CRYTOCOOLER: The Peltier element, often used to cool hotel minibars or CPUs in computers, can transform electric currents into heat currents. Researchers at the University of Zurich used it to cool a 9-gram piece of copper from over 100°C to significantly below room temperature without an external power supply. Cooling systems today collectively account for 17 percent of the electricity used worldwide. All together, that’s 8 percent of global greenhouse gas emissions. “What keeps me up at night is that our energy use for cooling might grow sixfold by the year 2050, primarily driven by increasing usage in Asian and African countries,” said Aaswath Raman, a professor of materials science and engineering at UCLA. “That is, emphatically, a good thing for the health, well-being, and productivity of people living in warmer climates. However, one of the most alarming things about climate change is that the warmer our planet gets, the more we’re going to need cooling systems — systems that are themselves large emitters of greenhouse gas emissions. This then has the potential to cause a feedback loop, where cooling systems alone could become one of our biggest sources of greenhouse gases...