Please or Register to create posts and topics.

how the water vapor greenhouse effect works

No time to my view on this on the air, no one want to listen to the climate change guy... so I’ll put it here in case someone wants to have a discussion.

Water vapor is the most powerful greenhouse gas. Some will imply that this means that the impact from CO2  isn't a major problem. If CO2 isn't as powerful as water vapor, which there's already a lot of, adding a little more CO2 couldn't be that bad, right? What this argument misses is the fact that water vapor creates what scientists call a 'positive feedback loop' in the atmosphere — making any temperature changes larger than they would be otherwise.

How does this work? The amount of water vapor in the atmosphere exists in direct relation to the temperature. If you increase the temperature, more water evaporates and becomes vapor, and vice versa. So when something else causes a temperature increase (such as extra CO2 from fossil fuels), more water evaporates. Then, since water vapor is a greenhouse gas, this additional water vapor causes the temperature to go up even further—a positive feedback.

How much does water vapor amplify CO2 warming? Studies show that water vapor feedback roughly doubles the amount of warming caused by CO2. So if there is a 1°C change caused by CO2, the water vapor will cause the temperature to go up another 1°C. When other feedback loops are included, the total warming from a potential 1°C change caused by CO2 is, in reality, as much as a 3°C.

The other factor to consider is that water is evaporated from the land and sea and falls as rain or snow all the time. Thus the amount held in the atmosphere as water vapour varies greatly in just hours and days as result of the prevailing weather in any location. So even though water vapour is the greatest greenhouse gas, it is relatively short-lived. On the other hand, CO2 is removed from the air by natural geological-scale processes and these take a long time to work. Consequently CO2 stays in our atmosphere for years and even centuries. A small additional amount has a much more long-term effect.

So it is right in saying that water vapor is the dominant greenhouse gas, but the water vapor feedback loop actually makes temperature changes caused by CO2 even bigger.


The following will give you a limited but general idea of why co2 is not a significant factor in any global warming scenario fact there is no evidence that the earths atomosphere is actually warming at this time....there is much more to be said about the subject including the ice records over hundreds of thousand of years showing co2 increases Following temperature increases not leading them. Below is the general idea that shows the co2 fallacy that have been voiced by countless numbers of scientists in slightly different ways.


Carbon Dioxide and Global Warming
Where We Stand on the Issue


C. D. Idso and K. E. Idso
Center for the Study of Carbon Dioxide and Global Change

There is little doubt the air's CO2 concentration has risen significantly since the inception of the Industrial Revolution; and there are few who do not attribute the CO2 increase to the increase in humanity's use of fossil fuels.  There is also little doubt the earth has warmed slightly over the same period; but there is no compelling reason to believe that the rise in temperature was caused by the rise in CO2.  Furthermore, it is highly unlikely that future increases in the air's CO2 content will produce any global warming; for there are numerous problems with the popular hypothesis that links the two phenomena.

A weak short-term correlation between CO2 and temperature proves nothing about causation.  Proponents of the notion that increases in the air's CO2 content lead to global warming point to the past century's weak correlation between atmospheric CO2 concentration and global air temperature as proof of their contention.  However, they typically gloss over the fact that correlationdoes not imply causation, and that a hundred years is not enough time to establish the validity of such a relationship when it comes to earth's temperature history.

The observation that two things have risen together for a period of time says nothing about one trend being the cause of the other.  To establish a causal relationship it must be demonstrated that the presumed cause precedes the presumed effect.  Furthermore, this relationship should be demonstrable over several cycles of increases and decreases in both parameters.  And even when these criteria aremet, as in the case of solar/climate relationships, many people are unwilling to acknowledge that variations in the presumed cause truly produced the observed analogous variations in the presumed effect.

In thus considering the seven greatest temperature transitions of the past half-million years - three glacial terminations and four glacial inceptions - we note that increases and decreases in atmospheric CO2 concentration not only did not precede the changes in air temperature, they followed them, and by hundreds to thousands of years!  There were also long periods of time when atmospheric CO2 remained unchanged, while air temperature dropped, as well as times when the air's CO2 content dropped, while air temperature remained unchanged or actually rose.  Hence, the climate history of the past half-million years provides absolutely no evidence to suggest that the ongoing rise in the air's CO2concentration will lead to significant global warming.

Strong negative climatic feedbacks prohibit catastrophic warming.  Strong negative feedbacks play major roles in earth's climate system.  If they did not, no life would exist on the planet, for some perturbation would long ago have sent the world careening into a state of cosmic cold or horrendous heat; and we know from the fossil record that neither of these extremes has ever occurred, even over billions of years, and in spite of a large increase in the luminosity of the sun throughout geologic time.

