Geoscience Reference
In-Depth Information
through smell, but normally is preceded by sonic qualities. The mixture of gases,
called a
flatus
, varies considerably within or between species of flatus emitters. For
example, in humans, a flatus produced by swallowed air that made its way through
the digestive tract approximates normal proportions of atmospheric elements and
compounds, which is 78% nitrogen (N
2
), 21% oxygen (O
2
), and less than a percent
of carbon dioxide (CO
2
), methane (CH
4
), and other gases. However, if originating
as a by-product of digestion, the proportions may include as much as 30% carbon
dioxide and/or 50% hydrogen and methane. Most of the unpleasant smells we as-
sociate with flatulence come from sulfurous gases, such as hydrogen sulfide (H
2
S).
In contrast, carbon dioxide is odorless, and methane, although detectable by smell,
is not as offensive as its sulfurous companions. Most of these gases, methane in-
cluded, areamongthewaste productsofanaerobic bacteria andbacteria-like organ-
isms (
archeans
) living in our guts.
Otherthaninitiatingtemporarysocialdiscomfort,adverseolfactorysensations,
embarrassment, or lowbrow humor, every flatus by all humans or other animals
contributes gases to the global atmospheric budget. Although each emission is
small, the joint effect of these gases from animal- and non-animal sources is what
changes the earth's atmosphere and ultimately affects climate. As everyone now
knows (with the exception of a few billionaires), the overproduction of certain
gases—such as carbon dioxide and methane—has insulating qualities in our atmo-
sphere, trapping infrared radiation (heat) and thus contributing to warmer global
temperatures.Thisisnotjustamatterofquantity,butalsothetypeofgas.Although
carbon dioxide is often vilified for its role in climate change, methane in smaller
concentrations has a greater impact, as it insulates much better than carbon diox-
ide—like the difference between using nylon or wool for a blanket.
In a 2012 paper, three scientists—David Wilkinson, Euan Nisbet, and Graeme
Ruxton—asked themselves this: Did dinosaur-produced methane contribute to
global warming? They then tried to answer it by applying a few biological prin-
ciples, ecological concepts, atmospheric chemistry, and a whole bunch of math. In
