Berkeley Earth is a non-profit organization based in Berkeley, California. It focuses on analyzing land temperature data to help scientists understand climate change. The group was started in early 2010 and was first called the Berkeley Earth Surface Temperature project. It was created to answer questions raised by people outside the scientific community about global warming and the accuracy of temperature records. The project aimed to use a clear and open method of analyzing data. In February 2013, Berkeley Earth became an independent non-profit. In August 2013, it received tax-exempt status from the U.S. government. Its main work involves studying air temperatures over land, but it also combines its land data with ocean temperature data from HadSST to create global datasets.

Berkeley Earth was founded by Richard A. Muller, who spoke with The Guardian.

As of December 2013, the group had received about $1,394,500 in unrestricted educational grants. Major supporters include Lawrence Berkeley National Laboratory, the Charles G. Koch Foundation, the Fund for Innovative Climate and Energy Research (FICER), and the William K. Bowes Jr. Foundation. These donors do not influence how the research is conducted or what is published.

The group shared its early results, data, and programs starting in December 2012. The study looked at scientific concerns, such as how heat from cities might affect temperature readings, the quality of temperature stations, and the possibility of biased data selection. The team found that the warming trend is real and that land temperatures increased by 0.91±0.05 °C over the past 50 years (from the 1950s to the 2000s). Their results match those from earlier studies by organizations like the U.S. National Oceanic and Atmospheric Administration (NOAA), the Hadley Centre, NASA’s Goddard Institute for Space Studies (GISS), and the Climatic Research Unit (CRU) at the University of East Anglia. The study also concluded that the urban heat island effect and poor station quality did not affect the results of these earlier studies.

Scientific team and directors

The Berkeley Earth team includes the following members:

• Richard A. Muller, founder and Scientific Director. He is a professor of physics at the University of California, Berkeley (UCB), and a senior scientist at the Lawrence Berkeley National Laboratory. He is a member of the JASON Defense Advisory Group and has previously criticized other climate temperature studies.
• Elizabeth Muller, founder and Executive Director.
• Robert Rohde, lead scientist. He holds a Ph.D. in physics from the University of California, Berkeley. His scientific interests include earth sciences, climatology, and scientific graphics. He is the founder of Global Warming Art.
• Zeke Hausfather, scientist.
• Steven Mosher, scientist and co-author of Climategate: The Crutape Letters.
• Saul Perlmutter, Nobel Prize-winning astrophysicist at the Lawrence Berkeley National Laboratory and professor of physics at UCB.
• Arthur H. Rosenfeld, professor of physics at UCB and former commissioner of California’s Energy Commission. He directed research at the Lawrence Berkeley National Laboratory that led to the development of compact fluorescent lamps.
• Jonathan Wurtele, professor of physics.
• Will Graser.
• Sebastian Wickenburg, Ph.D. candidate in physics.
• Charlotte Wickham, statistical scientist.
• Don Groom, physicist.
• Robert Jacobsen, professor of physics at UCB and an expert in analyzing large data sets.
• David Brillinger, statistical scientist and professor of statistics at UCB. He helped develop the theory of time series analysis.
• Judith Curry, climatologist and chair of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology.
• Pamela Hyde, Communications and Project Director.
• John Li, Energy Geoscience intern.
• Elizabeth Muller, president and chair, managing partner of Global Shale.
• Will Glaser, treasurer and founder of Pandora Music.
• Bill Shireman, secretary. He develops profitable business strategies that reduce pollution and increase profits.
• Richard Muller, board director.
• Art Rosenfeld, board director.
• Marlan W. Downey, board director. He was former president of the international subsidiary of Shell Oil, founder of Roxanna Oil, and former president of Arco International.
• Jim Boettcher, board director; investments.

Initial results

After analyzing a large set of land temperature data, which includes more than 1.6 billion temperature measurements from over 39,000 stations worldwide and more than 15 sources dating back to the 1800s, the group submitted four papers for review by other scientists and publication in scientific journals. The Berkeley Earth study did not examine ocean temperature changes or determine how much of the observed warming is caused by human activities. The team shared early results with the public on October 20, 2011, to allow others to review the findings. The data, analysis tools, and papers being reviewed were also made available to the public.

