Study Testing Skeptics’ Critiques Reconfirms Basic Climate Science

Climate skeptics have denounced studies of temperature rise because of alleged biases in data sets. So in an effort to get to the bottom of these critiques, a group of scientists launched the Berkeley Earth Surface Temperature study, using different methods with skeptics’ arguments in mind. Its findings are in, and they confirm that not only is the Earth’s land temperature warming, but the results mimic the very results of previous assessments that the skeptics had tossed aside.

Last week, the Berkeley Earth Surface Temperature study was released and it reconfirms the basic climate science. The objective of the study was to reevaluate land surface temperature data sets, including statistical methods, uncertainties, and ways that data were averaged. Led by Richard Muller of the University of California, the group analyzed 1.6 billion temperature reports from 39,000 temperature measurement stations to assess temperature changes.

The group has released several papers that are now entering the peer-review process with conclusions including:

Figure 1: Berkeley results

• The use of different data and assessment methodologies leads to similar results as those of previous studies – Using a new framework for assessing temperature data that includes a greater number of data and considers purported selection bias and uncertainties, the authors find that global land mean temperature has risen 0.91°C since the 1950s. They note that this finding is consistent with previous studies, with reduced uncertainty.

• Urban weather stations do not bias records of temperature change – Urban warming – for example due to absorption of solar radiation in non-reflective, manmade surfaces and changes in air circulation – does not “unduly bias estimates of recent global temperature change.” This finding debunks a key argument of climate skeptics, who have argued that the temperature record was unreliable due to weather stations being located in the heat islands produced by urban environments.

• The presence of “poor” quality weather stations does not bias records of temperature change – In a US-based study, the presence of data from “poor” weather stations was found not to bias land surface average monthly temperature trends. The authors suggest that there is no statistically significant difference between data from poor quality weather stations and those ranked of better quality.

These findings are consistent with an overwhelming amount of research which shows the Earth’s rapid warming trend over the last half century. As we noted in the latest review of climate science, the last decade, 2000-2009, has been the warmest decade on record since 1880. And this warming, compounding changes in precipitation and sea level rise, is rapidly transforming hydrological, physical and ecological systems. Sea level rise is now projected to be significantly higher than previous estimates; glaciers and ice caps are melting around the world at a rapid rate; ocean acidification is affecting entire food webs, even outside of the tropics; and there is new evidence for extinction risks to a number of different species, including penguins, tigers and lizards.

These changes will require steep reductions in greenhouse gas emissions, as well as a different approach to decision making. This is the focus of a major new report, Decision Making in a Changing Climate, which can help leaders integrate climate risks into everyday practices to increase the resilience of people, communities and ecosystems.

As the New York Times noted, hard-core climate skeptics may not be moved by the new research. But the facts are clear: the world is warming. No amount of wishful thinking is going to make that go way.

Read a Q&A with Kelly Levin on the latest climate science >>>