Nov 27, 2015 ·
The issue can be overwhelming. The science is complicated. Predictions
about the fate of the planet carry endless caveats and asterisks. We get
it. And so ...
Short Answers to Hard Questions About Climate Change
Photo
Credit
James Yang for The New York Times
The issue can be overwhelming. The science is complicated.
Predictions about the fate of the planet carry endless caveats and
asterisks.
We get it.
And so, as the Paris climate talks get underway, we’ve provided quick answers to often-asked questions about climate change. You can submit your own questions here.
1.
How much is the planet heating up?
1.7 degrees is actually a significant amount.
As of this October, the Earth had warmed by about 1.7 degrees
Fahrenheit since 1880, when tracking began at a global scale. That
figure includes the surface of the ocean. The warming is greater over
land, and greater still in the Arctic and parts of Antarctica.
The
number may sound low, but as an average over the surface of an entire
planet, it is actually high, which explains why much of the land ice on
the planet is starting to melt and the oceans are rising at an
accelerating pace. The heat accumulating in the Earth because of human
emissions is roughly equal to the heat that would be released by 400,000
Hiroshima atomic bombs exploding across the planet every day.
Scientists
believe most and probably all of the warming since 1950 was caused by
the human release of greenhouse gases. If emissions continue unchecked,
they say the global warming could ultimately exceed 8 degrees
Fahrenheit, which would transform the planet and undermine its capacity
to support a large human population.
2.
How much trouble are we in?
For future generations, big trouble.
The risks are much greater over the long run than over the next
few decades, but the emissions that create those risks are happening
now. Over the coming 25 or 30 years, scientists say, the climate is
likely to resemble that of today, although gradually getting warmer.
Rainfall will be heavier in many parts of the world, but the periods
between rains will most likely grow hotter and therefore drier. The
number of hurricanes and typhoons may actually fall, but the ones that
do occur will draw energy from a hotter ocean surface, and therefore may
be more intense, on average, than those of the past. Coastal flooding
will grow more frequent and damaging.
Longer term, if
emissions continue to rise unchecked, the risks are profound. Scientists
fear climate effects so severe that they might destabilize governments,
produce waves of refugees, precipitate the sixth mass extinction of
plants and animals in Earth’s history, and melt the polar ice caps,
causing the seas to rise high enough to flood most of the world’s
coastal cities.
All of this could take hundreds or even thousands
of years to play out, conceivably providing a cushion of time for
civilization to adjust, but experts cannot rule out abrupt changes, such
as a collapse of agriculture, that would throw society into chaos much
sooner. Bolder efforts to limit emissions would reduce these risks, or
at least slow the effects, but it is already too late to eliminate the
risks entirely.
3.
Is there anything I can do?
Fly less, drive less, waste less.
There are lots of simple ways to reduce your own carbon footprint,
and most of them will save you money. You can plug leaks in your home
insulation to save power, install a smart thermostat, switch to more
efficient light bulbs, turn off the lights in any room where you are not
using them, drive fewer miles by consolidating trips or taking public
transit, waste less food, and eat less meat.
Perhaps the biggest single thing individuals can do on their own is to take fewer airplane trips;
just one or two fewer plane rides per year can save as much in
emissions as all the other actions combined. If you want to be at the
cutting edge, you can look at buying an electric or hybrid car, putting
solar panels on your roof, or both.
If you want to offset your
emissions, you can buy certificates, with the money going to projects
that protect forests, capture greenhouse gases and so forth. Some airlines sell these to offset emissions from their flights,
and after some scandals in the early days, they started to scrutinize
the projects closely, so the offsets can now be bought in good
conscience. You can also buy offset certificates in a private
marketplace, from companies such as TerraPass
in San Francisco that follow strict rules set up by the state of
California; some people even give these as holiday gifts. Yet another
way: In states that allow you to choose your own electricity supplier,
you can often elect to buy green electricity; you pay slightly more,
with the money going into a fund that helps finance projects like wind
farms.
In the end, though, experts do not believe the needed
transformation in the energy system can happen without strong state and
national policies. So speaking up and exercising your rights as a
citizen matters as much as anything else you can do.
4.
