Sea Level Rise: New Measurements from GRACE Satellites

In summary, the latest paper suggests that ocean thermal expansion has slowed, leading to a plateau in sea level rise. This is contrary to global warming theory, which predicts an accelerating rise in sea level. However, the measurements are not accurate and it is likely that the trend is insignificant. Nonetheless, the sea level is still rising and it is likely that another ice age will occur soon enough as the Milankovitch cycle (earth's tilt, wobble and orbit shape) changes along with sunspot activity levels.
  • #1
Andre
4,311
74
There is a new paper about it, the results of the measurements of the GRACE satellites on the sea level changes.

http://sciences.blogs.liberation.fr/home/files/Cazenave_et_al_GPC_2008.pdf [Broken]

Good news.

From the IPCC 4th Assessment Report published in 2007, ocean thermal expansion contributed by ∼50% to the 3.1 mm/yr observed global mean sea level rise during the 1993–2003 decade, the remaining rate of rise being essentially explained by shrinking of land ice. Recently published results suggest that since about 2003, ocean thermal expansion change, based on the newly deployed Argo system, is showing a plateau while sea level is still rising, although at a reduced rate (∼2.5 mm/yr).
 
Last edited by a moderator:
Earth sciences news on Phys.org
  • #2
Very interesting.

If ocean thermal expansion has slowed, then that would mean it is not absorbing as much heat as it was previously. So, where is the heat going?

An interesting calculation would be to determine how much sea level would rise for a BTU going into thermal expansion compared to melting land based ice.
 
  • #3
Xnn said:
Very interesting.

If ocean thermal expansion has slowed, then that would mean it is not absorbing as much heat as it was previously. So, where is the heat going?

Yes, very interesting Andre. My first thought of 'where is the heat going?' was due to an increase in tidal deep-ocean overturning i.e. mixing with colder bottom waters. I have yet to read the report in full though.
 
Last edited:
  • #4
Andre said:
There is a new paper about it, the results of the measurements of the GRACE satellites on the sea level changes.

http://sciences.blogs.liberation.fr/home/files/Cazenave_et_al_GPC_2008.pdf [Broken]

Good news.

Why good news??

Afterall, the sea level is still rising.
 
Last edited by a moderator:
  • #5
This seems a bit at odds with 'global warming science/theory' surely the rise should be accelerating? CO2 has increased year on year surely?

Measuring the rise might not be an accurate method of measurung temperatue though, it depends on the shape of the container (amongst other things).

Anyway it's been as cold this winter here as I can remember, it seems more like global cooling around these parts :smile:

I tend to be rather sceptical, measuring one variable in a highly complex system and making huge projections from that seems to be rather a rather poor method of prediction, indeed the expression 'waste of time' springs to mind!

When you throw in another raft of simiilar predictions/assumptions, well... I think our would have more success predicting the outcome of the lottery.
 
  • #6
cripto88 said:
This seems a bit at odds with 'global warming science/theory' surely the rise should be accelerating? CO2 has increased year on year surely?


Part of the problem is that it is very difficult to accurately measure changes in sea level over short periods of time. Afterall, the oceans are not perfectly flat. There are all types of waves along with tides and surges. Storms can also push water around and shifting weather patterns can lower levels in some areas while raising it in others. Land masses can also move up or down and even the continents themselves move a little from plate tectonics.

So, it is possible that the change in the trend is insignificant and instead our measurements are more accurate than before.

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter5.pdf
 
  • #7
Xnn said:
Part of the problem is that it is very difficult to accurately measure changes in sea level over short periods of time. Afterall, the oceans are not perfectly flat. There are all types of waves along with tides and surges. Storms can also push water around and shifting weather patterns can lower levels in some areas while raising it in others. Land masses can also move up or down and even the continents themselves move a little from plate tectonics.

So, it is possible that the change in the trend is insignificant and instead our measurements are more accurate than before.

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter5.pdf


Another way of reading that is that 'part of the problem is that most our data is unreliable'.
 
Last edited by a moderator:
  • #9
Don't worry: Milankovitch cycle (earth's tilt, wobble and orbit shape) changes along with sunspot activity levels will insure another ice age soon enough...go get a suntan while you can.
 
  • #10
Naty1 said:
Don't worry: Milankovitch cycle (earth's tilt, wobble and orbit shape) changes along with sunspot activity levels will insure another ice age soon enough...
Really? How soon?
 
  • #11
Don't worry: Milankovitch cycle (earth's tilt, wobble and orbit shape) changes along with sunspot activity levels will insure another ice age soon enough...

Really? How soon?

