It's hot out there

By R.A. | WASHINGTON

A "HEAT dome" is descending on Washington. It's hovering over much of America, actually, sending temperatures into triple digits (or the upper 30s, if you prefer). This is just the latest in what has been a remarkable series of extraordinary weather events. America's south is experiencing a record drought. So, too, is the horn of Africa, where a famine may impact millions of people. In late June, an airport in Oman recorded the highest ever low temperature; on the evening of the 27th, the mercury failed to drop below 107 degrees Fahrenheit. Droughts, floods, deadly storms: the news is full of them. While it's not easy to attribute any individual event to climate change, it is clear that a hotter planet translates into a higher frequency of extreme weather events.

When we emit carbon into the atmosphere, we impose a tiny cost on society as a whole in the form of more rapid global warming and a greater intensity of the accompanying social ills. Views of the magnitude of this cost differ. Many studies peg it at somewhere between $5 and $150 per tonne of carbon. Other studies indicate that it could be far higher—perhaps more than $1,000 per tonne. But the cost is positive, and a crucial first step to dealing with climate change, therefore, is to charge people for the carbon they emit. If you put a positive price on carbon, this price will be reflected in the cost of transactions, people will internalise the effect of their behaviour on the climate, and emissions will fall.