"The study drew on current research on sea-level rise, now growing at 1ft per decade." ]
Oh dear, I think I smell more green bullshite.
Still, it's a lot less than Flannery and ******'s prediction of a 30 meter rise over the next few years lol.
Having read the links, I have to agree with Baccheus. The Guardian article doesn't make this clear; perhaps the journalist mis-understood too.
As an analogy, consider a helium balloon, partially inflated. If you released it it could reach, say, 23000 feet, but only after a very long time. Yet its initial rate of climb might be say, 3.18 feet per second. In other words, there is the height it will eventually rise to and there is the observed rate of increase; the ceiling and the rate of climb, different numbers representing different things.
Similarly, with sea level rise, there is the maximum amount which will eventually be reached a couple of thousand years down the road, assuming C02 levels remain constant, and there is the rate of increase which is currently 3.18mm/year.
Now, considering the balloon again; if you were to add a little more helium, you would increase the height that the balloon would eventually reach. Similarly, if we add more CO2 to the atmosphere, we increase the height that sea levels will eventually reach. It is this final height that is increasing at 12 inches/decade, not the 3.18mm/year that we currently observe.
So what the Guardian article should have said is something like;
By the end of this century, more than 1,700 American cities and towns – including Boston, New York, and Miami – will have significant areas below the high-water mark in a couple of thousand years, if CO2 levels increase as predicted. ... and so on.
Hope that helps; as Baccheus says, it is cumbersome wording!
Re; your added details:
<
Again, we are talking of the total rise due to 1C as 2.3m, as against the observed rise of 0.3m to date. It is the oceans which need to warm before we see the maximum values of both sea level rise and air temperatures at the surface. Clearly this is a relatively slow process. In the balloon analogy, it will eventually reach 2300ft, even if it has only risen 300 feet so far.
So the reason we have only seen lower figures than the projections is that the warming from the CO2 we have already released has only just begun. Much is still as they say " in the pipeline".
I see that they have revised the Guardian article; hopefully it is now clearer to all what they were getting at.
Regarding the IPCC, I don't recall them making this kind of projection. Their frame of reference seems to be for the end of this century and based on a number of emission scenarios. I've had a quick look and as far as I can see, there is no contradiction between their work and that of Strauss.
http://www.ipcc.ch/publications_and_data...
his article is about the current and future rise in sea level associated with global warming. For sea level changes in Earth's history, see Sea level.
Trends in global average absolute sea level, 1870-2008.
Changes in sea level since the end of the last glacial episode.
Sea levels around the world are rising.Current sea-level rise potentially affects human populations (e.g., those living in coastal regions and on islands) and the natural environment (e.g., marine ecosystems).Between 1870 and 2004, global average sea levels rose 195 mm (7.7 in).From 1950 to 2009, measurements show an average annual rise in sea level of 1.7 ± 0.3 mm per year, with satellite data showing a rise of 3.3 ± 0.4 mm per year from 1993 to 2009, a faster rate of increase than previously estimated. It is unclear whether the increased rate reflects an increase in the underlying long-term trend.
Two main factors contributed to observed sea level rise. The first is thermal expansion: as ocean water warms, it expands. The second is from the contribution of land-based ice due to increased melting. The major store of water on land is found in glaciers and ice sheets.
Sea level rise is one of several lines of evidence that support the view that the climate has recently warmed. The global community of climate scientists confirms that it is very likely that human-induced (anthropogenic) warming contributed to the sea level rise observed in the latter half of the 20th century.
You are right to not trust the Guardian's wording. The study they refer to is behind a pay wall but if you want to avoid the fee, you can find the author's (Ben Strauss) explanation at his organizations site. According to Strauss, the long term sea level rise that we are already locked-into is growing at a rate of 1 foot per decade. Perhaps said better, every decade we are adding enough CO2 to the atmosphere that the final sea level rise will be one incremental foot.
http://www.climatecentral.org/news/sea-l...
We are currently contributing each decade to a 1 foot sea level rise in the future.
Cumbersome wording, I know.
***************************************...
Your rambling question concluded that you did not understand the difference between what Strauss was saying and the current 3.1 mm per year. You asked for help understanding, and I provided it. If you now look at the guardian article, you will seen that since I answered they have provided a correction at the bottom which says just what I had already explained. Your "reasoning" did not appear in your question so I could not possible have judged it. You said "I'm not getting this" and now both I and the Guardian have explained it to you.
The 1 ft per decade increase, since it is in the future, is an unverifiable hypothesis...a nice euphemism for unscientific bs.
