Investing just 0.034 per cent of global GDP could transform the world's forestry sector, halving deforestation rates, slashing carbon emissions and creating up to five million new jobs by the middle of the century.That is the conclusion of a major new report from the UN Environment Programme (UNEP), which argues that investing an average of $40bn a year in forest protection would allow forests to absorb 28 per cent more carbon from the atmosphere than they do now.