Environmental Engineering Reference
In-Depth Information
We'll start with the potential source of risk: the greenhouse effect.
THE GREENHOUSE FEAR
The greenhouse effect is the centerpiece of the prediction of catastrophic climate change. There are basic-
ally three parts to the prediction. (1) Man-made greenhouse gases emitted by fossil fuel combustion will
cause dramatic warming of the global climate system. (2) Dramatic global warming will cause a dramatic,
harmful change in the global climate system. (3) Those changes will overwhelm human beings' capacity
for adaptation, rendering the planet far less livable.
Those are the steps that lead numerous scientists, environmental leaders, and political leaders to make
statements like that of James Hansen, probably the world's most politically prominent climate scientist:
“CEOs of fossil energy companies know what they are doing [by emitting CO
2
] and are aware of long-
term consequences of continued business as usual. In my opinion, these CEOs should be tried for high
crimes against humanity and nature.”
18
If any element of the greenhouse fear turns out to be false—if CO
2
emissions don't cause dramatic
warming, if dramatic warming doesn't cause harmful climate change, or if human beings can adapt well,
then CO
2
emissions are not catastrophic.
In investigating whether they are or not, we'll start with the foundation: the amount of warming caused
by the greenhouse effect from adding more CO
2
to the atmosphere.
WHAT EXACTLY IS THE GREENHOUSE EFFECT?
Thegreenhouseeffectisawarmingeffectthatcertain molecules, includingwaterandcarbondioxide,have
when they are in the atmosphere. When infrared radiation from the sun reflects off the planet and heads
toward space, these molecules, called infrared absorbers, reflect some of it back, causing heat.
19
The im-
pact of these gases in the atmosphere is analogized, in its warming impact, to the glass in a greenhouse
that helps keep plants warm.
Thanks to the greenhouse effect, the surface of Earth is many degrees warmer than it would otherwise
be. Many scientists say that without it, the planet would be some 33 degrees Celsius (59 degrees Fahren-
heit) colder—an ultra-Ice Age.
20
When fossil fuels—hydrocarbons—are burned, or
oxidized,
the hydrogen becomes H
2
O and the carbon
becomes CO
2
.
It's worth noting that every part of this process has climate impacts. The H
2
O introduces new water
vapor into the climate system and the burning of fossil fuels adds heat to the system—but both of these im-
pacts are too small to make a noticeable difference. Much more significant, the human activities powered
by fossil fuels are perfectly capable of affecting local climates. In cities, the bricks, pavement, and build-
ings impede the flow of ventilating winds, raising temperatures, especially nighttime lows, making heat
waves more frequent. This man-made local warming is often far greater than the global warming trend
over the last 150 years, which is .8 degree Celsius (1.44 degrees Fahrenheit), a quantity that cannot be per-
ceived without instruments).
21
