Now the biggest barrier to change is the will of our politicians to take
serious climate action.
Because its costs continue to slide with every quarter, solar
energy will be cheaper than fossil fuels almost everywhere on
the planet by the decade’s end. Photograph by Irfan Khan / Los Angeles Times / Getty
Author
Bill McKibben is a founder of the grassroots climate campaign
350.org and a contributing writer to The New Yorker. He
writes The Climate Crisis, The New Yorker’s newsletter on the environment.
Earth Week has come and gone, leaving behind an ankle-deep and
green-tinted drift of reports, press releases, and earnest promises
from C.E.O.s and premiers alike that they are planning to become
part of the solution.
There were contingent signs of
real possibility—if some of the heads of state whom John Kerry
called on to make Zoom speeches appeared a little strained, at least
they appeared. (Scott Morrison, the Prime Minister of Australia, the
most
carbon-emitting developed nation
per capita, struggled to make his technology work.)
But,
if you want real hope, the best place to look may be a little noted
report
from the London-based think tank Carbon Tracker Initiative.
Titled “The Sky’s the Limit,” it begins by declaring that “solar
and wind potential is far higher than that of fossil fuels and can
meet global energy demand many times over.” Taken by itself,
that’s not a very bold claim: scientists have long
noted
that the sun directs more energy to the Earth in an hour than
humans use in a year. But, until very recently, it was too
expensive to capture that power. That’s what has shifted—and so
quickly and so dramatically that most of the world’s politicians
are now living on a different planet than the one we actually
inhabit.
On the actual Earth, circa 2021, the report
reads, “with current technology and in a subset of available
locations we can capture at least 6,700 PWh p.a. [petawatt-hours
per year] from solar and wind, which is more than 100 times global
energy demand.” And this will not require covering the globe with
solar arrays: “The land required for solar panels alone to provide
all global energy is 450,000 km2, 0.3% of the global land area of
149 million km2. That is less than the land required for fossil
fuels today, which in the US alone is 126,000 km2, 1.3% of the
country.” These are the kinds of numbers that reshape your
understanding of the future.
We haven’t yet fully grasped this potential because it’s happened
so fast. In 2015, zero per cent of solar’s technical potential was
economically viable—the small number of solar panels that existed
at that time had to be heavily subsidized. But prices for solar
energy have collapsed so fast over the past three years that sixty
per cent of that potential is already economically viable. And,
because costs continue to slide with every quarter, solar energy
will be cheaper than fossil fuels almost everywhere on the planet
by the decade’s end. (It’s a delicious historical irony that this
evolution took place, entirely by coincidence, during the
Administration of
Donald Trump, even as he
ranted
about how solar wasn’t “strong enough” and was “very, very
expensive.”)
The Carbon Tracker report, co-written by
Kingsmill Bond, is full of fascinating points, including how
renewable energy is the biggest gift of all for some of the
poorest nations, including in Africa, where solar potential
outweighs current energy use by a factor of more than a thousand.
Only a few countries—Singapore, Japan, Korea, Taiwan, and a
handful of European countries—are “stretched” in their ability to
rely on renewables, because they both use a lot of energy and have
little unoccupied land. In these terms, Germany is in the
third-worst position, and the fact that it is nonetheless one of
the world’s leaders in renewable energy should be a powerful
signal: “If the Germans can find solutions, then so can everyone
else.”
Clearly, those few nations are going to be
importing some renewable energy—a more farsighted Australian Prime
Minister would be figuring out how to send ships full of
solar-generated hydrogen to Japan, not how to continue shipping
coal to China. (And, in fact, the world’s
largest
solar farm is set to end up in the Australian outback, connected
by at least two thick undersea cables to Singapore.)
The numbers in the report are overwhelming—even if the analysts
are too optimistic by half, we’ll still be swimming in cheap solar
energy. “We have established that technical and economic barriers
have been crossed by falling costs. It follows that the main
remaining barrier to change is the ability of incumbents to
manipulate political forces to stop change,” the report reads.
Indeed. And the problem is that we need that change to happen
right now, because the curves of damage from the climate crisis
are as steep as the curves of falling solar prices.
Given three or four decades, economics will clearly
take care of the problem—the low price of solar power will keep
pushing us to replace liquid fuels with electricity generated from
the sun, and, eventually, no one will have a gas boiler in the
basement or an internal-combustion engine in the car. But, if the
transition takes three or four decades, no one will have an ice
cap in the Arctic, either, and everyone who lives near a coast
will be figuring out where on earth to go.
That conundrum was illuminated on Friday, when
word came
that Governor Gavin Newsom, of California, who has been under
pressure from an unrelenting activist campaign, agreed to ban new
fracking permits in his state and end fossil-fuel production there
altogether. This is a stunning achievement—for the planet and also
for the California communities (and you can guess what kinds of
communities they are) that currently have oil wells in their
schoolyards and next to their hospitals.
The
environmentalists
who banded together in the Last Chance Alliance should be
incredibly proud; Newsom (who is now facing a recall election)
deserves credit, as well, because this is precisely the step that
his famously green predecessor, Jerry Brown, did not take. The
fracking ban, though, only affects a small percentage of
California’s oil production, and won’t take effect until 2024. The
ban on oil production would not happen until 2045, which in
climate terms is the very distant future—a decade past the date
when California will ban the sale of new gas-powered cars, which
are the main use of oil in the state.
It’s clear why
Newsom is slow-walking the changes. An executive secretary of a
building-trades council immediately responded, “We will work to
oppose this effort for our membership, their families, our
schools, and our future. I have one question for Gavin Newsom: Are
our jobs too dirty for you?”
Change is hard. The job of politicians is to make it easier for
those affected, so that what must happen can happen—and within the
time we’ve been allotted by physics. But that hard job is
infinitely easier now that renewable energy is suddenly so cheap.
The falling price puts the wind at our backs, as it were. It’s the
greatest gift we could have been given as a civilization, and we
dare not waste it.
Passing the Mic
Audrea Lim is a Brooklyn-based journalist who has written for
this magazine, and also for Harper’s, the Times, and
The Nation. She is the editor of the book “The World We Need: Stories and Lessons from America’s Unsung
Environmental Movement,” which the New Press will publish next week. For the book, she
surveyed America, finding the people who are powering the
environmental movement now. (Our conversation has been edited for
length.)
Bill McKibben: People may have an image in their mind of what an
environmentalist looks like—but what does an environmentalist
actually look like in 2021?
