Global warming and climate change are words that almost everyone knows these days. It is also known that we should take major steps to slow down this trend. But now a leading climate scientist has said that experts may be underestimating how fast global warming is happening. James Hansen, a prominent climate scientist, said that by 2050 the average temperature on Earth will rise by 2 degrees Celsius above pre-industrial levels. This level of increase is greater than estimated by groups such as the Intergovernmental Panel on Climate Change, or IPCC. IPCC estimates are generally considered the gold standard for climate predictions. In his new study, Hansen said the revised forecast is due to an earlier underestimation of the effect of greenhouse gases on the atmosphere, as well as the effect of aerosols, which mask some of the global warming. (Hansen)