Contrary to scientists’ belief global warming has replenished the rainforests with new form of vegetation. This surprising fact came to light after seven years of study by Smithsonian Tropical Research Institute, Panama team led by Carlos Jaramillo. To arrive at the truth they have studied the fossilized pollen samples from the Columbian and Venezuelan rainforests to understand its effects in the past.

Earth’s temperature has risen to Palaeocene–Eocene Thermal Maximum (PETM) - 3-5%- 56.3 million years ago. It had wiped out some of the plant families, but gave birth to new forms which reiterate the fact that global warming has positive effect on rainforests. "What we found was exactly the opposite of what we were expecting," says Jaramillo. "The diversity of the tropical forest increased really fast over a very short amount of time."

But scientists around the world fear that this study may prompt people to form a casual approach towards global warming. "Of course I'm worried some people will look at this and say 'we shouldn't care about global warming'," said Jaramillo. "…but this is what the fossil record is telling us."

While the study only shows the effect of rising temperature on tropical forest, researchers say the result may differ for forests in higher altitudes with lesser water supply.

According to them the result does not solely depend on the temperature rise, but also on the availability of water in the area of study. There was no water scarcity during the PETM. So, it is difficult to predict the future impact of global warming on the rainforests.

Jaramillo believes that more than climate change deforestation has threatening effect on tropical rainforests. "Deforestation is the real enemy," he says, "not the increase in temperature and carbon dioxide.