I've summarized
a longer article,
at the link above,
a longer article,
at the link above,
which also includes
a long list of references,
a long list of references,
and links to some of them.
Arctic summer
sea ice loss
is ramping up.
That's happened every year
since the Arctic had ice,
millions of years ago.
June 2019
happened to have
the second lowest
sea ice extent area,
for the month of June,
since 1979.
But in early July 2019,
there was still ice
near all major polar
bear denning areas
across the Arctic.
The Ten Fallacies:
1.
‘Sea ice is to the Arctic
as soil is to a forest‘.
False:
Sea ice will always re-form
in the winter and stay until spring.
Ice has formed in the Arctic
for several million years.
There has always been ice
in the winter and spring.
"I am not aware of a single
modern climate model
that predicts winter ice
will fail to develop
over the next 80 years
or so. "
2.
Polar bears need
summer sea ice
to survive.
False:
Bears that fed on young seals
in the early spring can live
off their fat for five months
or more until the fall.
Polar bears seldom catch seals
in the summer, because only
adult seals are available then,
and holes in the pack ice allow
them to escape.
Polar bears and Arctic seals
require sea ice from late fall
through early spring only.
3.
Ice algae is the basis
for all Arctic life.
Only partially true:
Plankton thrives in open water,
during the Arctic summer too,
which provides food for the fish
that seals eat.
Recent research has shown that
less ice in summer has improved
seal health.
4.
Open water in early spring
as well as summer ice melt
since 1979 are unnatural
and detrimental to
polar bear survival.
False:
Melting ice is a normal part
of Arctic seasonal changes.
In the winter and spring,
open water areas appear
because wind and currents
rearrange the pack ice.
The mix of ice and nutrient-laden
open water that attracts Arctic seals
and the seals are food for polar bears.
5.
Climate models
do a good job
of predicting
the future
polar bear habitat.
False:
The almost 50% decline
in summer sea ice,
not expected until 2050,
actually arrived in 2007,
and remained steady
since then, yet polar bears
are thriving.
6.
Sea ice is getting thinner
and that’s a problem
for polar bears.
False:
First year ice (less than 2 meters thick)
is the best habit for polar bears
because it's the best habitat for seals,
compared with very thick multi-year ice.
First year ice that melts every summer
creates a better habitat in the spring
for seals and bears in the spring,
when they need it the most.
7.
Polar bears in Western
and Southern Hudson Bay
are most at risk of extinction
due to global warming.
False:
Sea ice decline in Hudson Bay
has been less than one day
per year since 1979 compared to
more than 4 days per year
in the Barents Sea.
The ice-free season in Western
Hudson Bay since 1998 has been
about 3 weeks longer than it was
in the 1980s but has not changed
in the past 20 years despite
lots of carbon dioxide emissions.
8.
Breakup of sea ice
in Western Hudson Bay
now occurs three weeks
earlier than it did
in the 1980s.
False:
Breakup occurs 2 weeks earlier
in summer, than it did in the 1980s.
The total ice-free season is now
about 3 weeks longer, but with
lots of year-to-year variation.
9.
Winter sea ice
has been declining
since 1979,
putting polar bear
survival at risk.
Only partially true:
Sea ice in March has been declining
gradually since 1979, but there's
no evidence it hurt polar bears.
10.
Experts say that with
19 different polar bear
subpopulations across
the Arctic, there are
“19 sea ice scenarios
playing out“, implying
this is what
they predicted
all along.
False:
Biologists at the US Geological Survey
in 2007 grouped polar bear subpopulations
with similar sea ice types, and predicted
polar bear survival based on assumptions
of how the ice in the four sea ice regions
would change over time.
There was much more variation
than they expected, contrary
to predictions.