Audrea Lim: They don’t look any one way! Far from the
“white college-educated hippie” stereotype, environmentalists are
Black and brown youth transforming an abandoned jail into a
community farm; a former coal miner turned blogger and
environmental advocate; Asian, Latinx, and indigenous people
creating healthier and more equitable neighborhoods for their
kids.
“Environmentalist” just describes any people defending the quality
of their surroundings. This work can be local (protecting air or
water from toxic emissions or lead paint in the walls) or global
(protecting the glaciers and oceans that regulate local climates,
from Brooklyn’s streets to the Alaskan coast). The health, safety,
and well-being of their communities hang in the balance, but many
activists understand that these goals also require bigger changes,
from better access to parks, recreation, and community spaces to
more localized food systems and good, clean jobs.
I
think that’s why many environmentalists don’t even call themselves
“environmentalists.” They are culture-makers, or community,
housing, labor, and immigration activists who understand that
environmental issues are ingrained in every part of society, and
have simply made them a core element of their work.
Bill McKibben: What are the most important insights that came as, say, the
climate movement morphed into the climate-justice
movement?
Audrea Lim: That climate change will touch every
community, demographic, and region, but is also on track to
devastate poor and BIPOC communities the
most. Many of these communities already struggle to meet basic
needs—food, housing, education, physical and mental health—making
them more vulnerable to sudden shocks, as we’ve seen through
the pandemic.
Many of these communities also live near polluting
developments (factories, refineries, waste incinerators) or on
eroded and contaminated lands (mines, Superfund sites), or lack
proper water and sewage infrastructure. These are added risks when
the fires and floods arrive.
This uneven burden is part of America’s legacy of environmental
racism: a history of hazardous, polluting fossil-fuel developments
being concentrated in communities of color—sometimes by design and
often through neglect. It’s the conjoined twin of residential
segregation. But, in addressing this reality head on, the
climate-justice movement also has another important insight to
offer: everyone benefits when we empower these communities to
build more equitable, resilient local economies, and transition
away from the dirty industries long looming over them.
Bill McKibben: If you could pick one story that would really stick in
people’s minds and hearts, what would it be?
Audrea Lim: Eric Enos grew up on the Waianae Coast of
Oahu, with little knowledge of his Native Hawaiian culture,
including the central importance of taro, a root vegetable.
(Native culture was suppressed under U.S. colonialism.) After
graduating from college, in the seventies, he began teaching art
to Native youth-gang members, taking them to dive in the ocean,
protest the conversion of local fishing grounds into a resort, and
hike in the back of the desiccated Waianae Valley. Here they found
abandoned walls and terraces in the ground. These were clearly
cultural sites, but what were they?
Archeologists at the Bishop Museum found that the entire area was
once under taro cultivation, as well as other traditional Hawaiian
plants. The water had long ago been diverted toward colonial sugar
plantations, but, with guidance from a state senator and local
agencies, Enos, the youth, and community members built a new
irrigation system. A group of multi-ethnic taro farmers, whom they
had earlier helped defend against eviction from their lands,
helped prepare the terraces for cultivation. And, with seeds
donated from the Lyon Arboretum, they began growing native plants,
learning about the land, their own culture, and taro in the
process.
These were the beginnings of
Ka‘ala Farm, a cultural learning center that connects troubled youth to the
land. The story underscores how different institutions and people
from different communities can collaborate toward a more equitable
and resilient future.
Climate School
Two former Prime Ministers of Australia wrote
an insightful op-ed
about why their country, bathed in sun, continues to insist on
building more coal mines and gas wells. They note that “the main
thing holding back Australia’s climate ambition is politics: a
toxic coalition of the Murdoch press, the right wing of the
Liberal and National parties, and vested interests in the fossil
fuel sector.” Last week, the center-left Australian Labor Party,
too, said that it will not stand against building more coal mines,
and believes that the nation will be exporting the black rocks
past 2050.
A wonderful leftover from Earth Day: Tia Nelson, the daughter of
the late senator Gaylord Nelson, who launched the April day of
action, in 1970,
wrote
about how her father helped welcome
Joe Biden to
the Senate, in 1973, comforting him after his wife and infant
daughter had been killed in a car crash. Nelson said, of her
father, “It would delight him to see that something he started so
long ago, to shake the Washington establishment out of its
lethargy, still playing such an important role these many years
later. And he would be moved to see that the heartbroken young man
he helped recover from despair is carrying his legacy forward.”
It’s remarkable how long Biden has been around—one good effect is
that he’s known some superb people.
A new
study
has found that climate change will cause lakes in the Northern
Hemisphere to stratify earlier in the year and over longer
periods, and that “many of the ecosystem services that lakes
provide, ranging from the delivery of drinking water and food to
recreation, may be endangered by the projected change in
stratification phenology during the twenty-first century,
particularly in urbanized and agricultural regions where lakes are
already eutrophic.”
A sign of what’s to come: a new renewable-energy
project
in Oregon marries solar power, wind turbines, and large-capacity
battery storage. A spokesman for the local utility, Portland
General Electric, said, “We feel pretty certain that this is what
the future of renewable power looks like. It’s more diverse, and
it’s more flexible.” A little further south and looking a little
further into the future, the invaluable Sammy Roth, in his weekly
“Boiling Point” newsletter, discusses the
possibility
of covering California’s irrigation canals with solar panels, to
both generate clean energy and cut evaporation.
The Movement for Black Lives is launching a
Red Black and Green New Deal, with a virtual summit on May 11th. Its Web site states, “We are
organizing to introduce a National Black Climate Agenda that
includes federal legislation to address the climate crisis by
investing in Black communities and repairing past harms.”
A Yale team has developed a
podcast devoted
to climate policy and carbon pricing—the most recent episode is
about why conservatives might be comfortable with the tactic. As
Naomi Shimberg, a junior, explains, “Many conservatives echo the
classic economic argument: pricing harm across the economy, rather
than controlling it with direct forms of government regulation, is
the most efficient way to cut pollution.”
Scoreboard
A new report
from the World Meteorological Organization documented just how
dismal 2020 was in climatic terms: it was one of the three warmest
years on record, with more than eighty per cent of the world’s
oceans subject to at least one “marine heat wave;” extensive
flooding in the Greater Horn of Africa helped trigger a plague of
locusts; and severe drought in South America caused three billion
dollars in crop losses in Brazil alone.
