Researchers at James Cook University concluded the tropics had widened by up to 500 kilometres (310 miles) in the past 25 years after examining 70 peer-reviewed scientific articles.
They looked at findings from long-term satellite measurements, weather balloon data, climate models and sea temperature studies to determine how global warming was impacting on the tropical zone.
The findings showed it 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.' Read the rest of this story at Grist blog. Ironic that I'm reading about an Australian research study (James Cook University) from an American blog; they got it from Agence France-Presse.