Consider, in this regard, the water vapor that would be added to the atmosphere by enhanced evaporation in a warmer world.  The extra moisture would likely lead to the production of more and higher-water-content clouds, both of which consequences would tend to cool the planet by reflecting more solar radiation back to space.

A warmer world would also mean a warmer ocean, which would likely lead to an increase in the productivity of marine algae or phytoplankton.  This phenomenon, in turn, would enhance the biotic production of certain sulfur-based substances that diffuse into the air, where they are oxidized and converted into particles that function as cloud condensation nuclei.  The resulting increase in the number of cloud-forming particles would thus produce more and smaller cloud droplets, which are more reflective of incoming solar radiation; and this phenomenon would also tend to cool the planet.

All of these warming-induced cloud-related cooling effects are very powerful.  It has been shown, for example, that the warming predicted to result from a doubling of the air's CO2 content may be totally countered by: (1) a mere 1% increase in the reflectivity of the planet, or (2) a 10% increase in the amount of the world's low-level clouds, or (3) a 15 to 20% reduction in the mean droplet radius of earth's boundary-layer clouds, or (4) a 20 to 25% increase in cloud liquid water content.  In addition, it has been demonstrated that the warming-induced production of high-level clouds over the equatorial oceans almost totally nullifies that region's powerful water vapor greenhouse effect, which supplies much of the temperature increase in the CO2-induced global warming scenario.

Most of these important negative feedbacks are not adequately represented in state-of-the-art climate models.  What is more, many related (and totally ignored!) phenomena are set in motion when the land surfaces of the globe warm.  In response to the increase in temperature between 25°N latitude and the equator, for example, the soil-to-air flux of various sulfur gases rises by a factor of 25, as a consequence of warmth-induced increases in soil microbial activity; and this phenomenon can lead to the production of more cloud condensation nuclei just as biological processes over the sea do.  Clearly, therefore, any number of combinations of these several negative feedbacks could easily thwart the impetus for warming provided by future increases in the air's CO2 content.

Growth-enhancing effects of CO2 create an impetus for cooling.  Carbon dioxide is a powerful aerial fertilizer, directly enhancing the growth of almost all terrestrial plants and many aquatic plants as its atmospheric concentration rises.  And just as increased algal productivity at sea increases the emission of sulfur gases to the atmosphere, ultimately leading to more and brighter clouds over the world's oceans, so too do CO2-induced increases in terrestrial plant productivity lead to enhanced emissions of various sulfur gases over land, where they likewise ultimately cool the planet.  In addition, many non-sulfur-based biogenic materials of the terrestrial environment play major roles as water- and ice-nucleating aerosols; and the airborne presence of these materials should also be enhanced by rising levels of atmospheric CO2.  Hence, it is possible that incorporation of this multifaceted CO2-induced cooling effect into the suite of equations that comprise the current generation of global climate models might actually tip the climatic scales in favor of global cooling in the face of continued growth of anthropogenic CO2 emissions.

There is no evidence for warming-induced increases in extreme weather.  Proponents of the CO2-induced global warming hypothesis often predict that extreme weather events such as droughts, floods, and hurricanes will become more numerous and/or extreme in a warmer world; however, there is no evidence to support this claim.  In fact, many studies have revealed that the numbers and intensities of extreme weather events have remained relatively constant over the last century of modest global warming or have actually declined.  Costs of damages from these phenomena, however, have risen dramatically; but this phenomenon has been demonstrated to be the result of evolving societal, demographic and economic factors.

Elevated levels of atmospheric CO2 are a boon to the biosphere.  In lieu of global warming, a little of which would in all probability be good for the planet, where do the above considerations leave us?  Simply with the biospheric benefits that come from the aerial fertilization effect of atmospheric CO2enrichment: enhanced plant growth, increased plant water use efficiency, greater food production for both people and animals, plus a host of other biological benefits too numerous to describe in this short statement.

And these benefits are not mere predictions.  They are real.  Already, in fact, they are evident in long-term tree-ring records, which reveal a history of increasing forest growth rates that have closely paralleled the progression of the Industrial Revolution.  They can also be seen in the slow but inexorable spreading of woody plants into areas where only grasses grew before.  In fact, the atmosphere itself bears witness to the increasing prowess of the entire biosphere in the yearly expanding amplitude of the its seasonal CO2 cycle.  This oscillatory "breath of the biosphere" - its inhalation of CO2, produced by spring and summer terrestrial plant growth, and its exhalation of CO2, produced by fall and winter biomass decomposition - has been documented to be growing greater and greater each year in response to the ever-increasing growth stimulation provided by the ongoing rise in the air's CO2content.

