Time to ‘get scared’: World’s scientists say
disastrous climate change is here
A new report from the UN’s Intergovernmental Panel on
Climate Change lays out the consequences of global warming.
BY ZACK
COLMAN AND KARL MATHIESEN
August 9,
2021 10:13 am
The
long-feared era of disastrous climate change has arrived.
For the
first time, the planet's top scientists said in a monumental report released on
Monday they have definitively linked greenhouse gas emissions to the type of
disasters driven by a warmer climate that have touched every corner of the
globe this year: Extreme rainfall in Germany and China, brutal droughts in the
western U.S., a record cyclone in the Philippines and compound events like the
wildfires and heatwaves from the Pacific Northwest to Siberia to Greece and
Turkey.
This is the
world as it exists today, with an atmosphere 1.1 degrees Celsius hotter than it
was in the pre-industrial era. Even grimmer: There is no scenario in the new
analysis by the United Nations' Intergovernmental Panel on Climate Change in
which the world avoids breaching the threshold of 1.5 degrees Celsius that the
U.S., EU and several other countries have set as a target. Even the weaker
2-degree target that major polluters China and India have set as guideposts
will be eclipsed unless greenhouse gas emissions peak by mid-century.
Those
numbers have real-world consequences for billions of people, with cascading
impacts on agriculture, human migrations and even wars, numerous studies in
recent decades have warned.
An extreme
heatwave that once would have occurred only twice a century would instead hit
about every six years at the 1.5-degree threshold, the IPCC says. With 2
degrees of warming, you can expect them every four years.
"Human-induced
climate change is already affecting many weather and climate extremes in every
region across the globe," the IPCC authors concluded in the summary to the
report that brought 234 authors across 66 countries together to analyze more
than 14,000 studies. "Evidence of observed changes in extremes such as
heatwaves, heavy precipitation, droughts, and tropical cyclones, and, in
particular, their attribution to human influence, has strengthened since"
the previous report released in 2013.
The latest
climate report, which form the first of three parts of the sixth assessment
issued by the scientific body since 1990, comes as world leaders grapple with
policies to wring carbon dioxide and methane emissions from their economies —
and as the U.S. Senate moves forward on an infrastructure plan with $550
billion in new spending that takes only modest steps toward addressing climate
change.
Nations'
goals for reducing fossil fuels have grown far more ambitious in recent years —
particularly in the European Union since the adoption of the 2015 Paris climate
agreement, and more recently in the United States and China — but governments
now face the need to cut their climate-altering pollution even as they face the
type of weather-related catastrophes that once seemed off in the distant
future.
And the
message from those scientists about those disasters is stark: Get used to them.
The research shows nations must start playing defense to withstand the weather
disasters that will only grow worse unless emissions from fossil fuels are
eliminated.
“I think
people are more and more starting to get scared,” said Jim Kossin, senior
scientist with climate risk firm The Climate Service who was among the IPCC
authors for the chapter on extremes. “I think that'll help to change people's
attitudes. And hopefully that'll affect the way they vote.”
What’s
become virtually certain to scientists is that heatwaves are hotter,
longer-lasting and more frequent. Oceans are overheating, locking in further
warming. Glaciers and ice shelves will continue to melt for decades —
regardless of new action by governments — pushing tides higher to flood cities
and propel storm surges further inland.
Extreme,
rare events are happening in such quick succession that scientists barely have
enough time to recalibrate their models. Those calamities are buckling societal
institutions and physical infrastructure. And as scientists’ ability to project
those events improves, it’s making them even more nervous.
“They're
really the first kind of signs of this new climate condition,” Alexander Ruane,
a research physical scientist at the NASA Goddard Institute for Space Studies
and a report author, said in an interview. “And I wish I could say that there
is a new normal that is a decade away, but of course, it will be continuing to
change until some kind of climate policy disrupts the emissions.”
While
critics have for decades complained that the climate warnings lacked details
about how to prepare for catastrophic change, the new report highlights the
increased precision, particularly in scientists’ understanding of the behavior
of clouds, that allows them to narrow considerably the range of possible
futures, said Piers Forster, a climate physics professor at the University of
Leeds. That means gambling on future warming being lower than expected “can be
ruled out."
But the
good news, Forster said, is that researchers have “much stronger confidence”
that rapidly lowering greenhouse gas emissions would mean “temperature rise can
still be limited to 1.5C.”
The
scientists are also slightly more optimistic about whether the emissions that
have been accumulating in the atmosphere since the Industrial Revolution have
already triggered a runaway chain of events that would release even more carbon
or methane, such as thawing permafrost or giant fires. That offers hope that
countries can still avert such a scenario, although Forster said there were
still dynamics that weren’t fully understood. “There are still risks,” he said.
Breaking the bad news
In the
run-up to the IPCC report release, the scientists who combed through the
research and the politicians who approved the crucial recommendations for
policymakers clashed over how best to present the urgent need for action,
according to two people familiar with the discussions, who sought anonymity to
describe private discussions.
