This is a long weblog. The bottom line conclusions are written here to motivate reading the entire weblog.
CONCLUSIONS:
1. The primary focus on carbon dioxide inappropriately deemphasizes the first order importance of the other climate system heat system forcings (both cooling and warming forcings), as well as does not address the spatially complex, and incompletely understood, actual pattern of global climate system heat changes.
2. Attempts to significantly influence regional and local-scale climate based on controlling CO2 emissions alone is an inadequate policy for this purpose.
A starting point for the assessment of the relative fraction of global warming that is attributable to the radiative forcing of CO2 is the Summary Figure from the 2002 IPCC report (see). Clearly, according to their analysis, in comparing the change of radiative forcing since pre-industrial times until the present as estimated from the IPCC summary figure, the well-mixed greenhouse gases dominate the forcings which cause warming (about a 2.4 Watts per meter squared difference between these two time periods), of which about 1.4 Watts per meter squared is from CO2. Other warming forcings that they include, if the mean value plotted is used, are black carbon from burning fossil fuels (about 0.2 Watts per meter squared), tropospheric ozone (about 0.3 Watts per meter squared), and solar (about 0.25 Watts per meter squared).
Using these values about 58% of the radiative forcing of the well-mixed greenhouse gases results from CO2, and about 48% of the warming human-caused climate forcings result from the radiative forcing of CO2.
The following extracts from research studies reduce the relative contribution of the radiative forcing of CO2 as reported in the 2002 IPCC Report, as summarized above. These studies report the following,
“NASA scientists have found that a major form of global air pollution involved in summertime “smog� has also played a significant role in warming the Arctic……According to this new research, ozone was responsible for one-third to half of the observed warming trend in the Arctic during winter and spring. Ozone is transported from the industrialized countries in the Northern Hemisphere to the Arctic quite efficiently during these seasons. �
(see).
�Even within the well-mixed greenhouse gas forcings, there are new complications. Drew Shindell and colleagues, as reported in Pollution Online found that, ’According to new calculations, the impacts of methane on climate warming may be double the standard amount attributed to the gas. The new interpretations reveal methane emissions may account for a third of the climate warming from well-mixed greenhouse gases between the 1750s and today. The IPCC report, which calculates methane’s affects once it exists in the atmosphere, states that methane increases in our atmosphere account for only about one sixth of the total effect of well-mixed greenhouse gases on warming. ’� (see).
Moreover, from the 2006 Nature paper “Methane emissions from terrestrial plants under aerobic conditions” by Keppler et al,
” If our measurements are typical for short-lived biomass and scaled on a global basis, we estimate a methane source strength of 62–236 Tg yr-1 for living plants and 1–7 Tg yr-1 for plant litter (1 Tg = 1012 g). We suggest that this newly identified source may have important implications for the global methane budget and may call for a reconsideration of the role of natural methane sources in past climate change.”
“A recent study by the CERES Science Team has added to the uncertainty associated with the contributions of climate forcings to global warming by finding that for the period 2000-2004, their assessment of the shortwave albedo decreased by 0.0015 which corresponds to an extra 0.5 Watts per meter squared of radiative imbalance according to their assessment. (see)
“Deposition of BC aerosols over snow-covered areas can result in changes to the surface albedo (Chylek et al. 1983). Further reductions in albedo occur due to the enhanced melting that accompanies the heating of absorbing soot particles in snow. Chylek et al. (1983) estimate this enhancement to be up to a factor of ten in the rate of melting. Recent model results indicate radiative forcings of +0.3 W m−2 in the Northern Hemisphere associated with albedo effects of soot on snow and ice (Hansen and Nazarenko 2004).� (see)
We can summarize these findings below:
i) “ozone was responsible for one-third to half of the observed warming trend in the Arctic during winter and spring”.
ii) “The new interpretations reveal methane emissions may account for a third of the climate warming from well-mixed greenhouse gases between the 1750s and today”.
iii) “for the period 2000-2004, their assessment of the shortwave albedo decreased by 0.0015 which corresponds to an extra 0.5 Watts per meter squared of radiative imbalance according to their assessment.”
iv) “Recent model results indicate radiative forcings of +0.3 W m−2 in the Northern Hemisphere associated with albedo effects of soot on snow and ice”
v) There are a variety of direct and indirect aerosol effects that cause global warming including the black carbon direct effect, the semidirect indirect effect, and the glaciation indirect effect, with the thermodynamic effect having an unknown influence (see).
