Global temperature change observed over the last hundred years or so is well within the natural variability of the last 8,000 years, according to a new paper by a former Intergovernmental Panel On Climate Change (IPCC) lead author.
Dr. Philip Lloyd, a South Africa-based physicist and climate researcher, examined ice core-based temperature data going back 8,000 years to gain perspective on the magnitude of global temperature changes over the 20th Century.
What Lloyd found was that the standard deviation of the temperature over the last 8,000 years was about 0.98 degrees Celsius– higher than the 0.85 degreesclimate scientists say the world has warmed over the last century.
“This suggests that while some portion of the temperature change observed in the 20th century was probably caused by greenhouse gases, there is a strong likelihood that the major portion was due to natural variations,” Lloyd wrote in his study.
The United Nations’ IPCC claims there’s been 0.85 degrees Celsius of warming since the late 1800s, and concludes that most of this warming is due to human activities– mainly, the burning of fossil fuels and changes in land use. The IPCC says that “more than half of the observed increase in global average surface temperature from 1951 to 2010” have been caused by human activity.
If Lloyd’s results hold, the IPCC may have to revise how much warming it attributes to mankind. In any case, the IPCC’s estimate of man-made and natural warming (0.85 degrees) is still below the standard deviation for the last 8,000, according to Lloyd’s results. This means that warming is not very significant within the context of the Earth’s recent climate history. …