The fact that complex life exists on Earth seems to be a miracle of circumstance. From the life of the Sun, to the part of our galaxy where our solar system resides, to the dynamics that led to Earth retaining her global ocean and having an ozone layer, to the molten core and magnetic field that protects Earth’s surface, life on Earth may be far rarer in the universe than it seems from the perspective of a species that has yet to visit other stars.
From a biomass perspective, the Devonian’s primary change was the proliferation of land plants. Below is an artist's conception of a Devonian forest. (Source: Wikimedia Commons)
Writing is consciousness-raising." (pp.
Human-caused began with , which in turn drove their predators to extinction and had , particularly those resulting from the loss of . The so-called that scientists have been studying have been all human-induced, as humans eliminated predators, who were their energetic competitors. Driving the world's large animals to extinction was probably the impetus behind the Domestication Revolution, and .
Such a broad question requires several lines of evidence.
Brian O’Leary began his alternative energy career promoting traditional alternatives, and the plan that he developed for American looked . In his last years, Brian called traditional alternatives too little and too late to solve our energy problems. Although the organized suppression inflicted on technologies are partly why there is not much alternative energy technology on the market, their low EROI and low available energy are leading reasons why those traditional alternative energy sources are not viable replacements for hydrocarbon energy, which in 2014 amounts to . Nearly 40 years after Jimmy declared the moral equivalent of war on energy, traditional alternative energy still amounts to less than 1% of American energy production. dwarfs all alternative and mainstream energy sources, with available energy and EROIs that go off the scale.
These fairy tales serve a very important sociological purpose.
Almost all traditional alternative energy sources and related technologies have low EROIs (direct solar 2-to-8, wind turbines 18, geothermal less than 5). Those alternative sources all have the same problems that wind and water power had before the Industrial Revolution and more, such as , not much energy is available to begin with, and they all create environmental impacts that, although not as great as fossil and nuclear fuels, are still considerable. Wind turbines not only kill vast numbers of birds each year, but they are noisy and create inland turbulence. In order to replace fossil fuels, there would need to be about four hundred times as many windmills on Earth as there already are, and I have driven through several windmill farms in the USA, which are spread across many miles of suitable terrain. In order to raise humanity to the American standard of living, there would need to be far more than a thousand times as many windmills. There may not be enough suitable land on Earth to host those windmills, and windmills are considered the most viable traditional alternative. Direct solar, including photovoltaics, makes the most sense in deserts. It does not deliver much energy, but it is considered the next most viable alternative, and there would have to be about four thousand times as many photovoltaic arrays as already exist to raise the world to the American standard of living. Again, finding the land to host them is a problem, and the materials need to be mined. There are maintenance issues and other problems. Rock is not a good conductor, so heat is rapidly depleted from the geothermal source and it quickly goes “dry,” and has to go “fallow” to recover.
Students are unable to concentrate for any length of time.
Leaders in developing the concept of believe that an EROI of at least five, and closer to ten, is needed to run a modern civilization. The shale oil and tar sands that were touted in the first decade of the 21st century have EROIs of less than five and as low as two, and similarly promoted biofuels have an EROI of about one. Exploiting inferior energy sources is a classic resource depletion scenario that has played out numerous times during the human journey, as each energy resource was plundered to exhaustion, whether it was terrestrial megafauna, forests, soils, or whales. Industrial civilization is fast approaching the level where it cannot energetically sustain itself. Below is a chart of EROIs for various, mostly American, energy sources. (Source: Wikimedia Commons)