While we immediately understand the tragedy of the deaths and fires, the irony of the air conditioners seems to escape us. We just don't make the connection that most of the electricity we use to cool our homes and offices is actually causing the Earth to get hotter. We often assume that cars and industry are the main greenhouse gas culprits. But electricity generated by coal-fired power stations for residential and commercial use accounts for a huge proportion of global carbon dioxide-emissions, the major cause of global warming and climate change. In Australia for example a country where both recent droughts and current water shortages have been linked to global warming it's responsible for about half the nation's annual CO2 emissions.

Worldwide, nearly 40 per cent of the world's electricity comes from burning coal. It's the dirtiest fuel in terms of CO2 pollution: Coal-fired power stations currently release a disproportionate 72 per cent of all power-related CO2 emissions, and around a fifth of total CO2 emissions from all human activities. And current projections are that coal use in the power sector will grow by more than 60 per cent by 2020, releasing billions more tons of CO2 into our atmosphere each year. The consequences of this will go way beyond heat-related deaths and fires each summer. The World Meteorological Organization last year warned that the frequency of extreme weather events heat waves, droughts, hurricanes, floods, and the like might be on the increase due to climate change.

This year, Swiss Re, the world's second largest reinsurer, said that global warming is aggravating the economic costs of natural disasters, which threaten to double to $150 billion a year in 10 years

The damage is not just monetary. People and their livelihoods are already sirectly suffering, particularly in the developing world. Worsening droughts, famines, and floods as well as rising sea levels could create climate refugees, and have a direct impact on security. Scientists around the world agree that the only solution is to keep the maximum global temperature rise to less than 2 degrees Celsius. And that the only practical way this can be achieved is to immediately make drastic cuts to greenhouse gas emissions, and CO2 in particular.

Ways to do this already exist. For the electricity sector, the answer lies in clean, renewable energy sources such as biomass, wind, solar, and geothermal power, together with improved energy efficiency. Both approaches have been proven to work, and only lack political will to become more widely used.

Rarely in human history have scientists spelt out such dire warnings with enough time and technology to respond. And rarely have the nations of the world dithered for so long in tackling a known threat to global security. It's time for governments, the power sector, and business to get serious and urgently start a shift from coal to clean, renewable energy sources. Otherwise, we're only going to make things hotter for ourselves as we try to cool down each summer.

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Jennifer Morgan is director of the climate change program at WWF, the global conservation organization.

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