Friday, April 1, 2011

Berkeley team announces early results from global warming review

A group of scientists in California has released preliminary findings on how much the Earth is warming

What happens when a group of scientists and statisticians leave the comfort of their own fields and wander headlong into one of the most fraught and ugly debates of modern times?

The answer is slowly becoming clear, after a handful of academics at the University of California, Berkeley, came up with a plan to produce an independent assessment of global warming. For researchers used to the collegiate exchanges of campus life, the plan has all the makings of a first class ticket to Kill Zone 3.

The stated aim of the project is to publish a peer-reviewed assessment of global warming that is more accurate than those we have so far. Once the analysis is done, all the data and computer tools used to process the numbers will be made freely available on a website, so anyone with an interest can check them.

Richard Muller, the Berkeley physicist who chairs the group, says that publishing an independent record of global warming will address some valid points raised by sceptics and even end the war between them and the climate scientists they criticise. Few ideas seem as laudable, ambitious and naive all at once.

The vast majority of climate scientists agree that global warming is happening and that human activity plays a significant role in rising temperatures. For the best part, debate within the community centres on the precise magnitude of warming, the rate at which it is happening in different regions, and what can or should be done to mitigate its effects.

But still climate change is one of the most argued-over issues in science. The broad agreement among climate researchers is under fire from a minority of sceptics and large portions of the public might well sit confused on the sidelines.

Earlier today, Muller gave evidence to the House of Representatives committee on science, space and technology, and released a very preliminary analysis of historic land temperatures. I've pasted their findings below, but will give some background first.

There are three major groups of scientists who already produce assessments of global warming that feed into the UN's Intergovernmental Panel on Climate Change. There is Nasa's Goddard Institute for Space Studies in New York City, another US agency, the National Oceanic and Atmospheric Administration (Noaa), and finally a UK group led by the Met Office.

Each group takes readings from instruments around the world to come up with a rolling record of the Earth's mean surface temperature. The warming figures they arrive at differ very slightly because each group uses its own dataset and does its own analysis, but they reveal a common trend. Since pre-industrial times, all point to a warming of around 0.75C.

The Berkeley Earth project aims to incorporate a larger quantity of data, much of which comes from temperature stations installed since the 1960s. Arguably the most interesting aspect of Muller's project is the hope of dealing with biases in temperature data that might or might not be adequately dealt with in the analyses done by Nasa, Noaa and the Met Office. There are all kinds of things that can bias temperature readings, making them cooler or warmer than they should be. An oft-cited example is that a temperature station that was in a rural environment fifty years ago might today be on the fringes of a city, and feel more heat as a result. I gave a flavour of some other potential biases, and a more detailed explanation of the project, in an article on Muller last month.

The results announced by Muller today are exceedingly preliminary. The group has compiled 1.6 billion temperature measurements from 39,028 stations around the world, but used only two percent of these in the analysis. The stations used were picked at random, to avoid any bias towards older instruments (which have longer temperature records), poor quality stations, or any particular geographical region. But apart from these, no other sources of bias have been dealt with yet.

Clearly, there is very close agreement between the Berkeley analysis and the warming trends reported by the major three climate groups, that is a rise of around 0.7 degrees C since 1957. In notes prepared in advance of Thursday's hearings, Muller writes: "The Berkeley Earth agreement with the prior analysis surprised us, since our preliminary results don't yet address many of the known biases. When they do, it is possible that the corrections could bring our agreement into disagreement."

Another interesting outcome from the analysis so far regards the impact of temperature stations being located near buildings, car parks and other urban sources of heat. In 2009, a former TV weatherman, Anthony Watts, published a report claiming the problem with "poor stations" was serious enough to render the US temperature record unreliable. Based on preliminary work, Muller says this isn't true. "Over the past 50 years the poor stations in the US network do not show greater warming than do the good stations," his notes say.

There has already been some fuss over the Berkeley Earth project, with most criticism coming from bloggers who believe Muller has an agenda. You can get a flavour here. One point that is often raised is that some money for the project comes from the Charles G Koch Charitable Foundation. The man behind the outfit owns, with his brother David, , a company Greenpeace called a "kingpin of climate science denial". Muller says that the project, which is run under the auspices of Novim, a non-profit public interest group, has funders on both the left and right.

Here is a breakdown of funds behind the project, which total $623,087.

The Lee and Juliet Folger Fund ($20k)

Lawrence Berkeley National Laboratory ($188,587)

William K. Bowes, Jr. Foundation ($100k)

Fund for Innovative Climate and Energy Research, created by Bill Gates ($100k)

Charles G. Koch Charitable Foundation ($150k)

The Ann and Gordon Getty Foundation ($50k)

Private donations totalling $14,500.

As I have emphasised, these are very preliminary results. The data and the analysis are not yet peer reviewed, though a paper is being submitted to the Bulletin of the American Meteorological Society. We may have to wait several weeks or months for the full analysis that addresses all the sources of bias across the whole dataset.

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