If we use the IPCC estimate of the fraction of the radiative forcing change of the well-mixed greenhouse gases from the pre-industrial to the present (i.e. see), which is about 2.4 Watts per meter squared, we can use the estimates of the radiative forcing from the other human climate forcings that are listed above to compare with this value, and with the fraction of the well-mixed greenhouse gas forcing that is due to CO2.
It need to be emphasized that the IPCC figure of the radiative forcing of 1.4 Watts per meter squared due to CO2 is not the current radiative imbalance since, presumably, some of the imbalance earlier in the industrial period with respect to CO2 increases has been removed as the climate system warmed. Nonetheless, these values can be used to scale the relative contribution to global warming due to the radiative effect of CO2. Also, since the observed radiative imbalance based on the 2004 Willis et al assessment is significantly less than the change from preindustrial to the present, the effect of human climate forcings that cool the climate system are, of course, also occurring.
With respect to the finding listed above, methane has a value of 0.8 Watts per meter squared, the shortwave albedo change is 0.5 Watts per meter squared, and the albedo effect of soot is 0.3 Watts per meter squared (which, however, may not be independent of the “shortwave albedo change). Tropospheric ozone, the aerosol black carbon direct effect, the semidirect indirect effect, and the glaciation indirect effect also add Watts per meter squared.
By summing the 0.8 Watts per meter squared for methane and using the total of 2.4 Watts per meter squared of the well-mixed greenhouse gases from the IPCC Report, the radiative contribution of CO2 reduces to about 46% of this component of radiative forcing (1.1 Watts per meter squared). The 46% value, of course, assumes that none of the radiative forcing of CO2 emitted earlier in the industrial period has equilibrated, so that the 46% is actually a high number, but is used here to be conservative.
For all of the human-caused warming radiative forcings, which includes the 0.5 Watts per meter squared value for the shortwave albedo change, and estimating tropospheric ozone as 0.3 Watts per meter squared, the aerosol black carbon direct effect as 0.2 Watts per meter squared, the black carbon on snow and ice as 0.3 Watts per meter squared, the semidirect indirect effect as 0.1 Watt per meter squared, and the glaciation indirect effect as 0.1 Watt per meter squared (with the latter two forcings using a nominal value, since these forcings are very poorly known), the contribution due to CO2 will fall to about 28%.
This analysis also ignores solar influences on the heating in which a published paper concludes,
“We estimate that the sun contributed as much as 45–50% of the 1900–2000 global warming, and 25–35% of the 1980–2000 global warming. ‘ (see). Even the IPCC estimates that there has been a warming influence from the Sun in their radiative forcing summary figure of about 0.25 Watts per meter squared (see). Adding this 0.25 Watts per meter squared value reduces the percent contribution of CO2 to about 26.5%.
This calculation does not mean that there is not merit in reducing the human input of CO2 into the atmosphere, but it does mean that even in the context of global warming, it is only a fraction of the actual positive radiative forcings.
This specific weblog focuses on the specific subset of climate variability and change that is referred to as “global warming” However, the assessment of radiative forcing directly is not the most appropriate procedure to use to assess global climate system heat changes. As was discussed in 2003 in “Heat storage within the Earth system”, the ocean heat content change is the proper metric to monitor.
Moreover, the observed ocean heat content changes have been spatially complex as has been discussed on this weblog (see and see). As reported based on the paper in 2004 by Willis et al that has been discussed on Climate Science (e.g. see and see),
“Maps of yearly heat content anomaly show patterns of warming commensurate with ENSO variability in the tropics, but also show that a large part of the trend in global, oceanic heat content is caused by regional warming at midlatitudes in the Southern Hemisphere.�
This heating is
“…centered on 40S is spread more uniformly over the water column and warms steadily throughout the entire time series…�
The climate science that is presented in this weblog summarizes one of the reasons for the conclusion that,
‘Attempts to significantly influence regional and local-scale climate based on controlling CO2 emissions alone is an inadequate policy for this purpose. ” (see).