I would guess the best way to judge is to look at historical cycles...likely they will repeat for the eight hundred and twenty sixth time (I just made that up I don't know how many recorded cycles have good supporting evidence) again. Somehow Earth gets into periods of significant ice and again remerges, without mankind even being present, all on its own...even without high C02 levels.
 
  • #12
cripto88 said:
This seems a bit at odds with 'global warming science/theory' surely the rise should be accelerating? CO2 has increased year on year surely?
It's a complex system as you say, so this rise might have increased mixing and brought colder denser water nearer the surface.

Measuring the rise might not be an accurate method of measurung temperatue though, it depends on the shape of the container (amongst other things).
True but sea level rise is the most worrying effect. A 0.4C change in temperature is not a big deal locally, but even a 1/2m rise in sea level is a big deal for a lot of cities like New York or London.

Anyway it's been as cold this winter here as I can remember, it seems more like global cooling around these parts :smile:
That's why it's better to call it climate change rather than global warming.
Here in the Pacific North West it's likely to mean more snow, a warmer Pacific means more evaporation so more clouds and a 0.4C temperature rise is still going to leave that water falling as snow. But inland, reduced cloud cover could mean colder temperatures for the midwest (only an example - not a detailed model)

I tend to be rather sceptical, measuring one variable in a highly complex system and making huge projections from that seems to be rather a rather poor method of prediction, indeed the expression 'waste of time' springs to mind!
Dumping a few trillion watts of extra energy into a system is going to have an effect - predicting those effects and how they interact is tricky. But it is going to have an effect.
 
  • #13
Gokul..thanks for posting:
Physics Forums Guidelines and Privacy Policy
See this thread for writing Math expressions using LaTeX.
Links to useful shortcuts: BB Code, Hotkeys and Smilies

I had not noticed those before...
 
  • #14
Naty1 said:
I would guess the best way to judge is to look at historical cycles...likely they will repeat for the eight hundred and twenty sixth time (I just made that up I don't know how many recorded cycles have good supporting evidence) again. Somehow Earth gets into periods of significant ice and again remerges, without mankind even being present, all on its own...even without high C02 levels.
You still haven't asnwered the question of "how soon?".

Is "soon enough" going to happen over the next few decades or centuries or millenia or many tens of millenia?
 
  • #16
Gokul43201 said:
You still haven't asnwered the question of "how soon?".

Is "soon enough" going to happen over the next few decades or centuries or millenia or many tens of millenia?

Good question. This article explains.
 
  • #17
Mammo said:
Good question. This article explains.

Dissimilarly, this article explains that anthropogenic greenhouse gasses will delay coming ice ages, by something like half a million years.
 
  • #18
Bored Wombat said:
Dissimilarly, this article explains that anthropogenic greenhouse gasses will delay coming ice ages, by something like half a million years.

I actually agree with your article. See my thread starter 'Did AGW Start Thousands of Years Ago?'
 

1. How are GRACE satellites used to measure sea level rise?

GRACE (Gravity Recovery and Climate Experiment) satellites use a technique called satellite altimetry to measure sea level rise. They are able to detect changes in ocean height by measuring the distance between the satellite and the ocean surface using a radar signal.

2. What is the accuracy of the sea level rise measurements from GRACE satellites?

The accuracy of the sea level rise measurements from GRACE satellites is within a few millimeters. This is due to the fact that the satellites are able to detect even small changes in the Earth's gravitational field, which is directly related to changes in sea level.

3. How frequently are the sea level rise measurements from GRACE satellites updated?

The sea level rise measurements from GRACE satellites are updated on a monthly basis. This allows for more accurate and timely monitoring of sea level rise around the world.

4. How do GRACE satellite measurements compare to other methods of measuring sea level rise?

GRACE satellite measurements provide a comprehensive and global view of sea level rise, whereas other methods such as tide gauges and buoys may only provide local measurements. GRACE satellites also have the advantage of being able to measure changes in sea level over time, whereas other methods may only provide a snapshot in time.

5. What do the latest GRACE satellite measurements reveal about sea level rise?

The latest GRACE satellite measurements show that sea level has been rising at an average rate of 3.3 millimeters per year over the past two decades. This is faster than previous estimates and is a cause for concern for coastal communities and low-lying areas around the world.

Similar threads

  • Earth Sciences
Replies
10
Views
4K
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
10
Views
1K
  • Introductory Physics Homework Help
Replies
13
Views
6K
Replies
73
Views
13K
Writing: Input Wanted Great Lakes Earth Map
  • Sci-Fi Writing and World Building
Replies
6
Views
2K
  • Earth Sciences
Replies
10
Views
8K
Replies
28
Views
27K
Writing: Read Only Great Lakes Earth
  • Sci-Fi Writing and World Building
Replies
1
Views
3K
Replies
2
Views
3K
Back
Top