|The New NOAA|
In today's post let's take some data from recent science, then try to determine, using percentages, a projection of sea level rise (SLR).
The difficulty with calculating and then projecting the future dynamics of the ongoing SLR, all around this globe, is complicated by the nature of water.
Ocean water expands when it is warmed, as well as when it is frozen into ice, but, in addition to those thermal factors, the capacity and rate of expansion of ocean water is also determined by content, such its salinity levels, which is how much salt there is in a particular region of ocean's water.
What, then, are the most important factors that contribute to global SLR?
II. The Ratio and the Relation
First off, a recent paper indicates that in some senses it is a 50/50 scenario:
"Sea level rise is half due to melting ice and half due to ocean warming, including 13% from the deepest oceans, a new paper has found(New Research Reveals What's Causing Sea Level To Rise, emphasis added). That science writer's take on it is corroborated with this post:
The researchers recognised that changes to sea levels are mainly caused by thermal expansion of ocean waters as they heat, changes to the saltiness of water, and an increase in ocean waters as ice melts and flows into the sea."
"[SLR] reveals a lot about our changing climate. A rise in the mean sea level can be caused by decreases in ocean density, mostly reflecting an increase in ocean temperature — this is steric sea level rise. It can also be caused by an increase in ocean mass, reflecting a gain of fresh water from land. A third, and smaller, contribution to mean sea level is from glacial isostatic adjustment. The contribution of glacial isostatic adjustment, while small, has a range of possible values and can be a significant source of uncertainty in sea level budgets. Over recent decades, very roughly half of the observed mean sea level rise is owing to changes in ocean density with the other half owing to the increased in ocean mass, mostly from melting glaciers and polar ice sheets. The exact proportion has been difficult to pin down with great(Diagnosing Causes of Sea Level Rise, emphasis added). The mix is driven by global warming induced climate change, including changing rates of warming.
It is a roller coaster ride
Knowing the proportion of sea level rise (SLR) owing to mass addition versus thermal expansion is not only important for quantifying total SLR. Each component also imparts information about the effects of climate change. First, the ocean absorbs over 90% of the excess heat from greenhouse gas forcing. In order to monitor and model global warming accurately, we need to know where and how much heat is entering the ocean, and which is directly (although nonlinearly) related to steric SLR. Sea level rise is an important consequence of climate change, and quantifying rates of melting of land ice, including contributions from the massive Greenland and West Antarctica ice sheets is vital to understanding sea level rise. Knowing local rates of past SLR and what is driving those rates will help to improve global and local projections of SLR that are essential for informing adaptation strategies in coastal communities.
III. Quantifying the Maximum Potential SLR
The following table, prepared using USGS data, shows the maximum SLR possible from ice melt alone, and the locations of those potentials:
Table 1. Estimated potential maximum sea-level rise from the total melting of present-day glaciers and polar ice caps. Source: USGS
|Potential sea-level rise, |
|Percent of total|
|East Antarctic ice sheet|| |
|West Antarctic ice sheet|| |
|Antarctic Peninsula|| |
|All other (ice caps, ice fields, glaciers)|| |
NOTE: thermal sea level rise (caused when this ice melt water becomes ocean water, then heats up & expands) is not included in Table 1.
One thing occurred to me immediately: if the two factors, 1) the quantity of SLR caused by water melt from all sources entering the oceans, and 2) the thermal expansion thereafter, are added together would increase the SLR above the 263.5 feet figure.
IV. Quantifying and Timing the Rates of SLR
Another thing that occurred to me is that this 50/50 ratio is historical, i.e. "over recent decades," according to the articles quoted, which begs the question, how long will the 50/50 ratio hold?
I think that has been answered in principle in an earlier post of this series, quoting the Union of Concerned Scientists:
(Union of Concerned Scientists). Thus, it is like the race between the tortoise and the hare, or any NASCAR race for that matter, which is to say that the lead changes from time to time.
Sea level is rising — and at an accelerating rate — especially along the U.S. East Coast and Gulf of Mexico
Human activities, such as burning coal and oil and cutting down tropical forests, have increased atmospheric concentrations of heat-trapping gases and caused the planet to warm by 1.4 degrees Fahrenheit since 1880.
- Global average sea level rose roughly eight inches from 1880 - 2009.
- The average annual rate of global sea level rise accelerated from 1993 - 2008, increasing 65 - 90 percent above the twentieth century average.