The primary focus on carbon dioxide inappropriately deemphasizes the first order importance of the other climate system heat system forcings (both cooling and warming forcings), as well as does not address the spatially complex, and incompletely understood actual pattern of global climate system heat changes.
The main point of contention seems to be how a doubling of CO2 is handled in climate models particularly in relation to positive feedback (if it exists,in the light of Smith, T.M., Yin, X. and Gruber, A. 2006), whether there is a negative feedback, the Physics of infra-red absorption, and whether the realtionship between CO2 and temperature is linear or logarithmic.
Comment by Paul Biggs — April 27, 2006 @ 10:25 am
Of course, rather than obliquely referring to a paper that doesn’t look at 2x CO2 at all, we could, oh, check for ourselves how the major models give output for 2x CO2 and other outputs.
BTW, the second half of the sentence is simply obvious hand-waving.
Best,
D
Comment by Dano — April 27, 2006 @ 5:14 pm
CO2 is unique among the forcings. No matter what the purely physical response of additional CO2 in the atmosphere, it will increase cloudiness via an additional mode. One is the typical evaporation mode, wherein increased temperature creates more evaporation, and the second, unique mode: increasing flora which increases transpiration.
The ignorance of biospheric reaction to what may be considered the philosophical global equivalent of Manna is a sad and unbelievably major faux pas in the modeling world. Leaving it behind is the equivalent of leaving behind reality.
Looking at the Realclimate site, as large as it is, the term transpiration yields only 12 links (41 hits, but 12 non-duplicating links).
One must wonder why, in light of its probable major benefit, some people would concentrate on CO2 instead of other forcings.
Could it be something’s missing there?
Comment by Steve Hemphill — April 27, 2006 @ 6:07 pm
[...] ould almost certainly not exist, because we would have concluded it was not necessary. [...]
Pingback by Terryorisms » A load of hot air? — April 28, 2006 @ 6:07 am
Prof. Pielke; Your estimation on the contribution of CO2 to radiative forcing is very informative. But, since the IPCC report concludes that the infulence of human activity became clear from 1970’s, the estimation for this period would be further informative. Is it possible to calculate radiative forcings for the period 1970-2005 in a similar manner?
Comment by Kiminori Itoh — May 2, 2006 @ 12:42 am
Dr. Itoh - thank you for your question. With respect to the conclusion that there is a human influence on the climate system, in my view, this is obvious. Each of the first order human climate forcings that were identified in the 2005 NRC Report produce discernible effects.
The determination of their magnitude since 1970 is an important goal. An objective assessment of the contribution of each forcing (and the uncertainty of the estimates) should be one of the tasks of the IPCC. Such an assessment should include the diversity of published information on each forcing, of course, and not cherrypick to promote any particular perspective.
Comment by Roger Pielke Sr. — May 2, 2006 @ 5:13 am
I am having some trouble understanding your calculation. Perhaps you can clarify some of the following:
The value of 0.8 Watts per meter squared for methane is based on its input rate. The difference from the amount remaining in the air is its conversion to other gases, mainly ozone. But the ozone has already been counted, so this amounts to double counting.
You choose to compare carbon dioxide to a total that includes the positive human non-greenhouse effects, but not the negative human effects, which are greater. Including all the human effects would increase the ratio for carbon dioxide rather than decrease it.
The shortwave albedo change of 0.5 Watts per meter is measured over a short time period, and may simply be part of a cycle. I am not sure it should be included with other longer term forcings.
Even when you include solar forcing, I still see a CO2 contribution of around 50%. So, certainly we need more than a single minded focus on carbon dioxide, but I think you have minimized its importance more than it merits.
Comment by Blair Dowden — May 6, 2006 @ 7:13 pm
Blair- thanks for your request for clarification.
The value 0.8 Watts per meter squared for the radiative forcing of methane is based on the statement that
“The new interpretations reveal methane emissions may account for a third of the climate warming from well-mixed greenhouse gases between the 1750s and today.”
