Context:
In May, the atmospheric concentration of carbon dioxide temporarily surpassed
400 parts per million for probably the first time in human history. It was no surprise when the Intergovernmental Panel on Climate Change warned in its
latest report, published in September, that climate change “unprecedented
over decades to millennia” is altering natural environments in ways that could affect billions of people. Typhoon Haiyan’s record-breaking wind speeds demonstrated the destructive forces that the atmosphere can unleash — although the jury is out on
whether and how much global warming contributed (see
page 361).