India, Feb. 25 -- Donald Trump's America is emerging as the single biggest challenge to global climate efforts. On Monday, the United States (US), the largest historical emitter of greenhouse gases, was absent at the Intergovernmental Panel on Climate Change (IPCC)'s meeting in China and withdrew itself from the review of current climate science, mitigation efforts and the impact that is presently underway. This follows the Trump administration pulling the country out of the Paris Agreement, the hard-won consensus on the pathway to keeping warming to below 2degC from the pre-industrial global temperature.

Going ahead, the US could abandon the UN Framework Convention on Climate Change altogether, plunging the entire world into a deeper cr...