Barack Obama will not be pledging any cash to a near-empty fund for poor countries at a United Nations summit on climate change next week, the UN special climate change envoy said on Friday. The UN secretary general, Ban Ki-moon, has challenged the 125 world leaders attending the 23 September summit to make “bold pledges” to the fund, intended to help poor countries cope with climate change. The UN has been pressing rich countries to come up with pledges of between $10bn and $15bn. “We are putting a lot of pressure for them to do it at the summit on...