Archive for the ‘water vapor’ Category

Paper by William Gray and Barry Schwartz: water vapor feedback is negative

05/06/2010

1.  INTRODUCTION

Global warming scenarios from CO2 increases are envisioned to bring about rainfall enhancement and resulting upper tropospheric water vapor rise. This initial water vapor enhancement has been hypothesized and programmed in climate models to develop yet additional rainfall and water vapor increase. This causes an extra blockage of IR energy to space (a positive feedback warming mechanism). This additional rainfall and IR blockage is modeled to be approximately twice as large as the additional rainfall needed to balance the increased CO2 by itself. The reality of this additional warming and extra IR blockage has been questioned by many of us. This study analyzes a wide variety of infrared (IR) radiation differences which are associated with rainfall differences on different space and time scales. Our goal is to determine the extent to which the positive rainfall feedbacks as are included in the climate model simulations are realistic.  …

This analysis shows they are not realistic.  …

2.  FINDINGS

a)
The albedo increase occurring over the top of strong precipitation and cloudy regions rises at a greater rate than does the rate of decrease of IR within these rainy and cloudy areas. Rainy and cloudy areas are local places of enhanced net radiation to space (Tables 1 and 2 and in idealized form in Figure 3). We have many other areas of rain differences which give similar results. In almost all rain and cloud areas we find that albedo energy flux rises at a greater rate than IR energy flux is reduced.  …

3.  IMPLICATIONS OF THESE OBSERVATIONS

The above measurements are at odds with the Global Climate Model (GCM) simulations of precipitation increase associated with rising CO2 amounts. Models show large tropical upper tropospheric temperature and water vapor increases to be associated with increased rates of precipitation (due to CO2 increases) that are similar to increased rates of precipitation that this study measures. We do not observe such upper tropospheric temperature and moisture increases for rainfall enhancements as do the modelers.  …

The climate modelers have assumed that as CO2 increases it will cause a progressive blockage of IR energy to space and, in addition, a further blockage of IR energy to space will occur from the original increase in upper-level water vapor. Increased IR blockage brings about a gradual increase in global temperature.  …

Our observations do not agree with these GCM scenarios. Our observations indicate that tropical RH [relative humidity] and moisture (q) rather than rising with enhanced precipitation do the opposite and actually go down as precipitation rates increase.  …

We find that there is not a positive water vapor feedback as the modelers have assumed. In fact we see the opposite. As rainfall increases upper-level water vapor contents are weakly reduced.  …

8. CONCLUSION

We find that as rainfall increases that there is not a reduction of global net radiation to space as most of the climate models have assumed. There is a weak enhancement of radiation to space with increased rainfall. We find no positive water vapor feedback.  …

A reduction of upper level RH of about 4 percent to go along with a lowering of the emission level of 7 mb would allow a doubling of CO2 to proceed with no warming (Figure 20). We estimate the extra precipitation from a doubling of CO2 to cause a negative (not positive) temperature feedback of about minus 0.6oC.”  “THE ASSOCIATION OF OUTGOING RADIATION WITH VARIATIONS OF PRECIPITATION – IMPLICATIONS FOR GLOBAL WARMING”  h/t Climate Realists

Paper: water vapor feedback NEGATIVE

02/14/2010

Abstract: The National Centers for Environmental Prediction (NCEP) reanalysis data on tropospheric humidity are examined for the period 1973 to 2007. It is accepted that radiosonde-derived humidity data must be treated with great caution, particularly at altitudes above the 500 hPa pressure level. With that caveat, the face-value 35-year trend in zonal-average annual-average specific humidity q is significantly negative at all altitudes above 850 hPa (roughly the top of the convective boundary layer) in the tropics and southern midlatitudes and at altitudes above 600 hPa in the northern midlatitudes. It is significantly positive below 850 hPa in all three zones, as might be expected in a mixed layer with rising temperatures over a moist surface. The results are qualitatively consistent with trends in NCEP atmospheric temperatures (which must also be treated with great caution) that show an increase in the stability of the convective boundary layer as the global temperature has risen over the period. The upper-level negative trends in q are inconsistent with climate-model calculations and are largely (but not completely) inconsistent with satellite data. Water vapor feedback in climate models is positive mainly because of their roughly constant relative humidity (i.e., increasing q) in the mid-to-upper troposphere as the planet warms. Negative trends in q as found in the NCEP data would imply that long-term water vapor feedback is negative—that it would reduce rather than amplify the response of the climate system to external forcing such as that from increasing atmospheric CO2. In this context, it is important to establish what (if any) aspects of the observed trends survive detailed examination of the impact of past changes of radiosonde instrumentation and protocol within the various international networks.”  “Trends in middle- and upper-level tropospheric humidity from NCEP reanalysis data

Miskolczi's theory is testable

12/21/2009

As Miklos Zigoni notes (previous post), “During the 61-year period, in correspondence with the rise in CO2 concentration, the global average absolute humidity diminished about 1 per cent. This decrease in absolute humidity has exactly countered all of the warming effect that our CO2 emissions have had since 1948.” This is empirical evidence that Miskolczi’s theory is correct.

