Chinese companies have built or financed $1.5 trillion in roads, dams, mines, power plants and other projects around the world in recent decades. The projects have had enormous environmental impacts.By Nicholas Kusnetz, Georgina Gustin, Katie SurmaFor more than a decade, the Chinese government has overseen a trillion-dollar building spree across the globe, helping construct and finance a vast network of mines, ports, railways and other infrastructure outside its borders.