Atmospheric CO2 enrichment brings growth and prosperity to man and nature alike.  This, then, is what we truly believe will be the result of the ongoing rise in the air's CO2 content: a reinvigorated biosphere characteristic of those prior periods of earth's history when the air's CO2concentration was much higher than it is today, coupled with a climate not much different from that of the present.  Are we right?  Only time will tell.  But one thing is certain now: there is much more real-world evidence for the encouraging scenario we paint here than for the doom-and-gloom predictions of apocalypse that are preached by those who blindly follow the manifestly less-than-adequate prognostications of imperfect climate models.

Our policy prescription relative to anthropogenic CO2 emissions is thus to leave well enough alone and let nature and humanity take their inextricably intertwined course.  All indications are that both will be well served by the ongoing rise in atmospheric CO2.

enjoy  !

N6CMB - Chris has reacted to this post.
N6CMB - Chris

That’s an interesting take.

I’ll use some views from NASA. That said, let me know up front if we need to consider NASA data compromised? Significant portions of the following is cut directly from NASA documents.

Earth's climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 11,700 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives.

The current warming trend is of particular significance because most of it is extremely likely (greater than 95% probability) to be the result of human activity since the mid-20th century and proceeding at a rate that is unprecedented over decades to millennia.

Earth-orbiting satellites and other technological advances have enabled scientists to see the big picture, collecting many different types of information about our planet and its climate on a global scale. This body of data, collected over many years, reveals the signals of a changing climate.

The heat-trapping nature of carbon dioxide and other gases was demonstrated in the mid-19th century. Their ability to affect the transfer of infrared energy through the atmosphere is the scientific basis of many instruments flown by NASA. There is no question that increased levels of greenhouse gases must cause Earth to warm in response.

Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that Earth’s climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks. This ancient, or paleoclimate, evidence reveals that current warming is occurring roughly ten times faster than the average rate of ice-age-recovery warming. Carbon dioxide from human activity is increasing more than 250 times faster than it did from natural sources after the last Ice Age.

Evidence of rapid climate change...

Global Temperature Rise

The planet's average surface temperature has risen about 2.12 degrees Fahrenheit (1.18 degrees Celsius) since the late 19th century, a change driven largely by increased carbon dioxide emissions into the atmosphere and other human activities. Most of the warming occurred in the past 40 years, with the seven most recent years being the warmest. The years 2016 and 2020 are tied for the warmest year on record

Warming Ocean

The ocean has absorbed much of this increased heat, with the top 100 meters (about 328 feet) of ocean showing warming of more than 0.6 degrees Fahrenheit (0.33 degrees Celsius) since 1969. Earth stores 90% of the extra energy in the ocean.

Shrinking Ice Sheets

The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost an average of 279 billion tons of ice per year between 1993 and 2019, while Antarctica lost about 148 billion tons of ice per year.

Glaciers are retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska, and Africa.


    Decreased Snow Cover

    Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and the snow is melting earlier.

    Sea Level Rise

    Global sea level rose about 8 inches (20 centimeters) in the last century. The rate in the last two decades, however, is nearly double that of the last century and accelerating slightly every year.

    Declining Arctic Sea Ice

    Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades.

    Extreme Events

    The number of record high temperature events in the United States has been increasing, while the number of record low temperature events has been decreasing, since 1950. The U.S. has also witnessed increasing numbers of intense rainfall events.

    Ocean Acidification

    Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30%. This increase is the result of humans emitting more carbon dioxide into the atmosphere and hence more being absorbed into the ocean. The ocean has absorbed between 20% and 30% of total anthropogenic carbon dioxide emissions in recent decades (7.2 to 10.8 billion metric tons per year).

I list some of these indications because I’d like to hear what is causing them if it’s not rapid climate change of some kind?  

Now, it’s not surprising that we can find totally conflicting views. I mean, we do have flat earthers out there. I feel confident that the science confirms that the earth is not flat, but some will stick to their theory and won’t hear differently:

No science I quote will likely change their mind, but I’m always up to listen to what they have to say and respect the opinion.




I found this chart very intersting... notice the large impact of things growing! Also intersting to see such a focus on changing transport but its not the largest contributor.