Extreme weather linked to man-made global warming

Man-made global warming is causing extreme weather events, the UN warns. Photo / AP

Many of the deadly heatwaves and hurricanes, droughts and floods this decade have borne the imprint of man-made global warming, said a series of reports yesterday that warned of worse to come.

United Nations envoys yesterday gathered in Morocco for a second day of talks on putting the Paris Agreement into action.

According to the World Meteorological Organisation (WMO), the half-decade from 2011 to 2015 was the warmest five-year stretch on record, with 2014 and 2015 the hottest of all.

In a report issued on the sidelines of the Marrakesh gathering, it warned of "the increasingly visible human footprint on extreme weather and climate events with dangerous and costly impacts". Climate change "has increased the risks of extreme events such as heatwaves, drought, record rainfall and damaging floods", WMO secretary general Petteri Taalas said.

In a separate report, risk analysts Germanwatch said more than half-a-million people worldwide died as a result of almost 11,000 extreme weather events from 1996 to 2015.

These caused damage upwards of US$3 trillion ($3.07t).

Four of the 10 countries hardest hit by extreme weather events last year were in Africa, said Germanwatch.

Poor countries, which contributed least to the planet-warming greenhouse gases in Earth's atmosphere, were least prepared to deal with the fallout - superstorms, extreme drought, heatwaves and flooding.

The Paris Agreement, the world's first universal climate pact, vows to cap global warming to under 2C over pre-Industrial Revolution levels, while aiming for 1.5 C.

This will be done through curbing emissions of man-made greenhouse gases, mainly from burning coal, oil and gas for heat and energy.

The UN talks in Marrakesh will negotiate rules for implementing the accord, which entered into force last week.

Climate scientists find it difficult - when assessing an individual extreme weather event - to determine the proportion of blame ascribed to global warming instead of natural climate variability.

But rapidly-accumulating climate data has recently made it easier to compare what is happening to the climate to past predictions about the impacts of man-made warming.

Looking over five-year time scales helps smooth out natural year-to-year variations and reveal the role of climate change a little more clearly.

"Of 79 studies published by the Bulletin of the American Meteorological Society between 2011 and 2014, more than half found that human-induced climate change contributed to the extreme event in question," said the WMO report.

The correlation with climate change was strongest for high temperatures, according to the WMO, but less obvious for rain and snow.

Adding to the warnings, Britain's National Oceanography Centre said warming of 2C by 2040 would see more than 90 per cent of the world's coastal areas experience sea level rise of more than 20cm. The Atlantic coast of North America and Norway would see as much as 40 cm.

In a worst-case-scenario 5C-warmer world, 80 per cent of coastlines would have sea-levels rise over 1.8m by the end of the century.

Oceans rise partly due to water expanding as it warms, but also from the melting ice sheets of Greenland and West Antarctica.

Last year was the first year in which the average global surface temperature - across land and sea - was a full 1C over the pre-industrial benchmark. AFP