A prominent scientist who was skeptical of the evidence thatclimate change was real, let alone that it was caused by humans, now says he has made a "total turnaround." Richard Muller, a professor of physics at the University of California, Berkeley, says he has become convinced that "the prior estimates of the rate of warming were correct," and that humans are "almost entirely the cause" of that warming.
Muller co-founded
the Berkeley Earth Surface Temperature (BEST) team two years ago in order to independently assess what he viewed as questionable evidence of
global warming. In a series of papers published last year, BEST presented their statistical analysis of 1.6 billion temperature reports spanning the last 200 years, controlling for possible biases in the data that are often cited by skeptics as reasons to doubt the reality of global warming.
Their analysis indicated that global warming is real — that the average global land temperature has risen by 2.5 degrees Fahrenheit (1.4 degrees Celsius) since 1750, including 1.5 degrees F (0.9 degrees Celsius) in the past 50 years. The numbers closely agree with the findings of past studies by the National Oceanic and Atmospheric Administration (NOAA), NASA and others; but finally, they were rigorous enough to satisfy Muller.
Now, in a brand new study that probed the causes of that warming, the BEST team says it has cleared from blame the natural variations in Earth's climate that so often get implicated by skeptics. Muller and his colleagues implicate carbon dioxide emissions by humans as essentially the sole cause of global warming.
"The carbon dioxide curve gives a better match than anything else we've tried," he wrote Saturday (July 28) in a New York Times
editorial. "Its magnitude is consistent with the calculated
greenhouse effect — extra warming from trapped heat radiation. These facts don't prove causality and they shouldn't end skepticism, but they raise the bar: To be considered seriously, an alternative explanation must match the data at least as well as carbon dioxide does."
That's a high bar indeed. In graphs released with the new study, a red line representing the atmoaspheric concentration of CO2 crawls across the decades almost exactly tracing the black line representing the observed warming of the Earth. [
What Are Climate Change Skeptics Still Skeptical About?]
By comparison, the study found that natural variability, including variations in the solar cycle, El NiƱo events and the Atlantic multidecadal oscillation (shifts in sea-surface temperatures that run in cycles), could have accounted for no more than 0.17 degrees Celsius of temperature variation — either warming or cooling — during the past 150 years. These natural forces are much subtler than the warming seen during the same time period.
In fact, the new results indicate that humans have been warming the Earth for longer than climate scientists previously thought certain. "In its 2007 report, the [United Nations Intergovernmental Panel on Climate Change] concluded only that most of the warming of the prior 50 years could be attributed to humans," Muller wrote. "It was possible, according to the I.P.C.C. consensus statement, that the warming before 1956 could be because of changes in solar activity, and that even a substantial part of the more recent warming could be natural."
Not so, according to the new findings; variations in solar activity have a negligible effect on Earth's temperature. The handiwork is almost all our own.
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My uncle has a country place
That no one knows about
He says it used to be a farm
Before the Motor Law
And on Sundays I elude the eyes
And hop the Turbine Freight
To far outside the Wire
Where my white-haired uncle waits
Jump to the ground
As the Turbo slows to cross the borderline
Run like the wind
As excitement shivers up and down my spine
Down in his barn
My uncle preserved for me an old machine
For fifty odd years
To keep it as new has been his dearest dream
I strip away the old debris
That hides a shining car
A brilliant red Barchetta
From a better vanished time
All that we can do is just survive
All that we can do to help ourselves is stay alive
Ragged lines of ragged grey
Skeletons, they shuffle away
Shouting guards and smoking guns
Will cut down the unlucky ones
I clutch the wire fence until my fingers bleed
A wound that will not heal
A heart that cannot feel
Hoping that the horror will recede
Hoping that tomorrow we'll all be freed
Sickness to insanity
Prayer to profanity
Days and weeks and months go by
Don't feel the hunger
Too weak to cry
I hear the sound of gunfire at the prison gate
Are the liberators here?
Do I hope or do I fear?
For my father and my brother, it's too late
But I must help my mother stand up straight
Are we the last ones left alive?
Are we the only human beings to survive?
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