The study addressed concerns raised by scientists who questioned the accuracy of temperature records. These concerns included the urban heat island effect, the quality of temperature stations, and the possibility of bias in selecting data. The team’s initial conclusions are as follows:

• The urban heat island effect and poor station quality did not affect the results of earlier studies by the U.S. National Oceanic and Atmospheric Administration (NOAA), the Hadley Centre, and NASA’s GISS Surface Temperature Analysis. While urban areas experience significant local warming, they cover less than 1% of the land, so their impact on global temperature trends is small. Stations labeled as "poor" in quality still recorded the same average warming trend as other stations.
• Global temperature trends found by the Berkeley Earth team closely match those from previous studies by NASA GISS, NOAA, and the Hadley Centre. The team estimates that land temperatures have risen by 0.911°C over the past 50 years, which is 2% less than NOAA’s estimate. The team’s leader stated that this confirms earlier studies were accurate and that concerns about biases did not affect their results.
• About one-third of temperature stations with records lasting 70 years or longer showed cooling trends, including parts of the United States and northern Europe. However, two-thirds of stations showed warming. Individual temperature records from a single location can be unreliable, so combining many records is needed to understand global warming trends.
• The Atlantic multidecadal oscillation (AMO) has had a larger influence on global temperatures than previously thought. While the El Niño-Southern Oscillation (ENSO) is often linked to short-term temperature changes, the study found that global temperatures are more closely related to the AMO, which measures sea surface temperatures in the North Atlantic.

The Berkeley Earth analysis used a new method and compared its findings with data from NOAA and NASA. The team’s approach automatically assigns importance to each data point based on how consistent it is with other readings. This method allows the inclusion of unusual data without affecting the overall results. Traditional methods that require long, continuous data sets were avoided, making it possible to include shorter records from temporary weather stations. This innovation allowed the team to create a temperature record starting in 1800, but with high uncertainty because there were very few weather stations at that time.

Project leader Muller, who had previously expressed concerns about the quality of climate research, was expected by some critics to support their views. Anthony Watts, a climate change skeptic who had raised issues similar to those addressed by the Berkeley Earth team, said he believed the team’s methods were reliable. When the study’s results supported the existing scientific consensus, it was criticized by some skeptics. Watts told The New York Times that the study’s methodology was flawed because it used 60 years of data instead of the 30-year standard used in other studies. He also pointed to spelling errors as evidence of poor quality. Steven Mosher, a co-author of a book critical of climate scientists, said the study lacked transparency until its code was made public in a widely usable format. Stephen McIntyre, editor of Climate Audit, a climate-skeptics blog, said the team deserves credit for using primary data but questioned their analysis of urban heating and station quality.

In contrast, the study was praised by many climate scientists. James Hansen, a leading climate scientist and head of NASA’s Goddard Institute for Space Studies, said he was glad Muller was examining the issue and hoped the study would help people with honest questions about global warming. Phil Jones, director of the Climatic Research Unit at the University of East Anglia, said the findings were encouraging and aligned with his own research, which also found that urban heat islands have little effect on global temperatures. Michael Mann, director of the Earth System Science Center at Pennsylvania State University, said the team reached the same conclusions as other scientists and noted that even a critic like Muller found climate science to be reliable. Peter Thorne, from the Cooperative Institute for Climate and Satellites, said the study’s different approach to analyzing data supports confidence in existing temperature estimates. Eric Steig, an ice core research scientist, said it was not surprising that the study’s results matched earlier findings, as simple analyses of available data show that major changes in temperature trends are unlikely.

Expanded scope

Since 2013, when Berkeley Earth published its research papers, the organization has expanded its work. Berkeley Earth now focuses on three main areas: 1) conducting more scientific research about climate change and extreme weather events, 2) creating programs to teach others about climate science and share information, and 3) assessing how well efforts to reduce environmental harm are working in both developed and developing countries. This includes studying energy conservation and the use of natural gas as a temporary fuel source.

July 2012 announcement

In an opinion article published in The New York Times on July 28, 2012, Muller shared more results from his research project. He reported that the average temperature on Earth’s land had risen by 2.5 degrees Fahrenheit (1.4 degrees Celsius) over 250 years. In the past 50 years alone, the increase was 1.5 degrees Fahrenheit (0.8 degrees Celsius). He stated it was likely that this rise was caused entirely by human-produced greenhouse gases. His article began by explaining:

Muller said his findings were more certain than those in the IPCC Fourth Assessment Report. His team’s research, described in five scientific papers now being reviewed by other scientists, used special ways of analyzing data developed by Robert Rohde. They focused on solving problems that critics had raised, such as the urban heat island effect, poor quality of weather stations, and issues with how data was chosen and adjusted. In the fifth paper they shared, they compared temperature patterns to different factors, including volcanic activity, solar energy, and sunspots. They found that the temperature pattern most closely matched the expected effects of human-caused greenhouse gases. Muller noted that he still believed "much, if not most, of what is said about climate change is based on guesses, overstatements, or incorrect information. I have studied some of the most extreme claims, and my doubts about them remain unchanged."