Since the total for the well-mixed gases in the IPCC is 2.4 Watts per meter squared, I multiplied 1/3 times 2.4.
Ozone is not a well-mixed greenhouse gas which is why the IPCC reported it differently. It is a separate radiative forcing.
Adding the negative radiative forcing would DECREASE the fractional contribution of the radiative effect of CO2 on the climate system even further. The relative global contribution of the radiative effect of CO2 relative to all radiative forcings could be assessed by using the absolute value of the forcings.
On the short wave albedo change, there have been major landscape changes since 1750, and that are on-going. If there is a change in surface albedo (and likely effects on clouds), this will be a long lasting effect.
I appreciate your science questions. In estimating the relative contribution of the radiative effect of CO2 on the climate system, to make the point that this influence of CO2 is only a fraction of the total forcings, I adopted a generous allocation for CO2. As you have helped to identify, its fractional contribution is significantly less when the negative radiative forcings are included.
Comment by Roger Pielke Sr. — May 7, 2006 @ 5:33 am
About half of the 0.6C rise in ‘global average temperature’ occurred before any significant rise in CO2. If we apply Roger’s calculation to 0.3C, result is about 0.08C of warming due to the radiative forcing of CO2. Even if we use 0.6C, that’s only about 0.16C.
Alternatively, Shaviv and Veizer attribute two-thirds of warming to Solar/Cosmic Ray Flux, which leaves a third for anthropogenic forcings, including CO2.
Comment by Paul Biggs — May 7, 2006 @ 10:31 am
I am realising that each forcing is unique, and adding them together has problems no matter how you do it.
About methane, the original Shindell et al paper makes a clear distinction between Abundance based and Emissions based forcings. The IPCC used abundance based forcings, while he argues that using emissions based forcings may be more useful. Therefore I think it is not correct to mix an emissions forcing with the IPCC abundance forcings, as some of the ozone is indeed being counted twice. On the other hand, carbon dioxide emissions do not have the same impact relative to methane emissions that the IPCC method implies.
Dealing with negative forcings is another interesting issue. I want to subtract them on the basis that they cancel out some of the positive forcings. You want to add their absolute values to compare the impact of carbon dioxide to all other forcings. Maybe ignoring them was the best path to take. I do not think there is a single right answer here.
As for albedo, it certainly has the potential to be of the same order as carbon dioxide. There have been landscape changes for a long time, but are the forcings always in the same direction? On a regional basis they may all be important, but on a global basis they may cancel. We have no accurate data on albedo until recently, and recent results do not seem to be clear. CERES may report a decrease in albedo, but this Palle et al paper claims that ERBE and Earthshine data show the opposite. So while albedo is clearly critical, assigning it a value is problematic for the comparison you are making.
So while I conclude that carbon dioxide is still about one half of abundance based forcings, I also accept the point that in terms of changes we can make here on the ground, reducing carbon dioxide emisisons may have less actual impact than changing some of the other forcings.
Comment by Blair Dowden — May 7, 2006 @ 1:30 pm
Blair-
Thanks for your additional very constructive feedback! We still disagree on the fractional contribution of CO2 as a radiative forcing, but you have added to the scientific debate on this subject.
On the question of the albedo change forcing (and other radiative forcings) averaging to near zero in a global average, I agree with you. Such a behavior has been found by Feddema et al (2005), for example, with respect to found that the global average temperature change due to this effect was near zero. However, they also found that the regional effects on weather were quite significant!
This regional perspective, therefore, is where we need to focus with respect to climate forcings and responses, as discussed frequently on this website, including our newly accepted paper (Matsuit and Pielke, 2006).
REFERENCES:
Feddema et al. 2005: The importance of land-cover change in simulating future climates., 310, 1674-1678
http://blue.atmos.colostate.edu/publications/pdf/Feddema2005.pdf
Matsui, T., and R.A. Pielke Sr., 2006: Measurement-based estimation of the spatial gradient of aerosol radiative forcing. Geophys. Res. Letts., accepted.
http://blue.atmos.colostate.edu/publications/pdf/R-312.pdf
Comment by Roger Pielke Sr. — May 7, 2006 @ 2:02 pm
Steven Milloy claims that the direct response to CO2 accumulation in the atmosphere is non-linear. On his website junkscience.com, he argues that the response falls off (logarithmically) as levels increase, because the radiation band approaches the level of being completely closed. He claims that models showing large temperature increases in the 21rst century therefore must rely heavily on positive feedback mechanisms, because CO2 by itself won’t do the trick.
