A climate change study that projected a 2.4 degree Celsius increase in temperature and massive worldwide food shortages in the next decade was seriously flawed, scientists said Wednesday.

The study was posted Tuesday on EurekAlert, a independent service for reporters set up by the American Association for the Advancement of Science, and was written about by numerous international news agencies, including AFP.

But AAAS later retracted the study as experts cited numerous errors in its approach.

"A reporter with The Guardian alerted us yesterday to concerns about the news release submitted by Hoffman & Hoffman public relations," said AAAS spokeswoman Ginger Pinholster in an email to AFP.

"We immediately contacted a climate change expert, who confirmed that the information raised many questions in his mind, too. We swiftly removed the news release from our website and contacted the submitting organization."

Scientist Osvaldo Canziani, who was part of the 2007 Nobel Prize winning Intergovernmental Panel on Climate Change, was listed as the scientific advisor to the report.

The IPCC, whose figures were cited as the basis for the study's projections, and Al Gore jointly won the Nobel Prize for Peace in 2007 "for their efforts to build up and disseminate greater knowledge about man-made climate change," the prize committee said at the time.

Canziani's spokesman said Tuesday he was ill and was unavailable for interviews.

The study cited the UN group's figures for its projections, combined with "the business-as-usual path the world is currently following," said lead author Liliana Hisas of the Universal Ecological Fund (UEF), a non-profit group headquartered in Argentina.

But climate scientist Ray Weymann told AFP that the "study contains a significant error in that it confuses 'equilibrium' temperature rise with 'transient temperature rise.'"

He also noted that study author Hisas was told of the problems in advance of the report's release.

"The author of the study was told by several of us about this error but she said it was too late to change it," said Weymann.

Scientist Scott Mandia forwarded to AFP an email he said he sent to Hisas ahead of publication explaining why her figures did not add up, and noting that it would take "quite a few decades" to reach a warming level of 2.4 degrees Celsius.

"Even if we assume the higher end of the current warming rate, we should only be 0.2C warmer by 2020 than today," Mandia wrote.

"To get to +2.4C the current trend would have to immediately increase almost ten-fold."

Mandia described the mishap as an "honest and common mistake," but said the matter would certainly give fuel to skeptics of humans' role in climate change.

"More alarmism," said Mandia. "Don't get me wrong. We are headed to 2.4, it is just not going to happen in 2020."

Many people do not understand the cumulative effect of carbon emissions and how they impact climate change, Mandia said.

"This is something that people don't appreciate. We tied a record in 2010 (for temperature records) globally. That is primarily from the C02 we put in the atmosphere in the 70s and early 80s, and we have been ramping up since then," he said.

"So it is not good. We are seeing the response from a mistake we were making 20 years ago, and we are making bigger mistakes today."

Marshall Hoffman of the public relations firm that issued the report on the UEF's behalf said the group stands by the study.

"Earlier, NASA and NOAA estimated that the global temperature increased one degree from 2005-2010. If this stays on the same path, that will be two degrees by 2015. We see that path increasing more rapidly," Hoffman said, in part, in his explanation.

Asked for comment on Hoffman's response, Mandia told AFP: "He is still confused."