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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Climate Hustle

Global warming on Mars, ice caps melting

What the science says...

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Mars is not warming globally.

Climate Myth...

Mars is warming
"Some people think that our planet is suffering from a fever.  Now scientists are telling us that Mars is experiencing its own planetary warming: Martian warming. It seems scientists have noticed recently that quite a few planets in our solar system seem to be heating up a bit, including Pluto. 

NASA says the Martian South Pole’s “ice cap” has been shrinking for three summers in a row. Maybe Mars got its fever from earth. If so, I guess Jupiter’s caught the same cold, because it’s warming up too, like Pluto."  (Fred Thompson).

It is hard to understand how anyone could claim global warming is happening on Mars when we can’t even agree what’s happening on the planet we live on. Yet they do, and the alleged reasoning is this; if other planets are warming up, then there is some solar system-wide phenomena at work – and therefore that it isn’t human activity causing climate change here on Earth.

The broadest counter argument depends on a simple premise: we know so little about Mars that it's impossible to say what trends in climate the planet is experiencing, or why changes occur. We do have information from various orbiting missions and the few lander explorations to date, yet even this small amount of data has been misunderstood, in terms of causal complexity and significance.

There are a few basic points about the climate on Mars that are worth reviewing:

  • Planets do not orbit the sun in perfect circles, sometimes they are slightly closer to the sun, sometimes further away. This is called orbital eccentricity and it contributes far greater changes to Martian climate than to that of the Earth because variations in Mars' orbit are five times greater than the Earth.
  • Mars has no oceans and only a very thin atmosphere, which means there is very little thermal inertia – the climate is much more susceptible to change caused by external influences.
  • The whole planet is subject to massive dust storms, and these have many causal effects on the planet’s climate, very little of which we understand yet.
  • We have virtually no historical data about the climate of Mars prior to the 1970s, except for drawings (and latterly, photographs) that reveal changes in gross surface features (i.e. features that can be seen from Earth through telescopes). It is not possible to tell if current observations reveal frequent or infrequent events, trends or outliers.

A picture is worth a thousand words, but only if you understand what it is saying

The global warming argument was strongly influenced by a paper written by a team led by NASA scientist Lori Fenton, who observed that changes in albedo – the property of light surfaces to reflect sunlight e.g. ice and snow – were shown when comparing 1977pictures of the Martian surface taken by the Viking spacecraft, to a 1999 image compiled by the Mars Global Surveyor. The pictures revealed that in 1977 the surface was brighter than in 1999, and from this Fenton used a general circulation model to suggest that between 1977 and 1999 the planet had experienced a warming trend of 0.65 degrees C. Fenton attributed the warming to surface dust causing a change in the planet's albedo.

Unfortunately, Fenton’s conclusions were undermined by the failure to distinguish between climate (trends) and weather (single events). Taking two end points – pictures from 1977 and 1999 – did not reveal any kind of trend, merely the weather on two specific Martian days. Without the intervening data – which was not available – it is impossible to say whether there was a trend in albedo reduction, or what part the prodigious dust storms played in the intervening period between the first and second photographs. Indeed, when you look at all the available data – sparse though it is – there is no discernable long term trend in albedo.

At this time, there is little empirical evidence that Mars is warming. Mars' climate is primarily driven by dust and albedo, not solar variations, and we know the sun is not heating up all the planets in our solar system because we can accurately measure the sun’s output here on Earth.

Basic rebuttal written by GPWayne

Last updated on 1 August 2013 by gpwayne. View Archives

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Planet wide dust storm

A good example of how dust affects Mars climate: over 2007, Mars suffered a titanic dust storm that engulfed the entire planet. The dust storm contributed to a temporary warming effect around Mars, raising the temperature of the atmosphere by around 20-30°C. Interestingly, whereas the atmosphere of the planet heats up, the surface of the planet cools down because it receives much less solar heat.

Acknowledgements

Many thanks to Mark Richardson for his advice and materials on Martian climate. Thanks also to Jon for the heads-up on Mark Richardson's latest AGU presentation.

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Comments

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Comments 51 to 56 out of 56:

  1. Dutchwayne @49, it is difficult to take seriously a comment that says, "The biggest weakness though is on the side of the critics of Mars warming"  while ignoring that the evidence put forward for Mars warming by AGW "skeptics"  seems primarilly to be evidence of changing seasons.  See my comments at 29, and at 31, along with HK's comment at 40.

