We know that a lot of people will die because of the havoc wreaked by climate change. The World Health Organization (WHO) estimates that between 2030 and 2050, climate change will cause roughly 250 000 additional deaths per year, from malnutrition, malaria, diarrhea and heat stress. Most of these “excess deaths” will be due to the effects of extreme heat, variable rainfall, and the spread of infectious diseases. Developing countries and poor farmers will be especially hard hit. Compare the above to current excess deaths due to air pollution: WHO reports that in 2012 around 7 million people died as a result of air pollution exposure. The sources of air pollution mostly overlap with the sources of carbon emissions. Coal is by far the biggest cause of deaths caused by air pollution. In 2013, for instance, outdoor air pollution from coal caused an estimated 366,000 deaths in China. Coal also gives you more death per unit of energy.
This from Nexbigfuture:
Energy Source Death Rate (world average deaths per TWh)
Coal (26% of world energy) 100 (from 15 in US to 170 in China)
Oil (36% of world energy) 36
Natural Gas (21% of world energy) 4
Nuclear (5.9% of world energy) 0.04
(TWh = terawatt-hours)
Coal is not only the most deadly source of energy; it's alsothe biggest emitter of CO2 per unit of energy output - almost twice that of natural gas. No one's saying natural gas is clean or safe - only that it's a whole lot cleaner and safer than coal. Then there's nuclear: even counting the Fukushimas and Chernobyls, nuclear is the cleanest and safest around. Wind, solar and biofuels aren't yet at a scale that bears comparison in this club. Maybe someday but not yet.
Of course we want to keep developing alternative, non-emitting, energy sources so that eventually they become sufficiently cheap and scalable to compete with the Big Four - Coal, Oil, Natural Gas, and Nuclear. But if we care about saving lives, we'd get a lot more bang for our buck by encouraging natural gas and nuclear for now while continuing to work on their eventual replacements.