This essay has presented Earth’s many changing faces during its journey. Earth had molten beginnings, was , and may have . Later, and and . Earth experienced swings from to conditions as atmospheric gases dramatically changed, continents moved, and vast and of complex life played out on land and sea. But the changes happened over timescales of millions and billions of years, not hundreds. No climate scientist will deny that carbon dioxide traps infrared radiation and warms Earth’s atmosphere. The vented enough carbon dioxide into the atmosphere to create 200 million years of Greenhouse Earth conditions, when reptiles ruled Earth. Volcanism waned and around 150-to-100 mya. By 35 mya, and the Antarctic ice sheet began forming. Every paleoclimate study I have seen places greenhouse gas (and primarily carbon dioxide) concentrations as the primary determinant of global surface temperatures, after the Sun's radiation, but the Sun's output is considered to have been exceptionally stable and has risen slowly over the eons. , usually by accentuating the carbon dioxide with a positive feedback effect that may have reached runaway conditions at times.
When Turks conquered Constantinople, Venice lost its spice monopoly and perhaps the seminal event of Europe’s rise happened: attempts to find another route to obtain spices. are often made of defensive chemicals that plants produce to defend themselves from animals, and many have antibacterial properties. These properties were important for preserving food, particularly animal products (mainly meat), in warm climates before the advent of refrigeration, but the antibacterial properties of spices are important even today in warm-climate nations. Spices essentially preserved food energy so that humans could consume it rather than microbes.
In his , Charles Darwin sketched processes by which species appear and disappear, today called speciation and extinction. is a landmark in scientific history and is still immensely influential. But it was also afflicted by false notions that are still with us. Europe’s emergence from dogma and superstition has been a long, fitful, only partially successful process. In the 1500s, Spanish mercenaries to the unfortunate Indians that they conquered and annihilated that stated that Creation was about five thousand years old, as scholars of the time simply added up the “begats.” The is filled with tales of genocide, miracles, and disasters, with a global flood that the faithful survived. As geology gradually became a science and processes such as erosion and sedimentation were studied, the Judeo-Christian belief of Earth's being five thousand years old and the concept of arose in Europe.
are created by undisturbed organism remains that become saturated with various chemicals, which gradually replace the organic material with rock by . Few life forms ever become fossils but are instead consumed by other life. Rare dynamics lead to fossil formation, usually by anoxic conditions leading to undisturbed sediments that protect the evidence and fossilize it. Scientists estimate that only about 1%-2% of all species that ever existed have left behind fossils that have been recovered. Geological processes are continually creating new land, both on the continents and under the ocean. Seafloor strata do not provide much insight into life’s ancient past, particularly fossils, because the process in “mere” . The basic process is that, in the Atlantic and Pacific sea floors in particular, oceanic volcanic ridges spew out basalt and the plates flow toward the surrounding continents. When oceanic plates reach continental plates, the heavier (basaltic) oceanic plates are subducted below the lighter (granitic) continental plates. Parts of an oceanic plate were more than 100 mya and left behind plate fragments. On the continents, however, as they have floated on the heavier rocks, tectonic and erosional processes have not obliterated all ancient rocks and fossils. The oldest “indigenous” rocks yet found on Earth are . have been dated to 3.5 bya, and fossils of individual cyanobacteria have been dated to 1.5 bya. There are recent claims of finding . The oldest eukaryote fossils found so far are of . The first amoeba-like vase-shaped fossils date from about 750 mya, and there are recent claims of finding the first animal fossils in Namibia, of sponge-like creatures which are . Fossils from might be the first animal fossils, and some scientists think that animals may have first appeared about one bya. The first animals, or , probably descended from . The is a tail-like appendage that protists primarily used to move and it could also be used to create a current to capture food. Flagella were used to draw food into the first animals, which would have been sponge-like. When the first colonies developed in which unicellular organisms began to specialize and act in concert, animals were born, and it is currently thought that the evolution of animals probably only happened . In interpreting the fossil record, there are four general levels of confidence: inevitable conclusions (such as ichthyosaurs were marine reptiles), likely interpretations (ichthyosaurs appeared to give live birth instead of laying eggs), speculations (were ichthyosaurs warm-blooded?), and guesses (what color was an ichthyosaur?).
