The current results of more than two dozen climate models now in use suggest that it is very likely(with at least 90% certainty) that the earth's mean surface temperature will increase by1.5-4.5°C(2.7-8.1°F )between 2013 and 2100(Figure 15. C), unless we can sharply reduce deforestation along with our emissions of CO2, and other greenhouse gases In 2014, climate researcher Michael E.