Clear thinking required

摘要

IN VENICE, WATER in the canals is running clear, offering glimpses of fish swimming against the current. As human activity grinds to a halt, natural rhythms resume. A similar, less visible story is being played out in the skies. Around the world, levels of toxic air pollutants are dropping as places go into lockdown in an attempt to curb the spread of sars-cov-2, the virus causing a pandemic of a new disease called covid-19. Emissions of greenhouse gases are following a similar pattern.