- The U.S. East Coast and Gulf of Mexico experienced some of the world's fastest rates of sea level rise in the twentieth century due to local and regional factors.
- From 1880 - 2009, Miami faced 12 inches of local sea level rise; Boston, New York, and Charleston, SC, 13 to 16 inches; Virginia Beach, 30 inches; and Galveston, TX, nearly three feet.
- Rising temperatures are warming ocean waters, which expand as the temperature increases. This thermal expansion was the main driver of global sea level rise for 75 - 100 years after the start of the Industrial Revolution, though its relative contribution has declined as the shrinking of land ice has accelerated.
- Land ice—glaciers, ice caps, and ice sheets—is shrinking at a faster rate in response to rising temperatures, adding water to the world's oceans.
- As the rate of ice loss has accelerated, its contribution to global sea level rise has increased from a little more than half of the total increase from 1993 - 2008 to 75 - 80 percent of the total increase between 2003 - 2007 [recent papers: it is evening out]
That dynamic is easy to envision if we follow the flow of water from melt in Greenland or Antarctica to the point it has concluded its 100% melt contribution.
When it first enters the ocean it is ice cold melt, but when ocean currents later move that ice cold water into areas of more sunlight, as well as into already warmer waters, that ice cold water is going to go through thermal expansion as it warms up.
The delay between contribution to sea level rise by merely entering the ocean (the first part of the total) and contribution due to thermal expansion (the second part of the total) will vary depending on location of entry, then the eventual destination determined by the ocean currents in that area.
Another complication is that surges will take place from time to time, as was pointed out recently:
Why wouldn't they when this, among a hundred other climate changes, is happening:(Agnotology: The Surge - 16). This 2.52 inch a year surge was a local phenomenon, however, we also have evidence that it can happen on a broader scale:
Coastal sea levels along continental margins often show significant year-to-year upward and downward fluctuations. These fluctuations are superimposed on a longer term upward trend associated with the rise in global mean sea level, with global mean sea level rising at roughly 3 mm per year during the recent 20 years of accurate satellite measures. For society, it is the regional changes along any particular coastal zone that are most important. Our analysis of multi-decadal tide gauge records along the North American east coast identified an extreme sea-level rise event during 2009–2010. Within this relatively brief two-year period, coastal sea level north of New York City jumped by up to 128 mm [5.05 inches]. This magnitude of inter-annual sea level rise is unprecedented in the tide gauge records, with statistical methods suggesting that it was a 1-in-850 year event.(NOAA, An Extreme Event of Sea-level Rise, emphasis added). In other words, in the language of the warrior congress, "a surge."
The rate of sea level rise has been consistently underestimated by conservative scientists who don't want any surge of fear in the sheeple (cf. here and here).
That recent study shows how large the underestimations have been, because they incessantly fail to consider acceleration in ice sheet melts, along with other cumulative events in a damaged climate system.
The 128mm (5.04 inches) sea level rise in only two years is 2.52 inches per year, or 25.2 inches (2 ft. 1.2 in.) over ten years.
It is 85 years until 2100, by which time conservative scientists have said that a six foot sea level rise could take place (3 ft. says IPCC).
But, if there is a global 2.52 inch surge in only half (42.5) of those 85 years, the sea levels could rise about nine feet (2,52 * 42.5 = 107.1 in. / 12 = 8.93 ft.) --instead of only about six feet (the high estimate; 3ft. is the lower IPCC estimate).
Conservative as 3 ft. is, still that is a serious rate of sea level rise, which could accelerate, because among other things even the underlying non-surge rate is accelerating (Water, Water, Everywhere: Sea Level Rise in Miami).
On May 22nd, 2014, global sea surface temperature anomalies spiked to an amazing +1.25 degrees Celsius above the, already warmer than normal, 1979 to 2000 average. This departure is about 1.7 degrees C above 1880 levels — an extraordinary reading that signals the world may well be entering a rapid warming phase.(Global Sea Surface Temperatures Increase). The acceleration can be periodic over a longer span of time as well:
It is very rare that land or ocean surface temperatures spike to values above a +1 C anomaly in NOAA’s Global Forecast System model summary. Historically, both measures have slowly risen to about +.35 C above the 1979 to 2000 average and about +.8 C above 1880s values (land +1 C, ocean +.6 C). But since late April, sea surface temperatures have remained in a range of +1 C above 1979 to 2000 values — likely contributing to NOAA and NASA’s temperature indexes hitting first and second hottest in the climate record for the month. During May, ocean surface heating entrenched and expanded, progressing to a new high of +1.17 C last week. As of this week, values had exceeded +1.2 C and then rocketed on to a new extreme of +1.25 C (See Deep Ocean Warming is Coming Back to Haunt Us).
