Global warming on Mars?

Globally, the mean temperature of the Martian atmosphere is particularly sensitive to the strength and duration of hemispheric dust storms, (see for example here and here). Large scale dust storms change the atmospheric opacity and convection; as always when comparing mean temperatures, the altitude at which the measurement is made matters, but to the extent it is sensible to speak of a mean temperature for Mars, the evidence is for significant cooling from the 1970′s, when Viking made measurements, compared to current temperatures. However, this is essentially due to large scale dust storms that were common back then, compared to a lower level of storminess now. The mean temperature on Mars, averaged over the Martian year can change by many degrees from year to year, depending on how active large scale dust storms are.

In 2001, Malin et al published a short article in Science (subscription required) discussing MGS data showing a rapid shrinkage of the South Polar Cap. Recently, the MGS team had a press release discussing more recent data showing the trend had continued. MGS 2001 press release MGS 2005 press release. The shrinkage of the Martian South Polar Cap is almost certainly a regional climate change, and is not any indication of global warming trends in the Martian atmosphere. Colaprete et al in Nature 2005 (subscription required) showed, using the Mars GCM, that the south polar climate is unstable due to the peculiar topography near the pole, and the current configuration is on the instability border; we therefore expect to see rapid changes in ice cover as the regional climate transits between the unstable states.

Thus inferring global warming from a 3 Martian year regional trend is unwarranted. The observed regional changes in south polar ice cover are almost certainly due to a regional climate transition, not a global phenomenon, and are demonstrably unrelated to external forcing. There is a slight irony in people rushing to claim that the glacier changes on Mars are a sure sign of global warming, while not being swayed by the much more persuasive analogous phenomena here on Earth…

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62 comments on this post.
  1. Lynn Vincentnathan:

    I just read a news item about a Duke study showing solar output has been increasing at

    Anything to this? And how would it affect Earth & Mars?

    [Response: We recently discussed this very topic in this post (see also previous posts here and here) - Mike]

    (My thinking is that even if part of the warming on Earth has been caused by increasing solar output, that simply means we must redouble our efforts to do what we can to reduce GHGs, esp. since we have no control over the sun & its increased output could spell big trouble.)

    [Response:In essence, this work analyses the total solar irradiance (TSI) estimates by Willson & Mordvinov (2003) which is known to exhibit an increase in the TSI at solar minimum between solar cycles 21--22 and 22--23 (the most recent solar cycles, with minima at around 1986 and 1996 respectively). Their conclusion is therefore given by this choice. Had they used an other TSI record eg by Frolich & Lean (1998), they would have got a very different result. The interesting aspect of this study is that whereas the TSI is purpurted to have increased, other solar proxies (eg cosmic rays, 10.7 cm flux, the aa-index, or the monthly sunspot number) do not indicate any systematic change in the level of solar activity. In their analysis they also in effect compare the amplitudes of two series which have been band-pass filtered in a similar way, and do not provide convincing evidence that they really are related - there are wiggles of similar frequencies, as expected when they have been band-pass filetered, but they do not exhibit a convincing one-to-one correspondence (in neither phase or amplitude), and the authors do not discuss the level of statistical significance. -rasmus]

  2. Terry Wolfe:

    I have been trying to identify a measurement that says how much the climate has changed over a time frame that might represent human induced change. As hard as I try the answers are so variable as to be meaningless. It seems like the numbers selected are done more for political reason than science.
    Now comes a report that the sun’s output is having a significant effect on the temps we see. It makes me wonder if the rest of the changes we think we see are also caused by natural conditions much like what causes the end of an ice age and the warming that follows.
    Just a thought

    [Response: [[Attribution of recent climate change]] and the IPCC links therein should be what you are looking for – William]

  3. nanny_govt_sucks:

    Triton and Pluto are warming too.

  4. Steinn Sigurdsson:

    Just on the off-chance the 3rd comment is serious: Pluto has not been observed for a full orbit, so we have no data on secular changes in its mean temperature. However, it is currently headed into winter, its orbit is highly eccentric and surface temperatures are dominated by where it is in its orbit. So, the current trend is for Pluto to be cooling quite significantly.
    Triton is a moon in a close retrograde orbit, data is very sparse, its “year” around Neptune is short, but Neptune’s orbital period is longer than we have known about Triton, so again no data on long term secular trends. Further, internal tidal heating is significant on Triton, so insolation is not the only factor.

