Medford, Massachusetts

IN A POETIC irony, while world leaders met in Paris early this month to address the climate change threat, two of the major countries key to global warming saw their capitals - Beijing and Delhi - smothered in dense smog. Beijing even issued its first "Red Alert", urging citizens to stay indoors.

As the so-called 21st Conference of the Parties (COP21) concludes in Paris, there are commitments by countries to hold back carbon emissions and increase use of renewable and low-carbon energies like solar, wind, nuclear or hydropower. Despite such commitments, keeping the global warming below 2 degrees Celsius may be an impossible task. Scientists have warned that carbon emissions must drop as much as 70 per cent by mid-century to restrict the rise of global temperatures.