We have 12 years to limit climate change catastrophe, warns
UN
Urgent changes needed to cut risk of extreme heat, drought,
floods and poverty, says IPCC
Overwhelmed by climate change? Here’s what you can do
Jonathan Watts Global environment editor
Mon 8 Oct 2018 07.23 BST First published on Mon 8 Oct 2018
02.00 BST
The world’s leading climate scientists have warned there is
only a dozen years for global warming to be kept to a maximum of 1.5C, beyond
which even half a degree will significantly worsen the risks of drought,
floods, extreme heat and poverty for hundreds of millions of people.
The authors of the landmark report by the UN
Intergovernmental Panel on Climate Change (IPCC) released on Monday say urgent
and unprecedented changes are needed to reach the target, which they say is
affordable and feasible although it lies at the most ambitious end of the Paris
agreement pledge to keep temperatures between 1.5C and 2C.
The half-degree difference could also prevent corals from
being completely eradicated and ease pressure on the Arctic, according to the
1.5C study, which was launched after approval at a final plenary of all 195
countries in Incheon in South Korea that saw delegates hugging one another,
with some in tears.
“It’s a line in the
sand and what it says to our species is that this is the moment and we must act
now,” said Debra Roberts, a co-chair of the working group on impacts. “This is
the largest clarion bell from the science community and I hope it mobilises
people and dents the mood of complacency.”
Policymakers commissioned the report at the Paris climate
talks in 2016, but since then the gap between science and politics has widened.
Donald Trump has promised to withdraw the US – the world’s biggest source of
historical emissions – from the accord. The first round of Brazil’s
presidential election on Sunday put Jair Bolsonaro into a strong position to
carry out his threat to do the same and also open the Amazon rainforest to
agribusiness.
The world is currently 1C warmer than preindustrial levels.
Following devastating hurricanes in the US, record droughts in Cape Town and
forest fires in the Arctic, the IPCC makes clear that climate change is already
happening, upgraded its risk warning from previous reports, and warned that
every fraction of additional warming would worsen the impact.
Scientists who reviewed the 6,000 works referenced in the
report, said the change caused by just half a degree came as a revelation. “We
can see there is a difference and it’s substantial,” Roberts said.
At 1.5C the proportion of the global population exposed to
water stress could be 50% lower than at 2C, it notes. Food scarcity would be
less of a problem and hundreds of millions fewer people, particularly in poor
countries, would be at risk of climate-related poverty.
At 2C extremely hot days, such as those experienced in the
northern hemisphere this summer, would become more severe and common,
increasing heat-related deaths and causing more forest fires.
But the greatest difference would be to nature. Insects,
which are vital for pollination of crops, and plants are almost twice as likely
to lose half their habitat at 2C compared with 1.5C. Corals would be 99% lost
at the higher of the two temperatures, but more than 10% have a chance of
surviving if the lower target is reached.
Sea-level rise would affect 10 million more people by 2100
if the half-degree extra warming brought a forecast 10cm additional pressure on
coastlines. The number affected would increase substantially in the following
centuries due to locked-in ice melt.
Oceans are already suffering from elevated acidity and lower
levels of oxygen as a result of climate change. One model shows marine
fisheries would lose 3m tonnes at 2C, twice the decline at 1.5C.
Sea ice-free summers in the Arctic, which is warming two to
three times fast than the world average, would come once every 100 years at
1.5C, but every 10 years with half a degree more of global warming.
Time and carbon budgets are running out. By mid-century, a
shift to the lower goal would require a supercharged roll-back of emissions
sources that have built up over the past 250 years.
The IPCC maps out four pathways to achieve 1.5C, with
different combinations of land use and technological change. Reforestation is
essential to all of them as are shifts to electric transport systems and
greater adoption of carbon capture technology.
Carbon pollution would have to be cut by 45% by 2030 –
compared with a 20% cut under the 2C pathway – and come down to zero by 2050,
compared with 2075 for 2C. This would require carbon prices that are three to
four times higher than for a 2C target. But the costs of doing nothing would be
far higher.
“We have presented governments with pretty hard choices. We
have pointed out the enormous benefits of keeping to 1.5C, and also the
unprecedented shift in energy systems and transport that would be needed to
achieve that,” said Jim Skea, a co-chair of the working group on mitigation.
“We show it can be done within laws of physics and chemistry. Then the final
tick box is political will. We cannot answer that. Only our audience can – and
that is the governments that receive it.”
He said the main finding of his group was the need for
urgency. Although unexpectedly good progress has been made in the adoption of
renewable energy, deforestation for agriculture was turning a natural carbon
sink into a source of emissions. Carbon capture and storage projects, which are
essential for reducing emissions in the concrete and waste disposal industries,
have also ground to a halt.
Reversing these trends is essential if the world has any
chance of reaching 1.5C without relying on the untried technology of solar
radiation modification and other forms of geo-engineering, which could have
negative consequences.
In the run-up to the final week of negotiations, there were
fears the text of the report would be watered down by the US, Saudi Arabia and
other oil-rich countries that are reluctant to consider more ambitious cuts.
The authors said nothing of substance was cut from a text.
Bob Ward, of the Grantham Research Institute on Climate
Change, said the final document was “incredibly conservative” because it did
not mention the likely rise in climate-driven refugees or the danger of tipping
points that could push the world on to an irreversible path of extreme warming.
The report will be presented to governments at the UN
climate conference in Poland at the end of this year. But analysts say there is
much work to be done, with even pro-Paris deal nations involved in fossil fuel
extraction that runs against the spirit of their commitments. Britain is
pushing ahead with gas fracking, Norway with oil exploration in the Arctic, and
the German government wants to tear down Hambach forest to dig for coal.
At the current level of commitments, the world is on course
for a disastrous 3C of warming. The report authors are refuseing to accept
defeat, believing the increasingly visible damage caused by climate change will
shift opinion their way.
“I hope this can change the world,” said Jiang Kejun of
China’s semi-governmental Energy Research Institute, who is one of the authors.
“Two years ago, even I didn’t believe 1.5C was possible but when I look at the
options I have confidence it can be done. I want to use this report to do
something big in China.”
The timing was good, he said, because the Chinese government
was drawing up a long-term plan for 2050 and there was more awareness among the
population about the problem of rising temperatures. “People in Beijing have
never experienced so many hot days as this summer. It’s made them talk more
about climate change.”
Regardless of the US and Brazil, he said, China, Europe and
major cities could push ahead. “We can set an example and show what can be
done. This is more about technology than politics.”
James Hansen, the former Nasa scientist who helped raised
the alarm about climate change, said both 1.5C and 2C would take humanity into
uncharted and dangerous territory because they were both well above the
Holocene-era range in which human civilisation developed. But he said there was
a huge difference between the two: “1.5C gives young people and the next
generation a fighting chance of getting back to the Holocene or close to it.
That is probably necessary if we want to keep shorelines where they are and preserve
our coastal cities.”
Johan Rockström, a co-author of the recent Hothouse Earth
report, said scientists never previously discussed 1.5C, which was initially
seen as a political concession to small island states. But he said opinion had
shifted in the past few years along with growing evidence of climate
instability and the approach of tipping points that might push the world off a
course that could be controlled by emissions reductions.
“Climate change is occurring earlier and more rapidly than
expected. Even at the current level of 1C warming, it is painful,” he told the
Guardian. “This report is really important. It has a scientific robustness that
shows 1.5C is not just a political concession. There is a growing recognition
that 2C is dangerous.”
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