    We talked about the claim from Duke, and decided to pass it over for the purpose of the Mars climates trends. It is essentially irrelevant whether the insolation has changed at that level, both when trying to understand the regional south pole climate changes, and long term climate trends on Mars.

  5. Joel Shore:

    I had just been in a discussion of climate change on a messageboard where someone had triumphantly put up links to various blogs (including one that you noted here) drawing conclusions about the cause of the global warming here on earth on the basis of these recent measurements of Mars’s south polar cap!

    Thank you, RealClimate, for once again coming through to provide real scientific information to counter the ill-informed conclusions emanating from those people whose goal is to misuse and misinterpret scientific results to fit their own preconceived conclusions!

  6. Gregory Lewis:

    For a very interesting prediction of global climate change on Jupiter see the links at

    Really the prediction is about a 70 year climate cycle.

    From the UC Berkeley press release:

    “I predict that due to the loss of these atmospheric whirlpools, the average temperature on Jupiter will change by as much as 10 degrees Celsius, getting warmer near the equator and cooler at the poles,” says Marcus. “This global shift in temperature will cause the jet streams to become unstable and thereby spawn new vortices. It’s an event that even backyard astronomers will be able to witness.”

    According to Marcus, the imminent changes signal the end of Jupiter’s current 70-year climate cycle. His surprising predictions are published in the April 22 issue of the journal Nature.

  7. nanny_govt_sucks:

    #4 – “So, the current trend is for Pluto to be cooling quite significantly.”

    A simple google on “pluto warming” reveals much information to the contrary.

  8. Steinn Sigurdsson:

    Indeed. For example this succinct summary on
    The data is on atmospheric absorption during occultations, indicating short time scale variability.
    Note Pluto seems to have a very high obliquity; the atmosphere is on the edge of an atmospheric phase transition; and there is a possibility of volcanism (Pluto has a large, close moon – Triton’s short term atmospheric variability is almost certainly due to variable volcanism).
    The secular trend in Pluto’s average temperature is cooling, and it is driven by Pluto going into winter. You can no more infere warming from these measurements than you can infer warming from Santa Ana conditions in California in autumn, or “Indian Summer” warming in the US NorthEast in autumn.

  9. PHEaston:

    Interesting read. However, its unfortunate that an apparently good article should finish with a misleading jibe at those on the other side of the scientific debate.

    Those who legitimately question the case for man-made global warming (AGW) do not question whether glacier retreat is evidence of global warming. What they question is whether it is evidence of ‘man-made’ global warming (AGW). And given that at least some retreating glaciers reveal earlier habitations beneath (in Scandinavia for example), this is a highly legitimate question.

    [Response: You'll find pointless quibbling about the glacier stuff from skeptics, including plenty who question the reality of the warming, not just its cause. Also, I removed a small bit of trolling from your comment - William]

  10. Thermodynamist:

    nanny govt sucks said: Triton and Pluto are warming too. Triton!? Hahaha. Well there is the universal background heat radiation, the slowly cooling traces of the Big Bang. So, whatever the local conditions are the universe can only cool. Unless time can run backwards.

  11. RickN:

    To many scares the last couple of decades based on “scientific proof”, not enough facts.

  12. Lynn Vincentnathan:

    I don’t know squat about other planets (& not much about Earth), but it seems contrarians are using “warming of other planets” as a reason to deny AGW here on Earth.

    Well, for the sake of arguement, even if they’re right, this doesn’t mean ipso facto AGW can’t happen, it just means there are other factors that can warm or cool a planet. While we might HOPE FOR THE BEST – that there will be a cooling trend (less sun irradiance, etc) to exactly counteract our AGW trend (even so there is the negative effects of CO2, even without the warming – ocean acidification, crop loss to weed, etc) – we should then be trying to AVERT THE WORST with even more drastic GHG cuts. Would we really want several warming factors (solar, volcanism, etc), including AGW, to piggy-back on each other & send us into really dire straits? Contrarian arguments give me no solace at all, but just want to make me redouble efforts to reduce GHGs.

