Science shows that climate change is a certain threat

David Suzuki’s Science Matters column:

March 6, 2009 – Why does the public often pay more attention to climate change deniers
than climate scientists? Why do denial arguments that have been
thoroughly debunked still show up regularly in the media?

Some researchers from New York’s Fordham University may have found some
answers. Prof. David Budescu and his colleagues asked 223 volunteers to
read sentences from reports by the Intergovernmental Panel on Climate
Change. The responses revealed some fundamental misunderstandings about
how science works.

Science is a process. Scientists gather and compare evidence, then
construct hypotheses that “make sense” of the data and suggest further
tests of the hypothesis. Other scientists try to find flaws in the
hypothesis with their own data or experiments. Eventually, a body of
knowledge builds, and scientists become more and more certain of their
theories. But there’s always a chance that a theory will be challenged.
And so the scientists speak about degrees of certainty. This has led to
some confusion among the public about the scientific consensus on
climate change.

What Prof. Budescu and his colleagues found was that subjects
interpreted statements such as “It is very likely that hot extremes,
heat waves and heavy precipitation events will continue to become more
frequent” to mean that scientists were far from certain. In fact, the
term very likely means more than 90 per cent certain, but almost half
the subjects thought it meant less than 66 per cent certain, and three
quarters thought it meant less than 90 per cent.

According to an article in New Scientist, the researchers concluded
that scientists should use both words and numbers to express certainty.
For example, the IPCC considers “virtually certain” to mean more than
99 per cent likely; “very likely” to mean more than 90 per cent
certain; “likely” to be more than 66 per cent; “more likely than not”
more than 50 per cent; and so on.

It’s important to understand the distinctions. People who recognize the
urgency of the situation are more likely to get behind solutions. And
businesses and governments are more likely to work toward solutions
when the public demands that they do.

And how urgent is the situation? The IPCC has concluded it is “very
likely” that human emissions of greenhouse gases rather than natural
variations are warming the planet’s surface. Remember, that means they
are more than 90 per cent certain. That’s about as close to unequivocal
as science gets. The IPCC has also concluded that the consequences
could be catastrophic.

This is science that has been rigorously peer-reviewed and that has
been agreed upon by the vast majority of the world’s climate
scientists, as well as more than 50 scientific academies and societies,
including those of all G8 nations. There has been no peer-reviewed
scientific study that has called into question the conclusions of the
IPCC, which represents the consensus of the international scientific
community.

So why does the debate still continue? Why are we fiddling while Rome
burns? Well, as Prof. Budescu’s research shows, some people don’t
really understand how science works. And people with vested interests,
many of whom work with the oil and coal industries, are all too willing
to exploit that lack of understanding by sowing confusion.

It’s also true that many people fear change. We’ve seen examples of
economic prosperity and job creation brought about by investments in
green energy in places such as Germany and Sweden. And leading
economists, including former World Bank chief economist Nicholas Stern,
have warned that not doing anything to confront climate change will
cost us far more in the long run than acting now. But many people still
fear that any profound change will upset the economy or diminish their
quality of life.

We must also consider the rational argument for taking action on
climate change. Even in the highly unlikely event that all the world’s
climate scientists have got it wrong, if we still move forward to clean
up our act, we’ll end up with a cleaner planet and more sustainable
technologies and energy sources. On the other hand, if the scientists
are right and we decide to listen to the absurd arguments of the
deniers, we’re in trouble. It doesn’t seem like much of a choice.

We may never reach 100 per cent certainty on climate change and its
causes – that’s not what science is about – but one thing is certain:
if we don’t get together to work on solutions now we’ll have a much
tougher time dealing with the consequences later.

To check out all of Dr. Suzuki’s columns, check out the Science Matters Archive on the David Suzuki Foundation website.

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