Serina: A Natural History of the World of Birds

The Thermocene: 75 - 175 million years

The Thermocene

Though the world was always volcanic and experienced occasional eruptions on a local level, starting 66 million years PE, Serina experiences an increase in volcanism on a larger and more global scale than ever before. In particular, a large mantle plume known as the Striatan Traps developed in the north of Striata which started to steadily bubble up magma 9.5 million years ago and continued almost continuously for nearly 1.5 million years, producing a flood basalt near Serina's north pole. A series of rolling hills and plateaus of basalt rock at times over 8,000 feet high now covers an area of nearly 400,000 square kilometers, or just under the area of California. Though the main pulse of volcanism from the traps ended 8 million years ago, occasional smaller eruptions continue to occur every few hundred thousand years, adding to the flood which could return in earnest at any time though appears on the path to dormancy. By 75 million years PE, the Cryocene is over; in a dramatic 180 degree role reversal, the Thermocene, marked by a period of high global temperatures and widespread tropical conditions, begins.

The effect of the traps event on Serina's climate has been dramatic. Because the viscosity of basalt lava is very low, simply flowing rather than blowing up from the ground, and "traps" type volcanoes do not explode powerfully enough to release much ash or debris into the atmosphere, the Striatan traps never clouded the atmosphere as other types of volcanism may, saving an already highly temperate Serina from potentially freezing over entirely in a years-long winter. Instead, the past 10 million years have brought an extraordinarily intense and rapid period of warming. As the traps bubbled up over what was formerly Striata's tundra - a region abundant with carbon-rich peat bogs - enormous underground coal beds caught fire across the northern hemisphere, wildfires so large and intense to be visible as a ring from space which released great quantities of the greenhouse gas carbon dioxide into Serina's atmosphere. In less than one million years Serina's average temperature rose by as much as 27 degrees Fahrenheit - from 48 to 75. The ice caps receded and disappeared and tropical forests previously restricted to isolated bands on the moon's equator spread toward the newly inviting polar regions in just a few thousand years. Serina has seen a swift and almost complete extinction of all of its polar lifeforms as jungles and rich subtropical woodlands creep almost as far north and south as the edges of the former icecaps - only a handful of such polar life has managed to adapt to a warmer world. Few other groups of land animals were severely affected, even the largest among them; the warming climate has been a boon to most large egg-laying birds such as serestriders and aardgeese, giving them back a new competitive advantage to live-bearing vivas which experienced domination in the coldest environments of the Cryocene. The spread of tropical conditions also benefited Serina's ecothermic animals; the frog-like mudwickets, slithering eelsnakes, and other terrestrial fish descendents as well as insects have generally fared well in the new era, but perhaps most interestingly the warming world has begun to have a strange effect on certain endothermic birds which begin to graduate away from a warm-blooded biology to a less energy-intensive one dependent on the now generally reliable warm temperatures of the environment to maintain their body temperatures, giving them their own advantage in needing less food to get by than equivalent competitors.

The effect on the world's ecosystems has not been universally beneficial however - it was catastrophic for some. The sea has been the worst affected of all biomes, with surface temperatures at equatorial latitudes surpassing one hundred degrees Fahrenheit in the first few thousand years during the peak of volcanism. At first here almost all sea life beyond the microscopic died, with only a few types of bacteria and cyanobacteria persisting that could take the heat. Initially without either competitors or predators these tenacious organisms were able to form colorful blue, green, and red mats on the surface of the stagnant water, to the inadvertent result of shading and cooling it just enough so that over time a community of smaller fishes and invertebrates could return beneath it, feeding on the mats of plant material near the surface, though more than a few meters down the sea remained anoxic not unlike in Serina's earliest days. Over the following millions of years, equatorial seas would recover some of their diversity, but it will be some time yet before they are anything like their previous glory, for perhaps most notably, there are no longer any reefs. Acid rain reduced the pH of the oceans, dissolving the shells of the bivalves and hydra; the reefs formed by the former did not survive the end of the Cryocene, and though the latter persisted, it was only through the most exceptional already-established diversity of the group in comparison to coral on Earth. Though all reefs in the sea bleached and crumbled at the end of the Cryocene, primitive freshwater relatives of reef-building hydras in isolated environments less affected by acidification lived on to eventually reclaim what were formerly the polar oceans. Among larger animals, the largest filter-feeding whalebirds died out in a warming world as the population of plankton they relied on for their survival crashed with the warming of the cold polar seas; herbivorous pelicanaries related to the bloon as well as small coastal forms, however, survived, though it will be some time before they rival their forebears in size, for though the seas are stabilizing again, they are no longer as productive without cold polar waters rich in nutrients to give rise to large plankton blooms and few sea creatures at this time, sans some herbivores, grow much larger than a porpoise. The giant sea slugs too have gone extinct, survived only by far smaller representatives. Though the seas are overall less rich than in past, colder eras, they are larger; the loss of all of Serina's glaciation has resulted in a dramatic rise in sea level, illustrated perhaps most dramatically on the southeast landmass of Karii, now split apart by a massive inland sea. Flooding also divided the supercontinent formed by the fusion of Striata and Whalteria, and though South Anciska and Stehvlandea long ago collided as well, the rise in sea level has temporary divided these two lands once again as well. Even North Anciska has been split into two by a combination of continental drift and rising sea levels, with its northernmost section moving towards the pole.

Though their edges are obscured by the high sea levels, a general pattern is also beginning to take shape of the east and west converging toward a central point. Lying between the hemispheres, the Kyran Islands, now an archipelago, remain isolated, but they will one day soon find themselves squeezed between two much larger continents; a new supercontinent is set to form.

Despite rising global temperatures, most of Serina's terrestrial environments were saved from desertification by the shape and size of the land, preventing a potential mass extinction here as well. With its land divided into many small landmasses, rather than one or only a handful of large supercontinents, rainfall distributions remained wide enough to still support rainforests along most coasts and through many inland regions, though South Anciska, Karii, and Whalteria did develop large interior deserts. Cactus sunflowers and other desert flora quickly colonized these newly opened habitats while tropical grassland, sunflower woodland and ant-symbiotic bamboo jungles spread to dominate elsewhere, with floral groups specialized to cold polar areas, particularly the pineflower forests, finding only the peaks of the tallest mountains in polar regions sufficiently cool for their survival. They will ride out these climactic arks as long as they can, but it remains to be seen if the climate will be generous enough to leave these very last refuges suitable for their long-term survival, for though ten million years have passed since the start of the Striatan traps the climate has only cooled off again by a few degrees to nowhere near its Cryocene levels. Serina remains for now a true hothouse world, but eventually the carbon-sink will be restored by the world's plant life, and the moon will likely return to pre-traps temperature levels, if not the extreme seen during the Cryocene era.

Explore the Thermocene:

75 Million Years

Snapshot in Time

176.5 Million Years

Life at the Boundary

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The Thermocene: 75 - 175 million years

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100 Million Years

150 Million Years

175 Million Years