LAURIE GOERING  AS more countries, cities, investors and businesses set net-zero emissions goals, they now cover about half of the world's economy - but Africa is largely left out of the picture so far. Of its 54 countries, only South Africa has set a net-zero aim - and failure to revamp policies to benefit from a global low-carbon shift may mean Africa misses out on investment, said Wendy Hughes, a carbon markets manager at the World Bank Group. But officials from the continent noted that with sub-Saharan Africa currently producing less than 4% of global emissions, "carbon-cutting" goals have limited…