To
scientists, it was clear: The world will surpass 1.5 degrees Celsius under the
most likely pathways it studied, although the most aggressive climate-fighting
scenario eventually slotted the increase at 1.4 degrees — if carbon-storing
forests were dramatically increased and technology that can draw carbon from
the air was developed. But politicians argued for a more optimistic take: How
sharply must emissions be cut before maxing out the global carbon budget, a
term that conveys how much headroom for emissions the planet has before
crossing 1.5 degrees Celsius.
Political
leaders, in essence, wanted to inspire hope that concerted action can avert the
looming catastrophes, the people familiar with deliberations said.
Additions
to the report not found in previous assessments were included in response to
political demands as climate change-driven extreme weather events battered
towns, torched crops and upended livelihoods. That included new research in the
analyses using cutting edge scientific methods to compare the intensity of
specific weather events with and without human-caused emissions, as well
modeling the predictions on regional climate effects.
The
additions reflect both the advancement of the science and the political urgency
of the moment, authors said.
“Societally,
who cares about a very deep explanation of a process that produces this other
phenomenon?” said Claudia Tebaldi, an earth scientist at the Pacific Northwest
National Laboratory and an IPCC author for the regional effects chapter. “[We]
look at what the quantities that those people see connected to the impact. What
is important for human health in a heat wave? What is the minimum temperature,
the maximum temperature? is it three days, is it five days?"
Advanced
computing improvements have enabled those types of precision forecasts, said
Paul Durack, a research scientist at Lawrence Livermore National Laboratory in
California and an IPCC author on the science methods chapter. Scientists can
now run powerful simulations accounting for numerous variables that are getting
ever-more complex, such as modeling what happens with greenhouse gas emissions
from land-use change like deforestation or the thawing of methane-holding
Arctic permafrost.
Some of those
advances clarified that the world had already warmed 0.1 degree Celsius more
than previously thought, the report said.
Scientists
have also made “substantial progress” in offering far more detailed
projections, examining climate impacts on a geographical grid down to blocks of
4 kilometers, compared to 100-kilometer grid blocks previously, said William
Gutowski, an atmospheric scientist at Iowa State University who helped write
the regional effects chapter. That allowed the IPCC report to break down climate
impacts and trends into regions for the first time, enabling, for example, the
U.S. to be parceled into western, central and eastern portions.
François
Gemenne, who reviewed sections of Monday's IPCC report and authored a section
for a follow-up report due next year, said greater confidence on climate
science had enabled researchers to move “from projections to forecasting."
That means making more specific statements about the regularity of certain
extreme events in a given place.
“The
problem is that if we want policy decisions to be made, we need actual
forecasting rather than just projections, because projections are too vague for
policymakers to actually take them into account,” he said.
Global calamities
This summer
has had no shortage of storylines across the world. The report notes recent hot
extremes would have been “extremely unlikely” without human influence. Monsoon
and cyclone precipitation will increase, likely due to human activity. Extreme
sea level rise and rainfall events will increase flooding. Rarer extreme events
will become more frequent.
To put it
in context: The IPCC said that a once-in-a-decade drought would instead occur
every five years under the 1.5-degree scenario, and every four years under the
2-degree rise.
Even now,
with global average temperatures up more than 1 degree Celsius from the
1850-1900 average, the chance of a once-per-50 years drought has become likely
every decade, while the once-a-decade drought occurs about every six years.
“It's worse
than a lot of the rather dire statements that people like me have made in the
past,” said Michael Wehner, a senior scientist at the Lawrence Berkeley
National Laboratory and a report author who worked on the extremes chapter.
In past
years, scientists were reluctant to link any single event with climate change —
they would say events of that sort were in line with the impacts that models
had predicted. That wooliness created a communications problem for scientists,
journalists and policymakers as they grappled with how to explain to the public
what the future held.
But the
IPCC report said even that reality has changed with the advent of so-called
attribution science. The emerging field is propelled by improved computing
power that runs model ensembles with human-caused emissions against a world
without those emissions to tease out the human fingerprint in those events.
That science has shown human activity has made disasters ranging from Hurricane
Harvey’s rainfall in Texas in 2017 or the Pacific Northwest heatwave in June
more intense.
“When
climate change first came onto the agenda, people thought of it as something
that was far in the future — maybe that it was going to affect their grandkids.
But I think that that kind of debate has been shifting, partly because of these
event attribution studies and the extremes that we're observing,” said Nathan
Gillett, a research scientist at Environment and Climate Change Canada who led
the chapter on science methods.
For Belgian
climatologist Gemenne, that shift from conceptual to concrete has also been a
traumatic homecoming. In July, the flooded River Ourthe smashed through Liège,
the city where he grew up and now runs a research center at the local
university. The floods killed more than 200 across Belgium and in Germany,
where Chancellor Angela Merkel described the damage as “terrifying.”
“As a
researcher who has worked on events like this all around the world it's really
difficult to see it happen in your place,” said Gemenne. Next month, his
university team will start a research project unpicking the response to the floods.
“That will be a very strange situation, in a way to study yourself,” he said.
“You realize that the frontline is now home.”
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