Is MARS getting warmer? – #climate

While reading an article related to yesterdays posting I noticed that one of the very first comments to pop up under it was this …

Mars is currently warming without any human interference.  Google it.

Why did the left highjack this and politicize it?

The point he is attempting to make is that humans have not in any way influenced the observed increase in temperatures on Earth, and as evidence, the commenter points to Mars as an example of a climate change that involves no humans at all.

It is not a new claim, and has been around for a few years. For example here is a transcript of something said on the radio by Fred Thompson, the former United States senator from Tennessee. He was making this claim back in 2007 …

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.

Is Mars warming up?

The first serious proposal that Mars was warming up comes from a 2007 paper that was published in Nature. That appeared to highlight that Mars was indeed experiencing climate change.

The problem with that conclusion is that the paper was seriously flawed, it simply compared two data points as follows …

• composite snapshot of Mars from 1977 taken by the Viking spacecraft (top image below)
• a 1999 image compiled by the Mars Global Surveyor (bottom image below)

Because the top image was brighter, the paper calculated a 22 year global warming trend of 0.65°C on Mars.

If you make a comparison of just two data points without any climate context then you simply do not have enough information to be able to reach such a conclusion.

Let’s add a bit of context.

The data gathered in 1977 was just after a global dust storm had deposited dust over the southern latitudes and so that brightened up the planet’s surface. The “darker” 1999 snapshot was of Mars in it’s usual state. To verify this, there was also data gathered in 2001 after a global dust storm that reveals it to be even brighter than in 1977.

These variations on Mars are clearly being driven by global dust storms and are not evidence that solar activity drives warming.

Is that it?

Actually no, not quite.

There is solid evidence that Mars has warmed up and emerged from an Ice Age. A recent paper (May 2016) utilised radar measurements from NASA’s Mars Reconnaissance Orbiter to probe the planet’s polar ice caps. Layers within the ice allowed them to calculate how much ice was deposited at different times. The results provided evidence for a recent ice age on Mars.

So clearly Mars had indeed warmed up.

Don’t get too excited, this “recent” ice age on Mars was 370,000 years ago.

This warming is principally the result of orbital variations and the specific axial tilt of the planet. The paper makes that clear. They modelled it using orbital parameters and found exactly what was predicted …

Mars undergoes oscillations in obliquity, perihelion, and eccentricity that strongly affect the planet’s climate (1). This variability determines the amount of sunlight that reaches the surface and in turn the stability of ice at all latitudes, creating pronounced climate cycles

… Our findings constitute evidence for a recent, widespread, and predominantly northern polar erosion event followed by accelerated accumulation to the present day, signaling the end of a martian glacial period. Our conclusion is supported by models that use orbital parameters to predict climate change and by observations of ongoing, mid-latitude ice loss.

That perhaps does open up a possible question regarding Earth. Our own planet does have something similar but not as variable. These are  called Milankovitch cycles. This is a deeply complex topic and has been examined and considered as a possible explanation for climate change. It does to some degree account for past warming phases and ice-ages on earth, but does not in any way account for the current rapid climate change that we observe today, and so it has been eliminated as a cause.

The Myth that Pluto and other solar system objects are Warming up

SkepticalScience sums it all up here …

• Jupiter: the notion that Jupiter is warming is actually based on predictions, since no warming has actually been observed. Climate models predict temperature increases along the equator and cooling at the poles. It is believed these changes will be catalysed by storms that merge into one super-storm, inhibiting the planet’s ability to mix heat. Sceptical arguments have ignored the fact this is not a phenomenon we have observed, and that the modelled forcing is storm and dust movements, not changes in solar radiation.
• Neptune: observations of changes in luminosity on the surface of both Neptune and its largest moon, Triton, have been taken to indicate warming caused by increased  solar activity. In fact, the brightening is due to the planet’s seasons changing, but very slowly. Summer is coming to Neptune’s southern hemisphere, bringing more sunlight, as it does every 164 years.
• Pluto: the warming exhibited by Pluto is not really understood. Pluto’s seasons are the least understood of all: its existence has only been known for a third of its 248 -year orbit, and it has never been visited by a space probe. [true when he wrote this in 2010] The ‘evidence’ for climate change consists of just two observations made in 1988 and 2002. That’s equivalent to observing the Earth’s weather for just three weeks out of the year. Various theories suggest its highly elliptical orbit may play a part, as could the large angle of its rotational axis. One recent paper suggests the length of Pluto’s orbit is a key factor, as with Neptune. Sunlight at Pluto is 900 times weaker than it is at the Earth.

Claims that solar system bodies are heating up due to increased solar activity are clearly wrong. The sun’s output has declined in recent decades. Only Pluto and Neptune are exhibiting increased brightness.  Heating attributed to other solar bodies remains unproven.

Solar Activity vs Global Warming

If solar activity was driving the climate change that we observe then we should be able to create a graph that illustrates a correlation between solar output and global temperatures.

Draw such a graph and you find the hypothesis is falsified …

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 PMOD (see the PMOD index page for data updates).

You can dig into this in a lot more detail here.

In Summary

No, Mars is not evidence that solar energy explains global warming.

Solar activity as a possible cause of climate change has been examined, and dismissed because it does not explain what we observe and measure. This is not a controversial point, no serious climate scientist is making such an argument today (I may be wrong, I just can’t find one).

What is going on is that we are pumping out vast amounts of greenhouse gases into our atmosphere. We have precise measurements of the rate of increase. We know that greenhouse gases trap heat, that was established as a fact in 1859 by John Tyndall, and so the causality of what is being measured is understood. Claims that it is still under debate and needs further research is simply not factual, the causal debate ended decades ago within the scientific community.

The real debate is now focused on what we should do and also how to persuade others that decisive action is required.

One thing is abundantly clear, doing nothing is not a palatable option.