In the early 19th century, a dispute was personified by , a British lawyer and geologist, and , a French paleontologist. Their respective positions came to be known as and . Just as , so did uniformitarianism prevail in scientific circles. Under the comforting uniformitarian worldview, there was no such thing as a global catastrophe. Changes had only been gradual, and only the present geophysical, geochemical, and biological process had ever existed. The British Charles Darwin explicitly made Lyell’s uniformitarianism part of his evolutionary theory and he proposed that extinction was only a gradual process. Cuvier was , which contradicted the still-dominant Biblical teachings, even in the . Although Cuvier did not subscribe to the , his catastrophic extinction hypothesis was informed by his fossil studies. But Lyell and Darwin prevailed. Suggesting that there might have been catastrophic mass extinctions in Earth’s past was an invitation to be branded a pseudoscientific crackpot. That state of affairs largely prevailed in orthodoxy until the 1980s, after the was posited for the dinosaurs’ demise. An effort led by a scientist publishing outside of his field of expertise (a ) removed from its primacy. Only since the 1980s have English-speaking scientists studied mass extinctions without facing ridicule from their peers, which has never been an auspicious career situation. Since then, many and mass extinction events have been studied, but the investigations are still in their early stages, partly due to a dogma that prevailed for more than a century and a half, and Lyell’s uniformitarianism is influential. The ranking of major mass extinctions is even in dispute, , and a was recently .
Governor Romney's path to endorsement exemplifies the problem. “I don't speak for the scientific community, of course, but I believe the world is getting warmer,” Romney told voters in June 2011 at a town hall meeting after announcing his candidacy. “I can't prove that, but I believe based on what I read that the world is getting warmer, and number two, I believe that humans contribute to that.” Four days later radio commentator Rush Limbaugh blasted Romney on his show, saying, “Bye-bye nomination. Bye-bye nomination, another one down. We're in the midst here of discovering that this is all a hoax. The last year has established that the whole premise of man-made global warming is a hoax! And we still have presidential candidates who want to buy into it.
A look at down-ticket races suggests that things may get worse. The large crop of antiscience state legislators elected in 2010 are likely to bring their views into mainstream politics as they eventually run for Congress. In North Carolina this year the state legislature considered House Bill No. 819, which prohibited using estimates of future sea-level rise made by most scientists when planning to protect low-lying areas. (Increasing sea level is a predicted consequence of global warming.) The proposed law would have permitted planning only for a politically correct rise of eight inches instead of the three to four feet that scientists predict for the area by 2100.
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Today's denial of inconvenient science comes from partisans on both ends of the political spectrum. Science denialism among Democrats tends to be motivated by unsupported suspicions of hidden dangers to health and the environment. Common examples include the belief that cell phones cause brain cancer (high school physics shows why this is impossible) or that vaccines cause autism (science has shown no link whatsoever). Republican science denialism tends to be motivated by antiregulatory fervor and fundamentalist concerns over control of the reproductive cycle. Examples are the conviction that global warming is a hoax (billions of measurements show it is a fact) or that we should “teach the controversy” to schoolchildren over whether life on the planet was shaped by evolution over millions of years or an intelligent designer over thousands of years (scientists agree evolution is real). Of these two forms of science denialism, the Republican version is more dangerous because the party has taken to attacking the validity of science itself as a basis for public policy when science disagrees with its ideology.
If the data about global climate change are indeed valid and robust, any qualified scientist should be able to look at them and see if the prevailing scientific interpretation holds up. Indeed, such a test took place. Starting in 2010, a group led by U.C. Berkeley physicist Richard Muller re-examined all the temperature data from the NOAA, East Anglia Hadley Climate Research Unit, and the Goddard Institute of Space Science sources (see Figure 5 below). Even though Muller started out as a skeptic of the temperature data, and was funded by the Koch brothers and other oil company sources, he carefully checked and re-checked the research himself. When the GOP leaders called him to testify before the House Science and Technology Committee in spring 2011, they were expecting him to discredit the temperature data. Instead, Muller shocked his GOP sponsors by demonstrating his scientific integrity and telling the truth: the temperature increase is real, and the scientists who have demonstrated that the climate is changing are right. In the fall of 2011, his study was published, and the conclusions were clear: global warming is real, even to a right-wing skeptical scientist. Unlike the hired-gun scientists who play political games, Muller did what a true scientist should do: if the data go against your biases and preconceptions, then do the right thing and admit it—even if you’ve been paid by sponsors who want to discredit global warming. Muller is a shining example of a scientist whose integrity and honesty came first, and did not sell out to the highest bidder.
Figure 5. Plot contrasting the temperature data obtained by three original sources (NOAA, Goddard Institute of Space Sciences, and The Hadley Climate Research Unit of the University of East Anglia) with the data obtained by Richard Muller’s Berkeley group, which was originally attempting to deny the evidence of global warming, but found that in fact the original data were correct and the planet is getting warmer.