Climate change a grave security threat - Boris Johnson David Attenborough and activist Nisreen Elsaim are to address a UN session chaired by Boris Johnson. How will John Kerry fare as Joe Biden’s climate envoy?The former secretary of state is a good pick for what may prove to be a chastening task Climate crisis ‘biggest security threat humans have faced’, Sir David Attenborough tells UNAttenborough called for tougher action to address ‘climate security risks’ at a UN Security Council session chaired by Boris Johnson Climate crisis is driving insecurity, Johnson to tell world leadersPrime minister to use chairing of UN security council session to set scene for Cop26 climate conference Kerry: Climate change among 'most complex security issues we've ever faced'Special envoy John Kerry called climate change “among the most complex security issues we've ever faced” at the virtual Munich Security Conference on Friday.