    If we consider the more serious evidence of a warming Mars, it comes in two forms.  The first is the study by Fenton (2007) that showed changes in albedo on the Mars surface:

    Averaged across all areas, the surfuce darkened, implying a greater absorption of sunlight.  From this, Fenton deduced a global warming on Mars of surface by approximately 0.6 C.  Note that we do not possess independent measurements of Global Mean Surface Temperature of Mars of sufficient duration to independently confirm the magnitude of that increase.  Rather, from a change in albedo, we deduce a change in GMST for Mars.

    This immediately suggests a problem with your claim that we use Mars as "a cleaner way to determine the true solar radiation impact on Earth".  The GMST of Mars is not effected by incoming sunlight alone, as you claim, but also by changes in albedo.  Worse, while we know of the changes in albedo, we do not know the value of the change in GMST on Mars in any event in order to make your indirect measure.

    There is some direct, but inconclusive evidence of warming on Mars.  Specifically there have been reductions in the amount of CO2 ice at the South Pole, shown here:

     

    (See also here and here.)

    This evidence does show that there is polar warming at the South Pole of Mars, but does not show conclusively a reduction of martian GMST, as it may be matched by cooling elsewhere (particularly tropical regions, in some of which there are significant increases in albedo).  However, it also shows an increase in CO2 in the martian atmosphere - and consequently an increase in the martian greenhouse effect.  This introduces a second confounding factor to the martian GMST proxy of changes in insolation, measurements of which we do not have in any event.

    Given these two confounding factors (changes in martian albedo, and changes in martian atmospheric CO2) and the lack of long term temperture measurements on Mars, perhaps (as Eclectic sugggests @50) we should relly on the satellite record of Total Solar Irradiance.  That record, of course, shows an overall decline in TSI since the 1980s:

     

  2. Dutchwayne@49:
    "There is little heat being generated in the planet unlike Earth and therefore virtually all the thermal impact comes from only one driver: Solar radiance."

    That is also true for our own planet! The sun delivers about 240 watts/m2 or at least 2600 times more than the tiny 0.09 watts/m2 trickling out from the interior of Earth. The corresponding number for Mars is probably about ¼ of that. Only the gas giants have enough internal heat to make a large impact on their climate.

    "Mars is in fact a better indicator of Solar activity variation than Earth…"

    Maybe, but if we can measure the solar activity directly from Earth much more precisely, what’s the point in making a poor estimate based on very incomplete temperature data from Mars? Those measurements clearly show a reduction of the total solar irradiance (TSI) over the last 35 years or so, especially during the last solar cycle. (see the last chart in @51). In addition, the recent warming on Earth has certain fingerprints that don’t match what to expect from a warming caused by increased solar activity. Some of these fingerprints are more warming in winters and at high latitudes and a cooling of the upper atmosphere.

    If Mars actually has undergone a warming caused by the reasons mentioned by Tom in @51, it’s just a coincident and certainly not related to the warming on Earth, as there is no way albedo changes on one planet can have an impact on another.

  3. Updated links to Geissler 2005 and Szwast 2006.

  4. So you start off by saying there is no way to prove that Mars is warming. Then you go forth trying to explain why teh ice caps are shrinking.

    Very simple reason, the temperature has moved above the freezing point.  There is no other  reason you can give to explaiin what us happening.

    In layman's term it is WARMING.

    You just do nto want to accept it because it will mean anotehr factor in play with our own planets which cause temperatures to change.

    Most likely reason that could effect both planets ice caps????  SOLAR ACTIVITY.

    Response:

    [JH] Sloganeering and all-caps snipped. 

    Please note that posting comments here at SkS is a privilege, not a right.  This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

  5. The conclusion of Fenton, that  Mars temperature rose, is just a physics calculation that I remember from college Astronomy.  If the surface darkens, more sunlight is absorbed, the temperature will rise, causing more heat radiation (black body radiation).   Temperature will rise until the black body radiation of the higher temperature is in equilibrium with the new heat absorbtion.  It assumes TSI is constant.  So this is not a measurement per se.

    Regarding question by mj at 43, I think skeptics are correct in that mentioning Venus is not very useful in advancing GW argument.  By using the same albedo/black body radiation that was used for Mars..... Venus is 67M miles vs 93M miles so it absorbs twice the solar radiation.  If Venus had the same albedo and same greenhouse as earth, it would still be unbearably hot.   About 185 degrees Fahrenheit....too hot for me.  Greenhouse or not, I'd be dead on that planet. 

    Here is link on Planet tempearature and blackbody radiation: https://en.wikipedia.org/wiki/Planetary_equilibrium_temperature

  6. EE @50, I have responded to your comments on Venus on a more appropriate thread.

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