ABU DHABI (Reuters) - U.S. climate envoy John Kerry on Sunday outlined core principles for a "high-integrity" carbon offset plan meant to help developing nations speed their energy transition, and next steps including establishing a consultative group. The Energy Transition Accelerator (ETA), first announced at last year's COP27 climate conference, is being developed by the United States with the Bezos Earth Fund and the Rockefeller Foundation to mobilise private capital. Kerry told the Atlantic Council Global Energy Forum in Abu Dhabi the aim was to create bankable deals to accelerate reduction of emissions, stressing that the ETA was not a...