What’s the optimistic scenario?
Several things have to break our way.
In the best case that scientists can imagine, several things happen:
Earth turns out to be less sensitive to greenhouse gases than currently
believed; plants and animals manage to adapt to the changes that have
already become inevitable; human society develops much greater political
will to bring emissions under control; and major technological
breakthroughs occur that help society both to limit emissions and to
adjust to climate change.
The two human-influenced variables are
not entirely independent, of course: Technological breakthroughs that
make clean energy cheaper than fossil fuels would also make it easier to
develop the political will for rapid action.
Scientists say the
odds of all these things breaking our way are not very high,
unfortunately. The Earth could just as easily turn out to be more
sensitive to greenhouse gases than less. Global warming seems to be
causing chaos in parts of the natural world already, and that seems
likely to get worse, not better. So in the view of the experts, simply
banking on a rosy scenario without any real plan would be dangerous.
They believe the only way to limit the risks is to limit emissions.
You can submit your question about climate change here.
5.
What’s the worst-case scenario?
There are many.
That is actually hard to say, which is one reason scientists are
urging that emissions be cut; they want to limit the possibility of any
worst-case scenario coming to pass. Perhaps the greatest fear is a
collapse of food production, accompanied by escalating prices and mass
starvation. Even with runaway emissions growth, it is unclear how likely
this would be, as farmers are able to adjust their crops and farming
techniques, to a degree, to adapt to climatic changes. Another
possibility would be a disintegration of the polar ice sheets, leading
to fast-rising seas that would force people to abandon many of the
world’s great cities and would lead to the loss of trillions of dollars
worth of property and other assets. Scientists also worry about other
wild-card scenarios like the predictable cycles of Asian monsoons’
becoming less reliable. Billions of people depend on monsoons to provide
water for crops, so any disruptions would be catastrophic.
6.
Will a tech breakthrough help us?
Even Bill Gates says don’t count on it, unless we commit the cash.
As more companies, governments and researchers devote themselves to
the problem, the chances of big technological advances are improving.
But even many experts who are optimistic about technological solutions
warn that current efforts are not enough. For instance, spending on
basic energy research is only a quarter to a third of the level that
several in-depth reports have recommended. And public spending on
agricultural research has stagnated even though climate change poses
growing risks to the food supply. People like Bill Gates have argued
that crossing our fingers and hoping for technological miracles is not a
strategy — we have to spend the money that would make these things more
likely to happen.
7.
How much will the seas rise?
The real question is not how high, but how fast.
The ocean is rising at a rate of about a foot per century. That
causes severe effects on coastlines, forcing governments and property
owners to spend tens of billions of dollars fighting erosion. But if
that rate continued, it would probably be manageable, experts say.
The
risk is that the rate will accelerate markedly. If emissions continue
unchecked, then the temperature at the earth’s surface could soon
resemble a past epoch called the Pliocene,
when a great deal of ice melted and the ocean rose something like 80
feet compared to today. A recent study found that burning all the fossil
fuels in the ground would fully melt the polar ice sheets, raising the
sea level by more than 160 feet over an unknown period.
With all
of that said, the crucial issue is probably not how much the oceans are
going to rise, but how fast. And on that point, scientists are pretty
much flying blind. Their best information comes from studying Earth’s
history, and it suggests that the rate can on occasion hit a foot per
decade, which can probably be thought of as the worst-case scenario. A
rate even half that would force rapid retreat from the coasts and, some
experts think, throw human society into crisis. Even if the rise is much
slower, many of the world’s great cities will flood eventually. Studies
suggest that big cuts in emissions could slow the rise, buying crucial
time for society to adapt to an altered coastline.
Still have a question about climate change? You can submit one here.
8.
Are the predictions reliable?
They’re not perfect, but they’re grounded in solid science.
The idea that Earth is sensitive to greenhouse gases is confirmed by
many lines of scientific evidence. For instance, the basic physics
suggesting that an increase of carbon dioxide traps more heat was
discovered in the 19th century, and has been verified in thousands of
laboratory experiments.