A Baylor College of Medicine pediatrician and a University of
California, Davis, environmental economist published an
assessment, in Scientific American, of the actual health impact of
climate change. They argue that the Biden Administration should
set the “social cost” of carbon at a higher level, to reflect the
damage that it’s doing to “every organ system in the human body.”
Water levels in Lake Powell and Lake Mead are
expected
to drop to record lows in the coming months, and reduced snowpacks
and increased evaporation along the Colorado watershed may trigger
the first-ever official water-shortage declaration in the
area—and, hence, cuts in the water supply to Arizona and Nevada.
The student-body presidents of all the Ivy League schools signed a
joint call
for full fossil-fuel divestment last week. Meanwhile, divestment
campaigners at Harvard produced a
series of comic sketches
as part of their ongoing efforts, and Christiana Figueres, the
former head of the United Nations convention on climate change who
spearheaded the push for the
Paris accord,
criticized
the university for its investments in fossil-fuel companies,
warning that Harvard management is on the verge of “breaching its
true fiduciary responsibility.”
The Timesobtained
a detailed summary of an upcoming United Nations scientific
report, which makes clear that, in addition to cutting carbon
emissions, controlling methane emissions is crucial in solving the
climate crisis. Along with issuing calls for plugging leaks, the
report makes the critical point, according to the Times,
that “expanding the use of natural gas is incompatible with
keeping global warming to 1.5 degrees Celsius, a goal of the
international Paris Agreement.”
Warming Up
Bonnie Raitt and the Indigo Girls are among the artists who cut
“No More Pipeline Blues (On this Land Where We Belong),” to raise money and awareness for the fight against Minnesota’s
Line 3 pipeline. Listen for the voice of the first enrolled member
of a Native American tribe to be named U.S. Poet Laureate,
Joy Harjo.
Germany's climate change laws are insufficient and violate fundamental
freedoms by putting the burden of curbing CO2 emissions on the young, its
highest court has ruled.
It says the law fails to give enough detail on cutting CO2 emissions after
current targets end in 2030.
"The provisions irreversibly offload major emission reduction burdens on
to periods after 2030," it found.
The government will now have to revise the law by the end of the next
year.
The decision comes a week after the EU unveiled ambitious new climate
change targets.
Under the law, which was agreed between member states and the European
Parliament, the bloc will cut carbon emissions by at least 55% by 2030,
compared with 1990 levels.
What does the law say?
Like the EU legislation, Germany's domestic climate change law provides
for a 55% reduction in greenhouse gases by 2030.
The 2019 law was agreed as part of Germany's response to the 2016 Paris
climate deal, which aims to keep the global temperature rise well under 2C
- and preferably to 1.5C - to prevent the worst effects of climate change.
What is climate change?
But the German Constitutional Court said on Thursday that current measures
"violate the freedoms of the complainants, some of whom are still very
young" because they delay too much of the action needed to reach the Paris
targets until after 2030.
"In order to achieve this, the reductions still required after 2030 will
have to be achieved more urgently and at short notice," it said.
Should Germany use up most of its permitted CO2 emissions by this time,
future generations could face a "serious loss of freedom".
"Virtually any freedom is potentially affected by these future emission
reduction obligations, because almost all areas of human life are still
associated with the emission of greenhouse gases and are therefore
threatened by drastic restrictions after 2030," the court said.
How did Germans react?
Thursday's ruling partially upheld complaints brought by climate change
activists - most of them young - and environmental groups between 2018 and
2020.
Luisa Neubauer (L) with Swedish climate activist Greta Thunberg
and German activist Jakob Blasel at a protest in Berlin in 2019.
AFP
German climate activist Luisa Neubauer from the Fridays for Future movement
and one of the plaintiffs in the case, described the decision as a "huge win
for the climate movement".
"Today's inaction mustn't harm our freedom & rights in the future,"
she said.
One of the lawyers involved in the case, Felix Ekardt, hailed the
"ground-breaking victory".
"I would like to take the government to court because the politicians
aren't taking the impending climate catastrophe seriously enough, and I
want people in 100 to 150 years to still know what snow is," the pupil
wrote.
German Environment Minister Svenja Schulze also welcomed the decision,
which she described as "a clear strengthening of climate protection".
"I would have liked to have included a further interim goal for the 2030s
in the [2019] law but at the time there was no majority for that," she
said.
What are other countries doing?
Other countries have also focused on climate change in recent days, with
Poland reaching a draft agreement with trade unions to close all of its
coal mines by 2049 and organise severance payments for the tens of
thousands of workers affected.
Last week, the US hosted a virtual climate summit of 40 global leaders,
with President Joe Biden pledging to cut US carbon emissions by 50-52%
below 2005 levels by the year 2030.
Julia Rosen
is a journalist with a Ph.D. in geology. Her research involved
studying ice cores from Greenland and Antarctica to understand past
climate changes.
The science of
climate change
is more solid and widely agreed upon than you might think.
But the
scope of the topic, as well as rampant disinformation, can make it hard to
separate fact from fiction.
Here, we’ve done our best to present you
with not only the most accurate scientific information, but also an explanation
of how we know it.
How do we know climate change is really happening?
Climate change is often cast as a prediction made by complicated computer
models. But the scientific basis for climate change is much broader, and models
are actually only one part of it (and, for what it’s worth, they’re surprisingly accurate).
For
more than a century, scientists have understood the basic physics behind why greenhouse gases like
carbon dioxide cause warming. These gases make up just a small fraction of the
atmosphere but exert outsized control on Earth’s climate by trapping some of the
planet’s heat before it escapes into space. This greenhouse effect is important:
It’s why a planet so far from the sun has liquid water and life!
However, during the Industrial Revolution, people started burning coal and other
fossil fuels to power factories, smelters and steam engines, which added more
greenhouse gases to the atmosphere. Ever since, human activities have been
heating the planet.
We know this is true thanks to an overwhelming body of evidence that begins with
temperature measurements taken at weather stations and on ships starting in the
mid-1800s. Later, scientists began tracking surface temperatures with satellites
and looking for clues about climate change in geologic records. Together, these
data all tell the same story: Earth is getting hotter.
Average global temperatures have increased by 2.2 degrees Fahrenheit, or 1.2
degrees Celsius, since 1880, with the greatest changes happening in the late
20th century. Land areas have warmed more than the sea surface and the Arctic
has warmed the most — by more than 4 degrees Fahrenheit just since the 1960s.
Temperature extremes have also shifted. In the United States, daily record highs
now outnumber record lows two-to-one.
