The aftermath from the recent
blizzard striking the northeast provides a fascinating example of decision
making under uncertainty, without an available estimate of uncertainty. Meteorologists
knew that there was uncertainty in their forecasts of the expect path of the
blizzard, but most did not provide an estimate of that uncertainty. In
contrast, meteorologists who provide forecasts of hurricane trajectories
routinely provide a graphical assessment of landfall location probabilities,
and local weather forecasters almost always provide a probability of rain for
upcoming days.
Of course, as I have noted in
previous blog posts, water quality modelers generally do not provide an
estimate of the uncertainty in their forecasts. Without attempting to
understand why different approaches to scientific uncertainty have emerged in
these fields, it is quite clear that the deterministic forecasts of the
blizzard trajectory (particularly around New York City) were believed by many
to be precisely what would happen. Undoubtedly, the same people who expect
daily probability of rain forecasts apparently were willing to accept no
uncertainty in the blizzard forecasts.
After the blizzard, the “Monday
morning quarterbacks” criticized meteorologists for their “faulty” forecasts,
and they criticized decision makers for mandating extreme measures in
preparation for the expected blizzard. In retrospect, meteorologists should
have provided a “cone of uncertainty” in their forecasts of the trajectory of
the blizzard. In general, this would be useful
for individual and societal blizzard preparation decision making. Further, it
would have been helpful for other fields (such as water quality modeling) by
acknowledging scientific uncertainty to the public.
Yet, if the blizzard forecasters
had provided a visual estimate of uncertainty in the blizzard trajectory,
similar to the forecasts provided by their hurricane-forecasting brethren, what
might have changed? Probably very little, other than silencing most of the
Monday morning quarterbacks. I conclude this because the blizzard was a high-consequence
event, and people tend to be risk-averse.
Should blizzard preparation decisions have
been made by meteorologists who knew of the forecast uncertainty, as some
people have suggested? No. In my blog post “The Role of Scientists in Decision Making” (http://kreckhow.blogspot.com/2013/10/the-role-of-scientists-in-decision.html),
I stress the point that to inform public sector decisions, scientists provide
scientific assessment, but not the values necessary for decision making. These
are public values, and they are provided by elected or appointed public
officials as representatives of the public.
As I concluded in a previous blog post (“Scientific
Uncertainty and Risk Assessment,” http://kreckhow.blogspot.com/2013/04/scientific-uncertaintyand-risk.html),
every
day, we make decisions based on an
interplay, or mix, of uncertainty in an event (e.g., rain) and value (enjoyment) of an activity.
We are used to weighing these considerations in our minds and deciding. These same considerations--getting new information on the weather (which is analogous to supporting new scientific research, as in adaptive management), and deciding
how valuable the activity is to us (which is what we determine through cost/benefit analysis)--are key features of risk assessment. So let us move from our informal, everyday
risk assessment to formal, scientific risk assessment, and identify the lesson and the opportunity as they relate to environmental management.
To me, the lesson
in risk assessment is to recognize
that the science in support of environmental management is usually uncertain, and sometimes highly
uncertain. But the opportunity that is provided
by risk assessment should result
in improved decision making. To accomplish this, we must
first require scientists to quantify
or estimate the scientific uncertainty. Then we must require our decision makers
to use the estimate
of uncertainty to properly weigh the scientific
information (not unlike what we do in our informal, everyday risk assessment).
In the long run, this should improve environmental management decisions by
making better use of the available information.
