US Energy Secretary Steven Chu is warning that if countries don't do something about climate change, "some island states will simply disappear." The energy secretary is traveling with President Barack Obama to the two-island nation of Trinidad and Tobago for a summit of the Western Hemisphere's democracies. Chu told reporters at the Summit of the Americas on Saturday that Obama pushed leaders to work to stem rising temperatures. Chu said that rising temperatures lead to more damaging hurricanes and rising oceans. He said those results are scary. Chu also said Obama encouraged fellow leaders to consider energy efficiency to help fight climate change. Obama pointed to refrigerators, which are now larger and four-times more efficient than they were in 1975.