Source: NASA Goddard Institute for Space Studies. By Veronica
Penney
This warming is unprecedented in recent geologic history. A famous illustration,
first published in 1998
and often called the hockey-stick graph, shows how temperatures remained fairly
flat for centuries (the shaft of the stick) before turning sharply upward (the
blade). It’s based on data from tree rings, ice cores and other natural
indicators. And the
basic picture, which has withstood decades of scrutiny from climate scientists and
contrarians alike, shows that Earth is hotter today than it’s been in at least
1,000 years, and probably much longer.
In fact, surface temperatures actually mask the true scale of climate change,
because the
ocean has absorbed 90 percent of the heat trapped by greenhouse gases. Measurements collected over the last six decades by oceanographic expeditions
and networks of floating instruments show that every layer of the ocean is
warming up. According to
one study, the ocean has absorbed as much heat between 1997 and 2015 as it did in the
previous 130 years.
We also know that climate change is happening because we see the effects
everywhere. Ice sheets and glaciers are shrinking while sea levels are rising.
Arctic sea ice is disappearing. In the spring, snow melts sooner and plants
flower earlier. Animals are moving to higher elevations and latitudes to find
cooler conditions. And droughts, floods and wildfires have all gotten more
extreme. Models predicted many of these changes, but observations show they are
now coming to pass.
How much agreement is there among scientists about climate change?
There’s no denying that scientists love a good, old-fashioned argument. But when
it comes to climate change, there is virtually no debate: Numerous studies have found that more than 90 percent of scientists who study Earth’s
climate agree that the planet is warming and that humans are the primary cause.
Most major scientific bodies, from NASA to the World Meteorological Organization, endorse this view. That’s an astounding level of consensus given the
contrarian, competitive nature of the scientific enterprise, where questions
like what killed the dinosaurs remain bitterly contested.
Scientific agreement about climate change started to emerge in the late 1980s,
when the influence of human-caused warming began to rise above natural climate
variability. By 1991, two-thirds of earth and atmospheric scientists surveyed
for an early consensus study said that they accepted the idea of anthropogenic
global warming. And by 1995, the Intergovernmental Panel on Climate Change, a
famously conservative body that periodically takes stock of the state of
scientific knowledge,
concluded that
“the balance of evidence suggests that there is a discernible human influence on
global climate.” Currently, more than
97 percent of publishing climate scientists
agree on the existence and cause of climate change (as does nearly
60 percent of the general population
of the United States).
So where did we get the idea that there’s
still debate about climate change? A lot of it came from
coordinated messaging campaigns
by companies and politicians that opposed climate action. Many pushed the
narrative that scientists still hadn’t made up their minds about climate change,
even though that was misleading. Frank Luntz, a Republican consultant, explained
the rationale in an infamous
2002 memo
to conservative lawmakers: “Should the public come to believe that the
scientific issues are settled, their views about global warming will change
accordingly,” he wrote. Questioning consensus remains a common talking point
today, and the 97 percent figure has become something of a
lightning rod.
To bolster the falsehood of lingering scientific doubt, some people have pointed
to things like the Global Warming Petition Project, which urged the United
States government to reject the Kyoto Protocol of 1997, an early international
climate agreement. The petition proclaimed that climate change wasn’t happening,
and even if it were, it wouldn’t be bad for humanity. Since 1998, more than
30,000 people with science degrees have signed it. However, nearly 90 percent of
them studied something other than Earth, atmospheric or environmental science,
and the signatories included just 39 climatologists. Most were engineers,
doctors, and others whose training had little to do with the physics of the
climate system.
A few well-known researchers remain opposed to the scientific consensus. Some,
like Willie Soon, a researcher affiliated with the Harvard-Smithsonian Center
for Astrophysics, have
ties to the fossil fuel industry. Others do not, but their assertions have
not held up
under the weight of evidence. At least one prominent skeptic, the physicist
Richard Muller, changed his mind after reassessing historical temperature data
as part of the
Berkeley Earth
project. His team’s findings essentially confirmed the results he had set out to
investigate, and he came away firmly convinced that human activities were
warming the planet. “Call me a converted skeptic,” he wrote
in an Op-Ed
for the Times in 2012.
Mr. Luntz, the Republican pollster, has also
reversed his position
on climate change and now advises politicians on how to motivate climate
action.
A final note on uncertainty: Denialists often use it as evidence that climate
science isn’t settled. However, in science, uncertainty doesn’t imply a lack of
knowledge. Rather, it’s a measure of how well something is known. In the case of
climate change, scientists have found a range of possible future changes in
temperature, precipitation and other important variables — which will depend
largely on how quickly we reduce emissions. But uncertainty does not undermine
their confidence that climate change is real and that people are causing it.
Do we really only have 150 years of climate data?
How is that enough to tell us about centuries of change?
Earth’s climate is inherently variable. Some years are hot and others are
cold, some decades bring more hurricanes than others, some ancient droughts
spanned the better part of centuries. Glacial cycles operate over many
millenniums. So how can scientists look at data collected over a relatively
short period of time and conclude that humans are warming the planet? The
answer is that the instrumental temperature data that we have tells us a lot,
but it’s not all we have to go on.
Historical records stretch back
to the 1880s (and often before), when people began to regularly measure
temperatures at weather stations and on ships as they traversed the world’s
oceans. These data show a clear warming trend during the 20th century.
Source: NASA Goddard Institute for Space Studies. By Veronica
Penney
Some have questioned whether these records could be skewed, for instance, by
the fact that a disproportionate number of weather stations are near cities,
which tend to be hotter than surrounding areas as a result of the so-called
urban heat island effect. However, researchers regularly
correct for these potential biases
when reconstructing global temperatures. In addition, warming is corroborated
by independent data like satellite observations, which cover the whole planet,
and
other ways
of measuring temperature changes.
Much has also been made of the small dips and pauses that punctuate the rising
temperature trend of the last 150 years. But these are just the result of
natural climate variability or other human activities that temporarily
counteract greenhouse warming. For instance, in the mid-1900s, internal
climate dynamics and light-blocking pollution from coal-fired power plants
halted global warming for a few decades. (Eventually, rising greenhouse gases
and pollution-control laws caused the planet to start heating up again.)
Likewise, the so-called warming hiatus of the 2000s was partly a result of
natural climate variability that allowed
more heat to enter the ocean
rather than warm the atmosphere. The years since
have been the hottest on record.
