In the early 1970s, a different kind
of climate worry took hold:
As more people became concerned about pollutants people were emitting into the atmosphere, some scientists theorized the pollution could block sunlight and cool
In fact, Earth did cool somewhat between
1940-1970 due to a postwar boom in aerosol
pollutants which reflected sunlight away
from the planet.
The idea that sunlight-blocking pollutants could chill Earth caught on in the media, as in a 1974 Time magazine article titled “Another Ice Age?”
But as the brief cooling period ended
and temperatures resumed their
upward climb, warnings by a minority
of scientists that Earth was cooling
Part of the reasoning was that while smog could remain suspended in the air for weeks, CO2 could persist in the atmosphere for centuries.
Scientists explore and discover more as they widen their scope on the cause of our planet heating up. As it turns out, chlorofluorocarbons (CFC) are in widespread use up until this time and is slowly killing our protective blanket that is the Ozone Layer.
People started to believe
that this was an issue worth
noting. Since the late 1970s,
the use of CFCs has been
heavily regulated because
of their destructive effects
on the ozone layer.
The very first Earth Day was on April 22, 1970. About 20 million people attended the event.
By 1987, in response to a dramatic seasonal
depletion of the ozone layer over Antarctica,
diplomats in Montreal forged a treaty,
the Montreal Protocol, which called
for drastic reductions in the production
On March 2,1989, twelve European Community nations agreed to ban the production of all CFCs by the end of the century. The image shows the CFC concentration in 1979 versus 2008.
In 1990, diplomats met in London and voted to significantly strengthen the Montreal Protocol by calling for a complete elimination of CFCs by the year 2000.
By the year 2010, CFCs should have been completely eliminated from developing countries as well.