It’s a banner week for the
end of the world, because we’ve officially pushed atmospheric carbon levels
past their dreaded 400 parts per million. Permanently.
According to a blog post
last Friday from the Scripps Institution of Oceanography, “it already seems
safe to conclude that we won’t be seeing a monthly value below 400 ppm this
year—or ever again for the indefinite future.” Their findings are based on weekly
observations of carbon dioxide at Hawaii ’s
Mauna Loa Observatory, where climate scientists have been measuring CO2 levels
since 1958.
What’s so terrifying about
this number? For several years now, scientists have been warning us that if
atmospheric carbon were allowed to surpass 400 parts per million, it would mark
a serious “milestone.” In 2012, the Arctic was
the first region on Earth to cross this red line. Three years later, for the
first time since scientists had begun to record them, carbon levels remained
above 400 parts per million for an entire month.
This time, experts believe
we’re stuck here for good, due to the cyclical effects of Mauna
Loa ’s CO2 curve. Carbon levels usually reach an annual low point
near the end of September, Scripps notes, but this year, those numbers are
hovering around 401 parts per million. There’s a chance that we’ve haven’t seen
2016’s lowest carbon levels yet, but the institution deems that occurrence
“almost impossible.”
If there’s an inkling of a
silver lining here, it’s that scary numbers could scare people into action. For
example, the Paris Agreement—an international convention dedicated to fighting
climate change and its effects—has laid out some firm goals directly tied to
carbon levels.
All countries who adopt the
agreement are bound to prevent global average temperatures from rising beyond 1.5°C
above pre-industrial levels. One of the primary means for achieving that will
be to limit emissions, and enforce ambitious clean energy mandates. However, the
60 nations who have ratified the agreement so far only account for 47.76
percent of the world’s carbon emissions.
So in light of that, here
are some of climate change’s other permanent effects, listed in no particular
order.
Extinction
No explanation required here.
While difficult to estimate, extinction rates have accelerated to 1,000 times
their rate before the existence of modern Homo sapiens. The World Wildlife Fund
guesses 10,000 species could become extinct every year. Due to climate change, The
Nature Conservancy suggests one fourth of Earth’s species could be on their way
to extinction by 2050.
Food chain disruption
Inextricably tied to
extinction, food chains are likely to become permanently unbalanced as apex
predators and their prey begin to disappear. In the Arctic ,
for example, rising ocean temperatures are impacting the growth of sea algae, which
in turn, deprives populations of zooplankton, cod, seals, and polar bears of
vital nutrients. Over the last 50 years, average winter temperatures throughout
Alaska and western Canada have risen by as much as 7°F.
Rising sea levels
In the near future, humans, among
other species, will be catastrophically affected by sea level changes. As
ancient glaciers begin to melt, and thermal expansion occurs, coastlines
elsewhere will flood, and communities will become displaced. By 2100, approximately
13 million people in the US
are projected to lose their homes due to rising sea levels. In some parts of
the world, such as the Pacific Ocean , that's
already started to happen. Scientists theorize that even if we prevent global
average temperatures from rising above 2°C, earlier sea level changes could be
irreversible.
Ocean acidification and
coral bleaching
Considered a crucial
barometer of environmental health, ocean acidity is already wiping out entire
marine ecosystems. The planet’s oceans are constantly absorbing excess CO2, causing
their pH to decrease, literally acidifying the water. And as water temperatures
rise, vast expanses of life sustaining coral, such as Australia ’s Great Barrier
Reef , are also bleaching and dying. While coral polyps could still
take hold and regrow into reefs, scientists anticipate that bleaching events
will leave long-lasting marks on the face of ocean ecosystems.
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Corrections: This story
originally stated that 13 million people are projected to lose their homes due
to rising sea levels, and has been updated to say that number reflects US
populations alone. It has also been altered to reflect that most scientists say
the carbon levels at 400 parts per million are a “milestone,” not a “tipping
point.” We also altered the language in the extinction paragraph to reflect
that these are estimates from The Nature Conservancy. And we added that thermal
expansion is another cause of sea level rise, and corrected the implication
that ocean acidification was a cause of coral bleaching.