Recipes for Science
eBook - ePub

Recipes for Science

An Introduction to Scientific Methods and Reasoning

Angela Potochnik, Matteo Colombo, Cory Wright

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  1. 336 Seiten
  2. English
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eBook - ePub

Recipes for Science

An Introduction to Scientific Methods and Reasoning

Angela Potochnik, Matteo Colombo, Cory Wright

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Über dieses Buch

Today, scientific literacy is an essential aspect of any undergraduate education. Recipes for Science responds to this need by providing an accessible introduction to the nature of science and scientific methods, reasoning, and concepts that is appropriate for any beginning college student. It is designed to be adaptable to a wide variety of different kinds of courses, such as introductions to scientific reasoning or critical thinking, philosophy of science, and science education. In any of these different uses, the book helps students better navigate our scientific, 21st-century world.

Key Features

  • Contemporary and historical examples of science from many fields of physical, life, and social sciences.
  • Visual aids to clarify and illustrate ideas.
  • Text boxes to explore related topics.
  • Plenty of exercises to ensure full student engagement and mastery of the information.
  • Annotated 'Further Reading' sections at the end of each chapter.
  • Final glossary with helpful definitions of key terms.
  • A companion website with author-developed and crowdsourced materials, including syllabi for courses using this textbook, bibliography of additional resources and online materials, sharable PowerPoint presentations and lecture notes, and additional exercises and extended projects.

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Chapter 1
What Is Science?

1.1 The Importance of Science

After reading this section, you should be able to do the following:
  • Describe how scientific research supports the finding of human-caused climate change and why public opinion lags behind the scientific research
  • Discuss the nature of knowledge and the varieties of scientific knowledge
  • Articulate the limits of science and describe a type of project outside those limits

