As global economies come to a standstill, with much of the population ordered to stay at home, environmentalists see a silver lining - carbon dioxide emissions could fall this year by the largest amount since World War II.
Roisin Commane is Assistant Professor of Earth and Environmental Sciences at New York’s Columbia University.
(SOUNDBITE) (English) ASSISTANT PROFESSOR IN EARTH AND ENVIRONMENTAL SCIENCES AT COLUMBIA UNIVERSITY, ROISIN COMMANE, SAYING: "We've been measuring CO2 since about January.
And we have about six months of data from last year to compare it with as well for the same time period.
And it's been quite surprising to see how much of a reduction in CO2 we're seeing.” The improvements, while heartening, are for all the wrong reasons – shuttered factories, grounded airlines and millions of people forced to stay at home.
(SOUNDBITE) (English) ASSISTANT PROFESSOR IN EARTH AND ENVIRONMENTAL SCIENCES AT COLUMBIA UNIVERSITY, ROISIN COMMANE, SAYING: "So, the reduction in traffic has been above, some say, 30 percent.
Some are saying more.
This is the cleanest we've seen since we started measuring.” But experts warn that without structural change, the emissions decline could be short-lived.
(SOUNDBITE) (English) ASSISTANT PROFESSOR IN EARTH AND ENVIRONMENTAL SCIENCES AT COLUMBIA UNIVERSITY, ROISIN COMMANE, SAYING: "It's a short term, okay at least, there's something improving.
If you're asthmatic, it's much nicer to go for a run right now.
It's not gonna last that long.
So as soon as everybody gets back to normal, these emissions are going to start, unless we decide to do something different." With governments launching giant stimulus packages to keep their economies from collapsing, some investors are watching to see whether countries will start to embrace policies that encourage lower-emission energy sources.
That seems unlikely in the U.S., where President Trump has begun the process of pulling the country out of the landmark Paris Climate Accord.
And just this week, the Trump administration completed a rollback of vehicle emissions standards adopted under his predecessor, Barack Obama.
California and 22 other states are planning a legal challenge to Trump’s move.