Even the 3.1 mm /year figure quoted for the present is highly dubious. The measured change is about 1.7 mm / year. The rest is 'adjustments'. One of those adjustments is for the supposedly sinking sea floor. Another is for the 'steric' sea level increase. Thus, the 3.1 mm is a calculated, rather than measured, value.
Back home, they call stuff like this 'hocus pocus'.
If you take a planet like Earth that is covered by 70% water with two massive ice caps (Antarctica and Greenland) and warm it even by a little then sea level is going to rise as it has before during past interglacial's for natural reasons. But the same physics will apply if it is us that cause the warming.
The 3mm figure is one deniers like to throw around a lot, claiming it's tiny and indeed it is, but the problem is deniers are looking at a short period, the 3mm figure is only a about 20 years old (and it has grown slightly over that 20 years. The figure going back over the previous 100 years was more like 1.7mm per year. No mater what claims deniers may make up about this being a continuation of the end of the last ice age (glacial) the evidence doesn't support such a statement, it shows sea level rise rates slowing until they virtually stopped about 2000 years ago.
http://commons.wikimedia.org/wiki/File:H...
The current "tiny" 3.16mm per year is on the scale of the above graph 3.16m per thousand years, clearly a rate not seen in the data for ~7000 years and so far that rate has been caused by a rise in average temperature of just 0.8c.
If we get the minimum estimate of the IPCC by the end of the century then we are looking at a rise in temperature of 2-3c, what will follow such a rise is also clearly an increase in the rate of rise, thermal expansion is a physical fact, there is some play in the rate ice will melt at, so the models try to estimate a range, on what has happened so far the minimum rise now looks to be about 1m. At the current rate (without any increase) it would take about 300 years to see a 1m rise but given that sea level almost doubled in the space of 20 years (from the early 1990's onwards) from 1.7mm to 3.16mm, it would only have to do this twice more over the next 70 years to reach a figure that would be a little over 1m.
http://www.cmar.csiro.au/sealevel/sl_his...
Given that as ice melts it exposes more land and sea, that can then absorb more energy from the Sun and in the case of permafrost releasing more methane and Co2 this will only add to the effect, which will increase temperature and increase the rate of ice melt and in turn sea level rise further.
And while deniers fixate about Antarctic sea ice, data shows Antarctic glacial ice is melting
http://climate.nasa.gov/key_indicators#l...
As is Greenland ice and it only needs a contribution of about 1.5% of both of these to raise global sea level ~1m (without help from thermal expansion)
Sea level fluctuates on a short term basis, but is currently running above the long term average, (as the CSIRO graph shows) whether this is the start of the next increase only time will tell, but it certainly does not show this 15 years of cooling deniers have simply invented.
On the data so far 2013 is running as the 7th warmest year on record based on the January–June data for Land and Ocean, i.e. 50% of the year.
http://www.ncdc.noaa.gov/sotc/global/201...
Everyone would be yawning if they said an inch a decade so IMO they said a foot a decade without regard to facts. There are some cities such New Orleans that are largely below sea level due to subsiding basin soils but it becomes ludicrous when they suggest cities like Miami and New York are significantly threatened.
It depends who you listen to. Helen Cullen said 3 feet at a hearing . But all her predictions never happen ? And what do they base their Calculations on a Computer Model
with the worst possible scenario? History ? Math ?
A religious belief in Global Warming?
Have you ever considred that sea level rise could be non linear?
I find it funny that people say that climate is too complex to understand, and yet think that they can use linear extrapolation of sea level rise to predict how high it will be the next century.
From a recent Guardian article:
"A significant number of people in 1,700 American cities and towns will be living below sea-level by 2100"
"But dramatic cuts in emissions – much greater than Barack Obama and other world leaders have so far agreed – could save nearly 1,000 of those towns, by averting the sea-level rise, the study fund."
"The study drew on current research on sea-level rise, now growing at 1ft per decade."
http://www.guardian.co.uk/environment/2013/jul/29/climate-new-york-boston-miami-sea-level?CMP=twt_fd
As is usual, it's hard to take the Guardian at their exact word for articles like this so I've already done some legwork and dug up the two main scientific studies:
http://assets.climatecentral.org/pdfs/Strauss-PNAS-2013.pdf
http://www.marzeion.info/sites/default/files/levermann_etal_13.pdf
I'm still not getting most of this. First, I did not know nor have I seen support for a sea level rise growing at 1ft/decade. The most common number I see is about 3mm/year which is just over an inch per decade. Second, the Levermann study concerns a timescale of 2000 years while the Strauss commentary is less than 100 years (i.e. out to the year 2100).
If anyone can sort this out, please show your work.
