Page 135 - Environment: The Science Behind the Stories

Observe relationships
in nature
Table 5.1 ecosystem Services
Ecological processes do many things that benefit us:
Design hypothesis • Regulate oxygen, carbon dioxide, stratospheric ozone, and
to explain relationships other atmospheric gases
• Regulate temperature and precipitation by means of ocean
currents, cloud formation, and so on
Construct model • Protect against storms, floods, and droughts, mainly by
means of vegetation
• Store and regulate water supplies in watersheds and aquifers
Predict relationships
in nature • Prevent soil erosion
• Form soil by weathering rock and accumulating organic
material
Gather new data • Cycle carbon, nitrogen, phosphorus, sulfur, and other nutrients
• Filter waste, remove toxins, recover nutrients, and control
pollution
Refine model • Pollinate plant crops and wild plants so they reproduce
• Control crop pests with predators and parasites
• Provide habitat for organisms to breed, feed, rest, migrate,
and winter
Figure 5.13 Ecological modelers observe relationships
among variables in nature and then construct models to • Produce fish, game, crops, nuts, and fruits that people eat
explain those relationships and make predictions. They test • Supply lumber, fuel, metals, fodder, and fiber
and refine the models by gathering new data from nature and see-
ing how well the models predict those data. • Furnish medicines, pets, ornamental plants, and genes for
resistance to pathogens and crop pests
• Provide recreation such as ecotourism, fishing, hiking,
birding, hunting, and kayaking
Ecosystem services sustain our world • Provide aesthetic, artistic, educational, spiritual, and scientific
amenities
When scientists try to understand how ecosystems function,
it is not simply out of curiosity about the world. They also
know that human society depends on healthy, functioning
and undisturbed, they provide goods and services that we FaQ If we had to pay for the services provided
ecosystems. When Earth’s ecosystems function normally
by nature, what would it cost?
could not survive without. As we’ve seen, we rely not just Estimating the economic value of all of Earth’s ecosystem ser-
on natural resources (which can be thought of as goods vices is no easy task, but a study published in 1997 by an
from nature; p. 21), but also on the ecosystem services international team of scientists and economists put a rough
(p. 21) that our planet’s systems provide. (Table 5.1). dollar figure on the many benefits nature provides us (p. 170).
Ecological processes form the soil that nourishes our The team did not examine all of the biosphere’s services, but
crops, purify the water we drink and the air that we breathe, rather focused on 17 key ecosystem services from 16 biomes.
store and stabilize supplies of water that we use, pollinate the The authors defined ecosystem services as natural processes
food plants we eat, and receive and break down (some of) (such as nutrient cycling or regulation of the global climate) and
the waste we dump and the pollution we emit. The negative renewable natural resources (such as timber or food crops,
feedback cycles that are typical of ecosystems regulate and but not including nonrenewable minerals and fossil fuels) and
stabilize the climate and help to dampen the impacts of the calculated the economic value of these services.
disturbances we create in natural systems. On top of all these The study determined that the value of these 17 ecosystem
services that are vital for our very existence, ecosystems also services ranged from $16 to $54 trillion per year, with an aver-
provide services that enhance the quality of our lives, ranging age of $33 trillion ($48 billion in 2013 dollars when adjusted for
from recreational opportunities to pleasing scenery to inspira- inflation). This is a stunning quantity, especially when one con-
tion and spiritual renewal. Ecosystem goods and ecosystem siders that the sum total of the gross national products of every
services (Figure 5.14) support our lives and society in pro- nation in 1997 was only $18 trillion. That is, the ecosystem ser-
found and innumerable ways. vices provided by nature had a value 1.8 times higher than the
One of the most important ecosystem services is the entire economic activity of the planet. Such studies are useful
cycling of nutrients. Through the processes that take place because they allow us to more accurately conduct cost-benefit
within and among ecosystems, the chemical elements and analyses of proposed projects by considering both the expected
compounds that we need—carbon, nitrogen, phosphorus, economic gains from development and the economic costs from
water, and many more—cycle through our environment in the degradation of ecosystem services due to development.
134 complex ways.

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