  13. Steinn Sigurdsson:

    The Scafetta and West article on possible increase in total solar irradiance (averaged over a solar cycle) is to be found here.
    The mean insolation at Earth orbit is about 1366 W/m^2; the peak-to-peak variation over the 11 year solar cycle is about 3 W/m^2; the authors discuss two running averages derived from different satellite data sets and analysis derived by Willson and Mordvinov (2003) and Frohlich and Lean (1998) respectively. The latter show negligible change in the mean solar radiance over the data span (formally shows a statistically insignificant cooling) the latter suggest there is a possibly signifcant increase in the mean from 1980-1990 to 1990-2000.
    The change in the mean is about 0.05% or about 0.5 W/m^2, much less than the variation within a cycle. The corresponding first order fractional change in temperature (neglecting any feedbacks) would be about 0.01%, or about 0.03K at Earth. The temperature anomaly on Earth over the same period is about 10 times larger, hence the suggestion that IF the ACRIM inferred changes in the mean insolation are correct, then the inferred increase in solar radiance would account for about 10% of the temperature anomaly over the same period. Which would leave 90% of the anomaly to be due to other causes.
    Best I can tell, Scafetta and West want to push this up by using the 22 year solar cycle, which unfortunately is then exactly the data span, making it harder to compare changes between cycles. They then infer a higher temperature sensitivity to changes in radiance over this cycle and conclude that maybe 0.1 K temperature increase would be possible due to the variation in solar radiance, or about 30% (if you push it) of the total temperature anomaly over this period.

    BUT: a change in solar radiance of 0.5 W/m^2 at Earth, or about 0.05% fractional change over the period 1980-2000, is irrelevant to either the changes in Pluto’s atmosphere this year, or the changes at the Mars South Pole between 2001 and 2005. Those changes are local, occuring on a different time scale, and if due to direct external forcing would require higher changes in solar radiance than claimed.

    For example, 2005 is near solar minimum in the 11 year cycle, and radiance now is about 1-2 W/m^2 less than a few years ago, which means Pluto and Mars are getting LESS solar radiance on the time scale of the atmosphere and polar cap changes, EVEN IF the radiance averaged over the whole cycle was higher. In fact the mean radiance over 11 years would have to increase by several times the estimated amount in order to overwhelm the current minumum in radiance due to the 11 year cycle. This would be easily detected and is not there.

    The inference people are drawing from anecdotal news items about climate on Mars and Pluto is flat out wrong, and contrary to the facts. If you want to evaluate the relevance of such items, going to the primary source and reading it in context is necessary, not cherry picking from news articles.

    Let me repeat: the south pole of Mars is getting less sunlight in 2005, because of variation in solar radiance over the 11 year cycle, then it did in 2001 and 2003. This is the case even if there is a change in the mean radiance over decades (between solar cycles) because the year-to-year variation within a cycle is larger than the variation between cycles, and we measured solar radiance in 1999-2005.

  14. Steve Latham:

    This is really cool (no pun intended). My thanks to Steinn for the original post and his comments. Sorry for adding another comment not related to the science:

    RickN says, ‘To many scares the last couple of decades based on “scientific proof”, not enough facts.’ I have seen this written before, but I don’t get it. What scientific scares are these? Ozone depletion was a real threat — the warnings of scientists had the result that it has been somewhat adequately addressed. I’m not looking for a long argument, but perhaps someone can supply a simple list of recent scientific failures (I’ll google or wikipedia myself) where subsequently disproven “proofs” were cited that scared the public needlessly. Second, how many is too many? Thanks.

  15. Arun:

    You’ve been Luboshed! See the later part of:

  16. Steinn Sigurdsson:

    Readers may want to read string theorists Lubos Motl’s take on this.

    I will respond to Lubos’s comments in due course.

  17. Quantoken:

    You are welcome to go to my blog where I explained, in detailed calculation, why resource limitation will prevent us from achieving filling the atmosphere up to 400 ppmv of CO2:

    A case for the 400ppm CO2 limit

    I wish we spend more time debating the problem of oil depletion, which is much more meaningful and relevant, rather than global warming, which is irrelevant and meaningless and purely hypothetical.

    CO2 will not go beyond 400 ppmv under any circumstance, period.


    [Response: This is not on topic, and completely mistaken. There are enough fossil fuel reserves (in oil, coal, and methane hydrates) to continue to increase CO2 way beyond 400ppmv as will be seen in a very few number of years. See here for instance. Please find another venue to discuss this. -gavin]

  18. Steinn Sigurdsson:

    If current coal reserves are burned on a time scale short compared to time scales for carbon storage, then CO2 concentrations will go over 400 ppm rather easily.
    Same is true for any other rapid release of a large enough carbon reservoir, such as large enough methane deposits, if they exist, or carbonate rock, if large enough a mass is heated by large enough a magma.

  19. Michael Tobis:

    Re #17 and the referenced blog article:

    Quantoken ignores the geological carbon cycle, presuming that the entire present O2 inventory is identical to the O2 component of primordial CO2, and that no other sources or sinks of carbon or oxygen are relevant. Then Q. works backwards to obtain a carbon inventory, using various online sources.