Climate science does contain
uncertainties, of course. The biggest is the degree to which global
warming sets off feedback loops, such as a melting of sea ice that will
darken the surface and cause more heat to be absorbed, melting more ice,
and so forth. It is not clear exactly how much the feedbacks will
intensify the warming; some of them could even partially offset it. This
uncertainty means that computer forecasts can give only a range of
future climate possibilities, not absolute predictions.
But even
if those computer forecasts did not exist, a huge amount of evidence
suggests that scientists have the basic story right. The most important
evidence comes from the study of past climate conditions, a field known
as paleoclimate research. The amount of carbon dioxide in the air has
fluctuated naturally in the past, and every time it rises, the Earth
warms up, ice melts, and the ocean rises. A hundred miles inland from
today’s East Coast, seashells can be dug from ancient beaches that are
three million years old. These past conditions are not a perfect guide
to the future, either, because humans are pumping carbon dioxide into
the air far faster than nature has ever done.
9.
Why do people question climate change?
Hint: ideology.
Most of the attacks on climate science are coming from libertarians
and other political conservatives who do not like the policies that have
been proposed to fight global warming. Instead of negotiating over
those policies and trying to make them more subject to free-market
principles, they have taken the approach of blocking them by trying to
undermine the science. This ideological position has been
propped up by money from fossil-fuel interests, which have paid to
create organizations, fund conferences and the like. The scientific
arguments made by these groups usually involve cherry-picking data, such
as focusing on short-term blips in the temperature record or in sea
ice, while ignoring the long-term trends. The most extreme version of climate denialism is to claim
that scientists are engaged in a worldwide hoax to fool the public so
that the government can gain greater control over people’s lives. As the
arguments have become more strained, many oil and coal companies have
begun to distance themselves publicly from climate denialism, but some
are still helping to finance the campaigns of politicians who espouse
such views.
10.
Is crazy weather tied to climate change?
In some cases, yes.
Scientists have published strong evidence that the warming climate is
making heat waves more frequent and intense. It is also causing heavier rainstorms, and coastal flooding is getting worse
as the oceans rise because of human emissions. Global warming has
intensified droughts in regions like the Middle East, and it may have strengthened the drought in California.
In many other cases, though, the linkage to global warming for
particular trends is uncertain or disputed. That is partly from a lack
of good historical weather data, but it is also scientifically unclear
how certain types of events may be influenced by the changing climate.
Another
factor: While the climate is changing, people’s perceptions may be
changing faster. The Internet has made us all more aware of weather
disasters in distant places. On social media, people have a tendency to
attribute virtually any disaster to climate change, but in many cases
there is no scientific support for doing so.
11.
Will anyone benefit from global warming?
In certain ways, yes.
Countries with huge, frozen hinterlands, including Canada and Russia,
could see some economic benefits as global warming makes agriculture,
mining and the like more possible in those places. It is perhaps no
accident that the Russians have always been reluctant to make ambitious
climate commitments, and President Vladimir V. Putin has publicly
questioned the science of climate change.
However, both of those
countries could suffer enormous damage to their natural resources;
escalating fires in Russia are already killing millions of acres of
forests per year. Moreover, some experts believe countries that view
themselves as likely winners from global warming will come to see the
matter differently once they are swamped by millions of refugees from
less fortunate lands.
12.
Is there any reason for hope?
If you share this with 50 friends, maybe.
Scientists have been warning since the 1980s that strong policies
were needed to limit emissions. Those warnings were ignored, and
greenhouse gases in the atmosphere have since built up to potentially
dangerous levels. So the hour is late.
But after 20 years of
largely fruitless diplomacy, the governments of the world are finally
starting to take the problem seriously. A deal that is likely to be
reached in Paris in December will commit nearly every country to some
kind of action. Religious leaders like Pope Francis are speaking out.
Low-emission technologies, such as electric cars, are improving. Leading
corporations are making bold promises
to switch to renewable power and stop forest destruction. Around the
world, many states and cities are pledging to go far beyond the goals
set by their national governments.
What is still largely missing
in all this are the voices of ordinary citizens. Because politicians
have a hard time thinking beyond the next election, they tend to tackle
hard problems only when the public rises up and demands it. Still have a question about climate change? You can submit one here. end quote from:
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