Brazil pushed for concerted action to alleviate hunger Monday as it hosted a summit of the Group of 20 leading economies amid global uncertainty over two major wars and incoming U.S. President-elect Donald Trump.

In working group meetings in the run-up to the G20, ministers and negotiators discussed Brazil’s proposal to tax billionaires' incomes by 2%. According to French economist Gabriel Zucman, who worked as a consultant for Lula’s administration on the ...

Set against a backdrop of political turmoil, it's going to be a big ask for the leading rich and developing nations to sign up to any meaningful declarations.