"At a steady rate, the cumulative loss would be linear. It's quite clear the black line is curving down with time, indicating that the worldwide glacier melt has been accelerating." Paper recently published in the journal Nature analyzed by Dr. Mark H. Shapiro Watch Glacier Melt Is Speeding Up posted Sep 21 w transcript below
0:00
The melting of the world's glaciers is
0:03
the major contributor to sea level rise.
0:06
A paper recently published in the
0:09
journal Nature reports that the rate at
0:12
which the world's glaciers are melting
0:14
has increased significantly in recent
0:18
years. In this video, I examine the
0:21
implications of the increase in melting
0:24
for sea level rise.
0:28
Since the start of the industrial
0:30
revolution, increasing global
0:32
temperatures have caused the world's
0:34
glaciers to slowly melt. The melting of
0:37
these glaciers together with the melting
0:39
of the Greenland and Antarctic ice
0:42
sheets have been a major contributor to
0:45
rising sea levels globally.
0:48
Over the years, scientists have used a
0:51
variety of techniques to estimate the
0:54
area covered by the Earth's glaciers and
0:57
the equivalent amount of water contained
0:59
in those glaciers and to use repeated
1:03
observations of these quantities to
1:06
estimate how much the melting of the
1:08
world's glaciers is contributing to sea
1:11
level rise. Here I've listed the various
1:15
techniques used in the past to obtain
1:18
these estimates. To keep this video
1:21
short, I won't go into the details of
1:23
how each of these techniques work except
1:26
to say that each one has limitations.
1:30
The recently published paper in the
1:32
journal Nature reports the results of an
1:35
effort to bring together nearly all the
1:38
scientists who have been working on
1:40
these various glacier studies and to
1:43
carry out intercomparisons
1:45
that provide a better picture of the
1:48
area covered by all the world's glaciers
1:50
and most importantly how water content
1:54
of each of these glaciers is changing
1:57
with time.
2:00
The inner comparisons in the in the
2:03
Nature paper covered the 24-year period
2:06
from 2000 to 2023.
2:10
The detailed results of this study are
2:12
shown here. The 19 outer circles cover
2:15
the 19 regions of the Earth's surface
2:18
where significant glaciers are found.
2:21
The diameters of these circles are
2:23
proportional to the areas covered by
2:26
these glacier regions. And the red
2:29
wedges within the circles represent the
2:32
percentage of water lost from these
2:34
areas over the 24-year period. The red
2:38
wedge in the center circle represents
2:41
the percentage loss about 5.4%
2:45
of water globally from all these
2:48
glaciers over the 24-year period of the
2:50
study.
2:53
Both the cumulative water loss and the
2:56
annual water loss from the world's
2:58
glaciers over the 24-year period are
3:01
shown in this chart. The scale on the
3:04
left is for the cumulative loss, the
3:07
black line, while the scale on the right
3:10
is for the yearly losses, the pink bars.
3:13
If the world's glaciers were melting at
3:16
a steady rate, the cumulative loss would
3:19
be linear. But it's quite clear that the
3:22
black line is curving down with time,
3:25
indicating that the worldwide glacier
3:27
melt has been accelerating. The average
3:31
mass loss for melting glaciers over the
3:35
24-year period was 273
3:38
plus or minus 16 billion metric tons.
3:43
But the rate of loss was 36 plus or
3:46
minus 10% more uh during the second
3:50
12-ear period than during the first
3:53
12-ear period.
3:55
Note that the mass loss was not uniform
3:58
over the 19 regions in the study. 14 of
4:01
the regions experienced increased mass
4:04
loss. Three regions showed steady mass
4:08
loss and in two regions mass loss
4:11
decreased during the 24-year period.
4:15
In this chart, I have listed the major
4:18
contributions to global sea level rise
4:21
during the entire 24-year period covered
4:24
in the intercomparison study.
4:28
This results in an underestimate of
4:31
long-term global sea level rise from
4:33
glacia melt because we know that right
4:36
now rising global average surface
4:39
temperatures are responsible for about a
4:41
34%
4:43
faster melt during the latter half of
4:45
the study. At that rate, we would see
4:48
about 37 cm or about 15 inches of sea
4:54
level rise over the next century.
4:58
We don't know for certain how global
5:01
average surface temperatures are going
5:03
to change in the future, but right now
5:06
it seems unlikely that they're going to
5:09
level off or decline
5:12
during the next century. So we are
5:14
likely to see greater sea level rise in
5:17
the next 100 years than we have in the
5:21
past 100 years.
5:23
I should note that these are global
5:25
average numbers. Local nearshore changes
5:29
in sea level are are affected by several
5:32
factors including land subsidance,
5:35
changes in ocean currents, etc.
5:40
In closing, let me note some of the
5:43
consequences of glacier melting in
5:45
addition to the sea level rise that
5:48
threatens coastal residents and
5:50
low-lying regions. In many parts of the
5:53
world, glaciers are an important source
5:56
of fresh water. When glaciers shrink an
5:59
area, some of that source is lost. More
6:04
rapid glacier melt also can lead to
6:06
inland flooding and loss of habitat for
6:10
plants and animals. In addition,
6:13
glaciers reflect more of the incoming
6:16
sunlight than the surrounding areas. So,
6:19
as they shrink, the Earth warms more
6:22
rapidly.
6:24
I've also included here the link to the
6:26
journal article that I have based this
6:28
video on for those of you who may be
The melting of the world's glaciers is
0:03
the major contributor to sea level rise.