He further notes, “Similar computer simulations show that a hypothetical doubling of the carbon dioxide concentration in the air would cause a 3% decrease in the absolute humidity, keeping the total effective atmospheric greenhouse gas content constant, so that the greenhouse effect would merely continue to fluctuate around its equilibrium value.”

This prediction offers a simple further test of Miskolczi’s theory: if absolute humidity continues to decrease as atmospheric CO2 increases, keeping the greenhouse effect constant, that would be strong evidence for the correctness of the theory.

Miklos Zagoni: short summary of Miskolczi's saturated greenhouse theory

12/21/2009

“Here is the picture. The Earth’s atmosphere maintains a constant effective greenhouse-gas content and a constant, maximized, “saturated” greenhouse effect that cannot be increased further by CO2 emissions (or by any other emissions, for that matter). After calculating on the basis of the entire available annual global mean vertical profile of the NOAA/NCAR atmospheric reanalysis database, Miskolczi has found that the average greenhouse effect of the past 61 years (from 1948, the beginning of the archive, to 2008) is –

constant, not increasing;
equal to the unperturbed theoretical equilibrium value; and
equal (within 0.1 C°) to the global average value, drawn from the independent TIGR radiosonde archive.

During the 61-year period, in correspondence with the rise in CO2 concentration, the global average absolute humidity diminished about 1 per cent. This decrease in absolute humidity has exactly countered all of the warming effect that our CO2 emissions have had since 1948.

Similar computer simulations show that a hypothetical doubling of the carbon dioxide concentration in the air would cause a 3% decrease in the absolute humidity, keeping the total effective atmospheric greenhouse gas content constant, so that the greenhouse effect would merely continue to fluctuate around its equilibrium value. Therefore, a doubling of CO2 concentration would cause no net “global warming” at all.

Surface warming is possible only if the available energy increases. This may happen through changes in the activity of the Sun, or through variations of our planet’s orbital parameters, or through long-term fluctuations in the exchange of heat between the ocean and the atmosphere.

There are also some man-made sources. Air-pollution by aerosols (soot, black carbon, dust, smog etc.), and large-scale surface modifications according to urbanization and land-use change may—and probably do—alter the amount of absorbed and reflected shortwave energy, and can hence lead to change in the long-term energy balance.

These terms are all involved in the “available energy”. They can all modify the “effective temperature” of the Earth – i.e. the temperature of a planet with the Earth’s albedo (or reflectivity) at the Earth’s current distance from the Sun, without the presence of greenhouse gases in the air. The effective temperature is now 255 Kelvin, or –18 °C.

Miskolczi asserts that the surplus temperature from the greenhouse gases (about 33 C°, bringing global mean surface temperature up from –18 °C to 15 °C) is constant, maximized, and cannot be increased by our CO2 emissions, because it is the greenhouse effect’s theoretical equilibrium value.

It is possible that in the 21st century the effective temperature may change a little, just as it has changed in previous centuries. But the additional (greenhouse) temperature will be 33 C°, within a variation of about 0.1 C° of recent decades. Physically, it cannot increase (as the UN IPCC has predicted it will increase) to 35-38 C° to produce a 2-5 C° warming.

The conclusion is that, since the Earth’s temperature does not depend on our CO2 emissions in any way, trying to limit our emissions is bound to be entirely ineffective in protecting the climate from warming.” “CO2 CANNOT CAUSE ANY MORE “GLOBAL WARMING”

Miskolczi’s theory is testable

12/21/2009

As Miklos Zigoni notes (previous post), “During the 61-year period, in correspondence with the rise in CO2 concentration, the global average absolute humidity diminished about 1 per cent. This decrease in absolute humidity has exactly countered all of the warming effect that our CO2 emissions have had since 1948.” This is empirical evidence that Miskolczi’s theory is correct.

He further notes, “Similar computer simulations show that a hypothetical doubling of the carbon dioxide concentration in the air would cause a 3% decrease in the absolute humidity, keeping the total effective atmospheric greenhouse gas content constant, so that the greenhouse effect would merely continue to fluctuate around its equilibrium value.”

This prediction offers a simple further test of Miskolczi’s theory: if absolute humidity continues to decrease as atmospheric CO2 increases, keeping the greenhouse effect constant, that would be strong evidence for the correctness of the theory.