Is Milloy correct about the non-linear response? If so, it’s very worrisome. I’m of the opinion that we should take action, for many reasons, to reduce our use of fossil fuels and our CO2 emissions. But if Milloy’s right, then it seems likely that such measures won’t be enough, that the die is cast as it were. Worse still, Milloy argues that only about 1/3 of the 20th century warming can be accounted for by CO2 - if the other 2/3 is due in part to natural causes, then, um, we’re cooked. In addition to reducing emissions, perhaps it’s time to look at mitigations, including geoengineering ideas.
Comment by Doug — July 27, 2006 @ 9:51 am
Doug- You have asked two excellent questions.
First, the radiative effect of CO2 in the atmospheric is a function of the logarithm of the concentration. Thus the radiative effect of going from zero to pre-industrial CO2 concentrations is much greater than going from the pre-industrial level to a doubling.
The quantification of this effect is documented in our 2nd Edition of my book with Bill Cotton (Human Impacts on Weather and Climate; Cambridge University Press) which will appear later in 2006 or very early in 2007.
In addition, the radiative effect of CO2 is muted in regions with high concentrations of water vapor (such as the tropics), as there is an overlap in the wavelengths that absorb long wave radiation. For more information on this, please see
http://climatesci.colorado.edu/2006/05/05/co2h2o/
On your second question, please see my posts
http://climatesci.colorado.edu/2006/04/27/what-fraction-of-global-warming-is-due-to-the-radiative-forcing-of-increased-atmospheric-concentrations-of-co2/
http://climatesci.colorado.edu/2006/05/10/more-on-the-relative-importance-of-the-radiative-forcing-of-co2/
Comment by Roger Pielke Sr. — July 27, 2006 @ 10:40 am
Doug,
Why do you think we are ‘cooked’? Climate change has always created challenges for regional ecosystems and human civilizations. These regional changes have often been large and sudden, yet the world goes on.
Today, we have more ability to adapt than ever before. Our knowledge, transportation and communication systems are light-years ahead of our ancestors. If a farmer needs to grow a different crop, he can probably learn all he needs to know after spending a weekend on the internet. Sure it will take some work, and some bad decisions will be made, along with some good ones.
I just don’t see the reason for all the pessimism, at least not from the science.
Comment by Jim Clarke — July 27, 2006 @ 11:30 am
Hi Dr. Pielke! I am not at all connvinced that CO2 is doing much of anything to contribute to recent temperature increases in the global climate.
I just got done looking at atmospheric spectroscopy calculations done by the IPCC HITRAN data using the following parameters: Starting with CO2 at 285 ppmv ( pre industrial ) and making absorption of IR energy calculations from this and with double the CO2 in the presence of a water vapor mixing ratio of 4.8g/kg dry air. That equates to a dew point of 40 deg F, an average water vapor concentration in airmasses that are non polar, or as they give it, a vapor pressure of 7.75E-04 atm. The integration was done by line method, staring at .02 meters down to 4 microns, and the Planck Emission was taken from the 288K curve.
The spectral overlap is quite severe, and is precisely why
the results don’t produce much change. Absorption by CO2 and the indicated water vapor at 285 ppmv was 72.6% of the Planck Flux or 283.14 W/m^2. Double CO2 in the presence of the same water vapor concentration and you get 73.1% absorption or 285.09 W/m^2. The increase then is half that of which was absorbed, or 1.95W/m^2 / 2 or .975 W/m^2. Plug that into the Stephan Botzman equation and you get an increased temperature from this flux of .16 deg C! Hardly anything to worry about. Now how can the computer modelers screw a basic calculation ( with their own numbers! ) up such as this and wind up with predicted values up to as much as 50 times this amount of warming? There is obviously something wrong with the models, and I am astounded at the arrogance that apparently causes certain groups to claim the climate models of IPCC can be trusted and have been validated by data such as that from Mann who was discredited by his peers. I have dynamic meteorology texts that are 60 years old that basically state that only water vapor can modify the ground radiative flux. This many years later, IPCC’s own measurements and calculations back up the basic physics. Any thoughts?
