Berkeley Earth Surface Temperature (BEST) study

Please note, this page has been archived as of Feb 2013 and will not be updated. 

The Berkley Earth Surface Temperature (BEST) project was launched and chaired by Professor Richard Muller, a physicist at the University of California at Berkeley. It aims to address criticisms raised by climate skeptics about how existing records of the Earth's average surface temperature have been compiled. Team members include physicist Robert Rohde, climatologist Judith Curry, and other physicists and statisticians.

Research from the BEST group, released in October 2011, addressed concerns raised by skeptics about records of surface temperatures, including the urban heat island effect and poor weather station siting. These issues were not found to have a significant effect on the global land surface temperature record.

What does the latest BEST research show?

This latest research from the BEST team confirms that the Earth's average land temperature has risen by roughly 0.9 degrees Celsius since the 1950s, and by 1.5 degrees Celsius over the last 250 years. This is in line with existing records, which put average global land temperature rise over the last 50 years at 0.81 - 0.93 degrees Celsius:

BEST land temp

The study also uses a simple model to work out whether the change in global land temperature fits best with changes in atmospheric carbon dioxide levels, volcanic activity or solar activity - and find the best fit with a combination of change in atmospheric carbon dioxide and volcanic activity:

BEST land temp with forcings

The contribution of solar activity, it concludes, must be negligible.

Muller  notes this doesn't prove that carbon dioxide is responsible for warming, but adds:

"To be considered seriously, any alternative explanation must match the data at least as well as does carbon dioxide."

How do the latest BEST results differ from previous studies?

The BEST temperature reconstruction of global land temperature records differs from other records - produced by the NOAA National Climatic Data Center (NCDC), the NASA Goddard Institute for Space Studies (GISS), and a collaboration between the UK Met Office Hadley Centre and the Climatic Research Unit at the University of East Anglia (HadCRUT) - because it uses many more station records.

The BEST team also use a different statistical method to calculate the average land temperature record from the methods used by NOAA, GISS and HadCRUT. The team boasts that its approach is simple,  pointing out that it doesn't rely on complicated climate models.

The attribution of much of the last 50 years' warming to human activity is in line with  several recent studies  using  a variety of sophisticated approaches to calculate the contributions ofnatural and human causes of global warming. The studies agree that human activity is the dominant cause of warming over the last century, and particularly over the last 50 years.

Is the BEST research peer reviewed?

This new research is not yet peer reviewed. The BEST team explains why:

"Some people think that peer review consists of submitting a paper to a journal and waiting for the anonymous comments of referees. Traditional peer review is much broader than that and much more open. In science, when you have a new result, your first step is to present it to your colleagues [...] Such traditional and open peer review has many advantages. It usually results in better papers in the archival journals, because the papers are widely examined prior to publication. It does have a disadvantage, however, that journalists can also pick up preprints and report on them before the traditional peer-review process is finished."

When the BEST team last released papers they were also non-peer-reviewed preprints. Those papers have since been submitted to peer-reviewed journals. Only one out of those four, however, appears to have been accepted for publication so far, according to the BEST website.

The peer review process allows independent qualified experts to scrutinise scientific methods, results and interpretations before they are made public. It provides a kind of stamp of approval for new research, in that it shows that the research is considered valid, significant and original by experts in the field. So the fact that any BEST research has attracted so much media attention before even being peer reviewed is a little worrying - the research could turn out to be good, but could also turn out to be flawed or incomplete.

How much does the BEST study matter?

Beyond the media the new results have had a  mixed reception. Climate scientist William Connolley is  not impressed:

"[The BEST team has] done none of the attribution work you'd expect, in order to talk about attribution. And what they say [...] appears absurdly naive."

Climate scientist Ken Caldeira  points out:

"The basic scientific results have been established for a long time now, so I do not see the results of Muller et al as being scientifically important.  However, their result may be politically important.  It shows that even people who suspect climate scientists of being charlatans, when they take a hard look at the data, see that the climate scientists have been right all along."

BEST member Curry  describes its temperature record as "the best land surface temperature data set that we currently have", but  declined to be a co-author on the latest paper, since she disagrees with its interpretation attributing the temperature rise to atmospheric carbon dioxide.

The climate skeptic community meanwhile, is largely  dismissive of the new findings, and has been keen to point out that Muller was  never truly a skeptic.