Recently, two separate NASA studies illustrated the complex relationship
between human activity and our atmosphere.
First up, a team led by scientists at NASA's Jet Propulsion Laboratory
focused on drops in nitrogen oxide emissions during the COVID 19 lockdowns.
Nitrogen oxide comes from sources like power plants and car exhaust
and reacts to form surface level ozone, which is harmful to human health.
Using NASA satellites,
the team saw that the lockdowns left a distinct 'fingerprint' on ozone levels
in the lower atmosphere, which dropped about 2% globally.
And while this may seem small, such a drop in harmful
ozone would take about 15 years to achieve under even
the most aggressive emission control scenarios.
Interestingly enough, the team found that these drops were not uniform
across the globe.
That where and when the lockdowns
occurred was very important in determining the impact on the atmosphere.
Taking a look at these regions with blue representing below
normal levels of ozone in the lower atmosphere,
we could see that both Asia and the United States have
a substantial impact on harmful global ozone levels.
Factors like prevailing
winds, air temperature and moisture content all impact
how efficiently ozone is produced and moves
throughout the globe.
Like ozone, CO2 is a long lived gas that is easily
transported through the atmosphere, which means that any changes in emissions
is mixed with many different influences from both near and far.
This makes it challenging to track and measure how local changes in
human activity actually impact the levels of this greenhouse gas.
Using NASA's OCO -2 instrument and the GEOS model, NASA
researchers were able to spot short-term regional fluctuations in the atmosphere
due to drops in human activity related to the lockdowns.
This is the first time changes in CO2
measurements have been tracked at such a scale all over the globe.
The team's results
showed that the CO2 emissions dropped significantly in the Northern Hemisphere
from February through May and rebounded during the summer
when some restrictions eased.
The team
was also able to better distinguish which monthly CO2 fluctuations
were due to human activities and which were due to natural causes,
like the Australian wildfires and ocean circulation patterns.
This is important because distinguishing between human and natural causes
is a critical step towards measuring human activities' collective effects
on CO2 emissions in near real time.
The lockdown surrounding COVID 19 were an unprecedented global event
that highlighted the complex relationships between emissions and the atmosphere.
By studying
these relationships, we can gain insights that could help us better design
sustainable measures that can improve both human health and the climate.