How fairies control the transition of seasons

Question

I have a world of perpetual, consistent, and evenly distributed "daylight" (for purposes of this question, you don't need to worry about how this would be achieved). Left to its own devices, living on this world would be a lot like living in the temperate zone on Earth, but with no day & night, no winter & summer, no tropical & arctic zones, etc. But then an advanced race introduced biologically engineered organisms that are able to manipulate the world into having a summer/winter like cycle similar to that of Earth.

These organisms are divided into two categories: "summer fairies" and "winter fairies". They alternate between ~6 Earth months of activity and ~6 Earth months of hibernation and they each do something different to the environment of the world to raise or lower its temperature by an average of 12-14°C to bring the appearance of Earth like seasons. Summer and winter fairies do not necessarily have to be exactly 2 species. A symbiosis of species working together to make each season happen is okay, but I would like the process to require some action on the part of your stereotypical looking fairies (small, insect-winged, intelligent humanoids).

The mechanism I am looking for should not rely on the mechanics of the world itself; so, if you put the fairies and any symbiotic organisms they need onto another normal world, they should be able to influence the seasons there as well.

I am looking for a more-or-less scientifically sound explanation as to what these fairies are doing to control the seasons.

Answer 1

The faeries are in league with the trees.

Your world has a lot of trees, covering most of its land area (let's say about one third of its total surface). During the summer, the trees' leaves are dark, absorbing most of the light that hits them. Your planet's albedo - the amount of light that it reflects back into space - would be unusually low, about 0.1 compared to Earth's 0.3.

However, when the faeries give their trees the "winter" signal, their foliage changes drastically, displaying canopies of highly reflective, pure-white leaves that absorb less light. The total albedo of the planet rises to around 0.33, reducing the heat retained from sunlight by over a quarter. As the oceans cool, replacing low-albedo water with high-albedo ice, the effect grows even stronger, reflecting more and more sunlight away from your world and lowering temperatures further.

When the summer faeries emerge, they use some means (a chemical trigger, perhaps) to tell the great trees to switch back to their dark foliage and the process reverses. The trees trap more heat, which causes pack ice to thaw until it's a balmy summer once again.

Answer 2

There are so many of them. You don't really need two species. Once they emerge, for 6 months they live high in the atmosphere, living off of sunlight and blocking a substantial portion of light to the planet's surface. They are optically transparent (but not, say, to IR or UV) so you can still see the blue sky more or less. Then, 6 months later, they begin their hibernation and the sunlight returns. Presuming that they emerge and return over a period of time, you also get spring and fall for free.

Answer 3

Flatulence

I'm imagining incredibly flatulent fairies. At a certain moment eggs hatch fairies. The fairies come out and start consuming, creating massive anounts of methane and CO2 as a byproduct. So much that it would put the whole human race to shame. This leads to global warming on a massive scale, inducing summer.

The fairies settle down after a while, gestating all inefficiently acquired energy and supplementing it with sunlight. After roughly a season they are ready, using a form of photosynthesis they use the methane and CO2 in rapid succession, removing the surplus and creating their eggs. This creates the winter.

These eggs will take a long while before they hatch, starting the cycle anew. The world would have spring and autumn, as the heating and cooling isn't done in a day. CO2 and methane can be beneficial to vegetation, especially if it's used to such a cycle.

Finally, the fairies might create uneven seasons, as they might grow at different speeds in eggs or after hatching.