“It was fun writing those allegories about global warming,
Curmudge, but now I understand that you want to take a more scholarly look at
climate science. Like many other
topics that we have discussed, you don’t know diddly about anything higher into
the troposphere than the old man’s third-floor apartment.”
“I do so know diddly, Jaded Julie. I can forecast the weather: ‘Red sky in the morning, sailors
take warning. Red sky at night,
sailors’ delight.’ See? But my real reason for tackling this
topic is that too many people seem to accept the catastrophic global warming
dogma without giving it much thought.
Here’s an example. A local
church is asking its governing body to ‘request that Congress enact legislation
to fight climate change.’ “
“Part of that makes sense. If climate change is due to natural phenomena (‘acts of
God’), churches probably provide the best medium for making such a
request. The U.S. Congress is a
totally inappropriate intermediary.”
Climatology
101
“How can we teach climate, Curmudge? Neither of us has a degree in it.”
“Even if we did, Julie, it wouldn’t matter. With the exception of a few professors
and doctors, advanced degrees expire after 40 years. We’ve been reading climate stuff for weeks, so we can ‘wing
it.’ The Intergovernmental Panel
on Climate Change (IPCC) was created in 1988; and despite the alarmist tone of
their assessment reports, they do contain some useful information. We’ll quote excerpts from one of them
(1) as our main resource for Climatology 101. A more detailed discussion of climate fundamentals (not
quoted) is provided by Somerville (2).”
“I knew you were kidding about ‘expire after 40 years,’ so
put on your jacket with chalk dust on the sleeves. Class is in session.”
‘The climate system evolves in time under the influence of its own
internal dynamics and due to changes in external factors that affect climate
(called ‘forcings’). External forcings include natural phenomena such as
volcanic eruptions and solar variations, as well as human-induced changes in
atmospheric composition. Solar radiation powers the climate system. There are
three fundamental ways to change the radiation balance of the Earth: 1) by
changing the incoming solar radiation (e.g., by changes in Earth’s orbit or in
the Sun itself); 2) by changing the fraction of solar radiation that is
reflected, e.g., by changes in cloud cover, atmospheric particles or
vegetation); and 3) by altering the longwave radiation from Earth back towards
space (e.g., by changing greenhouse gas concentrations). Climate, in turn,
responds directly to such changes, as well as indirectly, through a variety of
feedback mechanisms.’
‘About 30% of the sunlight that reaches the top of the atmosphere is
reflected back to space. Roughly two-thirds of this reflectivity is due to
clouds and small particles in the atmosphere known as ‘aerosols’. Light-colored
areas of Earth’s surface – mainly snow, ice and deserts – reflect the remaining
one-third of the sunlight.’
‘The reason the Earth’s surface is this warm is the presence of
greenhouse gases, which act as a partial blanket for the longwave radiation
coming from the surface. This blanketing is known as the natural greenhouse
effect. The most important greenhouse gases are water vapor and carbon dioxide.
The two most abundant constituents of the atmosphere – nitrogen and oxygen –
have no such effect. Clouds, on the other hand, do exert a blanketing effect
similar to that of the greenhouse gases; however, this effect is offset by
their reflectivity, such that on average, clouds tend to have a cooling effect
on climate.’
“Wow, Curmudge, we
should be grateful for the natural greenhouse effect. Without it the earth would be as cold as the moon, and
uninhabitable.”
‘Energy is transported from the equatorial areas to higher latitudes via
atmospheric and oceanic circulations, including storm systems. Energy is also
required to evaporate water from the sea or land surface, and this energy,
called latent heat, is released when water vapor condenses in clouds.
Atmospheric circulation is primarily driven by the release of this latent heat.
Atmospheric circulation in turn drives much of the ocean circulation through
the action of winds on the surface waters of the ocean, and through changes in
the ocean’s surface temperature and salinity through precipitation and
evaporation. Changes in various aspects of the climate system, such as the size
of ice sheets, the type and distribution of vegetation or the temperature of
the atmosphere or ocean will influence the large-scale circulation features of
the atmosphere and oceans.’
‘There are many feedback mechanisms in the climate system that can
either amplify (‘positive feedback’) or diminish (‘negative feedback’) the
effects of a change in climate forcing. For example, as (or if) rising concentrations of greenhouse gases warm Earth’s
climate, snow and ice begin to melt. This melting reveals darker land and water
surfaces that were beneath the snow and ice, and these darker surfaces absorb
more of the Sun’s heat, causing more warming, which causes more melting, and so
on, in a self-reinforcing cycle. Detecting, understanding and accurately
quantifying climate feedbacks have been the focus of a great deal of research
by scientists unraveling the complexities of Earth’s climate.’
“With that
introduction, Curmudge, I’m now ready to read the original climatology
literature.”
“We’d be reading
forever, Julie, and fortunately it has been done for us. We’ll be discussing review articles;
our friends in health care call them meta-analyses.”
Kaizen
Curmudgeon
(1)
IPCC.
What Factors Determine Earth’s
Climate? http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-1-1.html
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