Not for a moment is there any suggestion here cleaner air and fewer greenhouse gas emissions combine as a “nice side effect” from the unfolding tragedy. It merely is a set of side effects that have developed as the world economy has headed into its devastating tailspin, with the awful impacts on industry, business, and billions of individuals.
New York City reported to the BBC last Thursday its carbon monoxide levels were down close to 50% from last March. (NYC has extensive mobile environmental instrumentation scattered across the city.) There was already good evidence of carbon dioxide reductions in stricken areas even weeks ago, from satellite-derived measurements. NASA has such an image made before and during the peak of China’s Covid-19 drastic control measures. This shows the sharp reduction in nitrogen dioxide, a toxic trace gas in nature which increases from the burning of fossil fuels.
NASA produced a video on the nitrogen dioxide reductions as well:
Similar nitrogen dioxide reductions have occurred in Europe as seen in this European Space Agency imagery:
NYC can serve as a real test lab for reductions in some greenhouse gases, being a hot spot in this crisis. According to Columbia University, local carbon dioxide levels were already down close to 10% last week, with an estimated 35% drop in vehicular traffic. Methane, a potent greenhouse gas, has also shown a solid drop. Since this data was published last week, further reductions in vehicle traffic have occurred, with likely further reductions in carbon monoxide, carbon dioxide, nitrogen dioxide and methane.
Actual numbers in future greenhouse gas emission drops are hard to come by. It is difficult to project just how far and for how long the industrial devastation will spread and last. It is also difficult to project the same for vehicular and air traffic over time. The reductions during the current crisis appear likely to surpass those of the great recession of 2008, quite possibly by a large margin.
We do know these terrible circumstances will continue for some time to come. We do not know how nations will respond to reductions in severity following spikes, and whether those nations will begin to ramp up activity at risk of secondary surges should controls be relaxed prematurely.
What can safely be assumed is there will eventually be a gradual return to relaxed controls when “herd immunity” rises, a vaccine arrives, and some possible antivirals prove to have efficacy. Every past decline has been followed by some degree of real recovery. Air traffic will not permanently create scenes like this one.
Grand Central Station looks even emptier this week than the “after” picture here taken on March 17, before even stricter restrictions went into effect.
Some time in the future, there will be an economic recovery, as there was following the worst recession since the Great Depression.
No one can project how strong the recovery will be, or how long it will take to start and gain momentum. The temporary reduction in greenhouse gases and pollution is just that
– temporary. Most will agree the terrible impacts of this global pandemic have pushed off to the side many climate concerns for at least as long as humanity is in the grip of this new virus. That is to be expected, which is why I emphasize these greenhouse gas reductions are not being presented as a “nice side benefit.”