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Is Mars warming?

What the science says...

Select a level... Basic Intermediate

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).

At a glance

You really have to hand it to climate science deniers. In the one breath, they claim global warming on Earth is all down to poor/badly-sited weather-station coverage. Then in the next, they assert that Mars is warming. How many weather stations are there on Mars? In that sense, this claim serves to point out the absurd depths that climate science deniers plumb at times.

But in another sense, it offers the opportunity to explore why the climates of Earth and its neighbour differ so much. For, in times long past, Mars had an atmosphere and running water in abundance. Not any more. It is a cold, dry and - so far as we know - dead planet.

We know there was water there on Mars from the layered, river- or lake-deposited sedimentary rocks there, examined by robotic landers. What happened to it? The answer lies in the Red Planet's global magnetic field. It collapsed billions of years ago.

Why Earth still retains a strong global magnetic field but Mars does not is still the subject of much research. What we do know is that on our planet the spinning, liquid metal outer core acts as a powerful dynamo. Our thus-generated global magnetic field works as a vital planetary shield against the Solar wind and cosmic rays. In contrast, Mars has little such protection any more: long ago, once it lost that shield, the vast majority of its atmosphere was stripped away by those Solar winds.

No atmosphere, no greenhouse effect as such. Mars instead experiences extremes of heat and cold (from -153 to +20 C according to NASA) depending on what part of the planet is facing the Sun - and constant drought. Long lived, sometimes planet-wide dust-storms can occur when the dry ground becomes especially warm, even on a planet whose atmosphere has a density of just 1% of Earth's. Because of that very low density, atmospheric pressure on the Martian surface is a fraction of that on Earth and winds are much lighter, but combine a stiff breeze, plentiful dust and the fact that hot air rises (hence dust devils, observed by those robotic landers) and you have the mechanism for getting that dust up.

In turn, the dust blocks some sunlight from getting down to the surface, so here we have a temperature regulating mechanism. But even the biggest dust-storms - that can be viewed with telescopes here on Earth - end at some point. Mars therefore has no long-term temperature trend but its inhospitable climate nevertheless varies  - but for completely different reasons than here on Earth.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

The motive for making inaccurate claims about other planets also experiencing warming is not hard to imagine: it's yet another variant of the "it's the Sun" family of arguments. All members of this group of myths depend on Solar irradiance steadily going up and up through time. Yes that does happen, hence the Faint Young Sun paradox, but there we're talking about a trend only detectable over geological timescales, not centuries.

As fig. 1 shows, in fact from around the mid 1970s onwards, global temperatures have risen while total Solar irradiance has declined. So that puts the "it's the Sun" family of arguments straight to bed.

 Annual global temperature change and Annual Total Solar Irradiance.

Figure 1: Annual global temperature change (thin light red) with 11 year moving average of temperature (thick dark red). Temperature from NASA GISS. Annual Total Solar Irradiance (thin light blue) with 11 year moving average of TSI (thick dark blue). TSI from 1880 to 1978 from Krivova et al. 2007. TSI from 1979 to 2015 from the World Radiation Center (see their PMOD index page for data updates). Plots of the most recent solar irradiance can be found at the Laboratory for Atmospheric and Space Physics LISIRD site.

With specific regard to Mars, it can readily be counter-argued that we know so little about Mars - compared to Earth - that we cannot yet talk about things like temperature trends. We just don't have the details, even though the orbiters and robotic landers are providing valuable and fascinating insights into some aspects of the Red Planet. Yet even this so far small amount of data can be misinterpreted, in terms of causal complexity and significance. And that's a funny thing about climate science denial. Its practitioners cast all sorts of aspersions regarding temperature measurements here on Earth, but in the case of Mars, all of a sudden their expectations are somewhat lowered, so this time they base their claims on limited spatial coverage and direct measurements taken over only a few decades.

