Panama Inferno

20 million years ago, a large meteor slammed into Earth, in the Indian Ocean, just two thousand kilometers off the coast of Java in Indonesia. The collision causes a massive dilluge across the Indian ocean, flooding much of the archipelagoes and coastlines. Opposite the world, however, a much greater impact is felt. A massive surge in volcanic activity occurs, accelerating the creation of a landbridge between the American continents. Over the next 20 million years, the continents would continue to collide, building up the landbridge in width and height, until it was over 323 km (200 miles) wide and at its height stood 4000 meters. The formation of this landbridge would have major consequences for millions of years to come. First, it blocked off the Altantic and Pacific Oceans, creating the Great Gulf Stream, and warming Europe, allowing African flora and fauna to migrate northward. This landbridge also redirected warm, wet currents to Europe, where it froze and became the first arctic ice cap, creating a premature ice age. The ice age dried up much of Europe and North Africa, which in turn accelerated the decline of tropical forests and forced many animals, including the forerunners of humanity to adapt. This resulted in the appearance of human-like animals much earlier than in our current timeline, but their spread was slowed by the other effects of the landbridge. Many lowlying coastal areas were flooded by the displaced ocean, including most of the Caribbean, the coasts of Mexico and Floridia, the Yucatan and Baja Penisulas, almost the whole Hawaiian archipelago, and even some regions of Southeast Asia and the Mediterranean. This would limit their ultimate expansion for centuries, particularly as the last ice age ended. With higher sea levels to begin with, the Bering Strait only marginally dried up, meaning that many American species, such as the horse and camel, barely made it to Eurasia. In contrast, in the Americas, the landbridge allowed much freer travel as it provided a much wider diversity of habitats, from tropical and temperate forests to alpine grasslands and tundra. This would play a critical part centuries later following the end of the last ice age, when a small trickle of arctic survivors stumpled along the coasts of the Americas and entered the New World.