0:06
A paper recently published in the
0:09
journal Nature reports that the rate at
0:12
which the world's glaciers are melting
0:14
has increased significantly in recent
0:18
years. In this video, I examine the
0:21
implications of the increase in melting
0:24
for sea level rise.
0:28
Since the start of the industrial
0:30
revolution, increasing global
0:32
temperatures have caused the world's
0:34
glaciers to slowly melt. The melting of
0:37
these glaciers together with the melting
0:39
of the Greenland and Antarctic ice
0:42
sheets have been a major contributor to
0:45
rising sea levels globally.
0:48
Over the years, scientists have used a
0:51
variety of techniques to estimate the
0:54
area covered by the Earth's glaciers and
0:57
the equivalent amount of water contained
0:59
in those glaciers and to use repeated
1:03
observations of these quantities to
1:06
estimate how much the melting of the
1:08
world's glaciers is contributing to sea
1:11
level rise. Here I've listed the various
1:15
techniques used in the past to obtain
1:18
these estimates. To keep this video
1:21
short, I won't go into the details of
1:23
how each of these techniques work except
1:26
to say that each one has limitations.
1:30
The recently published paper in the
1:32
journal Nature reports the results of an
1:35
effort to bring together nearly all the
1:38
scientists who have been working on
1:40
these various glacier studies and to
1:43
carry out intercomparisons
1:45
that provide a better picture of the
1:48
area covered by all the world's glaciers
1:50
and most importantly how water content
1:54
of each of these glaciers is changing
1:57
with time.
2:00
The inner comparisons in the in the
2:03
Nature paper covered the 24-year period
2:06
from 2000 to 2023.
2:10
The detailed results of this study are
2:12
shown here. The 19 outer circles cover
2:15
the 19 regions of the Earth's surface
2:18
where significant glaciers are found.
2:21
The diameters of these circles are
2:23
proportional to the areas covered by
2:26
these glacier regions. And the red
2:29
wedges within the circles represent the
2:32
percentage of water lost from these
2:34
areas over the 24-year period. The red
2:38
wedge in the center circle represents
2:41
the percentage loss about 5.4%
2:45
of water globally from all these
2:48
glaciers over the 24-year period of the
2:50
study.
2:53
Both the cumulative water loss and the
2:56
annual water loss from the world's
2:58
glaciers over the 24-year period are
3:01
shown in this chart. The scale on the
3:04
left is for the cumulative loss, the
3:07
black line, while the scale on the right
3:10
is for the yearly losses, the pink bars.
3:13
If the world's glaciers were melting at
3:16
a steady rate, the cumulative loss would
3:19
be linear. But it's quite clear that the
3:22
black line is curving down with time,
3:25
indicating that the worldwide glacier
3:27
melt has been accelerating. The average
3:31
mass loss for melting glaciers over the
3:35
24-year period was 273
3:38
plus or minus 16 billion metric tons.
3:43
But the rate of loss was 36 plus or
3:46
minus 10% more uh during the second
3:50
12-ear period than during the first
3:53
12-ear period.
3:55
Note that the mass loss was not uniform
3:58
over the 19 regions in the study. 14 of
4:01
the regions experienced increased mass
4:04
loss. Three regions showed steady mass
4:08
loss and in two regions mass loss
4:11
decreased during the 24-year period.
4:15
In this chart, I have listed the major
4:18
contributions to global sea level rise
4:21
during the entire 24-year period covered
4:24
in the intercomparison study.
4:28
This results in an underestimate of
4:31
long-term global sea level rise from
4:33
glacia melt because we know that right
4:36
now rising global average surface
4:39
temperatures are responsible for about a
4:41
34%
4:43
faster melt during the latter half of
4:45
the study. At that rate, we would see
4:48
about 37 cm or about 15 inches of sea
4:54
level rise over the next century.
4:58
We don't know for certain how global
5:01
average surface temperatures are going
5:03
to change in the future, but right now
5:06
it seems unlikely that they're going to
5:09
level off or decline
5:12
during the next century. So we are
5:14
likely to see greater sea level rise in
5:17
the next 100 years than we have in the
5:21
past 100 years.
5:23
I should note that these are global
5:25
average numbers. Local nearshore changes
5:29
in sea level are are affected by several
5:32
factors including land subsidance,
5:35
changes in ocean currents, etc.
5:40
In closing, let me note some of the
5:43
consequences of glacier melting in
5:45
addition to the sea level rise that
5:48
threatens coastal residents and
5:50
low-lying regions. In many parts of the
5:53
world, glaciers are an important source
5:56
of fresh water. When glaciers shrink an
5:59
area, some of that source is lost. More
6:04
rapid glacier melt also can lead to
6:06
inland flooding and loss of habitat for
6:10
plants and animals. In addition,
6:13
glaciers reflect more of the incoming
6:16
sunlight than the surrounding areas. So,
6:19
as they shrink, the Earth warms more
6:22
rapidly.
6:24
I've also included here the link to the
6:26
journal article that I have based this
6:28
video on for those of you who may be
6:31
interested.
6:34
I hope that you have found this video
6:36
informative. If you have any questions,
6:39
please note them in the comment section
6:41
and I will do my best to respond. And if
6:44
you haven't already subscribed to the
6:46
this YouTube channel, please do so.
6:49
Also, take some time to view some of my
6:51
other climate related videos.
6:54
Again, I thank you for watching***
Dr. Mark H. Shapiro is professor emeritus of physics at California State University, Fullerton. "This channel includes my videos on climate change and current news events"
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