Leaders from Germany and Spain are calling for a global tax on billionaires to help tackle the costs of the climate crisis. Brazil, which chairs the G20 group of the world’s largest economies, first proposed a tax on the super-rich at a meeting of finance ministers in February. Now, finance chiefs from Germany, Spain and South Africa have joined Brazil in fleshing out the proposal which could see the world’s 3,000 billionaires made to pay a minimum 2 per cent levy on their wealth. “It is time that the international community gets serious about tackling inequality and financing global public go…