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Cloudy outlook for albedo?

Filed under: — group @ 22 February 2006

Guest Commentary by George Tselioudis (NASA GISS)

In the past few years several attempts have been made to assess changes in the Earth’s planetary albedo, and claims of global dimming and more recently brightening have been debated in journal articles and blogs alike. In a recent article entitled “Can the Earth’s Albedo and Surface Temperatures Increase Together,” that appeared in EOS, Enric Palle and co-authors use recently released cloud data from the International Satellite Cloud Climatology Project (ISCCP) to explain how it is possible for the Earth to be warming even as it’s albedo is increasing. The need for an explanation arises from the author’s claim that the earth’s albedo has increased since the year 2000, an increase that was not followed by a decrease in surface temperature. They base this claim on Earthshine data (a measurement of the glow of the dark side of the moon that they use to deduce the earth’s reflectance) and on an albedo proxy derived from ISCCP parameters after they are regressed with two years of overlapping, but not global, earthshine observations. Subsequently they claim that the rising reflectance of the Earth has not led to a reversal of global warming because the difference between low and middle-plus-high ISCCP clouds has increased in the last four years. This they say implies that as the low-level, cooling clouds have decreased during the most recent years, the high-level, warming clouds have increased even more negating any potential cloud-induced cooling.

There are several issues connected to the use of earthshine data to calculate the earth’s albedo that have been discussed in peer-reviewed publications and that I will not discuss in this posting. I will say a few things, however, about the selective use of ISCCP data in this article to construct qualitative arguments that do not stand up to detailed quantitative analysis .

Palle et al (2006) albedo reconstructionFirst, let’s take the claim that the Earth’s albedo has increased in the last four years. This is based primarily on the huge earthshine-derived albedo increase in 2003, which the authors now admit may be caused by undersampling of the data but was the the highlight of the authors’ recent Science paper (Palle et al, 2004). The other three years have values close to zero (relative to the reference year) with two years having error bars extending into the negative territory. The earthshine-trained ISCCP reconstruction of the albedo is a purely statistical parameter that has little physical meaning as it does not account for the non-linear relations between cloud and surface properties and planetary albedo and does not include aerosol related albedo changes such as associated with Mt. Pinatubo, or human emissions of sulfates for instance. Even this albedo reconstruction, however, shows only a weak positive trend in the last four years.

The ISCCP group produces an independent estimate of the albedo, from performing a full radiative flux calculation that takes into account observations of all radiative forcings and produces top of the atmosphere, surface, and in-atmosphere fluxes (data, figure right). This has been shown to be in excellent quantitative agreement with satellite measurements at the top-of-atmosphere and with surface measurements. The year-to-year variations of these values show some qualitative agreement with the earthshine-trained ISCCP reconstruction but very large quantitative differences.

ISCCP albedo changesThe ISCCP estimate (right) shows a decreasing albedo trend of 1-2% in the 80s and 90s (as opposed to 7-8% in the earthshine-based proxy), a small increase of 1% form 1999 to 2001 and a flattening of the curve in the last three years. Quantitatively similar trends are derived from radiative flux retrievals by the ERBS and Terra and Aqua satellites.

Next consider the difference in trends between low-level and high-level clouds. It’s important that definitions be used carefully when we interpret satellite retrievals. First, the satellite can see actual low clouds only when higher cloud layers are not present. Second, the satellites retrieve the radiative, not the physical top of the clouds. As a result, a low cloud with a cirrus cloud overhead can be classified as a midlevel cloud in satellite observations. All these issues must be taken into account when calculating the radiative effect of clouds, as is done in the radiative calculations by the ISCCP group. More importantly, not all high-level and almost none of the middle-level clouds are radiative-warming agents. There is an optical depth threshold that depends on the cloud top height, above which the cloud becomes a cooling agent even with tops at high altitudes. Therefore the use of combined middle-plus-high clouds as a measure of the warming potential of the cloud field is a substantial overestimate of the effect. Moreover, a more careful look at the changes of ISCCP clouds by cloud type shows that the increase in total cloud cover from 2000 to 2004 is due to a small increases in high-level clouds and a larger increase in middle-level clouds that are mostly thermally neutral and therefore could not cause warming (see figures, data).

mid and high level clouds (ISCCP)
The increases in both high-level and middle level clouds (right) are caused by increases in the optically thicker cloud types, cirrostratus and cumulonimbus for the high-level and altostratus and nimbostratus for the mid-level clouds, that due to their large optical depths, cause radiative cooling. In fact, the same radiative calculations performed by the ISCCP group show that the outgoing longwave radiation increases during this time, opposite to the effect claimed. Therefore, the qualitative explanation given in the article is contrary to the quantitative analysis results derived from the ISCCP data.