    One crucial flaw is easy to spot. On geological (as opposed to historical) time scales the carbon inventory includes a great deal of mass that is in the earth’s interior. The system is replenished by vulcanism. Even assuming no other flaws in the argument this pretty much invalidates the whole thing. Sorry.

    See for example.

  20. Quantoken:

    I don’t think you know what you are talking about. There are certainly MUCH more carbon than what’s contained in the fossil fuel and the atmosphere, like lime stones are CaCO3. I am also well aware of that volcanoes will release lots of various gases including CO2. But that is NOT the topic!
    The topic is about carbon in biomass and in fossil fuels, and about CO2 released in burning them, not about the hypothetical super vivano eruption, like the yellow stone.
    I am NOT making the presumption of equaling today’s O2 with the oxygen contained in primordial CO2. You made it up and inserted it into my mouth. I am only assuming that today’s free O2 is 100% associated with biomass, and therefore, every one part of O2 exists today is associated with one part of CO2 being absorbed by biomass. Therefore you count how much O2 there is, and that gives you an idea how much carbon has ever been absorbed by biomass. Because, every one knows volcanoes do not release free O2 gases. Any free O2 has got to be made by plantations and therefore is associated with biomass. It could well be the primordial CO2 is much higher and a considerable portion is absorbed to form CaCO3, the lime stone. But still the part absorbed into biomass exactly equates the amount of O2 we see today! As a matter of fact, if you burn every little bit of fossile fuel and all the free carbons and any thing of biomass origin, you would exactly exhaust all oxygen and render the atmosphere back to the lifeless and oxygen depleted primordial environment.


  21. Quantoken:

    And the fact that my very rough estimate gave the exactly correct figure of current world petroleum reserve figure, speaks volume of its correctness. I figured out how much oil there is, by looking at the sky only, without having to search underground geologically . You can’t beat that!!!


  22. Michael Tobis:

    Re #20

    I am only assuming that today’s free O2 is 100% associated with biomass, and therefore, every one part of O2 exists today is associated with one part of CO2 being absorbed by biomass.


    Therefore you count how much O2 there is, and that gives you an idea how much carbon has ever been absorbed by biomass.

    This does not follow and is wrong. There are important oxygen sinks, notably the CaCO3 formation Q alluded to in the same posting.

    There are various other elementary errors in the presentation.

    Regarding the conclusion, another crucial flaw is that Q doesn’t seem to believe or care that coal combustion contributes to anthropogenic greenhouse gas emissions.

    RC editors should not allow more postings about this theory, in my opinion.

  23. A.Syme:

    I think from this question, people are looking for evidence of solar output affecting the planetary system. We have enough trouble trying to nail down the variables for earths’ climate, much less another planet. We are looking for variation in over all output from the sun. The influence from direct radiation would be similar, but the planets with a strong magnetic field would react much differently to charge particles than a planet like Mars with a weaker field.

  24. Ted Nation:

    Quantoken’s false assertions are unfortunate. Global warming and oil depletion are both very serious issues that have to be addressed at the same time. One of my worst fears is that the industrial world will turn to less efficient fossil fuel sources to maintain current levels of economic activity resulting in an accelerated release of CO2. Not only does Q fail to consider the carbon to be released by burning coal but he also totally ignores the tar sands, oil shales, and heavy oils that are being targeted to supplement remaining oil supplies. All have carbon cycles that release significantly more CO2 than that of petroleum per unit of useful work provided. He also totally ignores the carbon sinks like peat bogs and soils that may release CO2 and methane as they are warmed.

  25. Roger Coppock:

    This “Mars, Triton, and Pluto are warming, therefore the sun is warming too” line was created by the carbon fuel industry’s public relations firms. In other campaigns, these same PR ‘think tanks’ have shown a repeated tendency to lie by omission. For an example, once a week, the Idso’s ‘CO2 Science’ web site would cherry pick a single station in the US Historical Climatology Network that happened to show cooling, to ‘prove that there has been no global warming in the past 70 years.’ The Idsos would ignore both old and recent data, corrections, and the overwhelming majority of USHCN stations which showed warming trends.

    We know of about 5 dozen planets and their moons in our solar system. Given the very well established history of lying by omission in fossil fuel industry propaganda, did they just pick three bodies out of about 60 or so that happened to have some record of warming, no matter how flimsy that warming record is? Are we looking at a 5% sample of solar planets and their moons cherry picked for their warming climate?

