Has Gaia really been explained?

I was interested in a new paper which claims to be able to explain the Gaia hypothesis, first proposed by James lovelock, that life stabilises the earth’s climate.  The paper is described in an article in the Conversation. The paper itself is here.

Life has existed on Earth for the last 3.7 billion years during which time the sun’s output has increased 30% while the atmospheric content has changed dramatically, determined by life and geology. Lovelock proposed a simple ‘Daisy World’ model of white and black daisies to illustrate how life could regulate temperature by changing surface albedo. This new paper takes this idea much further by generalising to an ensemble of species and environments. Each species is best adapted to a particular set of environmental parameters where they flourish and struggles far outside this optimum. Their interaction with the environment is such as to maintain these ideal set of conditions.  The model assumes a Gaussian like distribution about these optimum conditions. There is then a competition between species, and external astronomy and geology which selects who survives and which species preferred environment wins out over time. They call this model “sequential selection”. It  is illustrated in their Figure 1. below.

The figure shows a hypothetical interaction between 4 species as the environment changes (eg. Solar increases). Life acts to dampen change as 4 species flourish and then die off. Environmental variable E could simply be temperature.

This mechanism can only work if each species interacts with its environment so as to dampen changes from its preferred value, i.e. it has a negative feedback.  If any Species evolves which globally has a positive feedback on an environmental variable, then it will quickly drive itself to extinction. This is where we find a bit of politics creeping into the article, because what is implied is that humans, despite our success, are nevertheless driving temperatures beyond the optimum value for our species.

What is true is that we are releasing a fraction of buried organic carbon back into the atmosphere over a relatively short time span, after which the atmosphere will slowly recover.  The effect on climate and on other species will be negative in some places and perhaps even positive in others. As a result these other species will begin to react to these changes so as to counterbalance this increase in CO2. Plants are an obvious example.

I don’t think “sequential selection” is really a fundamental breakthrough in understanding Gaia. Instead it is more like an ensemble of ‘Daisy’ like species each with a Gaussian value for its optimum ‘environment’, whose populations acts to stabilises each successive optimum. If one fails (goes extinct) another then takes over, until (hopefully never) none are left and the planet dies.

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3 Responses to Has Gaia really been explained?

  1. arationofreason says:

    Gaia etc.
    I think that we can spend billions on the random chaotic effects as they become identified and still never know the feedback factors let alone their sign.
    Let’s start with what we do know. Maxwell tells us that the earth in all its random chaotic(ness) will balance the input and output energy over some appropriate averaging time.
    IR output is ~33% thru the IR window. NASA HITRAN tells us that some ~~8% radiated from CO2 at altitude. Clive has done the delta altitude and delta radiation at 2x CO2 ~4 watts/m2 ie the GH effect. This leaves us with nominally ~59..61% to be radiated by the only significant molecule, water as the only available balancing factor to implement this quantity along with its T^4 effectiveness. And of course being the major conveyor of heat up to radiation altitudes only helps increase water effectiveness. It would therefore be a negative feed back factor (on the average).
    CO2 greenhouse is not a ‘forcing function’ in the sense that solar radiation into the surface is. The GH blanket adds no energy to the system and can therefore not control the total average evaporation rate and quantity of water vapor in the system. The warming surface and atmosphere not withstanding. There is no additional power to change the evaporation rate, the cloud quantity and quality cannot be changed by increased temperature of the system. They are constant taking place without change except for a slowly increasing altitude of formation (1.5 m/yr) at the very same condensation temperature and lapse rate as before the 1 C. temperature increase of the system began in response to the increasing CO2 radiation blanket. This is thermo 101 guys.
    Feedback of thermal energy from warming air is impossible. The air receives its energy from the surface. It cannot flow backwards from air to surface(remember on the average). It would be nice if it could since water is a negative feedback factor(the major coolant) in the system when it responds to an actual increased power as from the sun and clouds.
    CO2 blanket is 1 C/century, ~4 watts/m2 at the century mark as per Clyde’s calculation from the HiTRAN radiation code. Air to water ‘feedback’ is zero, there is no additional energy into the system to drive a positive loop. (If the CO2 GH were to create 3 C increase something would need to provide the extra 8 watts/m2 being radiated to space by the extra 2 C temperature increase. Air temperature is not a power source. It is merely a measure of the static energy contained in the atmosphere. No additional power is available as it establishes and maintains a constant flow of energy to space which is received into the system from the sun.

    Thanks for all of your efforts to lend to understanding of climate.

  2. Is one of the controls the fact that the warmer the earth gets, the more heat it looses, until it looses more than it gets from insolation, and returns to cooling; and that atthe depths of a glaciation it looses so little heat that eventually insolation brings more heat than is being lost and – warming returns

    • Clive Best says:

      The albedo of the surface changes global temperatures. This is what makes ice ages difficult to end for the last 9 cycles. Stefan Boltzmann ensures that thee is no runaway warming as you note, because the warmer the surface the faster it cools through radiation DS goes as T^3 DT.

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