February on course to break unprecedented number
of heat records
Rapid ocean warming and unusually hot winter days
recorded as human-made global heating combines with El Niño
Jonathan
Watts
@jonathanwatts
Sat 17 Feb
2024 06.00 GMT
February is
on course to break a record number of heat records, meteorologists say, as
human-made global heating and the natural El Niño climate pattern drive up
temperatures on land and oceans around the world.
A little
over halfway into the shortest month of the year, the heating spike has become
so pronounced that climate charts are entering new territory, particularly for
sea-surface temperatures that have persisted and accelerated to the point where
expert observers are struggling to explain how the change is happening.
“The planet
is warming at an accelerating rate. We are seeing rapid temperature increases
in the ocean, the climate’s largest reservoir of heat,” said Dr Joel Hirschi,
the associate head of marine systems modelling at the UK National Oceanography
Centre. “The amplitude by which previous sea surface temperatures records were
beaten in 2023 and now 2024 exceed expectations, though understanding why this
is, is the subject of ongoing research.”
Humanity is
on a trajectory to experience the hottest February in recorded history, after a
record January, December, November, October, September, August, July, June and
May, according to the Berkeley Earth scientist Zeke Hausfather.
He said the
rise in recent weeks was on course for 2C of warming above pre-industrial
levels, though this should be the brief, peak impact of El Niño if it follows
the path of previous years and starts to cool down in the months ahead.
That would
normally be good news if a temperature-lowering La Niña follows, but Hausfather
said the behaviour of the climate had become more erratic and harder to
forecast. “[Last year] defied expectations so much that it’s hard to have as
much confidence in the approaches we have used to make these predictions in the
past,” he said. “I’d say February 2024 is an odds-on favourite to beat the
prior record set in 2016, but it’s by no means a foregone conclusion at this
point as weather models suggest that global temperatures will fall back down in
the coming week. So while I think these extreme temperatures provide some
evidence of an acceleration in the rate of warming in recent years – as climate
models expect there to be if CO2 emissions do not fall but aerosols do – it’s
not necessarily worse than we thought.”
The first
half of February shocked weather watchers. Maximiliano Herrera, who blogs on
Extreme Temperatures Around the World, described the surge of thousands of
meteorological station heat records as “insane”, “total madness” and “climatic
history rewritten”. What astonished him was not just the number of records but
the extent by which many of them surpassed anything that went before.
He said
Morocco had seen 12 weather stations register over 33.9C, which was not only a
national record for the hottest winter day, but also more than 5C above average
for July. The northern Chinese city of Harbin had to close its winter ice
festival because temperatures crept above freezing for an unprecedented three
days this month.
In the past
week, monitoring stations as far apart as South Africa, Saudi Arabia, Thailand,
Indonesia, Kazakhstan, Colombia, Japan, North Korea, the Maldives and Belize
have registered monthly heat records.
In the
first half of this month, Herrera said 140 countries broke monthly heat
records, which was similar to the final figures of the last six record hottest
months of 2023 and more than three times any month before 2023.
Ocean
surface heat continues to astonish seasoned observers and raises the prospect
of intense storms later in the year. The hurricane specialist Michael Lowry
tweeted that sea surface temperatures across the Atlantic main development
region, where most of the US category 3 or stronger hurricanes form, “are as
warm today in mid-February as they typically are in middle July. Incredible.”
Global sea
surface temperatures are in “uncharted territory” according to Hirschi, who
expects March to break last August’s record by 0.1C to 0.2C. March is typically
the hottest time of the year for oceans because it is late summer in the
southern hemisphere, which is home to most of the world’s great seas.
The
temperature spikes were expected, though their amplitude came as a surprise.
Climatologists are now studying how to attribute weight to the different causes
behind such anomalies.
A strong El
Niño has pushed temperatures higher, but Francesca Guglielmo, a Copernicus
senior scientist, noted this was only one of several heating factors that
worked in combination. Every extra tonne of carbon dioxide emitted by humanity
increases pressure on the oceans. In some areas, the anomalous heat has also
been intensified by weak trade winds, a lethargic jet stream, fluctuations in
North Atlantic circulation and reductions in aerosol pollution, which exposes
more of the ocean to the sun.
Katharine
Hayhoe, chief scientist for The Nature Conservancy, said the uncertainty about
the interaction of the different factors was a reminder that we do not fully
understand every aspect of how the complex Earth system is responding to
unprecedented radiative forcing. “This is happening at a much faster rate than
ever documented in the past,” she said. “If anything, we are much more likely
to underestimate the impact of those changes on human society than to
overestimate them.”
El Niño is
now weakening, which should ease temperatures in the equatorial Pacific from
late spring or early summer. If the North Atlantic remains warm at that time,
this could herald intense hurricane activity, Hirschi warned.
Such risks
will increase every year unless human carbon emissions are slashed and forest
clearance reversed. “Slowing, stopping or reversing the warming trajectory we
are on is akin to changing the course of a supertanker. Results are not
immediate but the sooner we take action, the easier it will be for us to avoid
hitting trouble,” he said.
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