"Since the beginning of the 20th century, the seas have continued to rise at an average rate of 1.7 ± 0.5 mm per year, according to the IPCC ... first noted increase ... 1963 ... 1.8 ± 0.5 mm per year ... 1993 to 2003 ... 3.1 ± 0.7 mm yr ..."(Wunderground). The surge and acceleration factors, whether atmospheric, land, or oceans, are serious complications in terms of trying to be exact at predictions of future SLR.
But one thing is sure, the past attempts at predictions have all resulted in underestimations.
V. Attempts Based On Percentages
The rate of loss of ice is currently:
Measurements from ESA’s CryoSat mission have been used to map the height of the huge ice sheets that blanket Greenland and Antarctica and show how they are changing. New results reveal combined ice volume loss at an unprecedented rate of 500 cubic kilometres a year.(ESA Cryosat, emphasis added). What if we take that current ice melt rate (500 km3), based on volume of ice melt in Greenland (375 km3) and Antarctica (125 km3), then build an estimate based on that acceleration (e.g. doubling during the period from Jan 2009 to Dec 2013)?
The resulting maps reveal that Greenland alone is reducing in volume by about 375 cubic kilometres a year.
The researchers say the ice sheets’ annual contribution to sea-level rise has doubled since 2009. [Table 1 type contribution - i.e. thermal sea level rise (additional) is not included in that doubling]
Glaciologist Angelika Humbert, another of the study’s authors, added, “Since 2009, the volume loss in Greenland has increased by a factor of about two and the West Antarctic Ice Sheet by a factor of three."
VI. Ice Loss Volume Percentages
A. The 14.87% Formula
Let's use a formula L = [ (f / s)(1 / y) ] - 1 to calculate the annual-loss growth-rate percentage over multiple years:
Where:Ok, that checks out.
L = ice-volume-loss per yearL = [(500/250)(1/5)] - 1
f = final volume of loss-per-yr (~500 km3)
s = starting volume of loss-per-yr (~250 km3), i.e. half
y = number of years (~5)
L = (2.2) - 1
L = 1.148698355 - 1
L = .148698355
L = 14.87% annual ice loss increase Jan. 2009 thru Dec. 2013
2009) 250 x 1.148698355 = 287.17458875
2010) 287.17458875. x 1.148698355 = 329.876977695
2011) 329.876977695 x 1.148698355 = 378.929141631
2012) 378.929141631 x 1.148698355 = 435.275281653
2013) 435.275281653 x 1.148698355 = 500.000000006
B. The Annual SLR Rate Differences
It seems, then, that the doubling of the melt of polar ice from Jan. 2009 thru Dec. 2013 may be a rare surge rather than a trend (we better hope so as the graphs below show) or it could be because of faster-melting coastal ice.
A final observation using Table 1 figures:
32,328,300 km3 (total ice volume)Note that the 4.37% and 4.08% are estimated acceleration rates such as in previous IPCC reports (e.g. 4th Assessment) that are not tied to polar melt.
32,328,300 km3 − 180,000 km3 = 32,148,300 km3 (polar ice only)
500 km3 (loss per yr. now) ÷ 321,48,300 km3 = 0.000015553
263.5 ft. (total SLR potential)
263.5 ft. − 1.48 ft. = 262.02 (total polar SLR potential)
262.02 ft. * 0.000015553 = 0.004075197 SLR now (polar only)
IPCC estimate of SLR by 2100 (~38 in.):
Using the formula above SLR = [ (f / s)(1 / y) ] - 1 (in section "A")
SLR = rise per yearFor a 4.37% rate:
f = final rise-per-yr
s = starting rise-per-yr
y = number of years
SLR = [ (f / s)(1 / y) ] - 1
SLR = [ (38 / 1)(1 / 85) ] - 1
SLR = [ 380.011764706 ] - 1
SLR = 1.0437240469945364 - 1
SLR = .0437240469945364
SLR = 4.37% (acceleration rate yr.)
