By the early 2000s, a small group of scientific critics contended that global warming studies had been methodologically flawed and concluded it was premature to form a solid conclusion as to the existence and possible causes of global warming. One of those skeptics, world renown scientist Richard A. Muller, professor of physics at the University of California—Berkeley, thought the skeptics’ arguments had merit and determined to put an end to that uncertainty by establishing Berkeley Earth, an independent, scientifically-based 501(c)(3) non-profit to investigate the global surface temperature record. Berkeley Earth was partly funded by the Charles Koch Foundation, whose founder is a well-known funder of climate deniers, and by the Fund for Innovative Climate and Energy Research, which was founded by Bill Gates. Muller was the lead scientist in Berkeley Earth’s Surface Temperature (BEST) study that systematically and objectively addressed major concerns or potential biases that global warming skeptics had identified by gathering and analyzing worldwide historical land temperature measurements that had been collected from around 1750 and extended continuously to the present, a period of about 250 years.
BEST’s data analysis focused on the most likely cause(s) of global warming rise by plotting the upward temperature curve against suspected climatic “forcings”. Its analysis of the warming effects of solar activity found that the sun’s warming contributions, which constituted a major factor in the opinion of climate change skeptics, have been “consistent with zero.” Volcanic eruptions were analyzed and found to have caused minor variations in the temperature rise in the period 1750–1850, but “only weak analogues” in the 20th Century.
After the global surface temperature record study was complete, Muller and his co-author, physicist Robert Rohde, reached the following conclusion: “Much to my surprise, by far the best match was to the record of atmospheric carbon dioxide, measured from atmospheric samples and air trapped in polar ice.” Muller emphasized that the match between the data and the theory did not prove that carbon dioxide is responsible for the warming, but the good fit makes it the strongest contender. “To be considered seriously, any alternative explanation must match the data at least as well as does carbon dioxide.”
The study’s results mirrored those obtained from previous studies by the U.S. National Oceanic and Atmospheric Administration, Great Britain’s Hadley Centre for Climate Prediction and Research, NASA's Goddard Institute for Space Studies Surface Temperature Analysis, and the Climatic Research Unit at the University of East Anglia. The study also found that, contrary to claims from many climate change skeptics and deniers, data selection, data adjustment, the urban heat island effect, and poor station quality did not bias the results obtained from earlier studies.
Please note that the Berkeley Earth analysis did not depend on large complex global climate models that have been harshly criticized by climate skeptics for what are claimed to be hidden assumptions and adjustable parameters. The conclusion that warming is a result of human activities is based simply on the close agreement between the shape of the observed temperature rise and the known greenhouse gas increase.
In an effort to achieve full transparency, all study data, analytical techniques, computer coding, and findings are available on the BEST website so they can be examined freely by scholars from scientific disciplines that study climate change. Here's the web site:
http://berkeleyearth.org/
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