A Serious Practical Concern

April 22, 2016, was a historic day. While people worldwide celebrated Earth Day and expressed their support for protection of the environment, representatives of 177 nations signed the Paris Agreement at the UN headquarters in New York. The Paris Agreement followed up on the Kyoto Protocol to unite most countries on our planet to deal with climate change. Indeed, there was near-total international unity and consensus, and only two countries did not sign: Nicaragua, because the agreement did not go far enough, and Syria, because of their civil war and subsequent governmental collapse.
The Paris Agreement aims to keep the average global temperature rise this century to well below 2° Celsius. Two degrees might seem like a minor change in temperature, but as an average global temperature increase, it would be a really big deal. Think of this temperature increase like a fever. The human body maintains a relatively constant temperature in the range of 36.5–37.5° Celsius (97.7–99.5° Fahrenheit). Were your body temperature to increase just 2° Celsius, you would have a raging fever, as your temperature would be over 38.8° Celsius (102° Fahrenheit). If your body were suddenly that much warmer on average, it would be a serious and potentially devastating medical emergency—and all the more so without medical treatment options. An average global temperature increase of 2° Celsius would be similarly devastating for Earth, and there would be few if any treatment options.
But why, exactly, would it be so devastating? First, because it changes the Earth’s climate. The atmospheric concentrations of greenhouse gases, such as methane (CH4), carbon dioxide (CO2), and water vapor, are a major factor affecting the Earth’s climate. Greenhouse gases work like a blanket. As incoming radiation from the Sun permeates our atmosphere, some of this heat hits the Earth and is reflected back out to space. But greenhouse gases trap some of the heat in the atmosphere; this blanket of radiant heat warms the planet’s surface, making it hospitable to life. But increasing amounts of greenhouse gases trap increasing amounts of heat. As a result, mountain glaciers are shrinking and ice sheets are melting in the Arctic, Greenland, and Antarctica; sea levels are rising; precipitation patterns across seasons are more unstable; more droughts and heat waves are occurring; and the blooming times of flowers and plants are shifting. All these changes are consequences of global warming.
Second, the changing climate has other downstream effects. The rise in global temperature and resulting climate changes threaten to push some animal and plant species to extinction, collapse ecosystems, and make extreme weather more frequent. It also threatens to destabilize social conditions. Drinking water will become scarcer and droughts more frequent and severe; crop yields may decrease. Coastal cities and island nations are at risk of serious floods and devastating hurricanes. In this way, climate change is also affecting global health, poverty, hunger, and various nations’ security. Ultimately, global warming will make the Earth less hospitable for all creatures, including humans, and probably also a more unjust place in virtue of who will suffer and how this suffering will be managed.
Earth’s climate has never been static; it has been fluctuating for billions of years. Besides the concentration of greenhouse gases, factors that affect it include variations in the Earth’s orbit, the motion of tectonic plates, the impact of meteorites, and volcanism on the Earth’s surface. So, what’s special about the current climate changes? Why is this different?
What’s special about the current changes in Earth’s climate is the role of human activities in generating them. The basic reasoning behind this conclusion is simple and clear. We have known since the 18th century that burning carbon-based fossil fuels releases carbon dioxide (CO2) into the atmosphere. During the last three centuries, at least since the beginning of the Industrial Revolution, human activities have been releasing CO2 into the atmosphere at an unprecedented rate. Large-scale releases of CO2—one of the greenhouse gases—into the atmosphere increase its heat retention, thus increasing the Earth’s average global temperature. And scientists have in fact measured such an increase in average global temperature. So it’s clear that human activity during the last couple of centuries has increased the Earth’s average global temperature.
Systematic research on the relationship between CO2 emissions and climate change began in the 19th century, when the American engineer Marsden Manson noted that ‘the rate at which a planet acquires heat from exterior sources is dependent upon the power of its atmosphere to trap heat; very slight variations in the atmospheric constituents [produce] great variations in heat trapping power’ (Manson, 1893, p. 44). A few years later, the Swedish physicist and chemist Svante August Arrhenius (1859–1927) completed an extensive set of calculations, showing that the changes in CO2 function as a ‘throttle’ on other greenhouse gases like water vapor. He also calculated that there would be an Arctic temperature increase of approximately 8° Celsius (46.4° Fahrenheit) from atmospheric carbon levels two to three times their known value at the time. Arrhenius later predicted that ‘the slight percentage of carbonic acid in the atmosphere may, by the advances of industry, be changed to a noticeable degree in the course of a few centuries’ (1908, p. 54).
Just before the outbreak of World War II, a British steam engineer, Guy Callendar, presented a breakthrough paper to the Royal Meteorological Society entitled ‘The Artificial Production of Carbon Dioxide and Its Influence on Temperature’. Callendar pointed out that the atmospheric concentration of CO2 had significantly increased between 1900 and 1935, which he determined with temperature measurements from 200 meteorological stations. Based on further calculations, he concluded that:
As man is now changing the composition of the atmosphere at a rate which must be very exceptional on the geological time scale, it is natural to seek for the probable effects of such a change. From the best laboratory observations it appears that the principal result of increasing atmospheric carbon dioxide
 would be a gradual increase in the mean temperature of the colder regions of the earth.
(1939, p. 38)
Unfortunately, Callendar’s prescient recognition of the role of human activity on atmospheric temperatures had to wait several decades to become widely accepted.
Figure 1.1 Notable early scientists studying carbon dioxide (CO2) and climate
Figure 1.1 Notable early scientists studying carbon dioxide (CO2) and climate
In May 1958, the American scientist Charles David Keeling (1928–2005) installed four infrared gas analyzers at the Mauna Loa Observatory in Hawaii; these recorded an ever-increasing atmospheric CO2 concentration. These measurements have been collected continuously since 1958, resulting in the so-called Keeling Curve (see Figure 1.2), which is a graph plotting ongoing change in concentration of CO2 in the Earth’s atmosphere.
Keeling’s measurements provided evidence of rapidly increasing CO2 levels in the atmosphere, and a 1979 report by the National Research Council—an American nonprofit, non-governmental organization devoted to scientific research—connected this evidence to a rise in average temperature. This report predicted that doubling CO2 concentration in the atmosphere from 300 to 600 parts per million would result in an average warming of 2° Celsius to 3.5° Celsius. (Parts per million, or ppm, is a unit for measuring small amounts of a substance in some mixture.) We haven’t yet reached the ominous level of 600 ppm, but we’re now long past safe levels of CO2 in the atmosphere, which had been estimated to be about 350 ppm.
In the past several decades, climate scientists have been tracking CO2 levels in the atmosphere with ever more precise and sophisticated techniques. For example, ice cores taken from various locations in Antarctica have enabled scientists to extrapolate historic CO2 levels for comparison to recent levels (see Figure 1.3). A group of 78 scientists gathered data from ‘climate proxies’ besides ice cores—including tree rings, pollen, corals, glacier ice, lake and marine sediments, and historical documents about the climate—to
Figure 1.2 Keeling curve: ongoing increase in atmospheric concentrations of CO2
Figure 1.2 Keeling curve: ongoing increase in atmospheric concentrations of CO2
Figure 1.3 Ice core data from Antarctica
Figure 1.3 Ice core data from Antarctica
demonstrate that there are multiple lines of evidence for increasing levels of CO2 in the atmosphere (see Figure 1.4) and that the average temperature for the end of the 20th century is higher than in the previous two millennia (Ahmed et al., 2013).
Figure 1.4 Unprecedented increases in atmospheric CO2 in the past century
Figure 1.4 Unprecedented increases in atmospheric CO2 in the past century
The unprecedented pace of current climate change and its connection to human activities like burning fossil fuels, cattle ranching, and clear-cutting rainforests are clear. In the previous 800,000 years, the concentration of CO2 in the atmosphere had never been over 285 ppm. Since the Industrial Revolution—only 0.025% of the last 800,000 years—the concentration has spiked to 412 ppm. The milestone of 400 ppm was reached in March 2015 (see CO2 concentration measured 409.39 on May 30th 2017, the day before Donald Trump announced that he would withdraw the US from the Paris Agreement. One year later, in May 2018, the concentration has risen more to 412 ppm. The last time CO2 levels were this high, humans did not yet exist. The average temperature of our planet has gone up by about 0.85° Celsius (1.5° Fahrenheit) since 1880, and the last three decades are estimated to have been the hottest in the last 1,400 years.