The reconstruction of radiative fluxes from atmospheric properties is a very difficult and tedious job and both the ISCCP and ERBE/CERES groups are putting a great deal of effort into producing detailed and carefully evaluated radiative flux datasets. Both datasets show little or no albedo trend in the last four years. Thus explanations for how the albedo trends of the last four years are consistent with the surface warming and the ocean heat content increases are not necessarily required at this point in time.

45 Responses to “Cloudy outlook for albedo?”

  1. 1
    Steve Sadlov says:

    When considering clouds, is albedo the lone consideration? What else might clouds do, besides reflect radiation? Especially, what else might cumulonimbus do?

  2. 2
    Dwight Darden says:

    I’m going to copy a post I made on an online forum concerning global warming in this comment. I just wanted an opinion on this line of thinking and it’s validity, it may have some bearing on your article.

    “Am I just old school here, or is transpositioning of the earth’s axis not taught anymore. The wobble in the earth’s axis, as I was taught, it takes about 25,000 years to complete one full cycle; wherein the angle of the earth in relationship to the sun is not the same at the exact same point in time year after year. The eventual completion of a cycle would make the climate on earth go through long range changes of cooling and heating, repeating itself every 12,500 years, in and out of each high and low temperature range. Who could ever live long enough to really know how this phenomenon affects human life on earth in personal terms. Call it global warming? Cooling? Or whatever, it is going to change but ever so slowly. I mean this is 9th grade science stuff, when did it get disproved or forgotten?”

    After I posed this question I did a web search and found the following. here’s a link to a very lengthy and technical explanation of the transposition of the earth’s axis. If you skip over the technical stuff, the movement of the earth’s pole is well shown to be a proven fact, thus affecting our climate ever so slowly and continuously.

    [Response: See and our last post dedicated to Nick Shackleton. -gavin]

  3. 3
    Eli Rabett says:

    Back on Feb 1, I blogged on this EOS issue, (Blog whoring: ) There may be a way to get better whole Earth albedo data (see link).

  4. 4
    Hank Roberts says:

    See also Robert Simmon’s comment here

    I guess we need a bake sale to buy a launch vehicle.

    I’d bet subscriptions to a current ‘Whole Earth’ video feed would pay for the launch vehicle, myself.

  5. 5
    daCascadian says:

    Hank Roberts >”…I’d bet subscriptions to a current ‘Whole Earth’ video feed would pay for the launch vehicle…”

    Probably so

    Anyone know what it would cost to launch this satellite; what vehicle is required etc ?

    “Once a photograph of Earth, taken from outside, is available, once the sheer isolation of the Earth becomes plain, a new idea as powerful as any in history will be let loose” – Fred Hoyle (1948)

  6. 6

    I think there is a typo in “cirrostratus and cumulonimbus for the high-level and altostratus and nimbostratus for the high level clouds, ” It should be “mid and low level clouds” in the last part.

    [Response: Thanks. Fixed now. -gavin]

  7. 7

    As I understand it, clouds, in addition to cooling the Earth by reflecting away sunlight, also act as greenhouse agents in the thermal infrared. A British climate model uses absorption coefficients of 130 m^2 kg^-1 for low and middle clouds and 65 m^2 kg^-1 for high (ice) clouds. This is high enough that clouds are sometimes treated as blackbodies for wavelengths of 4 microns or greater. The Cytherian clouds (75% H2O solution) apparently block all IR from 1.2 microns and up, which is part of the reason the surface of Venus is as hot as it is.

    Does anyone know what the latest figure for the Earth’s bolometric Bond albedo is? The last figure I have (0.298) is from 1998.

