Walk through the Amazon rainforest today and you will find it is steamy,warm,damp and thick.But if you had been around 15,000 years ago,during the last ice age,would it have been the same?For more than 30 years,scientists have been arguing about how rainforests like the Amazon might have reacted to the cold,dry climates of the ice ages, but until now,no one has reached a satisfying answer.Rainforests like the Amazon are important for mopping up CO2 from the atmosphere and helping to slow global warming.Currently the trees in the Amazon take in around 500 million tons of CO2 each year: equal to