    Does anyone know of proxy climate records of other solar system bodies besides besides Mars, Triton, and Pluto?

  26. Lynn Vincentnathan:

    This is a bit off-topic. I’ve always flatly denied that GW has any impact on EARTHQUAKES and VOLCANIC ACTIVITY to those little people with even less knowledge than myself. But this ridiculous idea came to my mind — based on my own “kitchen” science knowledge. If you put an egg in boiling water, the shell may expand & crack. So, is this a flat “no” from the scientific experts that GW might increase earthquakes & volcanoes, and something totally out of the question & scientifically impossible (like superman flying backwards and reversing time), or what.

    Excuse my lack of scientific background, but my enquiring mind would like to know. (You can leave out “crazy” in your response.)

    [Response: Its totally out of the question. Whtever mechanism there may be would be related to ice loads, not temperature. And the earths skin is effectively elastic AFAIK. OTOH if you poke aound in Lovelocks Gaia stuff I think there is some speculation there about shifting loads of very large ice sheets might affect vulcanism - William]

  27. stephan harrison:

    Re number 26. There is certainly an increase in small-scale seismic activity when glaciers retreat and this is associated with isostaic rebound of the crust. With the melting of large ice sheets at the end of the Pleistocene there must have been significant volcanic and earthquake activity at this time. I don’t think this had anything to do with the thermal expansion of the earth though.

  28. Brooks Hurd:

    Re: 21
    Quantoken seems to missunderstand what estimated proven reserves means. This is a minimum based on the knowledge available at the time the estimate was prepared. The estimated reserves are not a maximum.

    If you look at the estimated reserves for any fossil fuel, you will see that it is increases over time.

  29. Brooks Hurd:

    Re; 26

    If weather were found to have a major effect on seismic activity, it would be published by the people who are working on earthquake prediction. Temperatures would be very easy to correlate with seismic events since the data is readily available. Other data which researchers are attempting to use is much more difficult to gather.

    Rest assured that if some team were able to correlate temperature with seismic activity, it would already be used for prediction.

    Those of us who live near active plate boundaries tend to stay current on earthquake prediction research.

  30. Lynn Vincentnathan:

    RE #26-29, well, maybe “global warming” is a misleading term then. If retreating glaciers can have an impact (small) on vulcanism/seismic activity, then this might relate to climate change, if not to “GW.” And then it might be one of those positive feedback mechanisms, since I do believe vulcanism (at least) has been responsible in the past for warming the earth (I guess after the (cooling) dust/aerosols clear).

    Now this is NOT to go to the contrarians as proof AGW is not happening, just because GW has happened in the past or on other planets….

  31. RayBender:

    Re #26: can GW affect seismic activity? On Earth, probably not – except for the effect of melting ice sheets. However, there has been speculation to this effect for the case of Venus. In that situation you have a runaway greenhouse heating the surface to several hundreds of degrees; this caused the crust to expand (thermal expansion) and has resulted in enormous fault features on the surface, and presumably earthquakes.

  32. A.Syme:

    Re #26—As we drift off course here and are talking about the weather, volcanism interaction, I have always thought it odd that Mt Pinatubo’s big explosion in 1991 was in the middle of a hurricane (typhoon). Could it be that the low barometric pressure of the storm unloaded the terrain below it enough to allow the big out venting of gas & lava?

  33. Andrew Dodds:

    Putting my geologist’s hat on, it is certainly plausable that (for instance) the passage of a low pressure system could bring forward an explosive volcanic eruption by a few hours; but extra precipitation reaching a magma chamber, or just lubricating faults around the chamber would be a bigger effect. However, this would only cause small changes in timing at best, so you could not blame the eruption on the weather.

    There is, I believe, some association between the tides and earthquakes, but this is (if it exists) just a minor trigger effect to an earthquake that would have happened very soon anyway.

    Because an Earthquake is in essence just a microquake that extends a few orders of magnitude larger than usual, and microquakes happen all the time, precise prediction will probably never be possible.

    Any earthquakes caused by the unloading effects of melting ice sheets would, by definition, happen in sparsely populated areas such as Greenland and West Antartica, of course. The same would apply to volcanoes in Antartica.

  34. Alastair McDonald:

    Re #33 – Torrential rain causing a landslide could reduce the pressure in a magma chamber an so cause melting. Reduction of ice caps on mountains, which is now occuring due to global warming, would have a similar effect. The recent earthquake in Kashmir happend in a fault where India was being suducted under the Himalayas. Reduction of the weight of the mountain ice caps may have allowed the subcontinent to slip under more easily causing the earthquake.

