A: Here's a simple definition of global warming. (And yes, it's really happening.) Over
the past 50 years, the average global temperature has increased at the
fastest rate in recorded history. And experts see the trend is
accelerating: All but one of the 16 hottest years in NASA’s 134-year
record have occurred since 2000.
Climate
change deniers have argued that there has been a “pause” or a
“slowdown” in rising global temperatures, but several recent studies,
including a 2015 paper published
in the journal Science, have disproved this claim. And scientists say
that unless we curb global-warming emissions, average U.S. temperatures
could increase by up to 10 degrees Fahrenheit over the next century.
Q: What causes global warming?
A: Global warming occurs when carbon dioxide (CO2)
and other air pollutants and greenhouse gasses collect in the
atmosphere and absorb sunlight and solar radiation that have bounced off
the earth’s surface. Normally, this radiation would escape into
space—but these pollutants, which can last for years to centuries in the
atmosphere, trap the heat and cause the planet to get hotter. That's
what's known as the greenhouse effect.
In the United
States, the burning of fossil fuels to make electricity is the largest
source of heat-trapping pollution, producing about two billion tons of
CO2 every year. Coal-burning power plants are by far the biggest
polluters. The country’s second-largest source of carbon pollution is
the transportation sector, which generates about 1.7 billion tons of CO2
emissions a year.
Curbing dangerous climate change
requires very deep cuts in emissions, as well as the use of
alternatives to fossil fuels worldwide. The good news is that we’ve
started a turnaround: CO2 emissions in the United States actually
decreased from 2005 to 2014, thanks in part to new, energy-efficient
technology and the use of cleaner fuels. And scientists continue to
develop new ways to modernize power plants, generate cleaner
electricity, and burn less gasoline while we drive. The challenge is to
be sure these solutions are put to use and widely adopted.
Q: How is global warming linked to extreme weather?
A: Scientists
agree that the earth’s rising temperatures are fueling longer and
hotter heat waves, more frequent droughts, heavier rainfall, and more
powerful hurricanes. In 2015, for example, scientists said that an
ongoing drought in California—the state’s worst water shortage in 1,200
years—had been intensified by 15 percent to 20 percent by global
warming. They also said the odds of similar droughts happening in the
future had roughly doubled over the past century. And in 2016, the
National Academies of Science, Engineering, and Medicine announced that
it’s now possible to confidently attribute certain weather events, like
some heat waves, directly to climate change.
The earth’s
ocean temperatures are getting warmer, too—which means that tropical
storms can pick up more energy. So global warming could turn, say, a
category 3 storm into a more dangerous category 4 storm. In fact,
scientists have found that the frequency of North Atlantic hurricanes
has increased since
the early 1980s, as well as the number of storms that reach categories 4
and 5. In 2005, Hurricane Katrina—the costliest hurricane in U.S.
history—struck New Orleans; the second-costliest, Hurricane Sandy, hit
the East Coast in 2012.
The impacts of global warming
are being felt across the globe. Extreme heat waves have caused tens of
thousands of deaths around the world in recent years. And in an
alarming sign of events to come, Antarctica has been losing about 134
billion metric tons of ice per year since 2002. This rate could speed up
if we keep burning fossil fuels at our current pace, some experts say,
causing sea levels to rise several meters over the next 50 to 150 years.
Q: What are the other effects of global warming?
A: Each year, scientists learn more about the consequences of global warming,
and many agree that environmental, economic, and health consequences
are likely to occur if current trends continue. Here’s just a smattering
of what we can look forward to:
Melting glaciers,
early snowmelt, and severe droughts will cause more dramatic water
shortages and increase the risk of wildfires in the American West.
Rising
sea levels will lead to coastal flooding on the Eastern Seaboard,
especially in Florida, and in other areas such as the Gulf of Mexico.
Forests,
farms, and cities will face troublesome new pests, heat waves, heavy
downpours, and increased flooding. All those factors will damage or
destroy agriculture and fisheries.
Disruption of habitats such as coral reefs and Alpine meadows could drive many plant and animal species to extinction.
Allergies,
asthma, and infectious disease outbreaks will become more common due to
increased growth of pollen-producing ragweed, higher levels of air pollution, and the spread of conditions favorable to pathogens and mosquitoes.
Q: Where does the United States stand in terms of global-warming contributors?
A: In recent years, China has taken the lead in global-warming pollution, producing about 28 percent of
all CO2 emissions. The United States comes in second. Despite making up
just 4 percent of the world’s population, we produce a whopping 16
percent of all global CO2 emissions—as much as the European Union and
India (third and fourth place) combined. And America is still number
one, by far, in cumulative emissions over the past 150 years. Our
responsibility matters to other countries, and it should matter to us,
too.
Q: Is the United States doing anything to prevent global warming?
A: We’ve
started. But in order to avoid the worst effects of climate change, we
need to do a lot more—together with other countries—to reduce our
dependence on fossil fuels and start using clean energy instead.
In
2015, the U.S. Environmental Protection Agency pledged to reduce carbon
pollution from our power plants by nearly a third by 2030, relative to
2005 levels, through its Clean Power Plan. The U.S. Department of
Transportation has proposed carbon pollution and fuel economy standards
that should cut emissions through the 2020s. Chemicals that contribute
to global warming, like hydrofluorocarbons (used in air conditioners),
are being phased out of production nationwide, and so are
energy-inefficient household items like incandescent lightbulbs. Also in
2015, solar and wind power provided more than 5 percent of the United
States’ electricity for the first time, and construction started on the
country’s first offshore wind power project.
Globally,
at the United Nations Conference on Climate Change in Paris, 195
countries—including the United States—agreed to pollution-cutting
provisions with a goal of preventing the average global temperature from
rising more than 1.5 degrees Celsius above preindustrial times.
(Scientists say we must stay below a two-degree increase to avoid
catastrophic climate impacts.)
To help
make the deal happen, the Obama administration pledged $3 billion to
the Green Climate Fund, an international organization dedicated to
helping poor countries adopt cleaner energy technologies. Under the
terms of the Paris agreement, participating nations will meet every five
years, starting in 2020, to revise their plans for cutting CO2
emissions. Beginning in 2023, they will also have to publicly report
their progress.
Q: Is global warming too big of a problem for me to help tackle?
A: Wondering how to stop global warming? Reduce your
own carbon footprint by following a few easy steps. Make conserving
energy a part of your daily routine and your decisions as a consumer.
When you shop for new appliances like refrigerators, washers, and
dryers, look for products with the government’s Energy Star label; they
meet a higher standard for energy efficiency than the minimum federal
requirements. When you buy a car, look for one with the highest gas
mileage and lowest emissions. You can also reduce your emissions by
taking public transportation or carpooling when possible.
And while new federal and state standards are a step in the right direction, much more needs to be done. Voice your support of
climate-friendly and climate change preparedness policies, and tell
your representatives that transitioning from dirty fossil fuels to clean
power should be a top priority—because it’s vital to building healthy,
more secure communities.
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