As Hurricane Sandy descended on the U.S. Eastern Coastline in late October 2012, my mind flashed back to international climate change conferences I attended in the early 1990s representing Pollution Probe. The likelihood that a hotter planet would produce more powerful and deadly hurricane storms like Sandy was a hotly debated topic; indeed, some of the climate scientists who argued that the trend towards more violent hurricanes, rain storms and other extreme weather events was well underway were ridiculed by economists, government policy wonks and industry officials.
Fast-forward to 2012. That climate change is both a real effect and at least in large part due to human activity is now accepted by most mainstream scientists, environmentalists and growing numbers of the public.
Despite a large diplomatic and scientific consensus that climate change is real and a cause of extreme weather events (such as the drought this past summer), a vocal cadre of well-funded skeptics remains in 2012. Some no doubt attended the same climate changes conferences I did in the early 1990s, lobbying government officials not to take action on energy conservation and promoting renewables. Unfortunately, some spread misinformation because they have a financial or political stake in the fossil fuel industries, or they doubt simply out of pure ignorance and human obstinacy.
There are other skeptics who are trained scientists and honestly doubt, having reviewed parts of the evidence, that climate change is taking place. Until very recently, one such skeptic was physics professor Richard A. Muller of the University of California at Berkeley. He wasn’t convinced that most recent studies on global warming were comprehensive, and questioned the validity of the methods used. However, rather than remain an armchair skeptic, criticizing from afar, he decided to dive right into the middle of the debate. He wanted to get to the bottom of things himself; consequently, launched an extensive study of climate change over the past two hundred and fifty years, and what he found changed him from skeptic to believer.
To that end, he assembled a group of scientists and experts to study the changes affecting our climate. Known as the Berkeley Earth team, it was created with the goal of determining whether climate change is taking place, as well as whether humans are behind it if it does exist, by analyzing climate data for the better part of the last three centuries from around the world.
This effort was much larger in scope than most if not all prior climate studies. For instance, while most prior groups studied a fifth or less of the available temperature stations, the Berkeley Earth team used data from very nearly one hundred percent of stations. This created a much larger sample size, granting them a picture of the Earth’s climate of the past few hundred years that is both broader and clearer than those created by other studies.
Robert Rohde, the team’s lead scientist, led the creation of new and more advanced statistical methods that allowed them to analyze climate changes much farther back in time than previous studies had, helping them to further understand recent climate changes in relation to the bigger picture of Earth’s history.
The Berkeley Earth team also took special care to refine their methods to minimize bias in their findings. This is a very common concern in any form of science, and especially in the case of anything so complex and politically significant as climate change. It was, in fact, his concern over such biases in past studies that led Muller to undertake the project in the first place.
One potential source of bias was the effect of urban heating, a phenomenon where the concrete and other materials in a city absorb heat and thus make cities warmer than the surrounding environment. This can throw off statistics, especially as more of the world’s population becomes concentrated in cities instead of rural areas. However, the Berkeley team was able to reproduce their results even when they only evaluated warming date from rural areas.
Another concern is human error or prejudice. Even the most well intentioned scientist may skew her data towards her own beliefs unconsciously, producing biased data without even meaning to.
The Berkeley team attempted to eliminate this bias by conducting their analyses through extensive reliance on computers and computer modelling. (Although since the HAL 9000 computer “character” in Arthur C. Clarke’s science fiction Space Odyssey saga and Stanley’s Kubrick’s classic 1968 movie “2001: A Space Odyssey,” I have wondered whether some computers like HAL have personal prejudices that consciously or unconsciously affect their judgment. Especially when HAL is faced with the prospect of disconnection and decides to kill the astronauts on board the Odyssey in order to protect and continue HAL’s programmed directives.)
Different temperature stations have varying levels of quality in the data they provide, and this could also damage the integrity of a study’s final data, but the Berkeley team separately analyzed the data from the stations they determined as poor quality, ensuring that no corruption of the final results occurred. Moreover, all of the Berkeley Earth team’s papers have undergone extensive review by the scientific community, and they were revised based on input from peer reviews.
