According to a new analysis of the most realistic climate models to date, global temperature rise by 2100 could be 15 percent higher than the highest projections from the United Nations' Intergovernmental Panel on Climate Change (IPCC). What this means is that cuts in greenhouse gases like carbon dioxide (CO2) will have to be even greater than expected to meet the Paris climate target of keeping global warming to less than 2 degrees Celsius. Motherboard reports: The world is a long way from making sufficient emission reductions to meet the Paris climate targets to begin with -- nevermind cutting out another 15 percent. But there's some good news, too. Both rich and poor countries have begun to move away from coal and oil, the two biggest CO2 sources, according to many energy analysts. Patrick Brown is a researcher at the Carnegie Institution for Science in Pasadena, California, a co-author of the study published Wednesday in Nature. "Our results imply 15 percent less cumulative emissions than previously calculated [are needed] in order to stay below 2 degrees Celsius," he told me. Brown and co-authors focused on finding out what future warming might be, using only the climate models that best replicate observations over the last 15-20 years. On a business-as-usual emissions trajectory, they found that the mean global temperature rise would be 4.8 degrees Celsius by 2100, compared to the IPCC estimate of 4.3 degrees Celsius. The latter estimate is considered catastrophic for our planet, and would lead to sea level rise of over 30 feet, potentially putting the homes of 600 million people underwater.