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Chapter 17

ANTA01H3 Chapter Notes - Chapter 17: Richard Branson, Bald Eagle, Lyme Disease

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Chapter 17 Human Disconnection
Human Impact on the Planet and on Other Life-Forms
By most standards, Homo sapiens is a successful species. There are
currently 7.3 billion humans living on this planet. Even so, we and all other
multicellular organisms contribute only a small fraction of all the cells on
earthmost of which are bacteria. So if we see life ultimately as a
competition among reproducing organisms, bacteria are the winners, hands
Humans have had an inordinate impact on the earth and its myriad forms of
life. In the past, our ancestors had to respond primarily to challenges posed
by nature. Today the greatest challenges for our species (and all others)
are the vastly altered environments of our own making. Through our
actions, which have caused widespread devastation of ecosystems all over
the world, from the deep seas to the upper atmosphere, we have
disconnected our species from its long evolutionary legacy. But at the same
time, we are still dependent on the ecosystems of which we remain a part.
Increasing population size is the single most important reason that our
impact has been so great. As human population pressure increases, more
and more land is converted to crops, pasture, construction, and human
habitation, providing more opportunities for still more humans and fewer (or
no) habitats for most other species.
Growth curve (orange) depicting the exponential growth of the world’s human
population. The vertical axis depicts world population size in billions. It wasn’t
until the mid-1800s that this figure reached 1 billion, but we now add 1 billion
people every 13 years or so. Population increase occurs as a function of some
percentage (in developing countries, the annual rate is over 3 percent). With
advances in food production and medical technologies, humans are currently
undergoing an unprecedented population explosion, as this figure illustrates.
The rate of population growth is not equally distributed among all nations.
The most recent United Nations report on world population notes that 95
percent of this growth is occurring in the developing world. Likewise,
resources are not distributed equally among all nations. Only a small
percentage of the world’s population, located in a few industrialized
nations, control and consume most of the world’s resources.
Humans and the Impact of Culture
The domestication of plants and animals is seen as one of the most
significant events in human history, one that was eventually to have far-
reaching consequences for the entire planet. Human impact on local
environments increased dramatically as soon as people began to live in
permanent settlements.
Unfortunately, humans began to exploit and increasingly depend on
nonrenewable resources. Forests can be viewed as renewable
resources provided they’re given the opportunity for regrowth. But in
many areas, forest clearing was virtually complete and was inevitably

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followed by soil erosion, frequent overgrazing, and overcultivation,
which in turn led to further soil erosion (Fig. 14-2). In those areas, trees
became a nonrenewable resource, perhaps the first resource to have
this distinction.
Destruction of natural resources in the past has also had severe
consequences for people living today. In 1990, a typhoon and
subsequent flooding killed over 100,000 people in Bangladesh, and the
flooding was at least partly due to previous deforestation in parts of the
Himalayas of northern India. There is also evidence that deforestation
has contributed to continued erosion and flooding in China. And millions
of people in Pakistan were affected by flooding in 2010, 2011, and 2015
that resulted in part from deforestation and dam construction along
tributaries of the Indus River. This flooding affected one-fifth of the
country and set back years of infrastructure development.
Global Climate Change
There are several atmospheric substances that warm the earth by
trapping heat. Collectively they are called greenhouse gases because
as they accumulate in the atmosphere, they reduce the earth’s ability to
radiate heat produced by the sun back into space. These greenhouse
gases include water vapor, ozone, nitrous oxide, methane,
chlorofluorocarbons, and carbon dioxide. Without them the earth would
freeze, but in abundance they can raise temperatures to dangerous
levels, and that is what is currently happening. We can say this
unequivocally because climate scientists are virtually unanimous in their
view that the earth is heating up; moreover, it’s happening more quickly
than predicted, and it’s due to human activities. Chief among these
activities is the burning of fossil fuels, especially oil and coal. Fossil
fuels release when burned, and is the most significant contributor to
global warming. Indeed, we currently release 35 billion tons of into the
atmosphere every year.
In 2012, scientists at the National Oceanic and Atmospheric
Administration (NOAA) reported for the first time that levels had reached
400 parts per million (ppm) in several northern locations. This figure
vastly exceeds the natural range for the last 800,000 years of 180 to
300 ppm. This is highly significant because for several years,
climatologists have warned that if we are to keep average worldwide
temperatures from increasing more than, the level of must be kept at
350 ppm. In turn, keeping the increase below is important because
many researchers consider that to be the maximum we can sustain
without disastrous consequences for the environment and for thousands
of species.
Public Perceptions of Climate Change

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Several prominent people who deny that climate change is occurring
or is the result of human activity call themselves “climate deniers” or
“skeptics.” Actually, skepticism is a necessary component of good
science, but not when it’s ideologically or financially based. As we
discussed in Chapter 1, scientific research involves collecting data,
evaluating the results, then publishing the findings in peer-reviewed
journals. In this way, scientific claims are constantly being evaluated,
critiqued, and revised. However, skepticism that is motivated
primarily by ideology or financial gain is not only bad science; it’s not
science at all.
An important example of how scientifically based skepticism (unlike
that shown by climate deniers) can add to our understanding of
global climate change involves research carried out by Richard
Muller, acclaimed physicist at the University of California, Berkeley.
A few years ago, Professor Muller became dissatisfied with the way
global warming was being evaluated. So he organized a highly
regarded research team and founded the Berkeley Earth Surface
Temperature Project. The team collected temperature data dating as
far back as 1753 from hundreds of reporting sites around the globe,
with most of the information coming from the United States and
United Kingdom. From this intensive scientific research, Muller
concluded that global warming is real and humans are almost
entirely the cause.
This is a perfect example of how skepticism based in critical thinking
can lead to a more accurate understanding of the world around us.
However, the skeptics who were driven by ideology were not at all
pleased with Muller’s conclusions. These included many members of
Congress as well as private individuals who helped fund the
Berkeley research, believing that Muller’s findings would support
their denials of climate change. Most notably, billionaire Charles
Koch, who is extremely partisan and ideological, provided
considerable financial backing for the project. Nevertheless, in the
end, good science won out.
One problem with climate science is that most people want definitive
answers to complex questions, and they don’t understand that
scientific research doesn’t necessarily provide definitive answers.
Climate change is perhaps the most complex of phenomena
because hundreds, if not thousands, of variables are involved. As
more data are collected and analyzed, explanations are modified.
This fact is something that most people, and apparently many
politicians, do not understand. It is also a fact that climate change
deniers take advantage of, because they can easily criticize what
they see as contradictory results. When scientists publish results
that appear to disagree with previous studies, they are reporting new
conclusions based on more recent data analysis or more recently
obtained evidence. While various studies may produce contradictory
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