Photo: cqwb.com.cn

The average global land temperature has increased by around one degree Cetigrade since the mid-1950s, American scientists announced last week after reviewing historical temperature records to date.

According to media reports, the scientists of the Berkeley Earth project have studied more than a billion temperature records dating back to the 1800s from 15 sources around the world.

And the result is in line with the estimate made by major institutions which keep official records on the global climate, including the Nasa's Goddard Institute for Space Studies in the US and the Met Office's Hadley Centre in Britain.

Meanwhile, the scientists established an open database for the climate records so that skeptics on climate change can assess climage change on their own.

Nevertheless, the finding of the scientists at the University of California, Berkeley did not convince climate change skeptics, according to a New York Times report.

Anthony Watts, one prominent US skeptics, claimed the study's "methodology was flawed". He also noted that the finding was submitted to journal Geophysical Research Letters before being peer-reviewed.

Richard Muller, a physicist and head of the project, argued that the decision to circulate the papers before publication was part a long-standing academic tradition of sanity-checking results with colleagues.

He added, cited by the Guardian, "We will get much more feedback from making these papers public before publication."