The Goldilocks Planet.

Neither too close nor too far from the Sun.

Towards the end of the lecture that Lord Martin Rees gave at  University of Melbourne’s Medical School in 2010, he spoke of the way that Planet Earth has warmed up these last 100 years, warmed up uniquely.  Why the word ‘uniquely’?  Because, for the first time in the ancient life of our planet, that warming is the result of the activity of a life species living on that planet; mankind.  It’s difficult to comprehend how special, how fragile and, therefore, how vulnerable is mankind’s ability to survive on Planet Earth.  That’s why a recent item on Martin Lack’s excellent blogsite Lack of Environment is published on Learning from Dogs with Martin’s kind permission.  But first let me quote a little from WikiPedia about the ‘goldilocks principle’,

In astronomy and astrobiology, the habitable zone is the region around a star where a planet with sufficient atmospheric pressure can maintain liquid water on its surface.[1]1 Since liquid water is essential for all known forms of life, planets in this zone are considered the most promising sites to host extraterrestrial life. The terms “ecosphere” and “Liquid Water Belt” were introduced by Hubertus Strughold and Harlow Shapley respectively in 1953.[2] Contemporary alternatives include “HZ”, “life zone”, and “Goldilocks Zone.”[3]

“Habitable zone” is sometimes used more generally to denote various regions that are considered favorable to life in some way. One prominent example is the Galactic habitable zone’ (the distance from the galactic centre). Such concepts areinferred from the empirical study of conditions favorable for life on Earth. If different kinds of habitable zones are considered, their intersection is the region considered most likely to contain life.

The location of planets and natural satellites (moons) within its parent’s star’s habitable zone (and a near circular orbit) is but one of many criteria for planetary habitability and it is theoretically possible for habitable planets to exist outside the habitable zone. The term “Goldilocks planet” is used for any planet that is located within the CHZ[4][5] although when used in the context of planetary habitability the term implies terrestrial planets with conditions roughly comparable to those of the Earth(i.e. an Earth analog). The name originates from the story of Goldilocks and the Three Bears, in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settling on the one in the middle, which is “just right”. Likewise, a planet following this Goldilocks Principle is one that is neither too close nor too far from a star to rule out liquid water on its surface. While only about a dozen planets have been confirmed in the habitable zone, the Kepler spacecraft has identified a further 54 candidates and current estimates indicate that there are “at least 500 million” such planets in the Milky Way.[6]

So now to Martin Lack’s post.

Goodbye Goldilocks Planet?

Is it time to say goodbye to the Goldilocks Planet?

I hope not, because the next-nearest one yet discovered is 600 light years away! However, if we are indeed now passing a tipping point (i.e. as the widespread rapid thawing of Siberian permafrost suggests) both mitigation and adaptation will be almost impossible. Therefore, if we cannot reverse the damage already done (i.e. how can we make permafrost re-freeze or reverse the retreat of mountain glaciers?), we may have to accept that temperatures will eventually rise to a level at which the Antarctic first became glaciated 35 million years ago; and that sea levels will now rise continuously for several centuries – making any permanent settlement anywhere near the coast impossible (seeJames Hansen in Storms of my Grandchildren).

If your response to all this is to accuse me of being alarmist, all I can say is that I am afraid denial is definitely not a good evolutionary survival mechanism. Furthermore, as American high school science teacher – and now climate change activist – Greg Craven has said,“Unfortunately, the experiment is already running; and we are all in the test-tube!” I believe we must therefore hope that humanity will not repeat the folly of the former inhabitants of Easter Island; who chopped down all their trees for firewood and allowed all the decent soil to be washed away so they could not grow anything.

I think it is fair to say that 2011 was a difficult year for humanity and the planet; and 2012 could be worse. We now seem to be facing both a financial and an environmental crisis: Even at the tender age of 46, I can appreciate that the prospect of 6 years of austerity measures (here in the UK) is completely without precedent; worse even than the great depression of the 1920s. In the UK, public sector workers have been demanding a better pension! What about a better economic system, or even a better planet? If necessary, please forgive my impertinence but, how can people demand justice for themselves whilst ignoring all the injustices we are inflicting on those least able to adapt; and/or bequeathing to our descendants?

This is almost as pessimistic as my recent answer on ClimateSight to the question “Why are people who want to reduce – and possibly eliminate pollution – and create a safer world, considered obstructionist naysayers?“, which is… “If everyone lived as we do in ‘the West’, the planet’s ecological carrying capacity would only be about 3 billion [Paul and Anne Ehrlich (1996)]. Therefore we cannot solve poverty without allowing a lot of people to die or by wealthy people agreeing to moderate their over-consumption of the Earth’s resources. Sorry to be so blunt but, this is the simple answer to the question.” …Despite what detractors say this is not misanthropic eco-Socialism, it is reality. There is not enough decent farmland and/or resources of every kind for 7 billion people or more to live like we currently do in ‘the West’. If we are not going to deny the legitimate aspirations of poorer peoples to attain a better standard of living, we will have to moderate our over-consumption and/or pollution of the Earth’s resources. We cannot have it both ways.

Conclusion
If we continue to burn all the Earth’s fossil fuels – just because they are there and because we can – we will most certainly have to say good bye to our Goldilocks Planet. However, now that we know that what we are doing is causing the problem, would it not be a good idea to stop doing it? You know: When in a hole, stop digging, etc… As the Good Book says, “As a dog returns to its vomit, so a fool repeats his folly” (Proverbs 26:11).