There are, however, a few general points about the climate on Mars that are worth listing:

  • 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.That's because the Martian orbit varies in eccentricity by over five times more 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. Because of that very thin atmosphere, the planetary greenhouse effect is also of negligible importance.
  • The whole planet is subject to massive dust storms, and these have many causal effects on the planet’s climate, aspects of which we don't understand yet. However we do know that on Earth dust-clouds can reduce the sunlight (and therefore heat energy) reaching the surface.
  • 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.

The 'global warming on Mars' argument had at least some of its roots in a paper written by a NASA team, entitled, "Global warming and climate forcing by recent albedo changes on Mars" (Fenton et al. 2007). But this paper is about changes in Martian albedo - the property of light surfaces to reflect incoming sunlight, Variations in brightness of parts of the Martian surface have been recorded ever since we have had telescopes powerful enough to look at the planet in detail.

The study compared pictures of the Martian surface taken in 1977 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 et al used a general circulation model to investigate further.

Results indicated the presence of relatively enhanced wind stress in recently darkened areas and decreased wind stress in brightened areas. This produced a positive feedback system in which the albedo changes strengthen the winds that generate the changes. The simulations also predicted a net annual global warming of surface air temperatures by ∼0.65 K over that 22-year period (the abstract was a bit confusing on this point - see corrigendum here), enhancing dust lifting by increasing the likelihood of dust devil generation. The increase in global dust lifting by both wind stress and dust devils may, they thought, affect the mechanisms that trigger large dust storm initiation, a poorly understood phenomenon, unique to Mars. They suggested that documented albedo changes affect recent climate change and large-scale weather patterns on Mars, and thus albedo variations are a necessary component of future Martian atmospheric and climate studies.

Let me repeat part of the last but one sentence above: "unique to Mars". That's right there, in the abstract. Neither the Martian atmosphere, environment nor climate are remotely like anything on Earth. Yes, albedo-change is important on Earth but is a feedback driven by other forcings unrelated to Martian goings-on. Furthermore, a 22-year long study-period with two endpoints and nothing much in between is not robust in terms of a climatic trend.

Indeed in a recently published paper (Scariah et al. 2023), analysis of the seasonal variation of evening temperature over Gale Crater and its surroundings from Martian years MY 12 to MY 35 (equivalent Earth years 1976–2020) was carried out using data from different orbiter missions. The data showed variability (including significant drops in temperature during MY 26 and MY 32) but a trend? No.

To conclude: Mars' cold, arid climate is primarily driven in the long term by orbital eccentricity and in the short term by changes involving dust and albedo, not solar variations. In any case, we know the sun is not heating up the planets in our solar system because we can accurately measure the sun’s output, both here on Earth and in nearby space.

Last updated on 29 October 2023 by John Mason. 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.


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.

Further viewing


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Comments 51 to 59 out of 59:

  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.


    [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:

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

  7. Our world has been changing over a period of time as a same as the universe. I think a climate is one of a factor that makes planet changed. Radiation from the sun can be a cause that makes the temperature change. I understand that each planet has their own relationship and effect. But I'm not really sure that effect from volcanos can make earth cooling and makes mars warming. Is this really true?

  8. The common est. of Earth's TSI [ Total Solar Irradiance ] is actually

    ca. 1365 W/m2 [ Watts per square meter ;  properly "W/m^2" ]  \ 


    ( Right now, 2022 Feb., it's measured at 1366 W/m^2 , w/ a variance thru the most recent solar cycle of 1.6 W/m^2 \ )  


    ( Just one of myriad sources for this :  LINK ) 


    ( This was just to correct an earlier commenter's mis-quote of it , as "240 W/m2" \ ) 





    [DB] Shortened link breaking page formatting

  9. Waking2Kindness #[cSSw#d0h @58,

    Your correction should perhaps be subject to a bit of give & take.

    Thus you are correct that the Sun gives out 1367Wm^-2 of TSI to the Earth. But this is for the disc of the Earth famously od area πR2.

    The Earth takes this TSI over its entire sphere of area 4πR2 and of this 30% is reflected back into space. Thus the actual planetary warming totals [70% of 1366 / 4 ≈]  240Wm^-2.

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