Three
degrees
does
not
sound
like
much
but
it
____________________
a
rise
in
temperature
compatible
with
the
global
heating
that
occurred
between
the
last
ice
age
,
some
15
,
000
years
ago
,
and
the
warmth
of
the
eighteenth
century
.
When
Earth
was
cold
,
giant
____________________
sometimes
extended
from
the
polar
-
regions
as
far
south
as
St
Louis
in
the
US
and
the
Alps
in
Europe
.
Later
this
century
when
it
is
three
degree
hotter
glaciers
everywhere
will
be
melting
in
a
climate
of
often
____________________
heat
and
drought
,
____________________
with
storms
and
floods
.
The
____________________
for
humanity
could
be
truly
horrific
;
if
we
fail
to
act
swiftly
,
the
full
impact
of
global
heating
could
____________________
us
along
with
vast
populations
of
the
plant
and
animals
with
whom
we
share
Earth
.
In
a
worst
case
scenario
,
there
might
-
in
the
22nd
century
-
be
only
a
____________________
of
humanity
____________________
out
a
____________________
existence
in
the
polar
-
regions
and
the
few
remaining
____________________
left
on
a
hot
and
arid
Earth
.
