Why do people talk about climate
change, the
greenhouse
effect, and global warming
all together?
The logical flow is this:
If you believe that the increase of CO2 in the
Earth's atmosphere is due to human actions,
then you might conclude, using this logical
path, that humans are changing the climate
of the Earth.
The greenhouse
effect, as I described it last time,
is a static equilibrium. Given a certain
distance from the Sun and a certain amount
of CO2 in the atmosphere, a specific,
static temperature increase is produced.
The only way this can change is if the
amount of CO2 in the atmosphere changes.
Global warming is a completely separate
supposed (and possibly true) phenomenon that may
or may not be linked to the greenhouse
effect.
You can imagine a situation, though, in which
CO2 in the atmosphere raises the planet's
temperature, which in turn -- for some
reason -- causes atmospheric CO2 to increase,
which raises the planet's temperature, etc etc.
In this case, the temperature goes up and
up in a situation called a
runaway greenhouse effect.
It is suspected that Venus may have
undergone a runaway greenhouse.