  8. 8
    John Fasullo says:

    Interesting piece George. I think your comments add value to the debate, particularly in regard to the role of clouds. It should also be pointed out, however, that the lack of consideration of water vapor in Palle et al discussion is glaring. There is a well established trend in water vapor (e.g. Trenberth et al. 2005, Climate Dynamics) that is obviously central to this issue. Discussion of global radiative budgets and their trends without consideration of water vapor (particularly given the title of Palle et al’s piece) is wholly simplistic.

    Further, there are numerous reasons to be suspicious of the earthshine data, and even a few to be wary of the ISCCP long term trends, that I suspect will be discussed in the upcoming IPCC.

  9. 9
    Lynn Vincentnathan says:

    Seems very complex. Is there any prediction that albedo will decrease in the future due to shrinking ice in the ocean & snowcover on land? I had sort of understood that might be a positive feedback factor in GW. And if this type of albedo were to decrease, would that decrease outweigh albedo increases, say, due to clouds or other factors?

  10. 10
    dobbins says:

    I read the original article in EOS, and was interested in seeing your response. Are you going to submit a note to EOS? I’m curious whether the forum for scientific discussions is moving out of journal space and into the blogosphere.

  11. 11
    Natassa says:

    Interesting point dobbins.

    However, for the moment (dunno about the future, it will be good to ponder about it) blogosphere *reports* on scientific discourse that ultimately has to appear in peer reviewed journals. EOS is not one of them, although there is an editor -generally knowledgeable but not necessarily an expert in each area.

    And, salute to our new blogmeister George!

    [Response: Are you by anyway related? – just asking…. ;) – gavin]

  12. 12
    Eli Rabett says:

    Thanks to Hank Robert’s for pointing to Robert Simmon’s comment. It reminded me of another reason why EOS rocks. New Blue Marbles! EOS pointed me to this page and of course I blogged on it!:)

  13. 13
    Hank Roberts says:

    And thanks to Eli and Robert and others who’ve written about Triana.

    The X-Prize foundation has been asking for feedback about their next steps toward private spaceflight. I suggested putting Triana at L1.

    Kids on Earth need that view of the world, I think. Live on video, it would be more compelling than all the old ideas they’re being fed now.

  14. 14
    george-t says:

    Steve Sadlov wrote: “When considering clouds, is albedo the lone consideration? What else might clouds do, besides reflect radiation? Especially, what else might cumulonimbus do?”

    Other than reflecting sunlight clouds trap heat and make rain. Cumulonimbus do all three very efficiently and their net energy effect is the result of a complex calculation that takes into account light, heat, and water.

    John Fasullo wrote: “Discussions of global radiative budgets and their trends without consideration of water vapor (particularly given the title of Palle et al’s piece) is wholly simplistic.”

    I agree John. Water vapor, as well as aerosols, should be part of any radiative balance calculation. They are both included, as best can be done at the present time, in the ISCCP flux calculations.

    Lynn Vincentnathan wrote: “Seems very complex.”

    It is very complex. This is why simplistic approaches confuse rather than clarify the issue.

    Dobbins wrote: “Are you going to submit a note to EOS?”

    We prefer the route of referred journal publications but we may write a letter to EOS since the preferred route is time consuming.

  15. 15
    CharlieT says:

    Re: Palle 2006
    Is the ~20year ‘oscillation’ in total cloud amount [His Fig.1 Top] reproduced (roughly) by the climate models?

  16. 16
    Steve Sadlov says:

    RE: #14. Good, at last someone bit. To develop it further, how well do we think we really understand the heat flow behavior in the tropics, and to a lesser extent, the mid latitudes vis a vis cold fronts? Consider an anvil. Analogously, consider the thermal slug on a microprocessor chip, in contact with a fansink.

  17. 17
    daCascadian says:

    Hank Roberts >#13 “…I suggested putting Triana at L1.

    Kids on Earth need that view of the world, I think…”

    I asked (#5) previously what sort of launch vehicle would be required; anyone know ?