Comment by chuck wiese — July 27, 2006 @ 3:59 pm
Chuck - thank you for your analysis. The CO2-H2O overlap issue needs further exploration.
My suggestion is that you seek to publish an analysis in the peer reviewed literature. This is the most effective venue to present such an analysis as it requires scrutiny by other specialists.
Comment by Roger Pielke Sr. — July 27, 2006 @ 4:13 pm
Dr. Pielke: I happened to note that I misread the H2O vapor pressure initialization off of the IPCC spreadsheet when I sent my comments yesterday. Its 7.75E-3 atm. This makes no difference in the bottom line as it was only a misread of the exponent on my part. Everything else is accurate, and I’m still waiting for enlightenment about the true effects of CO2 as they relate to global warming and climate change. I think the data shows it is unreasonable to assume that CO2 has had much if any impact on recent temperature changes, and it would take much more of an increase in CO2 concentrations that we can possibly anticipate from sink sources to ever begin to compete with the other natural forcings. The scientific community should give up beating on this dead horse and look for more reasonable explanations for the recent temperature increases. If there are anthropogenic forcings, the only convincing evidence I have seen is from urban heat islands, which have been measured and realized for quite some time. Whether these effects could spread beyond the localized regions they affect is questionable.
Comment by chuck wiese — July 28, 2006 @ 10:44 am
Chuck,
Radiative transport is at the edges for my experience and expertise, but these papers might provide information relative to your discussion. The first below addresses directly the effects of CO2 on radiative transfer in the atmosphere. It has a very provoctive conclusion in this regard. The second contains some details missing from the first. Note that these papers were published about 40 years apart. Note also the vast difference between the applications; solids and gases. Apparently Professor Essenhiigh has had a solution looking for a problem for about 40 years.
I do not have a record of where I got the papers. Try a Google.
1. Robert. H. Essenhigh, Prediction of the Standard Atmosphere Profiles of Temperature, Pressure, and Density with Height for the Lower Atmosphere by Solution of the (S-S) Integral Equations of Transfer and Evaluation of the Potential for Profile Perturbation by Combustion Emissions, Energy & Fuels, Vol. 20, pp. 1057-1067, 2006. DOI: 10.1021/ef050276y.
2. R. H. Essenhigh, On Radiative Heat Transfer in Solids, AIAA Paper Number 67-287, AIAA Thermophysics Specialist Conference, New Orleans, April 17-20, 1967.
Comment by Dan Hughes — July 28, 2006 @ 5:09 pm
Chuck,
PS: I forgot to mention that Chapters 11 and 12 in this book address directly radiative transport in the atmosphere:
Gary E. Thomas and Knut Stamnes, Radiative Transfer in the Atmosphere and Ocean, Cambridge University Press, Cambridge, 1999.
It seems to me that there should be a mapping between the approach by Essenhigh and the discussions in the book, but I have not yet completely understood the equations.
Endnote #16 in Chapter 11 cites a reference to a discussion of the correlated-k method as:
A. A. Lacis and V. Oinas, Journal of Geophysical Research, Vol. 96, 1991. The pages numbers are given as 9,027-63, but I’m not sure what that means. Maybe 9027-9063??
The modeling and calculations seem to be based on the correlated-k approach.
Comment by Dan Hughes — July 29, 2006 @ 5:58 am
If one describes any value that is less than or equal to one it is conventionally stated as singular. “Other warming forcings that they include, if the mean value plotted is used, are black carbon from burning fossil fuels (about 0.2 Watts per meter squared), tropospheric ozone (about 0.3 Watts per meter squared), and solar (about 0.25 Watts per meter squared).”. It should read 0.2 Watt, 0.3 Watt, etc. Seems not many know that.
Comment by Eric Goozen, USDMS, PLS — September 18, 2006 @ 11:33 am
Hi,
I’m just an amateur with an interest and I just find this a little confusing.
