers saw a strong historical influence of carbon fertilization in carbon absorption, that exchange does have its limits, Saleska said. If carbon dioxide levels in the atmosphere continue rising, more vegetation would be needed to maintain the size of the carbon sink Shevliakova and her colleagues reported.

"There is surely some limit to how long increasing carbon dioxide can continue to promote plant growth that absorbs carbon dioxide," Saleska said. "Carbon dioxide is food for plants, and putting more food out there stimulates them to 'eat' more. However, just like humans, eventually they get full and putting more food out doesn't stimulate more eating."

The researchers used the comprehensive Earth System Model (ESM2G), a climate-carbon cycle model developed by the National Oceanic and Atmospheric Administration's Geophysical Fluid and Dynamics Laboratory (GFDL), to simulate how carbon and climate interacted with vegetation, soil and marine ecosystems between 1861 and 2005. The GFDL model predicted changes in climate and in atmospheric concentrations of carbon dioxide based on fossil fuel emissions of carbon. Uniquely, the model also predicted emissions from land-use changes -- such as deforestation, wood harvesting and forest regrowth -- that occurred from 1700 to 2005.

"Unless you really understand what the land-use processes are it's very hard to say what the system will do as a whole," said Shevliakova, who worked with corresponding author Stephen Pacala, Princeton's Frederick D. Petrie Professor in Ecology and Evolutionary Biology; Sergey Malyshev, a professional specialist in ecology and evolutionary biology at Princeton; GFDL physical scientists Ronald Stouffer and John Krasting; and George Hurtt, a professor of geographical sciences at the University of Maryland.

"After the 1940s and 1950s, if you look at the land-use change trajectory, it's been slowed down in the expansion of agriculture and pastures," Shevliakova said. "When you go from extensive agriculture to intensive agriculture you industrialize the production of food, so people now use fertilizers instead of chopping down more forests. A decrease in global deforestation combined with enhanced vegetation growth caused by the rapid increase in carbon dioxide changed the land from a carbon source into a carbon sink."

For scientists, the model is a significant contribution to understanding the terrestrial carbon sink, Saleska said. Scientists only uncovered the land-based carbon sink about two decades ago, while models that can combine the effects of climate change and vegetation growth have only been around for a little more than 10 years, Saleska said. There is work to be done to refine climate models and the Princeton-led research opens up new possibilities while also lending confidence to future climate projections, Saleska said.

"A unique value of this study is that it simulates the past, for which, unlike the future, we have observations," Saleska said. "Past observations about climate and carbon dioxide provide a test about how good the model simulation was. If it's right about the past, we should have more confidence in its ability to predict the future."

source ... 145646.htm
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