Arctic ice loss could be making Britain's winters colder and snowier
- 28 Feb 2012, 14:45
- Verity Payne
Credit: NASA Earth Observatory
You've probably heard a lot in recent years about how Arctic sea
ice is melting. So what's the big deal? After all, the Arctic's a
fair distance away and you're not a polar bear.
Scientists worry that changes in the Arctic will have knock-on
effects in other parts of the world, including closer to home. This
includes on our winter weather, with three separate scientific
studies published this year linking the loss of Arctic sea to cold
and snowy winters here in Europe.
most recent of these studies, published in the journal
Proceedings of the National Academy of Sciences, comes from a team
of researchers (incidentally including well-known blogging
scientist Judith Curry) from Georgia Tech University, the Chinese
Academy of Sciences and Columbia University.
The team used observational data along with climate models to
examine whether there was a link between Arctic sea ice loss and
the unusually large snowfall in Northern Hemisphere winters over
The research showed that when Arctic sea ice melt is unusually
high in summer, the Arctic Ocean, Greenland, and northeastern
Canada have a warmer winter, while northern North America, Europe,
Siberia, and eastern Asia cool down and experience above average
How could sea ice loss make a cold snowy
Arctic sea ice changes seasonally, growing in winter and melting
in summer - this is why graphs of sea ice over time show an
up-and-down cycle. But at the same time sea ice is in decline -
over the past 40 years ice area or 'extent' has declined by around
12 per cent per
decade as shown in the graph below:
Scientists think that when Arctic sea ice melts more than usual
in summer it takes longer for the sea ice to regrow in the autumn,
leaving the ocean uncovered by ice for longer than normal.
Because sea ice reflects some of the sun's energy, more
uncovered ocean means the ocean warms more. In turn, this heat
escapes from the ocean into the atmosphere, warming the air up and
reducing the temperature difference between the Arctic and lower
This affects weather systems, allowing more 'blocking patterns'
to develop - where high pressure air masses sit over the European
continent, 'blocking' other air masses and bringing cold, snowy
conditions to the continent.
It was a large 'blocking pattern' that is
thought to have caused the unusually cold and snowy weather
experienced by much of Europe at the
start of February 2012, neatly shown in this satellite
These changes could also lead to more snowfall, as the study's
lead author Dr Jiping Liu, a senior research scientist in the
School of Earth and Atmospheric Sciences at Georgia Tech,
"We think the recent snowy winters could
be caused by the retreating Arctic ice altering atmospheric
circulation patterns ... and increasing the amount of moisture in
the atmosphere. These pattern changes enhance blocking patterns
that favor more frequent movement of cold air masses to middle and
lower latitudes, leading to increased heavy snowfall in Europe and
the Northeast and Midwest regions of the United States."
The link between Arctic sea ice loss and winter conditions in
the Northern continents has also been proposed by other two other
research papers published this year, in the journals
Tellus A and Environmental
It's even been suggested that conditions in the Arctic might be
linked to weather conditions in the mid-latitudes during summer. A
in press in the journal Geophysical Research Letters suggests that
Arctic warming slows weather patterns, increasing the chance of
extreme weather in the mid-latitudes, including drought, flooding,
cold-spells, and even heat-waves.
Outlook for European winter weather
Climate model projections indicate that the Arctic ocean is
likely to continue to lose sea ice, with some suggesting ice-free
a matter of decades. So as the Arctic warms, are we going to
see more severe winter weather here in the UK?
Well, it's complicated, because sea ice extent is not the only
thing affecting Northern Hemisphere winters. Solar activity might
play a role in determining
Northern Hemisphere winter conditions, particularly for Britain.
There's also the Arctic
Oscillation to consider - a natural regional climate cycle that
has a big role in controlling winter conditions.
Dr Lau told the BBC
"It's possible that future winters will
be colder and snowier, but there are some uncertainties."
Whether we're in for more snow or not, this kind of research
does lend weight to the argument that the loss of sea ice in the
Arctic isn't just of interest to climate scientists or shipping
companies. There are also likely to be impacts on the climate of
the rest of the world.