Miklos Zagoni: short summary of Miskolczi’s saturated greenhouse theory

12/21/2009

“Here is the picture. The Earth’s atmosphere maintains a constant effective greenhouse-gas content and a constant, maximized, “saturated” greenhouse effect that cannot be increased further by CO2 emissions (or by any other emissions, for that matter). After calculating on the basis of the entire available annual global mean vertical profile of the NOAA/NCAR atmospheric reanalysis database, Miskolczi has found that the average greenhouse effect of the past 61 years (from 1948, the beginning of the archive, to 2008) is –

constant, not increasing;
equal to the unperturbed theoretical equilibrium value; and
equal (within 0.1 C°) to the global average value, drawn from the independent TIGR radiosonde archive.

During the 61-year period, in correspondence with the rise in CO2 concentration, the global average absolute humidity diminished about 1 per cent. This decrease in absolute humidity has exactly countered all of the warming effect that our CO2 emissions have had since 1948.

Similar computer simulations show that a hypothetical doubling of the carbon dioxide concentration in the air would cause a 3% decrease in the absolute humidity, keeping the total effective atmospheric greenhouse gas content constant, so that the greenhouse effect would merely continue to fluctuate around its equilibrium value. Therefore, a doubling of CO2 concentration would cause no net “global warming” at all.

Surface warming is possible only if the available energy increases. This may happen through changes in the activity of the Sun, or through variations of our planet’s orbital parameters, or through long-term fluctuations in the exchange of heat between the ocean and the atmosphere.

There are also some man-made sources. Air-pollution by aerosols (soot, black carbon, dust, smog etc.), and large-scale surface modifications according to urbanization and land-use change may—and probably do—alter the amount of absorbed and reflected shortwave energy, and can hence lead to change in the long-term energy balance.

These terms are all involved in the “available energy”. They can all modify the “effective temperature” of the Earth – i.e. the temperature of a planet with the Earth’s albedo (or reflectivity) at the Earth’s current distance from the Sun, without the presence of greenhouse gases in the air. The effective temperature is now 255 Kelvin, or –18 °C.

Miskolczi asserts that the surplus temperature from the greenhouse gases (about 33 C°, bringing global mean surface temperature up from –18 °C to 15 °C) is constant, maximized, and cannot be increased by our CO2 emissions, because it is the greenhouse effect’s theoretical equilibrium value.

It is possible that in the 21st century the effective temperature may change a little, just as it has changed in previous centuries. But the additional (greenhouse) temperature will be 33 C°, within a variation of about 0.1 C° of recent decades. Physically, it cannot increase (as the UN IPCC has predicted it will increase) to 35-38 C° to produce a 2-5 C° warming.

The conclusion is that, since the Earth’s temperature does not depend on our CO2 emissions in any way, trying to limit our emissions is bound to be entirely ineffective in protecting the climate from warming.” “CO2 CANNOT CAUSE ANY MORE “GLOBAL WARMING”

William Gray on NASA's "breakthrough" announcement

12/18/2009

“”[NASA’s] AIRS [satellite] temperature and water vapor observations have corroborated climate model predictions that the warming of our climate produced as carbon dioxide levels rise will be greatly exacerbated — in fact, more than doubled — by water vapor,” said Andrew Dessler, a climate scientist at Texas A&M University, College Station, Texas.” “NASA Outlines Recent Breakthroughs in Greenhouse Gas Research

“We find that on a small space scale where rainfall is occurring OLR [outgoing longwave radiation] is greatly suppressed. But on the larger regional to global scales, OLR rises with increasing precipitation. This is due to increased return flow subsidence in the surrounding cloud free and partly cloudy areas. Globally, we are finding that net OLR increases with net increased amounts of global precipitation. This is the opposite of what most GCMs [general circulation models] have programmed into their models and, if I’m interpreting the new NASA announcement correctly, opposite to what they are currently reporting to the media.” “Is “several degrees” of warming “virtually certain” as NASA claims?

William Gray on NASA’s "breakthrough" announcement

12/18/2009

“”[NASA’s] AIRS [satellite] temperature and water vapor observations have corroborated climate model predictions that the warming of our climate produced as carbon dioxide levels rise will be greatly exacerbated — in fact, more than doubled — by water vapor,” said Andrew Dessler, a climate scientist at Texas A&M University, College Station, Texas.” “NASA Outlines Recent Breakthroughs in Greenhouse Gas Research

“We find that on a small space scale where rainfall is occurring OLR [outgoing longwave radiation] is greatly suppressed. But on the larger regional to global scales, OLR rises with increasing precipitation. This is due to increased return flow subsidence in the surrounding cloud free and partly cloudy areas. Globally, we are finding that net OLR increases with net increased amounts of global precipitation. This is the opposite of what most GCMs [general circulation models] have programmed into their models and, if I’m interpreting the new NASA announcement correctly, opposite to what they are currently reporting to the media.” “Is “several degrees” of warming “virtually certain” as NASA claims?

