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A28 SCIENCE
Tuesday 9 OcTOber 2018

U.N. report on global warming carries life-or-death warning

By SETH BORENSTEIN er those unprecedented
WASHINGTON (AP) — Pre- changes are acted upon.
venting an extra single de- "We have a monumental
gree of heat could make task in front of us, but it is
a life-or-death difference not impossible," Mahow-
in the next few decades ald said earlier. "This is our
for multitudes of people chance to decide what
and ecosystems on this the world is going to look
fast-warming planet, an in- like."
ternational panel of scien- To limit warming to the
tists reported Sunday. But lower temperature goal,
they provide little hope the the world needs "rapid and
world will rise to the chal- far-reaching" changes in
lenge. energy systems, land use,
The Nobel Prize-winning In- city and industrial design,
tergovernmental Panel on transportation and build-
Climate Change issued its ing use, the report said. An-
gloomy report at a meeting nual carbon dioxide pollu-
in Incheon, South Korea. tion levels that are still rising
In the 728-page docu- now would have to drop
ment, the U.N. organiza- by about half by 2030 and
tion detailed how Earth's then be near zero by 2050.
weather, health and eco- Emissions of other green-
systems would be in better house gases, such as meth-
shape if the world's leaders ane, also will have to drop.
could somehow limit future In this Oct. 26, 2015 file photo, fish swim over a patch of bleached coral in Hawaii's Kaneohe Switching away rapidly
human-caused warming to Bay off the island of Oahu. Warmer water is repeatedly causing mass global bleaching events to from fossil fuels like coal, oil
just 0.9 degrees Fahrenheit Earth's fragile coral reefs. and gas to do this could be
(a half degree Celsius) from Associated Press more expensive than the
now, instead of the glob- less ambitious goal, but it
ally agreed-upon goal of Natalie Mahowald, a lead In 2010, international ne- possible future scenarios would clean the air of other
1.8 degrees F (1 degree C). author on the report. gotiators adopted a goal kept warming below the pollutants. And that would
Among other things: Limiting warming to 0.9 de- of limiting warming to 2 1.5 goal without the tem- have the side benefit of
— Half as many people grees from now means the degrees C (3.6 degrees F) perature going above that avoiding more than 100
would suffer from lack of world can keep "a sem- since pre-industrial times. and somehow coming million premature deaths
water. blance" of the ecosystems It's called the 2-degree back down in the future. through this century, the re-
— There would be fewer we have. Adding another goal. In 2015, when the na- The pledges nations made port said.
deaths and illnesses from 0.9 degrees on top of that tions of the world agreed in the Paris agreement in "Climate-related risks to
heat, smog and infectious — the looser global goal to the historic Paris climate 2015 are "clearly insufficient health, livelihoods, food
diseases. — essentially means a dif- agreement, they set dual to limit warming to 1.5 in security, water supply, hu-
— Seas would rise nearly 4 ferent and more challeng- goals: 2 degrees C and a any way," one of the study's man security and econom-
inches (0.1 meters) less. ing Earth for people and more demanding target lead authors, Joerj Roeglj ic growth are projected to
— Half as many animals species, said another of the of 1.5 degrees C from pre- of the Imperial College in increase with global warm-
with back bones and plants report's lead authors, Ove industrial times. The 1.5 was London, said. ing" the report said, adding
would lose the majority of Hoegh-Guldberg, direc- at the urging of vulnerable "I just don't see the possibil- that the world's poor are
their habitats. tor of the Global Change countries that called 2 de- ity of doing the one and a more likely to get hit hard-
— There would be substan- Institute at the University of grees a death sentence. half" and even 2 degrees est. Princeton University cli-
tially fewer heat waves, Queensland, Australia. The world has already looks unlikely, said Appala- mate scientist Michael Op-
downpours and droughts. But meeting the more am- warmed 1 degree C since chian State University envi- penheimer said extreme
— The West Antarctic ice bitious goal of slightly less pre-industrial times, so the ronmental scientist Gregg weather, especially heat
sheet might not kick into ir- warming would require im- talk is really about the dif- Marland, who isn't part waves, will be deadlier if
reversible melting. mediate, draconian cuts ference of another half- of the U.N. panel but has the lower goal is passed.
— And it just may be in emissions of heat-trap- degree C or 0.9 degrees F tracked global emissions Meeting the tougher-to-
enough to save most of the ping gases and dramatic from now. for decades for the U.S. reach goal "could result in
world's coral reefs from dy- changes in the energy "There is no definitive way Energy Department. He lik- around 420 million fewer
ing. field. While the U.N. panel to limit global temperature ened the report to an aca- people being frequently
"For some people this is a says technically that's pos- rise to 1.5 above pre-in- demic exercise wondering exposed to extreme heat
life-or-death situation with- sible, it saw little chance of dustrial levels," the U.N.-re- what would happen if a waves, and about 65 mil-
out a doubt," said Cornell the needed adjustments quested report said. More frog had wings. lion fewer people being ex-
University climate scientist happening. than 90 scientists wrote the Yet report authors said they posed to exceptional heat
report, which is based on remain optimistic. waves," the report said. The
more than 6,000 peer re- Limiting warming to the deadly heat waves that hit
views. lower goal is "not impossi- India and Pakistan in 2015
"Global warming is likely to ble but will require unprec- will become practically
reach 1.5 degrees C be- edented changes," U.N. yearly events if the world
tween 2030 and 2052 if it panel chief Hoesung Lee reaches the hotter of the
continues to increase at said in a news conference two goals, the report said.
the current rate," the report in which scientists repeat- Coral and other ecosys-
states. edly declined to spell out tems are also at risk. The
Deep in the report, scien- just how feasible that goal report said warmer wa-
tists say less than 2 percent is. They said it is up to gov- ter coral reefs "will largely
of 529 of their calculated ernments to decide wheth- disappear."q