    I would suggest that lots of adults, in addition to kids, constantly need “that view”

    “space is the moral equivalent of war for earth” – moi or or

  18. 18
    Ike Solem says:

    The most surprising info in this post is that earthshine was used to measure Earth’s albedo. Isn’t there a satellite in orbit that can measure this parameter? I guess the answer is ‘obviously not’. There is a real need for more data gathering systems. Organizing such satellite missions is a major undertaking; my condolences and encouragement go out to the organizers of CryoSat, who just suffered a launch failure. The collection of accurate datasets is the most critical issue in all this.

    [Response: Various satellite campaigns do measure albedo. It’s surprisingly difficult to do right. A satellite looks at a piece of the Earth from only one angle. As the day progresses, the Sun is shining in from another angle. From this limited data, you have to use some kind of angular distribution model to figure out what the net reflected energy is. Meanwhile, the clouds are changing all the time, and the satellite (if it’s a polar orbiter, as is often needed for good observations) is moving around too. Also, you have a couple satellites wizzing around in different orbits, so you have intercalibration problems. A small miracle it can be done at all. Routine weather satellites don’t work — you need specially designed radiometers to be accurate enough. ERBE did it, but that was only five years. There are new satellites up, and more coming, but many delays. Hence, any new way of cross-checking the results, with a completely different technique with different possible errors, is very welcome. –raypierre]

  19. 19
    Hank Roberts says:

    > isn’t there …
    Rabbet summed up the problem, he gave a ‘tinyurl’ link earlier to his blog summary. It’s here:

  20. 20
    Pekka Kostamo says:

    Re #18. A very relevant response from Raypierre. Monitoring climate change is in general a major problem.

    “Climate” is factually a statistical expression of weather, so almost everyone assumes that the established weather measurement systems and networks, satellites etc. should suffice for climate monitoring as well.

    This is not true. Climate monitoring requires a far superior accuracy of measurement. The main difference is in long term stability requirements. There should be no change in measurement methods and their implementation over many tens of years. Or, if changes must be made, a most elaborate intercomparison and calibration between the instrument generations is necessary.

    A good example is in “The effect of radiosonde instrument changes on climate trends of global atmospheric precipitable water”, by Steven R. Schroeder,presented in the 18th conference on climate this year. He examined the global radiosonde record database, and was able to identify some 1600 suspect discontinuities, due to changes in instrument types, computation methods, reporting formats and so forth. Many of these would require bias corrections. However, the radiosonde observations have fully earned their reputation as one of the mainstays of daily weather forecasting work.

    Similar issues arise with the many generations of satellite sensors.

    Apparently climate change is not yet recognized as important enough to justify dedicated measurement systems. It should be.

  21. 21
    CharlieT says:

    Re#15 OK; If it isnt reproduced by the models: Are there any ideas on why such an oscillation occurred ?

  22. 22
    Lynn Vincentnathan says:

    This isn’t on this particular topic (tho it’s all interrelated), but I just read “New scientific theory, hydrate hypothesis, suggests GW catastrophe.” see:

    I thought that was an old, fairly well-established theory. Can RC do an article on it?

  23. 23
    llewelly says:

    Lynn, see
    which attempts to analyze the chances of a methane hydrate driven gw catastrophe.

  24. 24


    What I missed in the discussion is the “where” question. Earthshine may have an overweight from equatorial albedo changes and may have less influence from albedo changes at higher latitudes (e.g. reflection from cloud-free ocean parts). I suppose that most of the surface is covered by satellites, which measure everywhere at the same angle(s). That may explain -in part- the difference in trends.

    For the radiation budget it makes a lot of difference if the cloud(types) albedo change is in the (sub)tropics, mid-latitudes or near the poles. And as we have seen in the Arctic, cloud albedo changes even are seasonally different (but with a similar result on temperatures).

    Is it possible to have a look at differentiated (low, mid/high types) cloud trends for the tropics, mid and high latitudes and for different seasons?

  25. 25
    Steve Bloom says:

    RE #16 (SS): The comments on this site are a poor place to expect answers that recapitulate extensive areas of climate science as with the heat flow issues you raise. I suggest you try a climate science textbook or Google Scholar for the big picture material, and then ask more specific questions here.

