The evidence that humans are causing global warming is
strong, but the question of what to do about it remains controversial.
Economics, sociology, and politics are all important factors in planning
for the future.
Even if we stopped emitting greenhouse gases
(GHGs) today, the Earth would still warm by another degree Fahrenheit or
so. But what we do from today forward makes a big difference.
Depending on our choices, scientists predict that the Earth could
eventually warm by as little as 2.5 degrees or as much as 10 degrees
Fahrenheit.
A commonly cited goal is to stabilize GHG
concentrations around 450-550 parts per million (ppm), or about twice
pre-industrial levels. This is the point at which many believe the most
damaging impacts of climate change can be avoided. Current
concentrations are about 380 ppm, which means there isn't much time to
lose. According to the IPCC, we'd have to reduce GHG emissions by 50%
to 80% of what they're on track to be in the next century to reach this
level.
Is this possible?
Many people and governments are already working hard to cut greenhouse gases, and everyone can help.
Researchers
Stephen Pacala and Robert Socolow at Princeton University have
suggested one approach that they call "stabilization wedges." This means
reducing GHG emissions from a variety of sources with technologies
available in the next few decades, rather than relying on an enormous
change in a single area. They suggest 7 wedges that could each reduce
emissions, and all of them together could hold emissions at
approximately current levels for the next 50 years, putting us on a
potential path to stabilize around 500 ppm.
There are many
possible wedges, including improvements to energy efficiency and vehicle
fuel economy (so less energy has to be produced), and increases in wind
and solar power, hydrogen produced from renewable sources, biofuels
(produced from crops), natural gas, and nuclear power. There is also
the potential to capture the carbon dioxide emitted from fossil fuels
and store it underground—a process called "carbon sequestration."
In
addition to reducing the gases we emit to the atmosphere, we can also
increase the amount of gases we take out of the atmosphere. Plants and
trees absorb CO2 as they grow, "sequestering" carbon naturally.
Increasing forestlands and making changes to the way we farm could
increase the amount of carbon we're storing.
Some of these
technologies have drawbacks, and different communities will make
different decisions about how to power their lives, but the good news is
that there are a variety of options to put us on a path toward a stable
climate.
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