The recent European heatwave killed some 2,300 people with more than half of deaths attributable to human-caused climate change. But what if temperatures can be lowered using technology? It's a highly charged question. One of the ideas out there is to create a parasol of particles around the earth to reflect sunlight back into space. Cooling the planet this way is known as solar geoengineering. Many Europeans reject geoengineering outright. They say nobody should be playing God with the clima...