  26. 26
    Denis Royer says:

    Re #18. The comment by Pekka Kostamo raises the issue of long term monitoring of key climate variables.
    I am not a climatologist, but I would like to point out that such a challenge is also present and satisfactorily taken into account in other disciplines, sometimes with the help of amateur scientists communities.
    As an exemple, the follow-up of variable-stars relies partly on the work of amateur associations. Among them the AAVSO gather and intercorrelates data for almost hundred years, thanks to well established procedures and standards.
    I wonder if such a case can be transposed to climatology, an if ground based measurement, other than the networks of weather stations, can be set up on large scales. In this case what are the climate variables which would be both managable and of some use to the climatologists ?

  27. 27
    Steve Sadlov says:

    RE: #25. Overt ad hominem on your part. The truth is, you have no specific answer to it. Nor does anyone. There are theories and a few models. Sadly, there has been far too little invested in that particular thread of research. Although, there is something interesting – the incovenient fact of heat flow mechanisms that do not move heat / energy poleward are, shall we say, politically incorrect?

  28. 28
    daCascadian says:

    Here is a slight curve ball on all the conjecture/modeling

    “Europe’s “Little Ice Age” may have been triggered by the 14th Century Black Death plague, according to a new study. Pollen and leaf data support the idea that millions of trees sprang up on abandoned farmland, soaking up carbon dioxide from the atmosphere. This would have had the effect of cooling the climate, a team from Utrecht University, Netherlands, says. The Little Ice Age was a period of some 300 years when Europe experienced a dip in average temperatures…”

    This hypothesis of Dr Thomas van Hoof of Utrecht University is published in the journal “Palaeogeography, Palaeoclimatology, Palaeoecology”.

    I wonder how climate models might react under this scenario…

    “Proof depends on who you are. We’re looking for a preponderance of evidence, and some people need more of a preponderance than other people.” – John Kantner (Georgia State University)

    [Response: Unfortunately for this theory, the changes in CO2 are too small to have had a significant climate impact (around 10ppm max) in comparison to the changes in solar and volcanic forcings which are much more significant. In fact the CO2 changes are probably a response to the cooling, rather than the other way round in that case. -gavin]

  29. 29
    daCascadian says:

    Re: #28 Response by gavin

    gavin >”…In fact the CO2 changes are probably a response to the cooling, rather than the other way round in that case…”

    So you (or someone you trust) has actually run those scenarios ?

    “…human security can be defined better as ‘knowing risks’ rather than ‘eliminating risks’.” – Hans van Ginkel

    [Response: Gerber et al (2003) – gavin]

  30. 30

    A while back you did a piece on the carbon dioxide changes and how they will affect the oceans. I wanted to alert you to this piece in the UK Times today, which gives a frightening picture of what these changes might mean for the coral reefs and for marine life.

    Here is a link to our page which quotes the article and presses for our President to begin addressing these catastrophic environmental issues. Perhaps you will feature this issue on your site again?
    Bush Fiddles While Climate Changes

  31. 31
    Pat Neuman says:

    re 30. I don’t think G.W. Bush is the biggest reason (in the US) for fiddling while climate changes. 5,000 NOAA National Weather Service (NWS) employees have been saying things to the public like “global warming is nothing more than a statistical fluke” since the 1990s (164. at the Happy Birthday Darwin thread). TV-radio people get training and guidance from NWS and pass their views about global warming to the public almost every day, especially here in Minnesota during these warmer than “normal” Minnesota winters of the last 8-10 years. The explanations they give for the warm winters are weak or wrong, blaming warmer temperatures on a lack of snow cover (more albedo), roller coaster temperatures and “normals”, often ending their broadcasts with with something like … this is the way it’s supposed to be. Wrong.

  32. 32
    daCascadian says:

    Re: #29 Response by gavin

    OK, I`ll take that as a firm NO

    just wondering which scenarios actually have & have not been run

    “…it’s the ideas that count, not the number of trees you kill to print them.” – Phil Carter

  33. 33
    muirgeo says:

    RE #27

    Steve wrote,

    “Although, there is something interesting – the incovenient fact of heat flow mechanisms that do not move heat / energy poleward are, shall we say, politically incorrect?”

