Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Climate change and Earth reflectivity

  1. Aug 1, 2004 #1
    Although we see threads starting supporting Green House Gas global warming, we tend to overlook the publications that counter them.

    Here is one from May (almost overlooked):

    and some remarks in the conclusion:

    Translation: there is a high correlation between global temperatures and Earth's reflectivity (Albedo) whilst there is no correlation between carbon dioxide increase and this reflectivity. The less light is reflected, the higher the (global) temperatures.

    Now, is this the kind of pseudo-bad-scientific publications -conspiracy tales nonsense that the alarmists warn against?

    like this?

     
  2. jcsd
  3. Jan 23, 2005 #2
    Dug out this old one, since it gives us a rather good idea about the reflectivity (Albedo) of the Earth in the last couple of decades. With that in view, let's go to the lastest scary scenario of the BBC that upset the UK to a great extend last week.

    I wonder why the story did not made to these threads, but anyway.

    The Earth is dimming.

    Now why would that be? Let's follow the scientific method and formulate a possible hypothesis:

    Having formulated the hypothesis, next step is to test it against independent evidence. So if pollution is making the earth moere reflective, we should be able to find evidence of that. So:

    :bugeye: Oops, I'm afraid that hypothesis did not last very long. It would be an understatement that hypotheses that oppose reality 180 degrees, are not really commended for their reliability.

    So in what perspective need we to see?

     
    Last edited: Jan 23, 2005
  4. Jan 23, 2005 #3

    matthyaouw

    User Avatar
    Gold Member

    Do you have a link to the article/paper in which you found this? I was having a discussion about this with someone the other day, and I think it could be helpful.
     
  5. Jan 23, 2005 #4
  6. Jan 24, 2005 #5
    Interesting, thank you for the post.
     
  7. Feb 24, 2007 #6
    The first thing I notice about the Palle et al. graph is that it registers no effects from the Pinatubo eruption. Curious. The ISCCP graph shows a large fluctuation in albedo from the Pinatubo eruption as would be expected.

    Second is the huge peak in 2003, which I understand the authors have backed up somewhat from that and have admited that it may be caused by undersampling of the data, even though that year was one of the highlights the Palle et al., 2004 article.

    George Tselioudis, a NASA scientist at the Goddard Institute for Space Studies, states: "The ISCCP group produces an indpendent 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. 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." (Palle et al. base their claim on Earthshine data, which is a measurement of the glow of the dark side of the moon that they use to deduce the earth's reflectance and on proxy derived from ISCCP parameters after they are regressed with two years of overlapping, but not global,
    earthshine observations.)

    Tselioudis further points out that "satellites can see actual low clouds only when high clouds 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."

    He explains further "The increases in both high-level and middle level clouds 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."
     
  8. Feb 24, 2007 #7
    Hi, S, Thanks for the elaboration. Maybe you intended to post that in this thread?

    https://www.physicsforums.com/showthread.php?t=108165

    it would be good to know what the difference is exactly in the interpretation of the same data of Palle et al 2006. After all, you would expect a peer review of experts familiar with ISCCP data handling.

    I believe that also temperature graphs don't show a trend the last four years, temperatures remained roughly constant.

    Surely, considering trends in those short periods has little statical value indeed. However, the oceans apparently also reacted to the change in trend of the last four years:

    http://www.ocregister.com/ocregister/opinion/columns/article_1245606.php

     
  9. Mar 2, 2007 #8
    Palle's Earthshine Paper, Why there are less clouds?

    Attached is a link to Palle's Earthshine Data (Palle et al measured the planet's albedo by using telescopes and the brightness of the moon.)

    http://solar.njit.edu/preprints/palle1266.pdf

    The conclusion of Earthshine analysis is that from 1994/1994 to 2001 planetary cloud cover decreased by 5% +/-1.7%, which would result in an increase in planetary temperature. This finding is consistent with Palle's research that show satellite data support the same conclusion.

    The areas where the cloud decrease was observed to decrease is consistent with the mechanism "electroscavenging" where an increase in the global electric current, removes ions from the atmosphere and hence reduces cloud cover. As the continents are slightly radioactive there which continual creates ions, the affect is strongest over the ocean.

    Attached is a paper by Brian Tinsely the explains the mechanism. (See the picture of the global electric circuit.)

    Expanded version of a paper by Tinsley and Yu, “Atmospheric Ionization and Clouds as Links between Solar Activity and Climate”

    http://www.utdallas.edu/physics/pdf/Atmos_060302.pdf
     
  10. Mar 3, 2007 #9
    Solar Changes & Cloud Cover

    The following is a hypothesized cause to explain why there was an observed reduction in low cloud planetary cover for the period 1993 to 2001. (See my above comment, that asserts that an increase in the global electric current, which removed cloud forming ions through the process of "electroscavenging", caused the observed reduction in cloud cover 1993 to 2001.)

    Attached is a paper that shows there is close correlation between the solar wind speed and changes in the planetary temperature. The high speed solar wind is caused by cornal holes which have began to appear at the end of the solar cycle. Because of the high speed winds from coronal holes, there is no longer correlation with sun spot number and planetary temperature. See figure 6 in the attached paper that shows there is close correlation between observed global temperature anomalies and the solar index "ak".