    The effect of tides is interesting since the Indian earthquake followed an eclipse of the sun when the tidal forces from the moon and sun are aligned exactly. The last large earthquake in Turkey also followed an eclipse.

    Although one might expect earthquakes and eruptions in Antarctia due to reductions in ice loading caused by global warming, since they would be far from civilisation they would not recieve the same intensive reporting as those in populated areas. Moreover, there is little evidence that Antarctica is losing ice due to global warming. Warmer conditions are leading to more snow, in what is presently a desert. That is not true of Greenland or Iceland where the melting of glaciers is accelerating, and it will be interesting to see whether they experience more volcanicity, especially Iceland.

  35. Brooks Hurd:

    Re: 33, Andrew,

    Consider the pressures which cause an explosive volcanic eruption. These may be hundreds of atmospheres or more. Then compare that to the barometric pressure extremes experienced even in the most intense tropical cyclones. The change in atmospheric pressure is on the order of 0.01% or less of the pressures which cause an explosive volcanic eruption.

    A rain induced landslide is a different issue.

  36. Arun:

    This is fun:

    “Do ancient eastern sciences hold the key to earthquake prediction on the basis of unusual cloud patterns?

    It may seem likely as the ancient theory of ‘earthquake clouds’, which finds mention in the 6th century astronomermathematician Varahamihira’s Brihat Samahita, is also the subject of research at the Earthquake Prediction Centre, California, and under scrutiny in Pune.

    According to US-based quake researcher Zhonghao Shou, who has been using satellite imagery to predict quakes on the basis of peculiar cloud formations, ancient Chinese and Italians studied special clouds which were indicative of impending earthquakes.”

  37. Brooks Hurd:

    Re: 36

    If you Google “earthquake clouds” you will find a much better URL

    The conclusion of Terra Research is:

    Are these clouds accurate predictors?

    Although these sudden forming clouds are caused by powerful transient energy in the crust – and the transient energy is a true genesis process to earthquakes, not all transient series generate the ‘traditional earthquake’.

    Thus, many earthquakes may have earthquake clouds, but using them as a predictor would generate many false alarms.

  38. Tom Fiddaman:

    Re 36,37

    This stuff sounds pretty fishy – a bit like blacklightpower. I’m immediately skeptical when people start invoking new laws of physics on the basis of what appears to be anecdotal evidence (weird clouds forming in seconds across the sky?).

    Maybe scalar waves are warming the outer planets, too.

  39. Andrew Dodds:

    Re: 34

    Remember that these effects would – if they had an effect at all – merely change the timing of an eruption a bit. Earthquakes can genuinely be triggered by large scale melting, though; it seems that Norway had quakes up to magnitude 7 during the last deglaciation:

    Has some more data and pictures.

    Earthquakes that would have happened anyway can’t really be blamed on AGW.

    Re: 38

    Yes, it sounds like bunk. I wonder what statistical methodology these ancient Chinese and Italians used to find the ‘weird cloud’/'earthquake’ correlation…

  40. Gerald Machnee:

    RE #26 and #32 – Pinatubo started spewing gases in the spring of 1991. The eruptions started on June 9 with major explosions starting on June 12. Typhoon Yunya coincidentally passed by. It was not a strong typhoon. Typhoon Thelma in November, 1991 was one of the top 10 in history there. The following is from a USGS site – (Typhoon Yunya passed within 75 kilometers of Mount Pinatubo at approximately 1100 on June 15. Copious rainfall from the typhoon increased the weight of tephra accumulations and the destruction they caused. Modification of winds aloft by Typhoon Yunya also spread ash over a much wider range of azimuths than would have otherwise received ash.)

  41. Jim:

    “There is a slight irony in people rushing to claim that the glacier changes on Mars are a sure sign of global warming, while not being swayed by the much more persuasive analogous phenomena here on Earth…”

    Isn’t that comment in itself ironic, considering that the current “global warming” movement began in probably much similar fashion, with small amounts of data leading to further scrutiny of future recorded data.

    While jumping to any conclusions based on this information on Mars is a bit hasty, so is a lot of science no? At least, until it’s proven correct.

    Anyway, just to be sure I’m understanding you properly, according to you there is no way that Mars’ warming is linked to Earth’s current warming trends. Also, there is no possible way that the sun is involved in either Earth or Mars’ warming trends. Is this correct?

