Melting ice the greatest factor in rising sea levels

Jul 04, 2012 by Justin Norrie
Scientists have a better understanding of the contribution of melting glacier and ice sheets to sea level rise, but much remains uncertain. Flickr/ChrisGoldNY

Melting glaciers and ice sheets have contributed more to rising sea levels in the past decade than expansion from warming water, according to modelling in the latest report by the Antarctic Climate and Ecosystems (ACE) Cooperative Research Centre.

Before 2000 was the biggest factor in rising sea levels.

The shift was “a fairly sure sign that you’re getting out of the normal balance”, said report author Dr John Hunter, an oceanographer and expert in at the ACE.

Report Card: Sea Level Rise 2012 provides a summary of the past decade of peer-reviewed scientific research into rise, and is the most recent update since a report in 2008.

During the 20th century sea levels rose at a rate unmatched for 6,000 years, the report says. Satellite measurements have confirmed the global average rise of 1.9mm a year, as measured in tide gauges. “This present sea-level rise is due to a combination of thermal expansion of a warming ocean and the melting of glaciers and ice sheets.”

Dr Hunter explained that modelling had improved since the last update, at which time the contribution to sea levels from and ice sheets was not well understood.

“We’ve been better able to match up two things: observed sea level rises – which we get by looking at tide gauges until about 20 years ago, then after that tide gauges and also records from satellites – and estimates of sea level rises, which we get by looking at ocean temperatures and observing ice on land, the two biggest components, among other things,” Dr Hunter said.

“If we can get those estimates to agree with the observations from tide gauges and satellites, then we have a good understanding of sea level rise. At the time of the last assessment, that wasn’t all that well done, and we didn’t know very much about ice. We’ve got a better understanding now.”

But estimating the future rate of ice loss from the Greenland and Antarctic ice sheets remained the largest uncertainty in projecting sea-level rise over the next century, he said.

From 1993 to 2009, reconstructed tide-gauge data shows a rise of 2.8mm per year and satellite data shows a rise of 3.2mm per year.

Since 1972, thermal expansion contributed about 45% to total sea level rise, glaciers and ice caps another 40%, with most of the remainder from the ice sheets, the report says. Since 1993 the contribution of the ice sheets to sea-level rise has increased to about 30%.

The Intergovernmental Panel on Climate Change has estimated that projected sea level rise over the next century could vary from about 10-20cm to about 80cm.

Dr Hunter said it was “only just about now that we’re starting to observe melting from ice is starting to overtake thermal expansion. If you disturb the earth, the first thing that happens is that you just get thermal expansion from the heating of the water, and there’s quite a lag before melting from the ice starts to kick in, and eventually the ice becomes a greater contributor. This is always a fairly sure sign that you’re getting out of the normal balance.”

The two biggest impacts of the level will be flooding from inundation along hard shoreline, and coastal recession along soft shoreline, the report says. A relatively modest increase in mean sea level of 50cm will increase the frequency of flooding by a factor of roughly 300.

“In Australia we’re reasonably lucky in that the projections for inundation are pretty close to the global average,” Dr Hunter said, meaning sea level would be around 38cm higher in 2090 than in 1990. “On the east coast, where the water is warmer, the rise will be slightly greater than on the west coast – by 10cm to 20cm – by the end of the century.”

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User comments : 15

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NotParker
2.3 / 5 (6) Jul 04, 2012
Tide Gauges say Sea Level rise decelerated during 20th Century.

http://www.theaus...99350056

http://www.jcronl...-00157.1
djr
4.4 / 5 (7) Jul 05, 2012
From your own article Parker -

"What we are seeing in all of the records is there are relatively high rates of sea-level rise evident post-1990, but those sorts of rates of rise have been witnessed at other times in the historical record," he said.

"What remains unknown is whether or not these rates are going to persist into the future and indeed increase."
Vendicar_Decarian
2.4 / 5 (5) Jul 05, 2012
Figure 1 from ParkerTard's own references - link 2 - contradicts his own assertion (below).

Figure 1 clearly shows an acceleration in Ocean expansion as evidenced by the upward curvature in the plot.

"Tide Gauges say Sea Level rise decelerated during 20th Century." - ParkerTard

ParkerTard is mentally diseased and is now do demented that he is reporting contradictions to his own statements to support those statements.
Vendicar_Decarian
2.8 / 5 (6) Jul 05, 2012
Parker Tard's first link is to an article that uses 3 tidal gates in Australia to draw conclusions concerning the overall rise in oncean level.

This is not wise, since different regions of he ocean are rising at different rates.
NotParker
2.6 / 5 (5) Jul 05, 2012
Parker Tard's first link is to an article that uses 3 tidal gates in Australia to draw conclusions concerning the overall rise in oncean level.


Four.

The other paper: "we analyze monthly-averaged records for 57 U.S. tide gauges"

"It is essential that investigations continue to address why this
worldwide-temperature increase has not produced acceleration
of global sea level over the past 100 years, and indeed why
global sea level has possibly decelerated for at least the last
80 years."

The people who work in ports around the world laugh at claims of large sea level rise. Because it isn't happening.

djr
3.5 / 5 (6) Jul 06, 2012
"The people who work in ports around the world laugh at claims of large sea level rise. Because it isn't happening."

Do you have a source for that profound observation? I have a source - from an article that you linked - you might want to read it!

