BEIJING, July 6 (Xinhuanet) -- The earth's tropical zone is expanding rapidly, says an Australian study.
"The tropics have widened by up to 500 kilometres (310 miles) in the past 25 years after examining 70 peer-reviewed scientific articles," said researchers at James Cook University in north Queensland.
They said drought is becoming more common in the south, while the north is expected to see an increase in rainfall.
Professor Steve Turton said given the impacts on everything from farming and healthcare to viticulture and tourism, much more research is needed to help respond to this change.
The tropics have half the world's population, 80 percent of the world's biodiversity, very high infant mortality, high rates of tropical diseases and they make up around 20 percent of Gross World Product.
Professor Steve Turton said tropics now extended well beyond the traditional definition of the tropics, the equatorial band circling the Earth between the Tropic of Cancer and the Tropic of Capricorn.
He said that meant the subtropical arid zone which borders the tropics was being pushed into temperate areas, with potentially devastating consequences.
"Such areas include heavily-populated regions of southern Australia, southern Africa, the southern Europe-Mediterranean-Middle East region, the south-western United States, northern Mexico, and southern South America," Turton said.
"All of (them) are predicted to experience severe drying."
Turton said tropical diseases such as dengue fever were likely to become more prevalent.