Faint Young Sun Puzzle Flashcards
The central premise of the Gaia Theory
The central premise of Lovelock’s Gaia theory is that the Earth self-regulate in a habitable state, and your task is to create such a planetary scale self-regulating system.
Planet Ocean’s parent star
planet Ocean’s parent star is like the faint young Sun. It is about 30% less luminous than todays Sun, and will burn steadily brighter with time, tending to heat the planet and move the habitable zone outwards. The planet’s internal heat source will also slowly decay away, and there are likely to be occasional impacts from large asteroids and volcanic outpourings that could peturb the climate
The inner boundary of the habitable zone is set by:
The inner boundary of the habitable zone is set by a positive feedback called ‘water vapour feedback’. If you moved the ocean towards is star, the planet is warmed which increases evaporation from the oceans, increasing water vapour in the atmosphere. This absorbs long wave radiation and re-emits it in all directions – some back down increasing the surface temperature further.
The outer boundary of the habitable zone is set by:
The outer boundary of the habitable zone is set by a different positive feedback called the ‘ice-albedo feedback’. If you can move the planet away from its star, which acts to cool the planet. At some point, snow and ice caps form at the poles, which in turn tend to reflect more incoming radiation, adding to the cooling and increasing ice and snow cover. At some point this positive feedback can runaway and cloak the planet in ice
Silicate Weathering Feedback
The silicate weathering feedback is a negative feedback involving the concentration of CO2 in the atmosphere and the surface temperature of the planet and operates over millions of years. The source of CO2 to the atmosphere and ocean is volcanoes and the sink is a reaction with continental rocks.
The rocks are made of silicate materials. The silicates react with CO2 in the presence of water, to yield positively charged calcium ions and negatively charged bicarbonate ions. These are washed to the ocean where they combine to form calcium carbonates. Globally, this reaction removes the same amount of CO2 as comes up through volcanoes.
As the star brightens
As the star brightens you expect the warming to encourage the growth of the coolers, which will gradually take over from the heaters and counteract the warming
The problem evolution poses
The central problem that evolution poses for your efforts to make a planet that self-regulates is that it will not promote a process because it improves the environment for everyone. It will only promote traits that benefit their carriers by enabling them to leave more descendants
