This essay presents a , and nearly half of the events happened during the timeframe covered by this essay's first half, which includes almost the entirety of Earth's history. Humanity's tenure amounts to a tiny sliver of Earth's history, and surveying pre-human events was partly intended to help readers develop a sense of perspective. We are merely Earth's latest tenants. We have unprecedented dominance, but we are quickly destroying Earth's ability to host complex life. As my astronaut colleague openly wondered, is ? Is our path of destruction inevitable, as we plunder one energy resource after another to exhaustion? Will depleting Earth's hydrocarbons be the latest, greatest, and perhaps final instance?
For this essay’s purposes, the most important ecological understanding is that the Sun provides all of earthly life’s energy, either (all except nuclear-powered electric lights driving photosynthesis in greenhouses, as that energy came from dead stars). Today’s hydrocarbon energy that powers our industrial world comes from captured sunlight. Exciting electrons with photon energy, then stripping off electrons and protons and using their electric potential to power biochemical reactions, is what makes Earth’s ecosystems possible. Too little energy, and reactions will not happen (such as ice ages, enzyme poisoning, the darkness of night, food shortages, and lack of key nutrients that support biological reactions), and too much (such as , ionizing radiation, temperatures too high for enzyme activity), and life is damaged or destroyed. The journey of life on Earth has primarily been about adapting to varying energy conditions and finding levels where life can survive. For the many hypotheses about those ancient events and what really happened, the answers are always primarily in energy terms, such as how it was obtained, how it was preserved, and how it was used. For life scientists, that is always the framework, and they devote themselves to discovering how the energy game was played.
The Most Important Event in My Life so Far PAGES 2
Before the rise of humanity and industrial agriculture, the interplay of life, climate, and land masses created the that fed oceanic ecosystems. However, during the Cambrian Explosion the land was largely barren, as life had yet to significantly invade land. Also, have always been key hosts for oceanic ecosystems, as sunlight could reach the seafloor and nutrients were closer to the surface. When supercontinents broke apart or formed as the tectonic plates danced across Earth’s crust, shallow seas were often created, which were usually quite life-friendly. Those ancient shallow seas and swampy continental margins have great importance to today’s humanity, as our fossil fuels were usually created there. Earth’s were created in swampy floodplain conditions, usually near coasts, and the oil deposits were created by and that . The and its predecessors (, ) had a half-billion-year history that began in the Ediacaran, and the Tethys finally disappeared less than 20 mya. The shallow margins of those tropical oceans, and the anoxic events that dotted the eon of complex life, formed most of today’s oil deposits, and . Numerous shallow tropical seas .