"What we are seeing in all of the records is there are relatively high rates of sea-level rise evident post-1990, but those sorts of rates of rise have been witnessed at other times in the historical record," he said.

"What remains unknown is whether or not these rates are going to persist into the future and indeed increase."
NotParker
2.6 / 5 (5) Jul 06, 2012
In all cases, it is clear that sea-level rise, although occurring, has been decelerating for at least the last half of the 20th century, and so the present trend would only produce sea level rise of around 15cm for the 21st century."

Dr Brady said the divergence between the sea-level trends from models and sea-level trends from the tide gauge records was now so great "it is clear there is a serious problem with the models".

"In a nutshell, this factual information means the high sea-level rises used as precautionary guidelines by the CSIRO in recent years are in essence ridiculous"

Ridiculous is correct.
Vendicar_Decarian
2.8 / 5 (6) Jul 06, 2012
And yet your own reference shows that your claim is a lie.

Figure 1 from...

http://www.jcronl...-00157.1

"In all cases, it is clear that sea-level rise, although occurring, has been decelerating for at least the last half of the 20th century." - ParkerTard

Poor ParkerTard. His mental disease causes him to refuse to read and comprehend his own reference.

Who is paying him to post his delusional nonsense here?
Vendicar_Decarian
2.6 / 5 (5) Jul 06, 2012
He is referring of course to 3 tidal gauges in Australia, which don't agree with the satellite data either.

At an average of about 5 millimetres per year, sea levels are rising faster around Australia since 1993 than the global average. And the rate of sea-level rise varies around the coast of Australia.

In the north and north-west, sea levels are rising between 7 and 11 millimetres per year since 1993 that's two to three times the global average. On the central east coast and areas to the south of Australia rates are mostly similar to the global average.

http://www.abc.ne...1166.htm

"Dr Brady said the divergence between the sea-level trends from models and sea-level trends from the tide gauge records was now so great "it is clear there is a serious problem with the models"." - ParkerTard
Vendicar_Decarian
2.6 / 5 (5) Jul 06, 2012
And once again, we find when we look that Pareker Tard's own reference is based on a paper that claims the opposite.

In this instance, figure 1 (again)

http://www.jcronl...-00157.1

"It is essential that investigations continue to address why this
worldwide-temperature increase has not produced acceleration
of global sea level over the past 100 years, and indeed why
global sea level has possibly decelerated for at least the last
80 years." - ParkerTard

Hahahaha... You leave out that the "deceleration" that those researches propose is 2 orders of magnitude lower than the expansion rate and is statistically insignificant based on their own analysis.

Poor ParkerTard. None of his own references actually support his position yet because of his mental disease he continues to cling to the story that they do.

Get psychological help ParkerTard. Your mental disease might cause you to harm someone.
NotParker
2.3 / 5 (6) Jul 06, 2012
"In all cases, it is clear that sea-level rise, although occurring, has been decelerating for at least the last half of the 20th century, and so the present trend would only produce sea level rise of around 15cm for the 21st century."

"In a nutshell, this factual information means the high sea-level rises used as precautionary guidelines by the CSIRO in recent years are in essence ridiculous"

Ridiculous is correct.
Vendicar_Decarian
2.8 / 5 (6) Jul 06, 2012
And once again, we find when we look that Pareker Tard's own reference is based on a paper that claims the opposite.

In this instance, figure 1 (again)

http://www.jcronl...-00157.1

"It is essential that investigations continue to address why this
worldwide-temperature increase has not produced acceleration
of global sea level over the past 100 years, and indeed why
global sea level has possibly decelerated for at least the last
80 years." - ParkerTard

Hahahaha... You leave out that the "deceleration" that those researches propose is 2 orders of magnitude lower than the expansion rate and is statistically insignificant based on their own analysis.

Poor ParkerTard. None of his own references actually support his position yet because of his mental disease he continues to cling to the story that they do.

Get psychological help ParkerTard. Your mental disease might cause you to harm someone.
NotParker
2.3 / 5 (6) Jul 06, 2012
http://www.jcronl...-00157.1

"It is essential that investigations continue to address why this
worldwide-temperature increase has not produced acceleration
of global sea level over the past 100 years, and indeed why
global sea level has possibly decelerated for at least the last
80 years."
Vendicar_Decarian
not rated yet Jul 09, 2012
And once again, we find when we look that Pareker Tard's own reference is based on a paper that claims the opposite.

In this instance, figure 1 (again)

http://www.jcronl...-00157.1

"It is essential that investigations continue to address why this
worldwide-temperature increase has not produced acceleration
of global sea level over the past 100 years, and indeed why
global sea level has possibly decelerated for at least the last
80 years." - ParkerTard

Hahahaha... You leave out that the "deceleration" that those researches propose is 2 orders of magnitude lower than the expansion rate and is statistically insignificant based on their own analysis.

Poor ParkerTard. None of his own references actually support his position yet because of his mental disease he continues to cling to the story that they do.

Get psychological help ParkerTard. Your mental disease might cause you to harm someone.
NotParker
1 / 5 (1) Jul 09, 2012
http://www.jcronline.org/doi/pdf/10.2112/JCOASTRES-D-10-00157.1

"It is essential that investigations continue to address why this
worldwide-temperature increase has not produced acceleration
of global sea level over the past 100 years, and indeed why
global sea level has possibly decelerated for at least the last
80 years."


Please read the paper. Educate yourselves.

There is no dangerous sea level rise. It is rising very slowly and that rise is decelerating.