Still, could the entire 20th century just be one big natural climate wiggle?
To address that question, we can look at other kinds of data that give a
longer perspective. Researchers have used geologic records like tree rings,
ice cores, corals and sediments that preserve information about prehistoric
climates to extend the climate record. The resulting picture of global
temperature change is basically flat for centuries, then turns sharply upward
over the last 150 years. It has been a target of climate denialists for
decades. However, study after study has confirmed
the results, which show that the planet hasn’t been this hot in at least 1,000 years,
and probably longer.
How do we know climate change is caused by humans?
Scientists have studied past climate changes to understand the factors
that can cause the planet to warm or cool. The big ones are changes in solar
energy, ocean circulation, volcanic activity and the amount of greenhouse
gases in the atmosphere. And they have each played a role at times.
For example, 300 years ago, a combination of reduced solar output and
increased volcanic activity cooled parts of the planet enough that Londoners
regularly
ice skated on the Thames. About 12,000 years ago, major changes in Atlantic circulation plunged the
Northern Hemisphere into a frigid state. And 56 million years ago, a giant
burst of greenhouse gases, from volcanic activity or vast deposits of methane
(or both), abruptly
warmed the planet
by at least 9 degrees Fahrenheit, scrambling the climate, choking the oceans
and triggering mass extinctions.
In trying to determine the cause of current climate changes,
scientists have looked at all of these factors. The first three have varied a bit over the last few centuries and they have
quite likely had
modest effects on climate, particularly before 1950. But they cannot account for the planet’s rapidly
rising temperature, especially in the second half of the 20th century, when
solar output
actually declined
and volcanic eruptions exerted a cooling effect.
That warming
is best explained by rising greenhouse gas concentrations. Greenhouse gases have a powerful effect on climate (see the next question
for why). And since the Industrial Revolution, humans have been adding more of
them to the atmosphere, primarily by extracting and burning fossil fuels like
coal, oil and gas, which releases carbon dioxide.
Bubbles of ancient air
trapped in ice
show that, before about 1750, the concentration of carbon dioxide in the
atmosphere was roughly 280 parts per million. It began to rise slowly and
crossed the 300 p.p.m. threshold around 1900. CO2 levels then accelerated as
cars and electricity became big parts of modern life, recently topping
420 p.p.m. The concentration of methane, the second most important greenhouse gas, has
more than doubled. We’re now emitting carbon
much faster than it was released 56 million years ago.
Note: Total carbon dioxide emissions are from fossil fuels and
cement production and do not include land use and forestry-related
emissions. Russia data includes the Soviet Union through 1991, but
only the Russian Federation afterward.
Source: Research Institute for Environment, Energy and
Economics at Appalachian State University. By Veronica Penney
These rapid increases in greenhouse gases have caused the climate to warm
abruptly. In fact, climate models suggest that greenhouse warming can explain
virtually all of the temperature change since 1950. According to the
most recent report
by the Intergovernmental Panel on Climate Change, which assesses published
scientific literature, natural drivers and internal climate variability can
only explain a small fraction of late-20th century warming.
Another study put it this way: The odds of current warming occurring without
anthropogenic greenhouse gas emissions are less than
1 in 100,000.
But greenhouse gases aren’t the only climate-altering compounds people put
into the air. Burning fossil fuels also produces particulate pollution that
reflects sunlight
and cools the planet. Scientists estimate that this pollution has masked
up to half
of the greenhouse warming we would have otherwise experienced.
Since greenhouse gases occur naturally,
how do we know they’re causing Earth’s temperature to rise?
Greenhouse gases like water vapor and carbon dioxide serve an important role
in the climate. Without them, Earth would be far too cold to maintain liquid
water and humans would not exist!
Here’s how it works: the planet’s temperature is basically a function of the
energy the Earth absorbs from the sun (which heats it up) and the energy Earth
emits to space as infrared radiation (which cools it down). Because of their
molecular structure, greenhouse gases temporarily absorb some of that outgoing
infrared radiation and then re-emit it in all directions, sending some of that
energy back toward the surface and
heating the planet. Scientists
have understood this process since the 1850s.
Greenhouse gas concentrations have varied naturally in the past. Over millions
of years, atmospheric CO2 levels have changed depending on how much of the gas
volcanoes belched into the air and how much got removed through geologic
processes. On time scales of hundreds to thousands of years, concentrations
have changed as carbon has cycled between the ocean, soil and air.
Today, however, we are the ones causing CO2 levels to increase at
an unprecedented pace
by taking ancient carbon from geologic deposits of fossil fuels and putting it
into the atmosphere when we burn them. Since 1750, carbon dioxide
concentrations have increased by almost 50 percent. Methane and nitrous oxide,
other important anthropogenic greenhouse gases that are released mainly by
agricultural activities, have also spiked over the last 250 years.
We know based on the physics described above that this should cause the
climate to warm. We also see certain telltale “fingerprints” of greenhouse
warming. For example,
nights are warming even faster than days
because greenhouse gases don’t go away when the sun sets. And upper layers of
the atmosphere have actually cooled, because more energy is being trapped by
greenhouse gases in the lower atmosphere.
We also know that we are the cause of rising greenhouse gas concentrations —
and not just because we can measure the CO2 coming out of tailpipes and
smokestacks. We can see it in the chemical signature of the carbon in CO2.
Carbon comes in three different masses: 12, 13 and 14. Things made of organic
matter (including fossil fuels) tend to have relatively less carbon-13.
Volcanoes tend to produce CO2 with relatively more carbon-13. And over the
last century, the carbon in atmospheric CO2 has gotten lighter, pointing to an
organic source.
We can tell it’s old organic matter by looking for carbon-14, which is
radioactive and decays over time. Fossil fuels are too ancient to have any
carbon-14 left in them, so if they were behind rising CO2 levels, you would
expect the amount of carbon-14 in the atmosphere to drop, which is
exactly what the data show.
It’s important to note that water vapor is the most abundant greenhouse gas in
the atmosphere. However, it does not cause warming; instead
it responds to it. That’s because warmer air holds more moisture, which creates a snowball
effect in which human-caused warming allows the atmosphere to hold more water
vapor and further amplifies climate change. This so-called feedback cycle has
doubled the warming caused by anthropogenic greenhouse gas emissions.
Why should we be worried that the
planet has warmed 2°F since the 1800s?
