When Global Warming First Appeared on the Climate Record

When did global warming first appear? That's a good question. Now, scientists have taken a closer look at the data, revealing for the first time when and where the first clear signs of global warming appeared in the temperature record.

"We examined average and extreme temperatures because they were always projected to be the measure that is most sensitive to global warming," said Andrew King, the lead author of the new study, in a news release. "Remarkably our research shows that you could already see clear signs of global warming in the tropics by the 1960s but in parts of Australia, South East Asia and Africa it was visible as early as the 1940s."

So why did these changes first appears in the tropics? It's due to the fact that these regions generally experienced a much narrower range of temperatures. This meant that smaller shifts in the temperature record due to global warming were more easily seen.

The first signal to appear in the tropics was the change in average temperatures. Later extreme temperature events showed a global warming signal.

Closer to the poles, you can see the emergence of climate change later. However, most of the world showed signs of climate change from the period of 1980 to 2000.

One of the few exceptions to this clear global warming signal was in large parts of the continental United States, including the Eastern coast and up through the central states. These regions have yet to manifest obvious warming signals, though it's expected they will appear in the next decade.

"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," said Ed Hawkins, one of the researchers, in a news release. "This is likely to bring pronounced precipitation events on top of the already existing trend towards increasingly wet winters in these regions."

The findings are published in the journal Environmental Research Letters.

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