For a 4.08% rate:
SLR = [ (f / s)(1 / y) ] - 1
SLR = [ (38 / 1.265)(1 / 85) ] - 1
SLR = [ 30.040.011764706 ] - 1
SLR = 1.0408417523769657 - 1
SLR = .0408417523769657
SLR = 4.08% (acceleration rate yr.)
Never-the-less, with that in mind note that these rates (14.87%, 4.37%, or 4.08%) can still be used effectively, as will be shown.
C. The IPCC Rate Graph
So, the following graph is the result computed by software I wrote, which projects acceleration based on the 4.37% or 4.08% loss resulting in a final ~3 ft rise by Dec. 31, 2099 per the IPCC 5th Assessment.
The 4.37% or 4.08% per year IPCC derivation as a driving percentage for SLR acceleration, results in this graph:
|Click on graph to Enlarge|
D. Do 14.87% & 4.37% or 4.08% Rates Reveal Surges?
According to Table 1, Greenland will generate a 21.49 ft. SLR if all of its ice melts.
West Antarctica will generate a 26.44 ft. SLR if all of its ice melts.
Future ice-loss-caused-SLR (Greenland & W. Antarctica combined - 21,49 ft +26.44 ft = 47.93 ft) is measured in current ice loss at a rate of 500 km3 (500 cubic kilometers) a year.
Of that current loss, Greenland contributes 375 km3 and Antarctica contributes 125 km3 (500 km3 current total loss per year).
Thus, Greenland currently takes up 75% of the ice-loss volume, while West Antarctica currently takes up 25% of the ice-loss volume.
(Note: after the coastal ice melts, the initial rate of 14.87% acceleration in both polar areas will decline. At that point a 4.37% or 4.08% acceleration rate is used in the software calculation which generates the graphs below, because the interior ice, inland and away from the coast, generally melts slower.)
I am using only 30% of total Greenland ice as the coastal amount which the 14.87% acceleration rate is applied to initially.
I am using 80% of total West Antarctica ice as the coastal amount, accelerating @14.87%, with the remaining 20% of it melting at the slower 4.37% or 4.08% acceleration rate.
I do that because scientists expect a slowing down of the rate of acceleration once the coastal melt subsides, and there is nothing but inland ice remaining.
The interior or inland ice is more stable, so that is why the 4.37% or 4.08% acceleration rate is applied to it.
E. The Combined-Values Graph
The three are separated into three lines on the graph, only for the sake of contemplation.
Those two non-combined graph lines (red & black) are close together because W. Antarctica is larger, but Greenland is melting faster.
Here is the graph with the IPCC 3 ft. line near the bottom, which is based on what they say SLR will reach circa 2100 (shown alone in the graph above in section "C").
|Click on graph to Enlarge|
Notice that the ~3 ft. SLR takes place circa 2042 in these projected 14.87% -> 4.37% and 14.87% -> 4.08% acceleration details, rather than taking place circa 2100 as the IPCC projection expects.
What happens after 2042 in the graph indicates catastrophic SLR, if the current melt acceleration of 14.87% continues for perhaps another decade or so, as it has since 2009 until now.
Like I said though, it should decrease naturally as the "low hanging fruit" ice near the coasts of Greenland and W. Antarctica melt away, leaving only the more stable inland ice.
Ditto with E. Antarctica later on.
F. Concept Graph - Not To Scale
To pull it all together as a concept, here is the final graph:
|Click on graph to Enlarge|
The continuing SLR after that transition, even at the 4.37% or 4.08% acceleration rate, is due to the fact that we will then be into the internal, inland ice sheet melt which includes the vast E. Antarctica ice sheet (which generates a total of 212.58 ft of SLR per Table 1).
That SLR will also be due to the continuation of global warming, which by then could get into an increase of 4°C - 6°C.
And, it is also due to the continuing thermal expansion of all the oceans.
It is a slower growth period, in terms of acceleration rate, however, since vast ice sheets will be melting then, and the then-larger ocean will be expanding even more, because of additional heat and additional water.
This SLR is all because cities and countries all around the world are now, have been in the recent past, and will continue to be in the future, victims of the warmonger fossil fuel empire, called Oil-Qaeda.
The empire that led us into catastrophe (The Peak of Sanity - 3).
The next post (with updates) in this series is here, the previous post in this series is here.
A snowball's chance in hell argument ...
And an adult argument in response ...