A common source of confusion when it comes to climate change is the difference
between weather and climate. Weather is the constantly changing set of
meteorological conditions that we experience when we step outside, whereas
climate is the long-term average of those conditions, usually calculated over
a 30-year period. Or, as some say: Weather is your mood and climate is your
personality.
So while 2 degrees Fahrenheit doesn’t represent a big change in the weather,
it’s a huge change in climate. As we’ve already seen, it’s enough to melt ice
and raise sea levels, to shift rainfall patterns around the world and to
reorganize ecosystems, sending
animals scurrying
toward cooler habitats and
killing trees
by the millions.
It’s also important to remember that two degrees represents the global
average, and many parts of the world have already warmed by more than that.
For example, land areas have warmed about twice as much as the sea surface.
And the Arctic has warmed by about 5 degrees. That’s because the loss of snow
and ice at high latitudes allows the ground to absorb more energy, causing
additional heating
on top of greenhouse warming.
Relatively small long-term changes in climate averages also shift extremes in
significant ways. For instance, heat waves have always happened, but they have
shattered records in recent years. In June of 2020, a town in Siberia
registered temperatures of
100 degrees. And in Australia, meteorologists have
added a new color
to their weather maps to show areas where temperatures exceed 125 degrees.
Rising sea levels have also
increased the risk of flooding
because of storm surges and high tides. These are the foreshocks of climate
change.
And we are in for more changes in the future — up to 9 degrees Fahrenheit of
average global warming by the end of the century, in the
worst-case scenario. For reference, the difference in global average temperatures between now
and the peak of the last ice age, when ice sheets covered large parts of North
America and Europe, is about
11 degrees
Fahrenheit.
Under the Paris Climate Agreement, which President Biden recently rejoined,
countries have agreed to try to limit total warming to between 1.5 and 2
degrees Celsius, or 2.7 and 3.6 degrees Fahrenheit, since preindustrial times.
And even this narrow range has
huge implications. According to scientific studies, the difference between 2.7 and 3.6 degrees
Fahrenheit will very likely mean the difference between coral reefs hanging on
or going extinct, and between summer sea ice persisting in the Arctic or
disappearing completely. It will also determine how many millions of people
suffer from water scarcity and crop failures, and how many are driven from
their homes by rising seas. In other words, one degree Fahrenheit makes a
world of difference.
Is climate change a part of the planet’s
natural warming and cooling cycles?
Earth’s climate has always changed. Hundreds of millions of years ago, the
entire
planet froze. Fifty million years ago,
alligators lived in what we now call the Arctic. And for the last 2.6 million years, the planet has cycled between ice ages
when the planet was up to 11 degrees cooler and ice sheets covered much of
North America and Europe, and milder interglacial periods like the one we’re
in now.
Climate denialists often point to these natural climate changes as a way to
cast doubt on the idea that humans are causing climate to change today.
However, that argument rests on a logical fallacy. It’s like “seeing a
murdered body and concluding that people have died of natural causes in the
past, so the murder victim must also have died of natural causes,” a team of
social scientists wrote in
The Debunking Handbook, which explains the misinformation strategies behind many climate myths.
Indeed, we know that different mechanisms caused the climate to change in the
past. Glacial cycles, for example, were triggered by
periodic variations in Earth’s orbit, which take place over tens of thousands of years and change how solar
energy gets distributed around the globe and across the seasons.
These orbital variations don’t affect the planet’s temperature much on their
own. But they set off a cascade of other changes in the climate system; for
instance, growing or melting vast Northern Hemisphere ice sheets and altering
ocean circulation. These changes, in turn, affect climate by altering the
amount of snow and ice, which reflect sunlight, and by changing greenhouse gas
concentrations. This is actually part of how we know that greenhouse gases
have the ability to significantly affect Earth’s temperature.
For at least the last
800,000 years, atmospheric CO2 concentrations oscillated between about 180 parts per
million during ice ages and about 280 p.p.m. during warmer periods, as carbon
moved between oceans, forests, soils and the atmosphere. These changes
occurred
in lock step
with global temperatures, and are a major reason the entire planet warmed and
cooled during glacial cycles, not just the frozen poles.
Today, however, CO2 levels have soared to 420 p.p.m. — the highest they’ve
been in at least
three million years. The concentration of CO2 is also increasing about
100 times faster
than it did at the end of the last ice age. This suggests something else is
going on, and we know what it is: Since the Industrial Revolution, humans have
been burning fossil fuels and releasing greenhouse gases that are heating the
planet now (see
Question 5
for more details on how we know this, and
Questions 4
and
8
for how we know that other natural forces aren’t to blame).
Over the next century or two, societies and ecosystems will experience the
consequences of this climate change. But our emissions will have even more
lasting geologic impacts: According to some studies, greenhouse gas levels may
have already warmed the planet enough to
delay the onset of the next glacial cycle
for at least an additional 50,000 years.
How do we know global warming
is not because of the sun or volcanoes?
The sun is the ultimate source of energy in Earth’s climate system, so it’s a
natural candidate for causing climate change. And solar activity has certainly
changed over time. We know from satellite measurements and other astronomical
observations that the sun’s output changes on 11-year cycles. Geologic records
and sunspot numbers, which astronomers have tracked for centuries, also show
long-term variations in the sun’s activity, including some exceptionally quiet
periods in the late 1600s and early 1800s.
We know that, from 1900 until the 1950s, solar irradiance increased. And
studies suggest that this had a modest effect on early 20th century climate,
explaining up to 10 percent
of the warming that’s occurred since the late 1800s. However, in the second
half of the century, when the most warming occurred,
solar activity actually declined. This disparity is one of the main reasons we know that the sun is not the
driving force behind climate change.
Another reason we know that solar activity hasn’t caused recent warming is
that, if it had, all the layers of the atmosphere should be heating up.
Instead, data show that the upper atmosphere has actually cooled in recent
decades — a hallmark of
greenhouse warming.
So how about volcanoes? Eruptions cool the planet by injecting
ash and aerosol particles
into the atmosphere that reflect sunlight. We’ve
observed this effect
in the years following large eruptions. There are also some notable historical
examples, like when Iceland’s Laki volcano erupted in 1783, causing widespread
crop failures in Europe and beyond, and the “year without a summer,” which followed the 1815 eruption of Mount Tambora in Indonesia.