Is it possible that the forcing attributed to CO2 by the IPCC is correct for those levels of CO2(espeacially if you consider the dramatic rise there has been in CO2 levels in the last 30-50years, before 1960 CO2 levels were low enough that the forcing the can attributed to them was ~0.3-0.4 w/m2) and that the total forcing of 2.4 w/m2 is wrong espeacially if you include all the latent heat that must have absorded by the increasing amount of melting ice (I’m not sure if the latent heat of such large ice losses would have been factored into IPCC models as they didn’t predict the ice losses we are seeing now until 2100).
Therefore is it possible that the 2.4W/m2 is an underestimation and the forcings you mention lowering CO2 should not all be taken away from the CO2 forcing and some should be part of an increase in the overall heating forcing currently being experenced?
Is 2.4w/m2 to low to account for rate of change of world heating we are seeing?
Comment by Ranyl — October 30, 2006 @ 2:32 pm
Other than a few alpine glaciers (which are a miniscule fraction of the world’s ice) where is all that melting ice? Especially melting continental, snow deposited ice? Even if we consider sea ice, do you happen to know what the current sea ice extent anomaly is in the Northern Hemisphere?
Comment by Steve Sadlov — October 30, 2006 @ 5:07 pm
[...] Another approach is to consider the changes in forcing and temperatures since the industrial revolution. Roger Pielke Snr suggests about 27% of recent warming (0.6 degrees) can be explained by atmospheric co2 which implies a lambda of 0.11, but this may be an underestimate because there is a time lag between changed forcing and changed temperatures. [...]
Pingback by Global warming science « Thoughts on Freedom — November 23, 2006 @ 11:05 pm
Contribution by Liquid Water in Ice Clouds.
I just came across the following new research news article from an NOAA team at Eureka in the Canadian Artic:
“Arctic clouds could reveal clues about global warming
Researchers on Ellesmere Island in Nunavut try to determine whether clouds are one of the causes — or effects — of atmospheric change
Last Updated: Monday, November 27, 2006 | 9:43 AM ET
The Associated Press
Scientists are peering into the clouds near the top of the world, trying to solve a mystery and learn something new about global warming.
The mystery is the droplets of water in the clouds. With the North Pole just 1,100 kilometres away, they should be frozen, yet more of them are liquid than anyone expected.
So the scientists working out of a converted blue cargo container near Eureka, on the west coast of Ellesmere Island in Nunavut, are trying to determine whether the clouds are one of the causes — or effects — of Earth’s warming atmosphere.
“Much to our surprise, we found that Arctic clouds have got lots of super-cooled liquid water in them. Liquid water has even been detected in clouds at temperatures as low as minus 30 degrees Celsius,” said Taneil Uttal, chief of the Clouds and Arctic Research Group at the Earth Systems Research Laboratory of the U.S. National Oceanic and Atmospheric Administration (NOAA).
“If a cloud is composed of liquid water droplets in the Arctic, instead of ice crystals, then that changes how they will interact with the earth’s surface and the atmosphere to reflect, absorb and transmit radiation,” said Uttal.
“It’s a new science, driven by the fact that everybody doing climate predictions says that clouds are perhaps the single greatest unknown factor in understanding global warming.” (Note….article in cbc.ca continues)
We know that surface chemistry can exhibit paths and conditions different from what is found in bulk reactions. Could this investigation find atmospheric particulates playing a greater role than currently modelled, or something as yet unidentified?
Comment by D.A. Kelly — November 27, 2006 @ 2:45 pm
I echo the question of ranyl. I thought the forcing from co2 would be determined by the formula dF = alpha ln (C/Co) where:
dF = change in forcing
alpha = 5.35
C = current co2
Co = pre-industrial co2
That gives a about the 1.4WM^-2 as suggested by the IPCC. If we have now found that there are additional elements leading to more forcing then shouldn’t we simply increase the estimated total forcing?
Any clarification would be much appreciated. Thanks.
Comment by John Humphreys — November 28, 2006 @ 9:39 am
RE: #24 - Is it possible that there are aezeotropes of water and organics in the subject clouds?
