164
trends tend to occur over long time scales that are difficult for humans to perceive
directly, but mathematical models and the geologic record both show definite climate effects when CO 2 concentrations reach or exceed current atmospheric levels.
In 1824, French physicist Joseph Fourier identified the heat-trapping properties
of carbon dioxide during his investigations of atmospheric radiative heat transfer.
Fourier discovered that the carbon dioxide molecule is transparent to short wavelengths of infrared (IR) radiation, but it blocks and absorbs the longer IR wavelengths. Eunice Foote, a physicist from Seneca Falls, New York submitted her
paper: “Circumstances affecting the heat of the sun’s rays,” to the 1856 annual
meeting of the American Association for the Advancement of Science. Foote had
run some experiments with different gases in glass cylinders and discovered that the
cylinder with CO 2 trapped more heat and stayed hot longer (McNeill 2016). IrishEnglish scientist John Tyndall expanded this investigation in 1859 with different
gases like water vapor, carbon dioxide, ozone, and hydrocarbons. Tyndall thought
that changes in atmospheric chemistry could have been responsible for the Ice Ages
that were just being recognized in northern Europe and North America.
The Earth receives short-wave IR from the sun that penetrates the atmosphere
and heats the surface of the planet. This phenomenon is familiar to anyone who has
ever walked barefoot on the beach on a sunny summer day. The warm Earth then
re-radiates this heat energy back into space as longer wavelengths of IR radiation.
These longer wavelengths of IR are absorbed by CO 2 molecules in the air and warm
the atmosphere (Pierrehumbert 2011). An obvious clue that the atmosphere is
warmed by heat from the ground is the fact that the air gets colder with increasing
altitude. This is why jet aircraft leave contrails and lofty mountain peaks have snow
on them all year.
Fourier called this property the “hothouse effect” and determined that it was a
primary mechanism for keeping the atmosphere warm. We now know it as the
greenhouse effect (since the term “hothouse” went out of fashion in Victorian
times), and carbon dioxide and other heat-trapping gases are called greenhouse
gases or GHG. Greenhouse warming is important for keeping nighttime temperatures on the Earth from plummeting to far below freezing after sunset. Daily temperature swings on other planets with little or no greenhouse warming like Mars or
the moon can vary by hundreds of degrees between day and night. On planets like
Venus with extreme greenhouse warming, atmospheric temperatures are constantly
scorching hot, and there is little temperature difference between the day and
night sides.
Tyndall’s hypothesis that changes in the concentration of atmospheric gases
might have caused the Earth’s ice ages led a Swedish physicist and chemist named
Svante Arrhenius to construct and publish the first mathematical climate model
showing the influence of atmospheric carbon dioxide on global temperatures
(Arrhenius 1896). Professor Arrhenius was already well-known for formulating the
theory of electrolytic dissociation (i.e. passing an electric current through water to
break it down into hydrogen and oxygen), and he received the 1903 Nobel Prize for
that work. The carbon dioxide paper contains a fairly concise and constrained mathematical model showing how atmospheric gas composition may influence the
9 Fossil Fuels and Climate Change
trends tend to occur over long time scales that are difficult for humans to perceive
directly, but mathematical models and the geologic record both show definite climate effects when CO 2 concentrations reach or exceed current atmospheric levels.
In 1824, French physicist Joseph Fourier identified the heat-trapping properties
of carbon dioxide during his investigations of atmospheric radiative heat transfer.
Fourier discovered that the carbon dioxide molecule is transparent to short wavelengths of infrared (IR) radiation, but it blocks and absorbs the longer IR wavelengths. Eunice Foote, a physicist from Seneca Falls, New York submitted her
paper: “Circumstances affecting the heat of the sun’s rays,” to the 1856 annual
meeting of the American Association for the Advancement of Science. Foote had
run some experiments with different gases in glass cylinders and discovered that the
cylinder with CO 2 trapped more heat and stayed hot longer (McNeill 2016). IrishEnglish scientist John Tyndall expanded this investigation in 1859 with different
gases like water vapor, carbon dioxide, ozone, and hydrocarbons. Tyndall thought
that changes in atmospheric chemistry could have been responsible for the Ice Ages
that were just being recognized in northern Europe and North America.
The Earth receives short-wave IR from the sun that penetrates the atmosphere
and heats the surface of the planet. This phenomenon is familiar to anyone who has
ever walked barefoot on the beach on a sunny summer day. The warm Earth then
re-radiates this heat energy back into space as longer wavelengths of IR radiation.
These longer wavelengths of IR are absorbed by CO 2 molecules in the air and warm
the atmosphere (Pierrehumbert 2011). An obvious clue that the atmosphere is
warmed by heat from the ground is the fact that the air gets colder with increasing
altitude. This is why jet aircraft leave contrails and lofty mountain peaks have snow
on them all year.
Fourier called this property the “hothouse effect” and determined that it was a
primary mechanism for keeping the atmosphere warm. We now know it as the
greenhouse effect (since the term “hothouse” went out of fashion in Victorian
times), and carbon dioxide and other heat-trapping gases are called greenhouse
gases or GHG. Greenhouse warming is important for keeping nighttime temperatures on the Earth from plummeting to far below freezing after sunset. Daily temperature swings on other planets with little or no greenhouse warming like Mars or
the moon can vary by hundreds of degrees between day and night. On planets like
Venus with extreme greenhouse warming, atmospheric temperatures are constantly
scorching hot, and there is little temperature difference between the day and
night sides.
Tyndall’s hypothesis that changes in the concentration of atmospheric gases
might have caused the Earth’s ice ages led a Swedish physicist and chemist named
Svante Arrhenius to construct and publish the first mathematical climate model
showing the influence of atmospheric carbon dioxide on global temperatures
(Arrhenius 1896). Professor Arrhenius was already well-known for formulating the
theory of electrolytic dissociation (i.e. passing an electric current through water to
break it down into hydrogen and oxygen), and he received the 1903 Nobel Prize for
that work. The carbon dioxide paper contains a fairly concise and constrained mathematical model showing how atmospheric gas composition may influence the
9 Fossil Fuels and Climate Change