2010-09-05 21:12:59Basic rebuttal 49: Jupiter is warming
Graham Wayne

Argument number 49: Jupiter is warming

This argument is part of a greater one  that other planets are warming. If this is happening throughout the solar system, clearly it must be the sun causing the rise in temperatures – including here on Earth.

It is curious that the theory depends so much on sparse information – what we know about the climates on other planets and their history – yet its proponents resolutely ignore the most compelling evidence against the notion. Over the last fifty years, the sun’s output has decreased slightly: it is radiating less heat. We can measure the various activities of the sun pretty accurately from here on Earth, or from orbit above it, so it is hard to ignore the discrepancy between the facts and the sceptical argument that the sun is causing the rise in temperatures.

TSI from 1880 to 1978 from Solanki. TSI from 1979 to 2009 from PMOD.

But if the sun’s output has levelled off or even diminished, then what is causing other planets to warm up? Are they warming at all?

The planets and moons that are claimed to be warming total roughly eight out of dozens of large bodies in the solar system. Some, like Uranus, may be cooling. All the outer planets have vastly longer orbital periods than Earth, so any climate change on them may be seasonal. Saturn and its moons take 30 Earth years to orbit the Sun, so three decades of observations equates to only 1 Saturnian year. Uranus has an 84-year orbit and 98° axial tilt, so its seasons are extreme. Neptune has not yet completed a single orbit since its discovery in 1846.

This is a round-up of the planets said by sceptics to be experiencing climate change:


  • Mars: the notion that Mars is warming came from an unfortunate conflation of weather and climate. Based on two pictures taken 22 years apart, assumptions were made that have not proved to be reliable. There is currently no evidence to support claims that Mars is warming at all. (Specific aspects of the 'Mars' argument are addressed in a separate post "Global Warming on Mars?")
  • 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. 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.

2010-09-05 21:19:53Note
Graham Wayne

Because there is so very little to say about individual planets, I've written one text and used it for the Jupiter, Neptune and Pluto basic rebuttals, changing the bullet point order so the specific planet is the first in the list depending on which argument you look up. This text in turn is taken from a slightly expanded version done for the 'solar system' argument. Hope this is acceptible...

(PS - Mars has a full rebuttal of its own)

2010-09-08 00:09:26Basic #49 Jupiter warming


Please change:

"heating attributed to other solar bodies are unproven" to "heating attributed to other solar bodies is unproven" 

2010-09-09 01:41:52

There are too many planets. Where's a Vogon when we need one?
2010-09-09 04:05:52OK

2010-09-09 15:34:05Fine.


It's just perfect.


2010-09-10 22:48:57
Graham Wayne

jimalakirti - it's tedious there are so many versions of this, both for comment on and for updating! :)

I will of course catch this in all the versions.

2010-09-11 13:23:58Comment
Robert Way

Your link to PMOD is broke...
2010-09-11 17:10:36PMOD
Graham Wayne
Ok Robert - I've removed the link, because it's rather irrelevant in the basic version to link to raw data, but the attribution is still important.
2010-09-11 17:23:26
Rob Painting
Further approval here. 
2010-09-14 06:15:46
Paul D


Seems OK.

2010-09-14 07:26:32To John

Being the rebuttals about the same for all the planets they could represent just one single skeptic argument.
2010-09-15 06:49:24Published
John Cook

Yes, don't think I'll do a blog post for every planet, that would be repetitive. I'll just go and put this into all the planets. Thanks, Graham!
2010-09-15 08:34:48Hellloooooo way down there in Green-land!


That's a good idea....

(Have to catch a breath...)