    From the attached paper:

    "It has been noted that in the last century the correlation between sunspot number and geomagnetic activity has been steadily decreasing from - 0.76 in the period 1868-1890 to 0.35 in the period 1960-1982, ... According to Echer et al (2004), the probable cause seems to be related to the double peak structure of geomagnetic activity. The second peak, related to high speed solar wind from coronal holes (my comment: For example coronal hole 254 that produced the Dec 16, 2006 peak in solar wind, during a sun spot minimum, see attached link to Solar Observation Data), seems to have increased relative to the first one, related to sunspots (CMEs) but, as already mentioned, this type of solar activity is not accounted for by sunspot number. In figure 6 long term varations in global temperature are compared to the long-term variations in geomagnetic activity as expressed by the ak-index (Nevanlinna and Kataga 2003). The correlation between the two quantities is 0.85 with p< 0.01."

    2005 paper by Georgieva, Bianchi, & Kirov “Once again about global warming and solar activity”

    http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..969G.pdf

    http://www.dxlc.com/solar/
     
  11. Mar 3, 2007 #10
    Highest Solar Activity in 8000 yrs & affect on Climate

    In further support of the assertions that solar activity is responsible for a significant portion of the 20th century warming, attached is a link to the 2004 paper by Solanki, Usokin, Kromer, Shussler, Beer "Unusual activity of the Sun during recent decades compared to the previous 11,000 years"

    http://cc.oulu.fi/~usoskin/personal/nature02995.pdf

    The following is an excerpt from that paper:

    "According to our reconstruction, the level of solar activity during the last 70 years is exceptional, and the previous period of equally high activity occurred more than 8000 years ago. We find during the past 11,400 years the Sun spent only of the order of 10% of the time at a similar high level of magnetic activity and almost all of the earlier high-activity periods were shorter than the present episode." In the paper they also note that based on historical records there is only a 8% probablility +3%/-4% the current high solar level will continue for the next 50 years.

    Solanki et al, also state that the current high level of solar activity is not likely to account for planetary warming in the last 30 years, however, the data from Palle (see my above comments) from both satellite observation of clouds and the earthshine data, contradicts Solanki et al's statement. What is clear is that the sun has for the last 100 years been at very high activity levels. It appears based on information over the last year, the sun has began to move to a low activity state.

    Attached is a paper, by Lockwood, Stamper, and Wild that notes the sun's large-scale magnetic field has doubled in the last 100 yrs. As noted in the attached paper the solar large scale magnetic field reaches out into interplanetary space and helps shield the earth from Galactic Cosmic Rays (GCR). Palle's satellite data supports the assertion that GCR changes affect cloud formation, higher GCR more cloulds as clouds reflect the sun, less or more clouds would result in warmer or colder temperatures. A doubling of the sun's large scale field has resulted in less GCR which will reduce low level cloud cover.

    As noted in my previous comment cloud cover is also reduced by the process of "electroscavenging" which removes ions from the atmosphere.

    Doubling Sun’s Coronal Magnetic Field in Last 100 years
    http://www.nature.com/nature/journal/v399/n6735/abs/399437a0.html
     
  12. Mar 12, 2007 #11
    End of Global Warming?

    The papers referenced above provide data and analysis to support the assertions that there:

    Has been very significant Solar Changes in the 20th Century.
    1. That the solar activity in the 20th century is at its highest level in 8000 kyrs. (see papers for details.)
    2. That the solar large scale magnetic field has more than doubled in the last 70 years. (An increase in the large scale solar magnetic field reduces the number of Galactic Cosmic Rays (GCR) that reaches the earth's atmosphere. (See next comment as to how that affects cloud cover.)
    3. That the solar coronal holes have started to move towards the solar equator at the end of the solar cycle, which increases the solar wind at a period in the solar cycle when it would normally have been reduced. (The high speed solar wind from the coronal holes, causes an increase in the global electric current, which through the Tinsley's named process of "electroscavenging" removes cloud forming ions.)
    4. That there is direct correlation with planetary temperature and solar activity. (i.e. When the solar activity was reduced in 1950 to 1970, the planetary warming was abated and the planet cooled. See solar paper for details.)

    That the Solar Changes Affects the Amount of Low Level Clouds
    1. Svensmark and Palle have both used satellite data to show that there is an 99.5% correlation between Galactic Cosmic Rays (GCR) and low level clouds for the period 1983 to 1994. (Increase in GCR, causes an increase in clouds particularly over the oceans were there is a lack of ions to form cloud nucleus.) A decrease in low level clouds causes the planet to warm.
    2. From 1993 to 2001 "electroscavenging" results in a reduction in clouds which Palle theoretically calculates:
    The next set of questions to ask, do stars have cycles? Do stars move to an inactive stage after an active stage? (i.e. Solar cycle stops, solar large scale magnetic field decays, and solar iridescence is reduced.) How rapidly and how sever will the planet cool, based on the proxy climatic data or based on observations of sun like stars?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Climate change and Earth reflectivity
  1. Climate change (Replies: 12)

Loading...