Scientists as certain of climate change as they are that smoking kills

Scientists as certain of climate change as they are that smoking kills


Scientists as certain of climate change as they are that smoking kills

by Seth Borenstein – Associated Press

WASHINGTON – Top scientists from a variety of fields say they are about as certain that global warming is a real, man-made threat as they are that cigarettes kill.

They are as sure about climate change as they are about the age of the universe. They say they are more certain about climate change than they are that vitamins make you healthy or that dioxin in Superfund sites is dangerous.

They’ll even put a number on how certain they are about climate change. But that number isn’t 100 per cent. It’s 95 per cent.

And for some non-scientists, that’s just not good enough.

In science, no such thing as 100%

There’s a mismatch between what scientists say about how certain they are and what the general public thinks the experts mean, experts say.

That is an issue because this week, scientists from around the world have gathered in Stockholm for a meeting of a U.N. panel on climate change, and they will probably issue a report saying it is “extremely likely” — which they define in footnotes as 95 per cent certain — that humans are mostly to blame for temperatures that have climbed since 1951.

One climate scientist involved says the panel may even boost it in some places to “virtually certain” and 99 per cent.

Some climate-change deniers have looked at 95 per cent and scoffed. After all, most people wouldn’t get on a plane that had only a 95 per cent certainty of landing safely, risk experts say.

But in science, 95 per cent certainty is often considered the gold standard for certainty.

“Uncertainty is inherent in every scientific judgment,” said Johns Hopkins University epidemiologist Thomas Burke. “Will the sun come up in the morning?” Scientists know the answer is yes, but they can’t really say so with 100 per cent certainty because there are so many factors out there that are not quite understood or under control.

George Gray, director of the Center for Risk Science and Public Health at George Washington University, said that demanding absolute proof on things such as climate doesn’t make sense. Gray, who was chief scientist for the U.S. Environmental Protection Agency during the George W. Bush administration, noted:

[quote]There’s a group of people who seem to think that when scientists say they are uncertain, we shouldn’t do anything. That’s crazy. We’re uncertain and we buy insurance.[/quote]

With the U.N. panel about to weigh in on the effects of greenhouse gas emissions from the burning of oil, coal and gas, The Associated Press asked scientists who specialize in climate, physics, epidemiology, public health, statistics and risk just what in science is more certain than human-caused climate change, what is about the same, and what is less.

Almost as certain as gravity

They said gravity is a good example of something more certain than climate change. Climate change “is not as sure as if you drop a stone it will hit the Earth,” Princeton University climate scientist Michael Oppenheimer said. “It’s not certain, but it’s close.”

Arizona State University physicist Lawrence Krauss said the 95 per cent quoted for climate change is equivalent to the current certainty among physicists that the universe is 13.8 billion years old.

The president of the prestigious National Academy of Sciences, Ralph Cicerone, and more than a dozen other scientists contacted by the AP said the 95 per cent certainty regarding climate change is most similar to the confidence scientists have in the decades’ worth of evidence that cigarettes are deadly.

“What is understood does not violate any mechanism that we understand about cancer,” while “statistics confirm what we know about cancer,” said Cicerone, an atmospheric scientist. Add to that a “very high consensus” among scientists about the harm of tobacco, and it sounds similar to the case for climate change, he said.

Easy to nitpick reports

But even the best study can be nitpicked because nothing is perfect, and that’s the strategy of both tobacco defenders and climate deniers, said Stanton Glantz, a medicine professor at the University of California, San Francisco and director of its tobacco control research centre.

George Washington’s Gray said the 95 per cent number the Intergovernmental Panel on Climate Change will probably adopt may not be realistic. In general, regardless of the field of research, experts tend to overestimate their confidence in their certainty, he said. Other experts said the 95 per cent figure is too low.

Jeff Severinghaus, a geoscientist at the Scripps Institution of Oceanography, said that through the use of radioactive isotopes, scientists are more than 99 per cent sure that much of the carbon in the air has human fingerprints on it. And because of basic physics, scientists are 99 per cent certain that carbon traps heat in what is called the greenhouse effect.

But the role of nature and all sorts of other factors bring the number down to 95 per cent when you want to say that the majority of the warming is human-caused, he said.

Seth Borenstein can be followed at



15 thoughts on “Scientists as certain of climate change as they are that smoking kills

  1. “Some climate-change deniers have looked at 95 per cent and scoffed. After all, most people wouldn’t get on a plane that had only a 95 per cent certainty of landing safely, risk experts say”

    That analogy doesn’t fit!

    In our case, that imaginary plane has already taken off and we are on it. A problem has been discovered, and it has been determined that there is a 95% probability that the plane will crash if the problem is not corrected. Do we feel that lucky?

  2. The next IPCC report will be interesting. It is a fact that global surface temperatures have not risen at all in the past 10+ years and it is a fact that the polar icecap extent is very wobbly but not trending towards shrinkage in any statistically significant way over that time period. In fact if things don’t heat up in the next 3-5 years we will fall out of the 95% certainty envelope for climate change model predictions.

    Does that mean global warming has stopped? Who knows? What it does mean is that the models reflect an incomplete understanding about how this planet works.

    But guess what? Why should we care? Hydro-carbons are running out and long before the last barrel of oil is produced the prices will rise quickly and dramatically. So we need to kick the hydro-carbon habit. That will take a long time so we better get started.

    You might think that we have started. I would say that we have not. If the goal is to burn less hydro-carbons then solar panels and wind help us do that. But if the goal is to replace the burning of hydro-carbons in our generation of electricity solar panels and wind do NOT help and are consuming enormous amounts of money through direct subsidies. We need te refocus our support on energy storage technologies that could make wind a firm and dispatchable resource. PV + CSP solar will work in southern latitudes and deserve more support as well. PV by itself and PV in northern latitudes causes more problems than it solves.

  3. Mooney is quite rightly referring to the fact that most scientists, intellectuals and politicos quickly lose their integrity when money and vested interest are at stake. There’s massively more $ behind the pro CC fraud than big oil/coal etc, else it wouldn’t be such big news.

  4. I believe in man made climate change too. I see those planes creating the weather over my house almost every day.

    I also believe that the scientists of their day believed the world was flat and that smoking was good for you. Disagree and you could have been locked in mental institution put to death or ridiculed and most importantly..defunded.

    Not much has changed. Science has always been owned.
    The golden rules are still made by those with the gold. And climate change is another golden opportunity.

    1. The illogic of your contention, Mooney, is spectacular. What “gold” are you talking about? And, when it comes to gold, who has more of it than Big Oil, Big Gas and Big Coal? No one, that’s who. They have trillions of dollars at stake, a “bought and paid for” Congress in their pockets and all they need do is disprove the climate change consensus. So where’s their science disproving global warming?

      Sorry but your claim is farcical.

      1. Coal and Oil are not the big players in this game. Also you seem to assume they just won’t pass their costs on. Or get those “politicians in their pockets” to cut them a sweetheart deal.

        There’s real gold for the global bankers in the global carbon tax and credit schemes, which the alleged global warming is leading up to.

        There’s also the gold in the endowments and research funding.
        Tow the line or no funding.
        All this gold will be coming out of our pockets one way or another. If the overlords can get away with the global warming scam.

        I note neither you or the warmists make mention of the planes that regularly mess with our weather.

        Any science that doesn’t factor in those global operations, is just bullshit.

  5. Well then it’s a good thing they’ve got Fred Singer on the other side. He knows that smoking doesn’t kill. Just ask him.

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