Arguments
Dust-Up On Mars: Should Martians Be Sceptical of Global Warming?
Posted on 21 August 2010 by gpwayne
This post is the Basic version (written by Graham Wayne) of the skeptic argument "Mars is warming".
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.
Note: we're currently going through the process of writing plain English versions of all the rebuttals to skeptic arguments. It's a big task but many hands make light work. If you're interested in helping with this effort, please contact me.
The Yooper
Not true. We have detailed geographic evidence of changes in the climate on Mars.
How?
I couldn't tell it nearly as well as J Kelly Beatty of SkyandTelescope, so in his words;
"NASA's Mars Reconnaissance Orbiter has been circling the Red Planet since March 2006, for some 4 1/2 years.Yet it's the Mars mission that hardly anybody knows about.
As of June 18th, MRO'sprimary camera -- the High-Resolution Imaging Science Experiment, or HiRISE -- had made 16,077 observations and returned 13.4 trillion pixels of digital imagery.
Picture yourself viewing the Red Planet through an exquisite 20-inch (0.5 -meter) f/24 telescope without Earth's atmosphere to contend with. Naturally, you'd expect a great view. Now imagine goosing your magnification up another 20,000x by moving that scope to a vantage just 190 miles (300 km) above the Red Planet, and then throw in a camera able to capture long ribbons of terrain more than 20,000 pixels wide and as long as will fit on a 16-gigabyte memory card.
This is the reality of HiRISE, which boasts the largest scope ever floan to another planet.
With it Geologists once content to decipher Martian geology fron a patch-work of vague features a mile or so across are now able to follow the tracks of boulders that have rolled down from a crater's rim, or to count thin sedimentary layers in an ancient lakebed."
Ain't it a beautiful thing?
I'd love to continue, but Jack Horkheimer, my ambassador to the stars has died today at the age of 72, so I'll be in mourning the rest of the evening.
Probably in front of an eyepiece.
Keep looking up.
See the Sep 2010 issue of Sky and Telescope, the one off
So it is true. And 4.5 years is not long enough to gather any meaningful data about climate on Mars (particularly as I assume you mean Earth years).
But thanks for the interesting info about HiRISE.
gpwayne, John -- I think each of these short explanations should end with a sentence like: "If you'd like to know more, see our intermediate explanation." Where "intermediate explanation" is a link to the more detailed entry.
Not just of the ancient climate on the Red Planet, but because of the lack of water erosion, even of the recent history, right up to the present day.
Extra terrestrial astronomical forcing are the origin of all these cycles, long term (last 2.4 Ma, Pleistocene), middle term (last 127Ka, last interglacial - last glacial time-span) and short term, (the last 10.000 years (10Ka)), on both planets Earth and Mars.
See comment one at the "intermediate explanation" link.
That puts you a step in front of John Cross.
http://www.skepticalscience.com/medieval-warm-period.htm
http://www.ifa.hawaii.edu/~norb1/Papers/2008-milank.pdf
“Recent global warming is correlated strongly with not only levels of carbon dioxide but also increased geomagnetic activity.”
“The apparent relationship to human activity would be epiphenomenal.”
“The correlations between recent insidious elevations in global temperature and green house gases, which include water vapour as well as carbon dioxide, have been attributed in large part after the year 1945 to the behaviour of human beings (NAS 2010a,b,c; Tett et al, 1999). However concomitant with the increased magnitudes for human activity since about the year 1900 there has been a doubling of the solar corona (Lockwood, et al, 1999) and a gradual increase in average geomagnetic activity (Persinger, 2009a). A similar increase in global temperature has been observed recently within a more restricted time frame on MARS (Fenton et al, 2007) which is presumably independent of anthropogenic activities.”
“Correlations are not necessarily causations. For problems that are not amenable to the benefits of direct experimentation, the presence of other factors that are responsible for the occurrence of both variables that constitute the correlation must always be considered. These include changes in solar activity, alterations in the angle and orbit of Earth (Duhau and Jager 2010; Miyahara et al., 2010) and fluctuations in geomagnetic activity. Both El-Borie and Al-Thoyaib (2006) and Persinger (2009a) have shown that at least half of the variance in the global warming can be accommodated by the energy available from the upward drift in geomagnetic activity. That these factors associated with solar activity have been responsible for the epiphenomenal relationship between global warming, human activity and the concomitant increases in green house gases, would affect both humanity's approach to the solutions as well as the focus in the search for mechanisms.”
I recommend this paper: Solar cycle variations on the millennial times scale: a challenge for solar dynamo theory, Usoskin, 2010.;
... and two conclusions of the multimedia presentation: Grand Minima and Maxima of Solar Activity on multi-millennial time scale (Usoskin, Solanki, Kovaltsov, 2010):
- The Sun spends ~3/4 of the time at moderate activity, ~1/6 in a grand minimum and ~1/10 in a grand maximum state. The modern solar activity is a grand maximum.,
- Occurrence of Grand minima/maxima is not a result of long-term cyclic variations but is defined by stochastic / chaotic processes (Suess/de Vries cycle may operate at a shorter scale).
... and from this work: The Sun's role in regulating Earth's climate dynamics, Mackey, 2009.:
“Climate processes are interconnected and oscillating, yielding variable periodicities. Solar processes, especially when interacting, amplify or dampen these periodicities producing distinctive climatic cycles. As solar and climate processes are non-linear, non-stationary and non-ergodic, appropriate analytic methodologies are necessary to reveal satisfactorily solar/climate relationships.”
Warming on Mars must therefore be real and be a result of a complex (including magnetic) solar activity (f. e .QBO).
"Warming on Mars must therefore be real and be a result of a complex (including magnetic) solar activity (f. e .QBO). "
This is a very farfetch idea that provide a lot of information about the structure of your logic.
We have only a very few data point for Mars temperature. Also, I dont see any commun mecanism that could be invoke the have a comparable effect on MArs and Earth. In addition, in the observation perio, solar activities as gone done.
In addition, nobody claim than Sun has no impact on climate. However, even the most supporting analysis claim that it cant exceed 50% and is much likely to be below 25% of the observed warming.