Climate Change. In Space!
February 22, 2013
In light of the recent event involving a meteorite hitting Russia on the same day that an asteroid passed very close to Earth, I thought I’d use this post to say: 1) Space is awesome (even if it does try to kill us from time to time), and 2) Climate change doubters have looked to climate change on other planets to try to dismiss the impact humans are having on Earth’s climate. No really, I’m serious.
The climate change doubters have pointed to “warming on Mars and Pluto” to say that, “the recent warming on Earth is caused by an increase in solar activity, and not greenhouse gases” (Source). The argument then isn’t so much about climate activity on Mars and Pluto, but the Sun. Making a counter-argument here should, therefore, look to the Sun, and not to Mars and Pluto.
What’s the main problem with the Sun argument? Well, there is this slight problem: “The Sun’s energy output has not increased since direct measurements began in 1978." There is warming on Mars and Pluto, however it can’t be attributed to the Sun. If that was the case, the other planets and moons would be warming, as New Scientist explains.
Our solar system has eight planets, three dwarf planets and quite a few moons with at least a rudimentary atmosphere, and thus a climate of sorts. Their climates will be affected by local factors such as orbital variations, changes in reflectance (albedo) and even volcanic eruptions, so it would not be surprising if several planets and moons turn out to be warming at any one time.
Attributing a common cause, e.g. the Sun, to warming on different planets doesn’t work because of those local variations.
Here are some more facts about Mars, courtesy of Skeptical Science, explaining why talking about “global warming” on Mars in order to make comments about it here on Earth is misleading:
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.
In other words, climate science is complex and even more so when it’s on another planet different from our own in a number of key ways. There are lots of reasons for temperature variations on the red planet. The temperature variations may very well be weather variations, not long-term climate trends. A point brought up in the Skeptical Science article.
Learning about “global warming” on other planets is interesting, even if it can’t say a whole lot about global warming here on Earth. The science here is complex, and beyond my knowledge to summarize very well. What I can do, with some confidence, is to repeat the message that climate science (especially when looking at other planets) is complex. Be wary of those who are making claims about climate conditions on other planets and trying to find a common cause to attribute to warming back here on Earth.