We all experience growth, change, and new phases in life, and Earth is no exception. Over the course of its 4.5 billion-year lifespan, our planet has transitioned from an asteroid-battered ball of molten rock, to a life-bearing ocean orb, to the home of the only known technological civilization in the universe.
David A. Roberts, an artist and computer scientist, visualized this epic planetary story with a mesmerizing simulation written entirely in GLSL fragment shaders, which are part of the graphics programming language OpenGL. In a recent blog post, Roberts explains how he generated the progression of an Earth simulacrum across geological epochs at a rate of 60 frames per second.
Roberts had been tinkering around with simulations for some time and was inspired to create his planetary evolution video after finding the 1990 game SimEarth, which is part of the Sim series, on the Internet Archive.
“[SimEarth] had a really ambitious premise of simulating earth-like planets all the way from creation through to the distant future, but was quite limited by the computer hardware of the time, so I decided to see whether I could create something similar that exploits the power of modern GPUs,” Roberts said in an email.
“I actually created a mini-game first, which allows you to interactively alter terrain to see how it affects the simulated climate and ecology. And later on created the visual history which runs through everything automatically as I figured it was a bit easier for people to consume,” he added.
The simulation starts between a view of the spherical globe in its tortured early years as a protoplanet, when it was still cooking in the juices of planetary formation. It then switches to a flattened map projection to illustrate the origins and dynamics of plate tectonics, the process by which continental plates drift across Earth, and planets like it. From there, a completely different palette of colors is introduced to reveal how water flows sculpt and erode these continents, and how atmospheric climate patterns encircle the planet and influence its terrain.
Roberts built the simulation in his spare time over the course of a few months and entered it into the Shadertoy Competition 2018. His recent blog post outlines its development, which started with complex hydraulic erosion processes and then moved on to include plate tectonics, ecological models, and climate systems.
“The climate simulation was a particularly difficult one to approximate reasonably realistically but without requiring a supercomputer,” Roberts noted. “One source of inspiration here was the Monash Simple Climate Model. Although I couldn't use it as-is because it requires a lot of real Earth data (so doesn't work with simulated earth-like planets), it did help convince me that it was possible to come up with simple but realistic approximations.”
Eventually, these interlinked planetary processes on Earth helped to seed the right conditions for life as we know it, and life has, in turn, has profoundly shaped our world. Toward the end of Roberts’ simulation, the effects of a technologically advanced civilization become apparent on his digital Earth, as city lights light up the landscape and industrial greenhouse gas emissions begin to affect the global climate.
“The final section is intended to illustrate a possible future, though perhaps an improbable one,” Roberts said. “I wanted it to be dramatic, so it is an illustration of a particularly extreme outcome where literally all of the fossil fuels are burned, but I tried to keep the effects realistic otherwise, based on scientific articles I've read about such a hypothetical.”
The video’s renderings of Earth’s processes, combined with its rousing musical score, makes for a relaxing break from the daily grind. Roberts didn’t produce the simulation with any particular message in mind, beyond telling an interesting visual story about our planet and its inhabitants.
“I guess my aim was more to help people see first-hand how intimately all the various earth systems are linked, with changes in one influencing more changes in another,” he said. “I feel like education is a lot more effective when people can understand for themselves how all these things fit together, rather than just being told what the scientific consensus is.”
“I think simulations are a powerful tool for helping people to gain an intuitive understanding of systems, particularly when they can try changing something and then watch all the resulting consequences play out,” Roberts concluded. “I didn't quite achieve that level of interactivity with this project, but perhaps I'll follow through on that at some point in the future.”