The U.N.’s $100 billion Global Climate Fund, currently establishing itself but struggling to attract donor support, has adopted a travel policy that will allow eligible board members to fly business class on trips of more than nine hours’ duration. “The Fund is committed to reducing the greenhouse gas emissions [carbon dioxide and other substances blamed for climate change] arising from its travel operations,” reads the policy, adopted at a GCF board meeting in Paris this month. It mandates economy class for flights shorter than nine hours, and encourages train travel “wherever this is a viable option.” A World Bank study...