Last year's global weather was far more extreme or record-breaking than anything approaching normal, according to a new report.
The US National Oceanic and Atmospheric Administration yesterday released its annual checkup of the Earth, highlighting numerous records including hottest year, highest sea level, and lowest sea ice in the Arctic and Antarctica.
The 299-page report, written by scientists around the world and published in the Bulletin of the American Meteorological Society, shows that 2016 was "very extreme and it is a cause for concern", said co-editor Jessica Blunden, a NOAA climate scientist.
Researchers called it a clear signal of human-caused climate change. A record large El Nino, the warming of the central Pacific that changes weather worldwide, was also a big factor in last year's wild weather.
Georgia Tech climate scientist Kim Cobb, who had no role in the report, said "2016 will be forever etched in my brain as the year we crossed a new threshold of climate change - one that gave us a grim glimpse into our future".
Scientists examined dozens of key climate measures and found:
At any given time, nearly one-eighth of the world's land mass was in severe drought. That's far higher than normal and "one of the worst years for drought", said report co-author Robert Dunn of Britain's Met Office.
Extreme weather was everywhere. Giant downpours were up. Heat waves struck all over the globe, including a nasty one in India. Extreme weather contributed to a gigantic wildfire in Canada.
Global sea level rose another 3.4mm for the sixth straight year of record high sea levels.
There were 93 tropical cyclones across the globe, 13 per cent more than normal. That included Hurricane Matthew that killed about 1000 people in Haiti.
The world's glaciers shrank - for the 37th year in a row - by an average of about 1m.
Greenland's ice sheet lost 310 billion tonnes of ice. It has lost 4000b tonnes of ice since 2002.
Last year "was a year in the Arctic like we've never seen before", said NOAA Arctic research chief Jeremy Mathis, who called it "a clear and more pronounced signal of warming than in any other year on record". Some findings had already been released, including that last year was the hottest on record, meaning the record was set for three consecutive years. A study based on modelling and weather patterns shows three hot years in a row is close to impossible to be a natural coincidence.
The odds of three years in a row setting heat records without man-made global warming is only 0.7 per cent, compared to 30 to 50 per cent with greenhouse gases, according to a separate study published yesterday in the Geophysical Research Letters.
NOAA report co-editor Deke Arndt said the only notable normal global measure in 2016 was snow cover in the Northern Hemisphere.
Impact on river floods
Climate change is affecting the timing of river floods across Europe and societies may have to adapt to avoid future economic and environmental harm, scientists said yesterday.
River floods are among the costliest natural disasters worldwide, causing annual damages of more than US$100 billion ($137.3b). They affect millions of people each year.
Examining flood data across a 50-year period, researchers found significant shifts in timing along the Atlantic coast of western Europe from 1960 to 2010. According to a paper published in the journal Science, half of the measurement stations from England to Portugal showed floods were occurring on average at least 15 days earlier by 2010 compared with a half century earlier.
In northeastern Europe, earlier snow melts also brought river floods forward by at least eight days over the 50-year period, while areas around the North Sea are now seeing floods happen more than a week later.
"If the trends in flood timing continue, considerable economic and environmental consequences may arise, because societies and ecosystems have adapted to the average within-year timing of floods," the authors, led by Guenter Bloeschl of Vienna's Technical University, concluded.
While data on the timing of floods showed a clearer link with climate change than past studies that looked into flood severity, the researchers noted that several factors affect the timing of floods and that not all the shifts are necessarily caused by man-made global warming.