People rescued in flood. (Photos: AFP)

Extreme weather caused around $129 billion in economic losses last year, according to a report released on October 31 that warned the bill will keep climbing as climate change boosts droughts, storms and floods.

There was a 46 percent increase in weather disasters from 2010 to 2016, with 797 "extreme" events recorded last year, according to research published in The Lancet medical journal.

These "resulted in $129 billion in overall economic losses" - a figure which roughly matches the budget of Finland.

Losses were counted as damage to physical assets and did not include the "economic value" of deaths, injury or disease caused by extreme events.

An observed increase in weather disasters in recent years, the report said, cannot yet unequivocally be attributed to climate change.

But the evidence "might plausibly be interpreted as showing how climate change is changing the frequency and severity of these events", the authors wrote.

The carcass of a cow lies in the Black Umfolozi River, dry from the effects of drought in South Africa. 

Climate scientists are loath to blame any particular weather event on global warming, a phenomenon that needs to be monitored over decades.

But looking to the future, the authors are under no illusions that climate change will fuel the "frequency and severity" of tropical storms, droughts and flooding around the world.

The finances of poor countries are disproportionately hard hit, said the report compiled by experts from 24 academic institutions and inter-governmental bodies including the World Health Organization and the World Meteorological Organization.

Their losses from freak weather events were more than three times higher in 2016 than in 2010, and as a proportion of GDP, much greater than in rich nations.

Wheat and mosquitoes

In high income countries, about half of economic losses were insured, compared to less than 1 percent in poor nations.

Researchers calculated that rising temperatures caused a loss of about 5.3 percent in labor productivity in outdoor workers since 2000.

Vehicles stop on the side of a road as a tornado rips through a residential area in Oklahoma. 

Over the same period, the number of vulnerable people exposed to heatwaves - putting them at risk of heatstroke, heart failure or dehydration - increased by about 125 million.

The rising mercury also caused a nearly 10 percent rise since 1950 in the disease-spreading "vectorial capacity" of a mosquito bearing the potentially deadly dengue virus.

"Climate change is expected to have an impact on crop production, with a one-degree-Celsius rise in temperatures associated with a 6% decline in global wheat yields and a 10% decrease in rice grain yields," said a statement in The Lancet, warning of growing hunger.

The world's nations have pledged to limit average global warming caused by humankind's emissions of fossil fuel gases to two degrees Celsius (3.6 degrees Fahrenheit) from pre-Industrial Revolution levels.

US President Donald Trump has pulled his country out of the pact, though the withdrawal can only become effective in about four years.

On top of the risk to life and property from heatwaves, floods and storms, as well as the spread of water-borne diseases and disease-bearing insects, climate change may also pose longer-term health dangers, the report said.

"Indeed, emerging evidence is suggesting links between a rising incidence of chronic kidney disease, dehydration, and climate change," the authors wrote.

Experts commenting on the report agreed more research is needed to clearly attribute health impacts to climate change.

There was no doubt, however, of the link between temperature trends and human activities, nor about "the urgency of addressing the issues raised by this report", said Clare Goodess of the University of East Anglia's Climate Research Unit.