First signs of global warming felt as early as 1940s, scientists reveal

By @iamkarlatecson on
Drought in NSW
A river can be seen flowing through drought-affected farming areas in the western region of New South Wales March 19, 2015. According to the Australian Bureau of Meteorology, Australia recorded its second-hottest February since records began in 1910, with national maximum temperatures at 2.35 degrees above the average. Reuters/David Gray

The year 2015 has been touted as the hottest year on record as a result of climate change, but scientists suggest that global warming appeared as early as 70 years ago in parts of Australia, Southeast Asia and Africa. This is because these regions generally experienced a much narrower range of temperatures, making it easier to see smaller shifts due to global warming, according to the researchers. The team comes from Australia's ARC Center of Excellence for Climate System Science and the U.K.'s University of Reading. 

In the study published in the journal Environmental Research Letters, lead author Dr Andrew King notes that while there were already visible signs of global warming in the 1940s, clear signs were manifested in the 1960s. To determine when global warming started, the team analysed the change in average temperature.

"We examined average and extreme temperatures because they were always projected to be the measure that is most sensitive to global warming," said King, who is from the ARC Centre of Excellence for Climate System Science.

While average temperatures changed in the tropics, changes in the temperature record nearer the north and south poles emerged later but were evident between 1980 and 2000, the team claims. In the study, it was also observed that the continental U.S. showed fewer of these signs, especially the East Coast and the Midwest or central states. According to the researchers, these areas are not yet manifesting truly clear warming signals, but this will likely happen in the next decade.

The team also cautions in their report that climate impacts will likely intensify in the coming years. "We expect the first heavy precipitation events with a clear global warming signal will appear during winters in Russia, Canada and northern Europe over the next 10 to 30 years. This is likely to bring pronounced precipitation events on top of the already existing trend towards increasingly wet winters in these regions," said Dr Ed Hawkins from the National Center for Atmospheric Science at the University of Reading, who co-authored the report.

The new findings are closely similar with the observational datasets used by the Intergovernmental Panel on Climate Change, or IPCC, in its most recent report, which showed increasing temperatures caused by global warming. The IPCC stated that for the global average, warming in the last century has occurred in two phases, from the 1910s to the 1940s, at 0.35 degrees Celsius, and more strongly from the 1970s to the present, at 0.55 degrees Celsius. An increasing rate of warming has taken place over the last 25 years, and 11 of the 12 warmest years on record have occurred in the past 12 years, the IPCC added.

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