The study by Mr Wire was commissioned by the Optimum Population Trust, a British environmental charity.

ECONOMIST: Fewer people would mean lower greenhouse-gas emissions

The Optimum Population Trust goes further with proposals that government encourage couples to stop at two children and the introduction of a one-in one-out policy on immigration.

BBC: England and Wales population up

Britain's Optimum Population Trust offered summit attendees an opportunity to offset the estimated 1.1 tons of carbon emissions released into the atmosphere from their trans-Atlantic flights by donating money to a family planning program.

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