Since volcanoes mainly act as climate coolers, they can’t really explain
recent warming. However, scientists say that they may also have
contributed slightly
to rising temperatures in the early 20th century. That’s because there were
several large eruptions in the late 1800s that cooled the planet, followed by
a few decades with no major volcanic events when warming caught up. During the
second half of the 20th century, though, several big eruptions occurred as the
planet was heating up fast. If anything, they temporarily masked some amount
of human-caused warming.
The second way volcanoes can impact climate is by emitting carbon dioxide.
This is important on time scales of millions of years — it’s what keeps the
planet habitable (see
Question 5
for more on the greenhouse effect). But by comparison to modern anthropogenic
emissions, even big eruptions like Krakatoa and Mount St. Helens are just a
drop in the bucket. After all, they last only a few hours or days, while we
burn fossil fuels 24-7. Studies suggest that, today, volcanoes account for
1 to 2 percent
of total CO2 emissions.
How can winters and certain places
be getting colder if the planet is warming?
When a big snowstorm hits the United States, climate denialists can try
to cite it as proof that climate change isn’t happening. In 2015, Senator
James Inhofe, an Oklahoma Republican, famously
lobbed a snowball
in the Senate as he denounced climate science. But these events don’t actually
disprove climate change.
While there have been some memorable storms in recent years, winters are
actually warming across the world. In the United States, average temperatures
in December, January and February have increased by about 2.5 degrees this
century.
On the flip side, record cold days are becoming less common than record warm
days. In the United States, record highs now outnumber record lows
two-to-one. And ever-smaller areas of the country experience
extremely cold winter temperatures. (The same trends are happening globally.)
So what’s with the blizzards? Weather always varies, so it’s no surprise that
we still have severe winter storms even as average temperatures rise. However,
some studies suggest that climate change may be to blame. One possibility is
that rapid Arctic warming has affected atmospheric circulation, including the
fast-flowing, high-altitude air that usually swirls over the North Pole
(a.k.a. the
Polar Vortex). Some studies suggest that these changes are bringing more frigid
temperatures to lower latitudes and causing
weather systems to stall, allowing storms to produce more snowfall. This may explain what we’ve
experienced
in the U.S.
over the past few decades, as well as a wintertime
cooling trend in Siberia, although exactly how the Arctic affects global weather remains a topic of
ongoing scientific debate.
Climate change may also explain the apparent paradox behind some of the other
places on Earth that haven’t warmed much. For instance, a splotch of water in
the North Atlantic has cooled in recent years, and scientists say they suspect
that may be because
ocean circulation is slowing
as a result of freshwater streaming off
a melting Greenland. If this circulation grinds almost to a halt, as it’s done in the geologic
past, it would alter weather patterns around the world.
Not all cold weather stems from some counterintuitive consequence of climate
change. But it’s a good reminder that Earth’s climate system is complex and
chaotic, so the effects of human-caused changes will play out differently in
different places. That’s why “global warming” is a bit of an
oversimplification. Instead, some scientists have suggested that the
phenomenon of human-caused climate change would more aptly be called “global weirding.”
Wildfires and bad weather have always happened.
How do we know there’s a connection to climate change?
Extreme weather and natural disasters are part of life on Earth — just ask the
dinosaurs. But there is good evidence that climate change has increased the
frequency and severity of certain phenomena like heat waves, droughts and
floods. Recent research has also allowed scientists to identify the influence
of climate change on specific events.
Let’s start with
heat waves. Studies show that stretches of abnormally high temperatures now happen
about five
times more often
than they would without climate change, and they last longer, too. Climate
models project that, by the 2040s, heat waves will be about 12 times more
frequent. And that’s concerning since extreme heat often causes increased
hospitalizations and deaths, particularly among older people and those with
underlying health conditions. In the summer of 2003, for example, a heat wave
caused an estimated
70,000 excess deaths
across Europe. (Human-caused warming
amplified the death toll.)
Climate change has also
exacerbated droughts, primarily by increasing evaporation. Droughts occur naturally because of
random climate variability and factors like whether El Niño or La Niña
conditions prevail in the tropical Pacific. But some researchers have found
evidence that greenhouse warming has been affecting droughts since even
before the Dust Bowl. And it continues to do so today.
According to one analysis, the drought that afflicted the American Southwest from 2000 to 2018 was
almost 50 percent more severe because of climate change. It was the worst
drought the region had experienced in more than 1,000 years.
Rising temperatures have also increased the intensity of heavy
precipitation events and the flooding that often follows. For example, studies
have found that, because warmer air holds more moisture, Hurricane Harvey,
which struck Houston in 2017, dropped between 15 and 40 percent
more rainfall
than it would have without climate change.
It’s still unclear whether climate change is changing the overall frequency of
hurricanes, but it is
making them stronger. And warming appears to favor certain kinds of weather patterns, like the
“Midwest Water Hose” events that caused devastating flooding across the
Midwest in 2019.
It’s important to remember that in most natural disasters, there are multiple
factors at play. For instance, the 2019 Midwest floods occurred after a recent
cold snap had frozen the ground solid, preventing the soil from absorbing
rainwater and increasing runoff into the Missouri and Mississippi Rivers.
These waterways have also been reshaped by
levees
and other forms of river engineering, some of which failed in the floods.
Wildfires are another phenomenon with multiple causes. In many places, fire
risk has increased because humans have aggressively fought natural fires and
prevented Indigenous peoples from carrying out traditional burning practices.
This has allowed fuel to accumulate that
makes current fires worse.
However, climate change still plays a major role by heating and drying
forests, turning them into tinderboxes. Studies show that warming is the
driving factor behind the recent increases in wildfires;
one analysis
found that climate change is responsible for doubling the area burned across
the American West between 1984 and 2015. And researchers say that warming will
only make fires bigger and more dangerous in the future.
How bad are the effects of climate change going to be?
It depends on how aggressively we act to address climate change. If we
continue with business as usual, by the end of the century, it will be
too hot to go outside
during heat waves in the Middle East and
South Asia.
Droughts will grip
Central America, the Mediterranean and southern Africa. And many island
nations and low-lying areas, from Texas to Bangladesh, will be overtaken by
rising seas. Conversely, climate change could bring welcome warming and
extended growing seasons to the
upper Midwest, Canada, the Nordic countries and Russia. Farther north, however, the loss
of snow, ice and permafrost will upend the traditions of Indigenous peoples
and threaten infrastructure.
