Credit: Walter Siegmund
SYDNEY: The past decade was the warmest on record, the 2009 State of the Climate report released last week revealed.
It had already been announced that the past decade was the hottest yet recorded in Australia - and now we know we didn't suffer alone.
The year 2009 saw the end of the warmest decade worldwide, since record began in the late 1800s. For the last 20 years or so, the U.S. National Oceanic and Atmospheric Administration (NOAA) has annually released a report analysing the global climate for the year before.
Records began 1870
"The report is the most comprehensive annual summary that NOAA have produced so far, as it involved over 300 scientists from 48 countries," said climatologist Lisa Alexander of the University of New South Wales in Sydney, one of the authors of the report.
"[The year] 2009 marked the end of the first decade of the 2000s, so the last 10 years could be put in the context of all other decades since about 1870," she said.
Global surface temperature increased between 0.56°C and 0.92°C during the last century, according to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), and was expected to rise further still during this century.
Progressively getting hotter
"Each of the last three decades has been progressively warmer than all earlier decades," Alexander said.
"[The] warming that has been experienced in recent decades, in tandem with increases in greenhouse gases, does provide supporting evidence for human-induced changes in climate and therefore would point to a further warming for the coming decades."
Around the world, scientists collected data from weather stations, ships and buoys, weather balloons and satellites. Global surface temperature analyses from three major independent global datasets were compared. This information was analysed by over 300 scientists and compiled into the exhaustive report on the State of the Climate in 2009.
El Niño, other variations taken into account
The researchers studied warming temperatures across decades so as not to prejudice the data with natural climactic variations, such as El Niño. Changes in average temperature from decade to decade reveal a long-term warming, according to the report.
Climatologist David Karoly from the University of Melbourne, a major contributor to the IPCC's Fourth Assessment Report, said that the 2009 State of the Climate report adds to a growing body of evidence of global warming.
He says the report provides "a synthesis of evidence that shows ongoing evidence of climate change due to increased presence of greenhouse gases". It is clear from the report that the climate is changing, he said.
"We need to adapt to climate change and reduce the emissions that will make it worse in future."