    Almost as inconvenient as the observed fact that the poles and temperate regions ARE warming and their glaciers are melting….dramatically…..their oceans warming as well. Mother nature…HER laws of physics knows nothing of your political incorrectness or of your plain old incorrectness….you’ll not coax the cumulonimbus to do your bidding against her wishes…indeed.

  34. 34
    Pat Neuman says:

    31 should read … warmer temperatures due to less albedo from less than 100 percent snow coverage, which is unusual for late February in Minnesota.

    Snow depths and rankings in Minnesota are shown at the link below. On Feb 23rd there was less than one inch of no snow cover in a band from southwest Minnesota through the southern Twin Cities area into western Wisconsin. That area is near or at the bottom of the snow depth ranking scale, as compared to historical records of snow depth. Weather forecasts try to account for the bare ground heating in their forecast adjustments from the modeled forecasts, especially on days with lots of sun, but it still often gets warmer than what they issue. The explanation given to the public is that it’s getting so unusually warm because of all the bare ground around which usually isn’t snow free in late February. There is rarely if ever any mention of climate change or global warming in the explanations given to the public.

  35. 35
    Pat Neuman says:

    34 should read … was less than one inch of snow cover …

    Also, some of you may be interested in

    “The ultimate source for snow … The National Operational Hydrologic Remote Sensing Center (NOHRSC) National Snow Analysis.

    NOHRSC is the third NWS office in Chanhassen, MN, one building for 3 NWS offices.

    NWS NOHRSC has national operational responsibility for modeling and measuring snow depth and snow water equivalent. NOHRSC measures the water equivalent of a snowpack by making many flights above hundreds of established flight lines. NOHRSC has been operational for the last 25 years. The water equivalent flight line data is used to update snow hydrologic models which are used in NWS river forecast center probabilistic spring flood outlooks, and river forecasting. Is the data worth the cost in money and GHG emissions?

    What do you think is the public value of NOAA NWS NOHRSC National Snow Analysis? Positive or negative?


    PS … the weather people on TV are talking about the roller coaster again. Forecast high temp. tomorrow is 43 F, and rain.

  36. 36
    Steve Sadlov says:

    RE: #33. That post does not merit a response. Its author probably barely passed undergrad Physics, assuming such a course was even taken.

  37. 37
    Steve Sadlov says:

    Lots of talk here about snow cover in the upper midwest. First point, a long known fact is that the upper midwest (meaning, the northern tier, west of the 25 inch annual average rainfall line) has a Summer precipitation maximum, so dry winters can indeed be expected. Second point is, on top of all that, that area is definitely experiencing a drought. These are interesting climate observations …. with respect to precipitation. And that tells us what?

  38. 38
    Pat Neuman says:


    There hasn’t been a “decent” winter in southern Minnesota and Wisconsin (the heart of the Upper Midwest) since 2001. Lake ice this year never got thick enough for ice fishing.

    The really unusual thing about the winter of 2006 was the absence of cold air. Climate stations in eight states in the north central U.S. had record high January average daily mean temperatures. Only few days in February had below zero F temperatures, the rest of the month was mild by old Minnesota-Wisconsin standards.

    * Highest of record (1897-2006) for January Avg. Daily Mean Temp.
    *Leech Lake Dam MN
    *Milan 1 NW, MN
    *Park Rapids 2 S MN
    *Pine River Dam MN
    *Dickinson ND
    *Jamestown ND
    *Langdon ND
    *Forestburg SD
    *Brodhead WI
    *Lancaster WI
    *Oconto WI
    *Prairie Du Chein WI
    *New London WI
    *Solon Springs WI
    *Spooner Exp Stn WI
    *Stevens Point WI
    *Ironwood MI
    *Atlantic IA
    *Windsor IL
    *Lamar, MO
    *Salem, MO
    *David City NE
    Temperature plots at:

    I’m monitoring the monthly temperature averages for the period of record in the regions for each of the NWS Cooperative Climate Stations (rural, forested and small town areas) and creating average monthly temperature plots because I think someone needs to be doing this. This should be a government agency function but I don’t see any government agency people doing it. I think the gov people are afraid to stick their neck out and show the public that the climate is indeed warming. The proof is in the data, but the agencies that collect the data aren’t doing anything with it to show the public what’s happening, nor are they monitoring what’s really going on.