Comment by Steve Sadlov — November 28, 2006 @ 10:33 am
Re #25 -
The problem with that approach is that there are also elements leading to less forcing - but *they* tend to get glossed over by the alarmists. But you do bring up a valid point - a single theoretical forcing has, sometimes, little to do with the reality of the big picture.
Comment by Steve Hemphill — November 29, 2006 @ 10:10 am
[...] It’s a synergy- impacts and solutions Oil is one source of CO2. I have no reason to doubt that since oil has huge geopolitical implications today and arguably wars are fought over it today, it’s end of use will have huge environmental benefits and also have huge geopolitical consequences. I think we all realize they will fight for what’s left until they fight for what’s next. Someone is going to find a way, one day, to tax us for our daily solar exposure. There is also the unforgotten and almost never talked about byproducts of humankind and that’s plain old "heat". what’s here that produces heat or emissions that wouldn’t be here if we weren’t here. It goes way beyond oil. The Environmental Literacy Council - Sources & Sinks Sources & Sinks Greenhouse gases in the atmosphere play a critical role in shaping the global climate, and human activities have significantly modified the concentrations of many of these gases. A key area of scientific research in understanding the effects of human activities on global climate is the identification and quantification of these greenhouse gas flows. What of: Flatulence - Wikipedia, the free encyclopedia Warming hits ‘tipping point’ | Special reports | Guardian Unlimited Warming hits ‘tipping point’ Siberia feels the heat It’s a frozen peat bog the size of France and Germany combined, contains billions of tonnes of greenhouse gas and, for the first time since the ice age, it is melting Climate Science: Roger Pielke Sr. Research Group Weblog » What Fraction of Global Warming is Due to the Radiative Forcing of Increased Atmospheric Concentrations of CO2? CONCLUSIONS: 1. The primary focus on carbon dioxide inappropriately deemphasizes the first order importance of the other climate system heat system forcings (both cooling and warming forcings), as well as does not address the spatially complex, and incompletely understood, actual pattern of global climate system heat changes. 2. Attempts to significantly influence regional and local-scale climate based on controlling CO2 emissions alone is an inadequate policy for this purpose. “We estimate that the sun contributed as much as 45–50% of the 1900–2000 global warming, and 25–35% of the 1980–2000 global warming. ‘ (see). Even the IPCC estimates that there has been a warming influence from the Sun in their radiative forcing summary figure of about 0.25 Watts per meter squared (see). Adding this 0.25 Watts per meter squared value reduces the percent contribution of CO2 to about 26.5%. This calculation does not mean that there is not merit in reducing the human input of CO2 into the atmosphere, but it does mean that even in the context of global warming, it is only a fraction of the actual positive radiative forcings. __________________ Don’t let other peoples limitations become your highest expectations. [...]
Pingback by Peak Oil... and? - AboutMyPlanet Community — January 4, 2007 @ 7:06 pm
Here is the unvarnished truth about the Peak Oilers, as told by one of their web sites:
http://dieoff.org
Some pretty radical stuff there.
Comment by Steve Sadlov — January 5, 2007 @ 12:47 pm
In his web site dr. Erren states: “In deep winter conditions the atmosphere spectrum has emission bands for CO2, so adding more CO2 leads to higher emission in winter, and subsequent cooling.”
He shows a plot of the emission spectra as it was measured by the IRIS Michelson interferometer on Nimbus 4.
Prof. Pielke, do you have some related thoughts?
Look at his not added on March 2005 here:
http://home.casema.nl/errenwijlens/co2/howmuch.htm
Comment by Paolo M. — January 16, 2007 @ 2:57 am
Paolo- Thank you for your interesting question. I will follow up.
Comment by Roger Pielke Sr. — January 16, 2007 @ 5:41 am
Paolo- I have not yet found a definitive final answer (but am still searching), but clearly if the CO2 addition were well mixed at least throughout the troposphere and stratophere, it must be a positive radiative forcing. Only if all of the CO2 absorption lines were saturated, such as the result of even a relatively thin overcast, would there be no added warming below the cloud from added CO2 (since such a cloud is essentially a blackbody in the long wave).
Comment by Roger Pielke Sr. — January 21, 2007 @ 5:33 pm