The Role of Science

We have already articulated the reasoning leading to the conclusion that human activities are radically altering Earth’s climate. But how do scientists really know? The short answer is that scientists know this in the same way that they have come to know anything else. Scientists know that the structure of DNA is a double helix, that Neptune takes more than 164.79 years to orbit the Sun, that HIV is a retrovirus that attacks T-cells, and so on. These and other facts all have good science behind them. None were obvious to begin with; scientists had to reason their way to the correct answer.
Understanding how scientists acquire new knowledge, the basis for science’s authority as a source of knowledge, and the limits of that authority gives us greater reason to trust scientific knowledge. This is so whether the knowledge is about DNA, Neptune’s orbit, HIV, or climate change.
First, it’s important to consider the nature of expertise. You should trust climate scientists to do climate science in the same way you trust your mechanic with your car or your favorite restaurant with your dinner. The types of expertise required for these positions takes years, even decades, to develop, and the expertise doesn’t neatly transfer from one domain to another. Don’t trust the average climate scientist to fix your car or make you a delicious meal. Similarly, politicians and policy-makers know things about political and legislative matters, but they should not be looked to as authorities on climate change. This includes politicians who deny climate change, as well as those who grant its existence.
Reputable scientists and scientific societies, including the national science academies of the world and the Intergovernmental Panel on Climate Change (IPCC), agree that human-caused, or anthropogenic, climate change is occurring. This includes virtually all climatologists. In 2004, for instance, the historian of science Naomi Oreskes analyzed 928 abstracts on climate change published in peer-reviewed scientific journals from 1993 to 2003; none expressed disagreement with the consensus position that anthropogenic climate change is occurring (Oreskes, 2004). In 2010, a group of researchers studied the views of the top 200 climate scientists (defined as the scientists with the most extensive publication records) and confirmed that more than 97% actively affirm the existence of anthropogenic climate change as described by the IPCC (Anderegg et al., 2010). So there is striking agreement among climate scientists about the existence of anthropogenic climate change.
Climatologists’ agreement on climate change is grounded in a rich body of independent sources of evidence that support the same conclusion: human activities are causing Earth’s atmosphere to heat up. Well-established theories in physics explain how heat radiation works. Physical chemistry shows how CO2 in the atmosphere traps heat, contributing to greenhouse effects. As we pointed out, at least since the 1890s, scientists have known about the relationship between CO2 buildup and average global temperature. Satellites and other technology have enabled scientists to collect many different types of information about relevant changes on our planet—including variations of sea level and of oceans’ temperatures, and the decreasing mass of polar ice sheets. Since the 1950s, scientific models and computer simulations have been helping scientists to make testable predictions about what would happen to the global climate in response to different changes in human activities. Evidence has confirmed these predictions.
And, yet, despite decisive scientific evidence, public awareness and concern for climate change lag behind the research (Lee et al., 2015). As of 2016, four out of every 10 adults worldwide hadn’t even heard of climate change. Whether or not people are sensitive to the risks of climate change mainly depends on understanding its human causes and on one’s level of education. In some countries, like the US, however, being better educated doesn’t guarantee that one is more likely to believe that climate change is really happening and is caused by human activities. Instead, political views are a better predictor of Americans’ belief in and concern about the reality of climate change.
People who don’t know much about some topic also tend to experience an illusion of understanding, where a lack...