Guardian: 1 Global warming must be limited to 2C Every year, carbon emissions from cars, factories and power plants across the planet rise inexorably. The resulting elevation in carbon dioxide levels in the atmosphere mean that in 30 years temperatures on Earth will be 2C hotter than they were in pre-industrial times, scientists say. This is the maximum temperature that they believe the world can tolerate without there being devastating environmental consequences: spreading deserts, worsening storms and widespread...