Washington -- The verdict is in: Global warming is real and greenhouse-gas
emissions from human activity are the main cause.
This, according to Richard A. Muller, professor of physics at the University
of California, Berkeley, a MacArthur fellow and co-founder of the Berkeley
Earth Surface Temperature project.
The United Nations Intergovernmental Panel on Climate Change and hundreds of
other climatologists around the world came to such conclusions years ago, but
the difference now is the source: Muller is a long-standing, colorful critic of
prevailing climate science, and the Berkeley project was heavily funded by the
Charles Koch Charitable Foundation, which, along with its libertarian petrochemical
billionaire founder Charles G. Koch, has a considerable history of backing
groups that deny climate change.
In an opinion piece in Saturday's New York Times titled "The Conversion
of a Climate-Change Skeptic," Muller writes:
"Three years ago I identified problems in previous climate studies
that, in my mind, threw doubt on the very existence of global warming. Last
year, following an intensive research effort involving a dozen scientists, I
concluded that global warming was real and that the prior estimates of the rate
of warming were correct. I'm now going a step further: Humans are almost
entirely the cause."
The Berkeley project's research has shown, Muller says, "that the
average temperature of the earth's land has risen by 2 degrees Fahrenheit over
the past 250 years, including an increase of 1 degree over the most recent 50
years. Moreover, it appears likely that essentially all of this increase
results from the human emission of greenhouse gases."
He calls his current stance "a total turnaround."
Tonya Mullins, a spokeswoman for the Koch Foundation, said the support her
foundation provided, along with others, has no bearing on results of the
research.
"Our grants are designed to promote independent research; as such,
recipients hold full control over their findings," Mullins said in an
email. "In this support, we strive to benefit society by promoting
discovery and informing public policy."
Some leading climate scientists said Muller's comments show that the science
is so strong that even those inclined to reject it cannot once they examine it
carefully.
Michael E. Mann, director of the Earth System Science Center at Pennsylvania
State University, said Muller's conversion might help shape the thinking of the
"reasonable middle" of the population "who are genuinely
confused and have been honestly taken in" by attacks on climate science.
On his Facebook page, Mann wrote: "There is a certain ironic
satisfaction in seeing a study funded by the Koch Brothers -- the greatest
funders of climate change denial and disinformation on the planet --
demonstrate what scientists have known with some degree of confidence for
nearly two decades: that the globe is indeed warming, and that this warming can
only be explained by human-caused increases in greenhouse gas concentrations. I
applaud Muller and his colleagues for acting as any good scientists would,
following where their analyses led them, without regard for the possible
political repercussions."
Muller's conclusions, however, did not sway the most ardent climate
contrarians, like Marc Morano, a former producer for Rush Limbaugh and former
communications director for the Republicans on the Senate Environment and
Public Works Committee.
"Muller will be remembered as a befuddled professor who has yet to
figure out how to separate climate science from his media antics. His latest
claims provide no new insight into the climate science debate," Morano
said in an email.
Muller's New York Times commentary follows research he did last year that
confirmed the work of scientists who found that the Earth's temperature was
rising. In the past, Muller had criticized which global temperatures had been
used in such research, contending that some monitoring stations provided
inaccurate data. Now, Berkeley's research has weighed in on the causes of the
temperature rise, testing arguments that climate contrarians have used.
"What has caused the gradual but systematic rise of 2 degrees?"
Muller writes. "We tried fitting the shape to simple math functions
(exponentials, polynomials), to solar activity and even to rising functions
like world population. By far the best match was to the record of atmospheric
carbon dioxide, measured from atmospheric samples and air trapped in polar
ice."
Muller asserted that his findings were "stronger" than those of
the UN's intergovernmental panel. But neither Berkeley's research from last
year nor the new findings on causality have been published in peer-reviewed
journals, which has raised criticism and concerns among climatologists and contrarians
alike.
Benjamin D. Santer, a climate researcher at the Lawrence Livermore National
Laboratory and a lead author of the 1995 UN climate report, said he welcomed
the involvement of another research group into "detection and
attribution" of climate change and its causes. But he said he found it
troubling that Muller claimed such definitive results without his work
undergoing peer-review.
"If you go into the public arena and claim to have generated evidence
that is stronger than the IPCC, where is the detailed, scientific evidence? Has
he used fundamental new data sets?" Santer said. "Publish the science
and report on it after it's done."
He added: "I think you can do great harm to the broader debate. Imagine
this scenario: that he makes these great claims and the papers aren't
published? This is in the spirit of publicity, not the spirit of science."
Elizabeth Muller, co-founder and executive director of the Berkeley project
and Richard Muller's daughter, said the papers had been peer-reviewed, but not
yet published. But because of the long lead-up to publication, she said, the
Berkeley team decided to place its papers online, in part to solicit comment
from other scientists. The papers were posted on the BerkeleyEarth.org website
on Sunday.
"I believe the findings in our papers are too important to wait for the
year or longer that it could take to complete the journal review process,"
Elizabeth Muller wrote in an email. "We believe in traditional peer
review; we welcome feedback from the public and any scientists who are
interested in taking the time to make thoughtful comments. Our papers have
received scrutiny by dozens of top scientists, not just the two or three that
typically are called upon by journalists."