It’s complicated, but the underlying message is simple: unchecked climate
change will likely
exacerbate existing inequalities. At a national level, poorer countries will be hit hardest, even though they
have historically emitted
only a fraction of the greenhouse gases
that cause warming. That’s because many less developed countries tend to be in
tropical regions where additional warming will make the climate increasingly
intolerable for humans and crops. These nations also often have greater
vulnerabilities, like large coastal populations and people living in
improvised housing that is easily damaged in storms. And they have fewer
resources to adapt, which will require expensive measures like redesigning
cities, engineering coastlines and changing how people grow food.
Already, between 1961 and 2000, climate change appears to have harmed the
economies of the poorest countries while boosting the fortunes of the
wealthiest nations that have done the most to cause the problem, making the
global wealth gap
25 percent bigger than it would otherwise have been. Similarly, the
Global Climate Risk Index
found that lower income countries — like Myanmar, Haiti and Nepal — rank high
on the list of nations most affected by extreme weather between 1999 and 2018.
Climate change has also contributed to increased human migration, which is
expected to
increase significantly.
Even within wealthy countries, the poor and marginalized will suffer the most.
People with more resources have greater buffers, like air-conditioners to keep
their houses cool during dangerous heat waves, and the means to pay the
resulting energy bills. They also have an easier time evacuating their homes
before disasters, and recovering afterward. Lower income people have fewer of
these advantages, and they are also more likely to live in
hotter neighborhoods
and work outdoors, where they face the brunt of climate change.
These inequalities will play out on an individual, community, and regional
level. A 2017
analysis of the U.S.
found that, under business as usual, the poorest one-third of counties, which
are concentrated in the South, will experience damages totaling as much as 20
percent of gross domestic product, while others, mostly in the northern part
of the country, will see modest economic gains. Solomon Hsiang, an economist
at University of California, Berkeley, and the lead author of the study, has
said that climate change “may result in the largest transfer of wealth from
the poor to the rich in the country’s history.”
Even the climate “winners” will not be immune from all climate impacts,
though. Desirable locations will face an influx of migrants. And as the
coronavirus pandemic has demonstrated, disasters in one place quickly ripple
across our globalized economy. For instance, scientists expect climate change
to increase the odds of multiple crop failures occurring at the same time in
different places, throwing the world
into a food crisis.
On top of that, warmer weather is aiding the spread of infectious diseases and
the vectors that transmit them, like
ticks and mosquitoes. Research has also identified troubling correlations between rising
temperatures and increased
interpersonal violence, and climate change is widely recognized as a “threat multiplier” that
increases the
odds of larger conflicts
within and between countries. In other words, climate change will bring many
changes that no amount of money can stop. What could help is taking action to
limit warming.
What will it cost to do something about climate change,
versus doing nothing?
One of the most common arguments against taking aggressive action to combat
climate change is that doing so will kill jobs and cripple the economy. But this implies that there’s an alternative
in which we pay nothing for climate change. And unfortunately, there isn’t. In
reality, not tacklingclimate
change will cost a lot, and cause enormous human suffering and ecological
damage, while transitioning to a greener economy would benefit many people and
ecosystems around the world.
Let’s start with how much it will cost to address climate change. To
keep warming well below 2 degrees Celsius, the goal of the Paris Climate
Agreement, society will have to reach net zero greenhouse gas emissions by the
middle of this century. That will require
significant investments
in things like renewable energy, electric cars and charging infrastructure,
not to mention efforts to adapt to hotter temperatures, rising sea-levels and
other unavoidable effects of current climate changes. And we’ll have to make
changes fast.
Estimates of the cost vary widely. One
recent study
found that keeping warming to 2 degrees Celsius would require a total
investment of between $4 trillion and $60 trillion, with a median estimate of
$16 trillion, while keeping warming to 1.5 degrees Celsius could cost between
$10 trillion and $100 trillion, with a median estimate of $30 trillion. (For
reference, the entire world economy was about $88 trillion in 2019.) Other
studies have found that reaching net zero will require annual investments
ranging from less than
1.5 percent
of global gross domestic product to as much as
4 percent. That’s a lot, but within the range of
historical energy investments
in countries like the U.S.
Now, let’s consider the costs of unchecked climate change, which will fall
hardest on the most vulnerable. These include damage to property and
infrastructure from sea-level rise and extreme weather, death and sickness
linked to natural disasters, pollution and infectious disease, reduced
agricultural yields and lost labor productivity because of rising
temperatures, decreased water availability and increased energy costs, and
species extinction and habitat destruction. Dr. Hsiang, the U.C. Berkeley
economist, describes it as “death by a thousand cuts.”
As a result, climate damages are hard to quantify.
Moody’s Analytics
estimates that even 2 degrees Celsius of warming will cost the world $69
trillion by 2100, and economists expect the toll to keep rising with the
temperature. In
a recent survey, economists estimated the cost would equal 5 percent of global G.D.P. at 3
degrees Celsius of warming (our trajectory under current policies) and 10
percent for 5 degrees Celsius. Other research indicates that, if current
warming trends continue, global G.D.P. per capita will decrease between
7 percent and
23 percent
by the end of the century — an economic blow equivalent to
multiple coronavirus pandemics
every year. And some fear these are
vast underestimates.
Already, studies suggest that climate change has
slashed incomes
in the poorest countries by as much as 30 percent and reduced
global agricultural productivity
by 21 percent since 1961. Extreme weather events have also racked up a large
bill. In 2020, in the United States alone, climate-related disasters like
hurricanes, droughts, and wildfires caused
nearly $100 billion
in damages to businesses, property and infrastructure, compared to an average
of $18 billion per year in the 1980s.
Given the steep price of inaction, many economists say that addressing climate
change is
a better deal. It’s like that old saying: an ounce of prevention is worth a pound of cure.
In this case, limiting warming will greatly reduce future damage and
inequality caused by climate change. It will also produce so-called
co-benefits, like
saving one million lives every year
by reducing air pollution, and millions more from eating healthier,
climate-friendly diets. Some studies even find that meeting the Paris
Agreement goals could
create jobs
and
increase global G.D.P. And, of course, reining in climate change will spare many species and
ecosystems upon which humans depend — and which many people believe to have
their own innate value.
The challenge is that we need to reduce emissions now to avoid damages later,
which requires big investments over the next few decades. And the longer we
delay, the more we will pay to meet the Paris goals. One
recent analysis
found that reaching net-zero by 2050 would cost the U.S. almost twice as much
if we waited until 2030 instead of acting now. But even if we miss the Paris
target, the economics still make a strong case for climate action, because
every additional degree of warming will
cost us more
— in dollars, and in lives.
