The Planet Is on Course to Breach Warming Limit of 1.5°C Within 10 years, Scientists Warn

Author: Climate News Network | EcoWatch ||

By Tim Radford

Australian scientists have warned that planetary average temperatures

could breach the internationally agreed target barrier of a 1.5°C rise

as early as 2026.


Although global warming is driven by human behavior—and in particular the prodigal burning of fossil fuels at an ever-accelerating rate to dump ever-greater quantities of

carbon dioxide in the atmosphere

—it is also influenced by natural climate rhythms.

And, said scientists from Australia’s Centre of Excellence for Climate System Science, one of these is a slow-moving oceanic and atmospheric cycle called the Interdecadal Pacific Oscillation (IPO), which blows hot and cold and then hot again, every decade or so.

The latest hot phase could be about to push the global thermometer beyond the

ideal limit set

by the UN

climate conference in Paris

in 2015. They wrote in

Geophysical Research Letters

that since 1999 the IPO has been perhaps keeping the world cooler than it might have been, as the

rate of increase in global warming appeared to slow

between 1998 and 2012.


Global records

But the last three years have all breached successive

global temperature records

, and they think this could mean that the IPO is beginning to have a positive effect.

“Even if the IPO remains in negative phase, our research shows we will still likely see global temperatures break through the 1.5°C guardrail by 2031,” said

Ben Henley

of the University of Melbourne, who led the study.

“If the world is to have any hope of meeting the Paris targets,

governments will need to pursue policies

that not only reduce emissions but remove carbon dioxide from the atmosphere,” Henley emphasized. “Should we overshoot the 1.5°C limit, we must still aim to bring global temperatures back down and stabilize them at that level or lower.”

Carbon dioxide levels for most of human history oscillated at around 280 parts per million. Since the beginning of the Industrial Revolution, they have risen inexorably, to reach 400ppm.



Global average temperatures have crept up to almost 1°C higher than the historic levels. In fact, the Paris Agreement talked of aiming to keep them “well below 2°C,” but 1.5°C has always been an ideal limit.

Henley and his co-author are not the only scientists to cast doubt on the world’s capacity to achieve the Paris promise. Two of the giants of climate science

pointed out within a month of the historic decision

that current greenhouse gas emissions would take the world to the 2°C target very swiftly.

Their pessimism has been echoed by British scientists who pointed out that there was

already enough carbon dioxide in the atmosphere

to breach the 1.5°C guardrail at least for temperatures over land (which accounts for only about 30 percent of the planet). Other studies have warned that the world

will overshoot the 1.5°C ideal

, although it might return to this peak by 2100.

So although the latest warning from Australia sounds ominous, it is consistent with other thinking. The nations that signed up to the Paris accord have—mostly—made declarations of their plans to reduce emissions, but many of these have yet to be implemented and in any case are widely understood to be insufficient.


Acceleration in warming

Nor is the latest study without challenge. At least one analysis points out that it

starts with the assumption

that humankind takes little or no action to reduce emissions. And the Paris target of containment to a 1.5°C rise was intended to be an average over a 20- to 30-year period, rather than a barrier not to be breached in any one year.

So the Melbourne study could best be considered as yet another reminder of the urgency of international action.

“Although the earth has continued to warm during the temporary slowdown since around 2000, the reduced rate of warming in that period may have lulled us into a false sense of security,” said Henley. “The positive phase of the IPO will likely correct this slowdown. If so, we can expect an acceleration in global warming in the coming decades.

“Policymakers should be aware of just how quickly we are approaching 1.5°C. The task of reducing emissions is very urgent indeed.”



Reposted with permission from

Climate News Network

.

Read more

By | 2017-05-19T07:08:55+00:00 May 19th, 2017|Climate change, EcoWatch|

About the Author:

EcoWatch is one of the nation's leading environmental news sites engaging millions of readers every month. We are at the forefront of uniting all shades of green to ensure the health and longevity of our planet. EcoWatch is leading the charge in using online news to drive fundamental change.