  42. Terry M.:

    This article published on does show the 1500 year solar cycle does indeed affect world wide weather and with the last mini-ice age just 600 years ago it would seem logical that we are getting nearer to a warming temperature peak and thus world wide avgerage atmospheric temperature that is quoted so often “Should Be Rising” now and for the next 100 to 300 years. Per the article our next mini-ice age is only 1100 years +/- 500 years away. We are heading up the slope, not down and temps should be rising.

    [Response: If you really believe that the climate is so sensitive to such small perturbations, then you should be even more worried about GW, which is an even bigger preturbation. ``The climate system is extremely sensitive to weak forces, such as solar variability,'' Bond said. ``That should make us that much more worried about greenhouse warming.'' as the article says - William]

  43. Deep Thought:

    What really gets me about those who are claiming that Pluto, Mars, etc. are also heating up, presumably due to the sun getting hotter, is this:

    IF the sun is getting hotter, this will clearly be a potentially critically dangerous threat, one conceivably capable of wiping out all life on earth. So therefore, I would suggest that if they really believe that to be the case, they should immediately push for the impeachment of both the President and both houses of Congress which are willing to ignore such an obvious threat to the continued existence of humanity and instead waste time on (what this relegates to) trivial issues like Iraq, Social Security, Medicare, taxes, terrorism, fiscal budget deficits, Katrina, abortion, Bird flu, the Supreme Court, education, etc. Figuring out if there is any way to prevent at least a segment of humanity from being roasted as the sun continues to heat up (how can we be certain it isn’t a Nova in the making?) should be the only thing they are thinking about. Every scientist in the country should put be ordered to put down their work and devote full effort to what can be done to save us as the sun grows warmer.

    Of course, I don’t think those who oppose global warming actually believe the stuff they are posting, they are latching onto whatever partial or faulty data they can find for ideological reasons. And they know very well it is faulty, or they would be demanding what I just said in the last paragraph. The sun won’t heat up significantly for billions of years (and if it does, then Lord Help Us).

  44. Steinn Sigurdsson:

    To answer comment #41 from Jim:

    The Sun affects climate.
    If the Sun becomes more luminous, then to first order, the Earth and Mars both get warmer.
    (To second order, possible albedo changes make this more complicated, but that is detail).

    The Earth is getting warmer, on a time scale of decades.

    Mars temperatures have only been measured for about 30 years, and only systematically and well for about a decade.
    Mars mean temperatures are dominated by the frequency of large scale dust storms (more storms, the warmer the surface, as a rule).

    Within the limits of the sparse data we have, Mars has cooled over the 30 year baseline (but I’d not trust that much) and the main reason is more big storms back when.

    The change in the South Pole is measured over a 6 year (3 Martian year) baseline, since 1999.

    The Sun’s luminosity is measured on that time scale.

    From 1999 to 2005, the Sun became less luminous, because of the 11 year solar cycle.

    Therefore, any warming on Mars between 1999 and 2005 can not possibly be due to the Sun’s luminosity increasing, because we measured the Sun’s luminosity to decrease!

    This is independent of climate sensitivity, whether the Martian warming is local or global, and second order sensitivities to solar spectrum and flux.

  45. Le Rayon Vert » Ian Plimer on the Science Show:

    [...] that this is what he could be referring to, but if you want to know about it you can try here or here for details. I think the most likely candidate for how astronomy is left out of AGW theory is the [...]

  46. Climate Progress » Blog Archive » The “other planets are warming” myth:

    [...] Mars does appear to be experiencing short-term regional warming, not long-term global warming, as the climate scientists of have explained. [...]

  47. » links for 2007-08-20:

    [...] RealClimate » Global warming on Mars? (tags: climate environment) [...]

  48. World clock - Page 2 - - The Thailand Forum:

    [...] bollocks. For a thorough and comprehensive rebuttal of this favourite of the pyjama-brigade read Unlike creationist bloggers and Exxon PRs, these guys know what they’re talking about. [...]

  49. Climate Progress » Blog Archive » Fred Thompson, Global Warming Denyer and Sun Worshiper:

    [...] Mars does appear to be experiencing short-term regional warming, not long-term global warming, as the climate scientists of have explained. [...]

