Reports suggesting that global warming stopped 16 years ago are “misleading”, the Met Office said yesterday.
It had been claimed that the Exeter-based Met Office “quietly released” figures which showed little rise in aggregate global temperatures from the beginning of 1997 until August 2012.
Critics suggested that the computer models being used to predict future warming were “deeply flawed”.
The Met Office yesterday stressed it had not “issued a report” on the figures which come from an update on a global temperature data set compiled jointly with the University of East Anglia’s Climate Research Unit.
“As we’ve stressed before, choosing a starting or end point on short-term scales can be very misleading,” a Met Office spokesman said.
“Climate change can only be detected from multi-decadal timescales due to the inherent variability in the climate system.
“Looking at successive decades over this period, each decade was warmer than the previous – so the 1990s were warmer than the 1980s, and the 2000s were warmer than both. Eight of the top ten warmest years have occurred in the last decade.
“Over the last 140 years global surface temperatures have risen by about 0.8C.
“However, within this record there have been several periods lasting a decade or more during which temperatures have risen very slowly or cooled.
“The current period of reduced warming is not unprecedented and 15-year long periods are not unusual.”
Some climate change models have suggested the Earth could experience a warming of 0.2C per decade. The effect is blamed on human activity and the volume of carbon dioxide being pumped into the atmosphere.
The possible consequences of global warming – more frequent weather extremes and rising sea levels – influence swathes of Government policy.
The Met Office explained that climate change computer modelling showed “large variations in the rate of warming from year to year and over a decade” due to external factors like oceanic cycles. As a result, it said, “such a period is not unexpected”. The spokesman added: “We have limited observations on multi-decadal oceanic cycles but we have known for some time that they may act to slow down or accelerate the observed warming trend.
“In addition, we also know that changes in the surface temperature occur not just due to internal variability, but are also influenced by ‘external forcings’, such as changes in solar activity, volcanic eruptions or aerosol emissions.
“Combined, several of these factors could account for some or all of the reduced warming trend seen over the last decade – but this is an area of ongoing research.”