uter accuracy, and as a result there is no irm consensus on exactly how
much warming a certain level of atmospheric carbon dioxide would
cause. Specialists in each field related to climate change studies can easily
add to this list.
Yet those specialists have also declared their conviction that global
warming is happening and is being caused by human beings. We can only
conclude that for them this much is certain; the uncertainties arise in
how to describe some of the mechanisms by which warming takes place,
in how much warming might take place under certain circumstances, and
what exact consequences might emerge in the course of time. 171 The limi-
tations in our knowledge do not undercut the fundamental reality that
we are changing Earth's climate in an unprecedented way. The consensus
position, in short, is now seen as so elementary, so difficult to dispute,
that it is taken for granted by scientists in the field, who have moved on to
examine other questions.
But the hesitation with regard to certainty nevertheless does reveal
something crucial about our current dilemma. After all, very few of us
have ever been asked to assess the state of scientific expertise before mak-
ing up our minds about something central to our lives. We're not used to
being in this position. What's more, while scientists live with uncertainty
as part of their profession, we laymen typically think in a different way:
we want clear, concise answers and ask our politicians, journalists, and
leading figures to supply them as often as possible. We don't like the mis-
match between scientific caution and our everyday demand for clarity.
Our dissatisfaction with the scientific response to our demand for cer-
tainty comes out of this mismatch.
But it's worth asking whether our defensiveness on climate makes
sense. Do we truly seek certainty in every area of our own lives? For
example, do we buy fire insurance only if we know for sure we'll need it
down the line? When we go on a trip, do we take only those items we
can prove we'll need? As a nation, do we demand military preparedness
only if we know precisely what other forces will threaten us—and when
they will do so?
When we think about our situation in this light, it's prety clear that
insisting on total certainty about climate change before we act gets every-
thing backwards. What would you do if you were told that if you drove