Climate models invert observed negative feedback

10/10/2009

Reference
Paltridge, G., Arking, A. and Pook, M. 2009. Trends in middle- and upper-level tropospheric humidity from NCEP reanalysis data. Theoretical and Applied Climatology: 10.1007/s00704-009-0117-x.

Background
The authors write that “water vapor feedback in climate models is large and positive,” and that “the various model representations and parameterizations of convection, turbulent transfer, and deposition of latent heat generally maintain a more-or-less constant relative humidity (i.e., an increasing specific humidity q) at all levels in the troposphere as the planet warms,” and they say that this “increasing q amplifies the response of surface temperature to increasing CO2 by a factor or 2 or more.” Consequently, knowledge of how q responds to atmospheric warming is of paramount importance to the task of correctly predicting how air temperatures respond to increasing CO2 concentrations.

What was done
Paltridge et al. explored this important subject by determining trends in relative and specific humidity at various levels in the atmosphere based on reanalysis data of the National Centers for Environmental Prediction (NCEP) for the period 1973-2007.

What was learned
The three researchers report that “the face-value 35-year trend in zonal-average annual-average specific humidity q is significantly negative at all altitudes above 850 hPa (roughly the top of the convective boundary layer) in the tropics and southern midlatitudes and at altitudes above 600 hPa in the northern midlatitudes.”

What it means
Paltridge et al. conclude that “negative trends in q as found in the NCEP data would imply that long-term water vapor feedback is negative – that it would reduce rather than amplify the response of the climate system to external forcing such as that from increasing atmospheric CO2.” The ultimate outcome of this dilemma must therefore await a thorough study of the reliability of the pertinent NCEP data, in order to establish, in the words of the three scientists, “what (if any) aspects of the observed [humidity] trends survive detailed examination of the impact of past changes of radiosonde instrumentation and protocol within the various international networks” that collected the globe-spanning data that comprise the NCEP reanalysis archive. And until such an examination is completed, it would foolish in the extreme to forge ahead with any type of “cap and trade” legislation, such as is currently under consideration in the U.S. Senate, or with any international treaties designed to limit anthropogenic CO2 emissions, because the findings of Paltridge et al. suggest that the future warming predicted by today’s climate models may well be far greater than what could actually occur in the real world.” “Tropospheric Humidity and CO2-Induced Global Warming

Climate models invert observed negative feedback

10/10/2009

Reference
Paltridge, G., Arking, A. and Pook, M. 2009. Trends in middle- and upper-level tropospheric humidity from NCEP reanalysis data. Theoretical and Applied Climatology: 10.1007/s00704-009-0117-x.

Background
The authors write that “water vapor feedback in climate models is large and positive,” and that “the various model representations and parameterizations of convection, turbulent transfer, and deposition of latent heat generally maintain a more-or-less constant relative humidity (i.e., an increasing specific humidity q) at all levels in the troposphere as the planet warms,” and they say that this “increasing q amplifies the response of surface temperature to increasing CO2 by a factor or 2 or more.” Consequently, knowledge of how q responds to atmospheric warming is of paramount importance to the task of correctly predicting how air temperatures respond to increasing CO2 concentrations.

What was done
Paltridge et al. explored this important subject by determining trends in relative and specific humidity at various levels in the atmosphere based on reanalysis data of the National Centers for Environmental Prediction (NCEP) for the period 1973-2007.

What was learned
The three researchers report that “the face-value 35-year trend in zonal-average annual-average specific humidity q is significantly negative at all altitudes above 850 hPa (roughly the top of the convective boundary layer) in the tropics and southern midlatitudes and at altitudes above 600 hPa in the northern midlatitudes.”

What it means
Paltridge et al. conclude that “negative trends in q as found in the NCEP data would imply that long-term water vapor feedback is negative – that it would reduce rather than amplify the response of the climate system to external forcing such as that from increasing atmospheric CO2.” The ultimate outcome of this dilemma must therefore await a thorough study of the reliability of the pertinent NCEP data, in order to establish, in the words of the three scientists, “what (if any) aspects of the observed [humidity] trends survive detailed examination of the impact of past changes of radiosonde instrumentation and protocol within the various international networks” that collected the globe-spanning data that comprise the NCEP reanalysis archive. And until such an examination is completed, it would foolish in the extreme to forge ahead with any type of “cap and trade” legislation, such as is currently under consideration in the U.S. Senate, or with any international treaties designed to limit anthropogenic CO2 emissions, because the findings of Paltridge et al. suggest that the future warming predicted by today’s climate models may well be far greater than what could actually occur in the real world.” “Tropospheric Humidity and CO2-Induced Global Warming