Biologically Terraforming a Hot Planet like Venus

How to biologically Terraform a Hot Planet. From the writer of The Terraformers’ Toolkit. (The Terraformers’ Toolkit: Everything you have ever wanted to know about terraforming and our future in space. The where, why, when, how and what of terraforming.) www.amazon.co.uk/dp/B09X6739P...
Land Life
Venus has two volcanic regions separated by large areas of flat lava. If the planet were terraformed the volcanoes would become continents and the lava shallow seas. Because Venus is closer to the Sun than Earth and cooling would take a long time, after terraforming it would be a warm, tropical planet.
Hot planets like Venus will need far more species than cold ones like Mars. This is particularly true in Venus’ mountainous regions, where every hundred metres of mountainside will require its own large and complex set of species to provide sufficient oxygen, food, water and other products and services that human colonists would need.
There are more species in Earth’s tropics than closer to the poles. If you counted the number of trees in Vermont, you would find about 50. If you then drove south to Massachusetts, you would find about 55, and then about 200 in North Carolina. Further south still in Belize, you would find about 700, and then in Peru you would find about 1,035, which is about 50 times the number in the whole of Canada. It also means a square mile of habitat in the tropics contains ten times more species than the same area in colder regions. This is called the latitudinal diversity gradient.
Tropical forests contain ten times more species than forests in the temperate latitudes. 170,000 or 68% of the world’s vascular plant species are found in rain forests in the tropics and sub-tropics. Colombia has 1,525 bird species, 30% of the world’s 9,040 bird species are found in the Amazon and another 16% in Indonesia. There are similar patterns for ants, butterflies, beetles and many others. This means that each species has a very narrow set of environmental requirements constrained by temperature and water availability. Adding an animal or plant in the wrong place on a Venus mountain side would guarantee its extinction. Its requirements would have to be known in huge detail before any introductions were even contemplated.
Long-term stable temperatures in the tropics cause species to adapt to stable temperature ranges and have limited thermal tolerances. This results in these regions having many more species than colder places. Cold regions would support many more species were they not constantly pruned by huge summer to winter temperature and weather variations.
Ocean Life
With its vast lava plains, Venus would have an ocean that is almost totally composed of shallow water. Oceans on Venus are projected to have less than a quarter of the volume of the terrestrial oceans, but a greater percentage of the surface of the planet (80 to 90%) would be covered by water. Shallow waters less than 1.5 kilometres (0.93 miles) deep are expected to cover 70 - 80% of Venus’ surface.
It would seem easier for our terraforming descendants to just introduce a few species, and let the rest evolve. However, after the Permian mass extinction event 252 million years ago, 90% of marine species became extinct and it took a full 5 million years for ocean life to recover. The slow rate of diversity recovery probably ties in with the rate at which new species evolve. This means that when our descendants come to add new species to Venus, they will need to have a highly diverse pool of species as their source material. If this is not the case, and many are long extinct, it could take 5 million years for new tropical heat-adapted species to evolve naturally.
Carbon cycle
One good thing about Venus is that it will have active volcanoes even after terraforming, which means that an active carbon cycle will be in place. But if volcanoes continued to pump carbon dioxide into the atmosphere the planet would start heat up again because this is a greenhouse gas and would prevent heat radiation escaping into space. To keep temperatures right for life carbon dioxide would need to be removed by photosynthesis and locked away on the surface. Plants including trees, grass, seaweeds and phytoplankton would be critical to achieving this.
Additionally to maximise plants’ carbon removal abilities, animals would be needed to eat leaves and stems, locking away carbon in their own bodies. Additionally animals both fertilize flowers and distribute seeds, so an active and efficient ecosystem would be needed to keep the surface cool enough for life.
Even though hot planet terraforming is many thousands of years in our future, to allow our descendants to make it a reality on Venus or even outside our solar system we need to leave them our planet’s diverse wildlife so they have the tools to do the job.

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Fascinating!