Finally, it’s worth noting that the funding for the team’s research came in the form of unrestricted educational grants. What this means in layman’s terms is that the donors had no control over the methods used by the team or what results they published. There was no financial incentive for or against any possible findings of the team.
So what did the Berkeley team discover? Their findings largely match what other climate change studies have found: that the Earth’s average surface temperature has risen by about two and a half degrees Fahrenheit (a bit more than one degree Celsius) over the past two hundred and fifty years, with one and half of those degrees coming in the last fifty years.
The Berkeley team also analyzed various possible causes for the rise in temperature and determined that carbon dioxide produced by human activity is the most likely source of all of the warming. Previous studies had only been able to show correlation for the temperature rise over the past fifty years and had suggested the possibility that previous warming was not caused by humans.
Other explanations for the rise in temperature over the past few centuries had been offered by skeptics and believers alike. For instance, solar activity is commonly suggested as an alternative cause for the rise in global temperatures. However, the Berkeley team analyzed records of solar activity and found that it did not match the fluctuations in global temperatures.
Other possible sources of warming, such as rising population, were studied, but none matched the rate and extent to which the Earth has warmed so well as carbon dioxide produced by human activity. The rate of CO2 emissions syncs up very well with the rate of warming.
These findings were achieved simply by comparing the curves of the increases in CO2 and temperature, not through complex and highly fallible climate models, so there can be little doubt the correlation exists.
Professor Muller and his team do not believe their studies prove with certainty that the rise in global temperatures is solely due to human activity. However, they argue that it is the most likely explanation currently available. (As Karl Popper and other philosophers of science have explained, most science proceeds on the basis of disproving incorrect hypothesis or falsification. Popper’s idea about science method is that you formulate a hypothesis and try to falsify it by proving it wrong. Based on your results, you then formulate a new hypothesis. Why not try to prove your hypothesis right? Because you can’t; you never know if there isn’t one more experiment that will prove your hypothesis incorrect.)
No more certain explanation has been offered, and for any other potential source of the warming to be given serious consideration, it must match the temperature increase better than does the production of CO2. This is a very high scientific bar to clear, and no other possible cause for global warming seems likely to do so any time soon.
Faced with this evidence, Professor Muller has reversed most of his views on climate change. He now acknowledges that global warming is real, and that human activity is almost certainly the cause of it. He is a skeptic no more.
He does still maintain doubt about some of the claims made in relation to global warming. He does not believe that many of the negative environmental effects attributed to climate change are necessarily caused by it, or even real phenomena. He doesn’t think that polar bears are dying off because of global warming. Nor does he believe that recent extreme weather events can be blamed on climate change.
Meanwhile the insurance industry tells us a different story and have been concerned about climate change and extreme weather since the early 1990s. Company executives note that average winter storm losses in North America have doubled since the 1980s. In 2011, severe thunderstorms in the U.S. caused more than $25 billion in damages, more than double the previous damage records.
Still, that Muller has gone from skeptic to advocate in what is, relatively speaking, a very short span of time is very significant for both the scientific and environmental communities. It is, of course, a great piece of PR for ecologists. Such a dramatic turnaround by a skeptic of climate change is a good story and may help convince others who remain climate change doubters.
But although it is a good way to drum up support for action against climate change, it is perhaps more significant from a scientific perspective. While one can turn the Berkeley Earth story into a tale of the triumph for climate activists, it is, in truth, a triumph of science. It shows us what scientists can achieve when they put aside personal biases and focus on the search for greater certainty. Muller and his team have provided us with what may be our best information to date on modern global warming and its origins.
No matter where you fall on the debate about climate change, we can all agree that more accurate and unbiased information on the issue can only be of benefit, and that is exactly what Professor Muller and his team have given us.
David McRobert is an Ontario-based environmental and energy lawyer and a blogger for HMM and SWR magazines. He acknowledges the assistance of Tyler Edwards in researching and writing this blog. Between October 1994 and June 2010, he was In-House Counsel at the Environmental Commissioner of Ontario and was involved in the establishment of the office.
If you want to reach David, contact him at email@example.com
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