  50. Global Warming - the Final Word - Page 8 - - The Thailand Forum:

    [...] This is what the IPCC (the world’s most authoritative body on climate change) had to say on solar forcing in its most recent report "Continuous monitoring of total solar irradiance now covers the last 28 years. The data show a wellestablished 11-year cycle in irradiance that varies by 0.08% from solar cycle minima to maxima, with no signifi cant long-term trend. New data have more accurately quantifi ed changes in solar spectral fl uxes over a broad range of wavelengths in association with changing solar activity. Improved calibrations using highquality overlapping measurements have also contributed to a better understanding. Current understanding of solar physics and the known sources of irradiance variability suggest comparable irradiance levels during the past two solar cycles, including at solar minima. The primary known cause of contemporary irradiance variability is the presence on the Suns disk of sunspots (compact, dark features where radiation is locally depleted) and faculae (extended bright features where radiation is locally enhanced). {2.7} The estimated direct radiative forcing due to changes in the solar output since 1750 is +0.12 [+0.06 to +0.3] W m2, which is less than half of the estimate given in the TAR, with a low level of scientific understanding. The reduced radiative forcing estimate comes from a re-evaluation of the long-term change in solar irradiance since 1610 (the Maunder Minimum) based upon: a new reconstruction using a model of solar magnetic fl ux variations that does not invoke geomagnetic, cosmogenic or stellar proxies; improved understanding of recent solar variations and their relationship to physical processes; and re-evaluation of the variations of Sunlike stars. While this leads to an elevation in the level of scientific understanding from very low in the TAR to low in this assessment, uncertainties remain large because of the lack of direct observations and incomplete understanding of solar variability mechanisms over long time scales. " This graph shows the relative importance of solar forcing when compared to other factors. As you can see, greenhouse gases have a forcing of around 2.5 Wm-2, against the solar forcing of 0.12 Wm-2. For a debunking of the Mars stuff, see the always fantastic RealClimate at RealClimate Global warming on Mars? [...]

  51. Climate Progress » Blog Archive » Answers to Questions the Drudge Report poses to Al Gore, including one from Climate Progress (!):

    [...] Mars does appear to be experiencing short-term regional warming, not long-term global warming, as the climate scientists of have explained. [...]

  52. super-structure » 25 Reasons Why You Should Understand Neil Boortz Is Wrong | Jason Coleman:

    [...] is no global warming on Mars (nor any other of our solar system’s planets), at least not anything at all like what we have [...]

  53. Al Gore: Nobel Prize Winner -

    [...] Recently, there have been some suggestions that "global warming" has been observed on Mars. These are based on observations of regional change around the South Polar Cap, but seem to have been extended into a "global" change, and used by some to infer an external common mechanism for global warming on Earth and Mars. But this is incorrect reasoning and based on faulty understanding of the data. RealClimate Global warming on Mars? [...]

  54. Fred Thompson on global warming « Clastic Detritus:

    [...] context? Perhaps. Still, he might want to comment on the matter more seriously. Here’s a more thorough discussion of the whopping 3 years of Mars data. Jupiter? Where’d he get that information? Again, we [...]

  55. Water the future coal. - WebProWorld:

    [...] change caused by Mars’ own orbital cycles, like what happened during the earth’s glacial cycles. RealClimate Global warming on Mars? [...]

  56. Dynamics of Cats:

    Carnival of Space #36…

    As the 211th meeting of the American Astronomical Society powers on in Texas, us homebodies bring you the 36th Carnival of Space, for your reading pleasure………

  57. Debunking a climate change debunker « 3E Intelligence:

    [...] RealClimate: Global warming on Mars? [...]

  58. WND: Jack Cashill thinks he wins science debate « Notes from Evil Bender:

    [...] conspiracy theory I’ve ever seen named–is all over this so-called problem, which isn’t a problem at all.  There’s very little reason to find the Mars story even a little credible, and a lot [...]

  59. Carbon Coalition | Blog » Blog Archive » Thompson and Griffin Make Headlines:

    [...] For the record, the sun is not getting hotter.  If you care to wade through the data, it is here.  And there are other reasons for warming on Mars and you can read about them here. [...]

  60. Debate time: Global Warming - Page 11 - Offtopicz:

    [...] BTW, your completely wrong, and since you insulted me I do not wish to explain. So here is a link: RealClimate __________________ Dammit, leave my siggy alone stop suppressing my siggy rights! If your mad at [...]

  61. Uno spazio calduccio | hilpers:

    [...] pianti Ma ROTFL! PS: Sulla ricerca (da quelli che l’hanno fatta, e non da Newton), puoi leggere [...]

  62. How Al Gore celebrated "Earth Hour"Page 11:

    [...] is experiencing more warming than us. Wrong. [...]