Suggested New Year’s Resolution:
If we want things to change, I believe we must acknowledge that Clive Hamilton is right: climate change is a failure of modern politics – representative democracy is not working! Therefore, we must all take a much more active role in the process of government – this is called participatory democracy – and we must start by demanding that our politicians dismantle (or at least stop being misled by) the fossil fuel lobby who do not want their business as usual programme interrupted.

Having said all that, I would still like to sincerely wish you all the best for 2012 (although I hope the Mayan Calendar is wrong).

9 thoughts on “The Goldilocks Planet.

  1. I think the habitable zone is a massive oversimplification given there are many other forces which can produce conditions in which life might survive. For example, there is talk of liquid water under the surface of Europa, kept warm by (if I remember correctly) the tidal forces exerted on the moon by Saturn.

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    1. Adam, looking at your own Blog, which looks very interesting by the way, I immediately realise that I am not competent to debate the point you made. Hopefully, Martin Lack, whose guest post I republished, will be able to add to your comment.

      But, whatever, a big thanks for stopping by Learning from Dogs. Paul

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    2. With the greatest of respect to you, Adam, I feel your comment is an attempt to dodge the issue (a bit like citing China’s greenhouse gas emissions as reason for doing nothing to curb our own).

      Given the mind-boggling scale of the Universe there is almost certainly other intelligent life out there somewhere. Some scientists have even speculated that under extremely different circumstances (e.g. liquid methane on Titan – one of Saturn’s moons) very different life forms could evolve. Whereas Io and Europa – two of Jupiter’s moons – have also attracted much interest. Although Io is the most vocanically-active, I think it is Europa that you were thinking of… Nevertheless, I have also heard it argued that life is most likely to be found where water is present in liquid form (because water is a very unusual liquid with many useful properties) and therefore, under Earth-like conditions, evolution will always tend to produce similarly-designed winners (two eyes, two legs, etc)…

      However, to return to my opening remark, all such speculation risks missing the point that life on Earth is very well adapted to the climate that has persisted here for at least the last 7000 years. Human activity has now put that climate stability at risk and – along with it – the stability of sea levels. If it had not been for the onset of this stability (i.e. the Holocene era) at the end of the last Ice Age, agriculture, cities, and modern civilisation would not have been possible. Indeed, if the melting of ice in polar regions continues to accelerate and sea levels start rising (only just beginning to become obvious), this is likely to go on for centuries and thus make all 3 things very difficult to sustain.

      I therefore think that James Hansen is not an environmental alarmist. On the contrary, those who label him as such are in denial of a reality which he warned us of 24 years ago but is only now becoming self-evident. I have written about this at great length on my blog (see James Hansen and Storms of my Grandchildren categories).

      Therefore, if not now then certainly within the lifetime of my children and grandchildren, it may well be time to run to the hills…

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      1. I’m not trying to suggest that global warming is not an issue or that it should be ignored, just that the phrase “goldilocks planet” is something of a misnomer and – in an effort to be as accurate with one’s speech as possible – one should avoid misnomers.

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      2. I think my comments about liquid water are legitimate. Furthermore, this – rather than the size of a planet – is clearly the key criteria used to define the goldilocks zone in a cosmological context.

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      3. Is not “goldilocks planet” referring to being with the so-called “habitable zone” which refers more to spatial positioning in relation to the sun than the presence/absence of liquid water.

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      4. They are one and the same thing. The habitable zone is that in which distance from the Sun and atmospheric pressure are capable of ensuring the retention of liquid water on the surface of a planet. Wikipedia has a good summary: http://en.wikipedia.org/wiki/Habitable_zone

        Goldilocks Planet is a useful term because it is effective in conveying an idea – as is Greenhouse Effect – but neither is actually an accurate descriptor of the science involved. Big deal. It is not important. With regard to the latter, it is time to move on and start taking action that will solve our problem.

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  2. Interestingly, in terms of the dialogue between Martin and Adam, Patrice Ayme has just published a long muse about a variety of ideas, which included this:

    “We have detected more than 150 planets. It seems one star out of ten, at least, has planets. Some have been detected in the habitable zone, where liquid water is found. But the water has to be continuously present for billions of years. Continuously (which did not happen on Mars and Venus).

    400 billion stars in our galaxy. The big question is how many planets can harbor advanced (=oxygen breathing) life. No inkling of that. There are plenty of planets out there, indeed, but most hostile to life. So far. How Much Intelligent Life Out There? On Earth, it took 1.5 billion years to go from advanced life to intelligent, civilized life. A lot of things can go wrong in 1.5 billion years.

    That advanced life did not develop on Mars or Venus is not an accident: although on the outskirts of the habitable zone, either planet did not have what it took. Mars was too small, and, just like Venus was not protected by a powerful plate tectonic, with accompanying magnetic field, among other problems (so the solar wind blowing the top of the atmosphere stole the hydrogen, hence water, etc.)

    My hunch is that most planets in the hospitable zone, when found, will be bereft of advanced life, although primitive life may be quite frequent. Reason? Too many miracles at work for billions of years in the solar system. Especially in light of what we find out there (We see plenty of Jupiter size planets in close orbits around their suns, presumably after sweeping their entire system clean; OK, that’s partly a result of the method used to find planets presently, but the fact is, we find such situations aplenty! The presence of Jupiter out there, as our guardian protecting Earth from comets looks quite miraculous…)”

    With Patrice’s permission I will be reproducing his Post on the 23rd, give or take, but if you want to read it now, then go here http://patriceayme.wordpress.com/2012/01/11/aphorism-january-2012/

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