    In my opinion, the government agencies in the U.S. are failing badly in serving the public good on climate change. They’re not doing what they should be doing in a time of global crisis… then they fired me for wanting to do what I believed was my job – to evaluate and take account of climate changes on the hydrology within the NC states of the U.S. for modeling and flood prediction purposes. It made no sense to me to use the same one set of calibrated parameters for snowmelt, evaporation and transpiration in a basin where I knew climate change was going on within the historical period of runoff calibration for the river basin.

  39. 39
    muirgeo says:

    RE: 36

    I got all A’s in Physics and P Chem. How’d you do on the test about the spectrophotometric properties of carbon dioxide?

  40. 40
    Kenneth Blumenfeld says:


    You say:

    Lots of talk here about snow cover in the upper midwest. First point, a long known fact is that the upper midwest (meaning, the northern tier, west of the 25 inch annual average rainfall line) has a Summer precipitation maximum, so dry winters can indeed be expected. Second point is, on top of all that, that area is definitely experiencing a drought. These are interesting climate observations …. with respect to precipitation. And that tells us what?

    Your definition of the Upper Midwest is new to me (and probably every other climatologist and operational meteorologist in the country), but it sounds like it includes northwest MN and ND only (since the rest of MN, and points east have average annual rainfall greater than 25,” SD is not the “northern tier,” and nobody would ever put MT in the Upper Midwest) Note that this definition excludes most of the area to which Pat was referring.

    Using your definition, your first statement is accurate, and can, in fact, be expanded to include most of the continental portions of North America, especially if we replace “summer precipitation maximum” with “winter precipitation minimum.”

    Your next statement, again, using your definition, is patently false. Note where the drought areas are:

    If you use what most folks consider to be the Upper Midwest (ND,SD,NE,MN,IA,WI, maybe MI, maybe IL) then you are doing a little better, but still only on the far southern end of the region.

    Next, you are confusing snow depth with precipitation. The recent “non-winter” effect in much of the real Upper Midwest has been accompanied by isolated “snow droughts” (2002-03, last year…jury still out on this one), but otherwise normal, near-normal, and above-normal levels of snowfall. In fact, the recent snowfall levels are not low in a historical context. But if the snow depths are, what does that tell you? It tells you that the snow is melting before it accumulates to levels we normally experience, which is temperature-related.

    So, the “interesting climatic observations…with respect to precipitation” that you note, are actually about persistent and consistent abnormally warm wintertime temperatures. That should answer your final question (“and that tells us what?”).

  41. 41
    Steve Sadlov says:

    RE: #39. I aced it. Anything having to do with Boltzman I aced. Plus other things.

  42. 42
    daCascadian says:

    Re : #5, #13, #17
    Hank Roberts > “…I suggested putting Triana at L1.

    daCascadian >”…I asked (#5) previously what sort of launch vehicle would be required; anyone know ?…”

    The quoted price then was ~$25×10^6 for a Ukrainian rocket

    not that difficult for a campaign to raise

    probably well worth the investment, particularly if there was a revenue stream from the live video etc

    “Once a photograph of Earth, taken from outside, is available, once the sheer isolation of the Earth becomes plain, a new idea as powerful as any in history will be let loose” – Fred Hoyle (1948)

  43. 43
    Eli Rabett says:

    Hi daCascadian,

    L1 is mondo far. Can an off the shelf rocket get there with a payload??

  44. 44
    JHM says:

    Can the Earth’s Albedo and Surface Temperatures Increase Together? Ask Venus.

  45. 45
    John Butler says:

    Re. #15 and #21. I imagine several people will have spotted that the length of the apparent cycle in the top figure of Palle et al. (EOS) is close to the length of the Sun’s magnetic cycle (the Hale cycle) which is about 22 years. I discussed this with Enric Palle last year after his talk in Beijing.

    The minimum in their Fig 1 occurs close to the last solar maximum at about 2000.5 AD. It is well known that the solar magnetic cycle strongly modulates the cosmic ray flux observed on Earth and there have been a number of papers concerning apparent correlations between cosmic rays and cloud cover. However, its unlikely that any climate models have incorporated the physical processes involved as they are just too uncertain, controversial and speculative at this time.