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SCIENCEMonday 28 December 2015
Researchers: Paris climate goals say emissions
Less Arctic sea ice means more precipitation
need to drop below zero to work
DAN JOLING Ice floes float in Baffin Bay above the arctic circle seen from
Associated Press the Canadian Coast Guard icebreaker Louis S. St-Laurent. The KARL RITTER
ANCHORAGE, Alaska (AP) Arctic is seeing more precipitation as sea ice diminishes from Associated Press
— The Arctic is seeing more climate warming, according to a research paper by U.S. and STOCKHOLM (AP) — If governments are serious about
precipitation as sea ice Canada scientists. the global warming targets they adopted in Paris, sci-
diminishes from climate entists say they have two options: eliminating fossil fu-
warming, according to a (AP Photo/The Canadian Press, Jonathan Hayward) els immediately or finding ways to undo their damage
research paper by U.S. and to the climate system in the future.
Canada scientists. tic sites. Center at the University of The first is politically impossible — the world is still hooked
The study by three Dart- “In terms of the entire pro- Colorado in Boulder, said on using oil, coal and natural gas — which leaves the
mouth College researchers portion that will reach a site previous studies have sug- option of a major cleanup of the atmosphere later this
and one from Carleton Uni- in, say, Alaska, that local gested a link between less century.
versity in Ottawa, Ontario, moisture becomes more September sea ice and an Yet the landmark Paris Agreement, adopted by 195
concludes the effects from important,” he said. increase in snow in the Si- countries on Dec. 12, makes no reference to that,
a changed hydrologic The scientists studied pre- berian Arctic. which has left some observers wondering whether pol-
cycle is a potential ma- cipitation data collected “At least statistically there’s iticians understand the implications of the goals they
jor component of climate between 1990 and 2012 a correlation between less signed up for.
change that could cre- at three sites in the Cana- sea ice and more precipi- “I would say it’s the single biggest issue that has to be
ate uncertainty in climate dian Arctic and three in the tation in certain parts of the resolved,” said Glen Peters of the Cicero climate re-
predictions. They also say Greenland Sea, looking for Arctic,” she said. search institute in Oslo, Norway.
it’s too soon to tell whether changes in the source of Before the ocean can re- Scientists refer to this envisioned cleanup job as nega-
more precipitation will slow precipitation as sea ice has freeze, she said, it has to tive emissions — removing more greenhouse gases
warming or add to it. diminished. Moisture from a release heat it gained in from the atmosphere than humans put in it.
Scientists have generally warm source can be distin- summer. If it’s shown that Right now we’re putting in a lot — about 50 billion tons
assumed that less sea ice guished from a cold source additional precipitation a year, mostly carbon dioxide from the burning of fossil
would mean more evapo- through measurements of is from a local source, it fuels for energy.
ration and more precipi- isotope compositions, Ko- would match other stud- There are methods to achieve negative emissions to-
tation, said Ben Kopec, a pec said. As sea ice dimin- ies suggesting additional day but they would need to be scaled up to a level
Dartmouth earth scienc- ished over two decades, precipitation from waters that experts say could put climate efforts in conflict
es doctoral student and precipitation at the Arctic formerly covered by ice at with other priorities, such as eradicating hunger. Still, if
lead author of the paper sites increased and the per- that time, Stroeve said. the Paris climate goals are to be achieved, there’s no
published Monday in the centage from local sourc- Kopec said if precipitation way to avoid the issue, said Jan Minx of the Mercator
journal, Proceedings of the es grew. The researchers falls as snow, it could in- Research Institute on Global Commons and Climate
National Academy of Sci- concluded that when sea crease the days that land change in Berlin.
ences. ice decreases by 100,000 reflects solar energy, pro- “My view is, let’s have this discussion,” he said. “Let’s
“Our goal with this work square kilometers, or 38,610 viding a cooling effect. involve ourselves in developing these technologies.
was to try to actually use square miles, the percent- If the additional precipita- We need to keep learning.”
observations of precipita- age of local-sourced mois- tion falls as rain, it could The Paris Agreement was historic. For the first time all
tion around the Arctic to ture increased by 18.2 per- cause earlier spring melt or countries agreed to jointly fight climate change, pri-
get at this question of how cent in the Canadian Arc- later onset of autumn snow marily by reducing the emissions of carbon dioxide
much does sea ice influ- tic and 10.8 percent in the coverage, contributing to and other greenhouse gases.
ence precipitation, and if Greenland Sea. more warming. Governments vowed to keep global warming “well
we lose sea ice, how much “We can say that with less “It’s important for us in the below” 2 degrees Celsius (3.6 degrees Fahrenheit)
precipitation do you think sea ice, more of that mois- future to nail down wheth- compared with preindustrial times. But even 2 degrees
will increase?” he said in a ture that fell was sourced er this is going to be more of warming could threaten the existence of low-lying
phone interview. from the Arctic,” Kopec snow or more rain,” Kopec island nations faced with rising seas. So governments
Arctic precipitation is com- said. said. “But we were able agreed to try to limit warming to 1.5 degrees C (2.7 de-
posed of moisture from lo- Julienne Stroeve, senior re- to say, ‘This could have a grees F), which is just half-a-degree above the global
cal and distance sources, search scientist at the Na- large impact on the ener- average temperature this year.
he said. tional Snow and Ice Data gy balance.”q That goal is so ambitious — some would say far-
“Most of the world gets its fetched — that there’s been very little research de-
moisture from the warm voted to it. In Paris, politicians asked scientists to start
waters in the subtropics,” studying how it can be done.
Kopec said. As moisture Minx and others said it’s clear the goal cannot be
moves north from lower lat- reached without negative emissions in the future, be-
itudes, including the North cause the atmosphere is filling up with greenhouse
Pacific in Alaska’s case, gases so fast that it may already be too late to keep
much of it falls before the temperature rise below 1.5 degrees C.
reaching the Arctic. “We are late with climate policy. We need to buy
An increase in moisture back some time,” Minx said.q
from local sources, Kopec
said, though small in com-
parison to evaporation in
warmer oceans, could dis-
proportionately affect Arc-
