While much of the media focus on the effects of climate change has been on the Arctic, researchers at Australia’s James Cook University reveals that in the past 25 years there’s been a expansion of the world’s tropical zones and that human activity has contributed to it.
climatologists and meteorologists consider to be the tropics (which is defined differently than in geography) have expanded at minimum 300 kilometers (186 miles).
Future expansion of these zones is harder to predict, but based on what’s now known the planet could see a further spread of the tropical conditions over the next 25 years of between 222-553 kilometers (138-338 miles).
The implication of this is that sub-tropical arid zones which border the tropics are being pushed into areas which previously had a more temperate climate, with more pronounced differences in seasonal temperatures and precipitation.
Furthermore, the expansion of tropical diseases such as dengue fever could hit areas where the diseases was previously not endemic or where epidemic levels of dengue were previously not present. Researchers said the literature showed that these areas include the southern United States, China, northern Africa in the northern hemisphere, and parts of South America, southern Africa, and most of Australia in the southern hemisphere.
– from treehugger