The dark eyes and hair of the Pakistanis, Bangladeshis, and Afghans almost blend with the other migrants’. The brown skin tones are also not giveaways, but ask them where they come from, and you notice the hesitation – trying hard to blend into the crowd of Syrian migrants at Europe’s border crossings, afraid of being spotted and sent back.

As most of the world’s governments are puzzling out what they can offer to combat global climate change, a sensitive but critical aspect of the problem is coming into clearer focus: population. The word appears 20 times in a new 66-page synthesis of country pledges to cut greenhouse-gas emissions by the UN Framework Convention on Climate Change’s Secretariat. And those are the mentions of population in the context of size or growth, not the word’s more frequent use as a synonym for “people.”

For all its flaws, the United Nations remains the only plausible forum for engaging broad global challenges like sustainable development. The most important environmental achievements of the past 40 years – the rise of environmental awareness, the birth of key ideas such as sustainability or the common heritage of humanity and the most important global treaties for environmental protection – all bear the UN stamp in one way or another. We could have added environmental human rights to that legacy last month, but we failed.