Doubts, Uncertainties, and Qualms - Global Climate Change - page 29

Doubts, uncertainties, anD Qualms  3

Global Perception

coming years some of the principles now
assumed to govern climate change will
themselves change as our science advances.
It is the normal scheme of things for ideas
about nature to change as we observe the
workings of the natural world.

There are a number of important uncer-
tainties in the science of global change.
The Intergovernmental Panel on Climate
Change (ipcc) is painfully aware of them
and lists them in its various publications,
especially in those published by the United
Nations Environmental Programme (unep)
publications, written for laypersons and
available from www.earthprint.com. These
uncertainties are not the Achilles' heels
of global change. “It's almost certain that
you can't put a trillion tons of CO 2 into
the atmosphere without something nasty
happening.” This is according to James
Lovelock, environmental thinker and fu-
turist. Global change is a certainty and the
direction of change is well understood. But
rates, volumes, and levels remain uncer-
tain.
There are a number of examples of well-
founded and scientifically reasonable, peer-
reviewed studies that question some of the
numbers floating around the global climate
change realm. None that we are aware of,
however, question the reality of global
warming and the human connection. In

Most fundamentally, scientists are not ex-
actly sure what will happen when we reduce
greenhouse gas (ghg) emissions. What level
of ghg emissions is required to halt global
warming or to bring CO 2 concentrations
in the atmosphere to a particular level? If
we succeed in reducing CO 2 , how fast will
global changes already occurring reverse
themselves? For example, according to the
ipcc, sea level rise caused by the heating
of ocean water will continue for centuries
even after CO 2 levels have been stabilized.
Roger Pielke Jr. of the environmental
studies program at the University of Colo-
rado, Boulder, is one who argues that reduc-
ing greenhouse gases will not have a per-
ceptible impact for decades. Although he
is strongly in favor of reducing our green-
house gas emissions, Pielke argues that the
only effective response to global warming
is adapting to new conditions rather than