Three billion years ago, the Earth’s temperature reached a certain level of equilibrium that made life possible. Remarkably (and thankfully), this temperature remained very stable despite the fact that our Sun has become about 30 percent hotter. Now, human activity is posing an existential threat to the Earth’s climate and to our very own existence.

Let’s ponder on why our planet has been so kind to all living things for so long. The “trick” is summarized in one word: equilibrium. To expand on this, a parable is perhaps useful. In the 1980s, scientists James Lovelock and Andrew Watson asked us to imagine a planet identical to Earth which they called Daisy World. On this planet are two types of daisies: black and white. Their colors have a stabilizing effect on Daisy World’s temperature as it evolves from a very cold state to a very hot state, much like the Earth’s temperature trajectory.

This is how it works. The black daisies absorb more heat than the white ones, so they have a selective advantage when Daisy World was very cold. Gradually, black daisies begin to out-compete white daisies and eventually change the reflectance (the amount of light and radiation reflecting off a surface). Daisy World thus becomes darker and warmer, until it reaches a tipping point where daisies die off in large numbers.

Now it becomes the turn for the remaining white daisies to have a selective advantage because they reflect heat and are able to grow faster. White daisies start to take over and once again, change Daisy World’s population and its reflectance, thus stabilizing the temperature.

Interestingly this parable has the flavor of an economic model called a “Regime-switching” model. A regime is a state of a system that persist for a certain period. Booms and busts are examples of economic regimes, as are bull and bear stock markets.

Regimes stabilize a system by self-correcting a system’s extreme phases. The self-corrections in Daisy World are the spikes and drops in the population of black and white daisies, that, for a time helped kept Daisy World’s temperature relatively stable. However, this equilibrium is a precarious one. At some point, the Sun’s temperature will become so hot that even the white daisies can’t survive. At this point, all daisies are wiped out and the feedback relationship that holds Daisy World’s temperature stable breaks down. This is Daisy World’s moment of no return.

This parable has a striking parallel to what is happening to our own planet, except that the tipping point in climate change is largely our own doing. In 2014, the G20 nations agreed to invest US$70 trillion in new infrastructure by 2030, which translates into 25 million more kilometres of roads, hundreds more dams, 90 percent of which will be built in the tropics. The environmental impact of this infrastructure tsunami will easily dwarf the impact of the already ominous climate changes taking place. Until recently, the scientific consensus was that it will be another billion years before the Sun gets so hot that the oceans will evaporate completely. There are now reasons to believe that all the reflectance that human activities generate will bring forward this day of reckoning to our children’s lifetime. This will be our Daisy Moment.

Further Study

The original paper by Lovelock and Watson is: Watson, A.J., and J.E. Lovelock (1983), “Biological homeostatis of the global environment: the parable of Daisy World”, Tellus B. International Meteorological Institute. 35 (4): 286–9. Bibcode:1983TellB..35..284W. doi:10.1111/j.1600-0889.1983.tb00031.x.