The Hansen et al. paper arguing that a vaunted 2°C temperature rise is dangerous is now open for comment at Atmospheric Chemistry and Physics Discussion, an open-access journal published by the European Geosciences Union (ACPD, "2°C Global Warming is Highly Dangerous", PDF).
Today, I will only address the sea level rise (SLR) aspects of that paper.
I am convinced that SLR is the prominent danger being created by the increase of greenhouse gases in the Earth's atmosphere and oceans as a result of Petroleum Civilization's burning of fossil fuels (Petroleum Civilization: The Final Chapter (Confusing Life with Death), 2, 3, 4).
I mentioned the Hansen et al. paper on Wednesday, not having read it then, but I kept that post limited to "sea levels rising as much as 10 feet in the next 50 years," and "sea level rise is the big impact of human made climate change" (New Climate Catastrophe Policy: Triage - 13).
Today, with that paper in hand, I want to address those issues with quotes directly from the paper itself, rather than from journalists.
II. What Danger?
The title of the paper ("2°C global warming is highly dangerous") indicates that the 16 co-authors feel that the assumption that we can live with a 2°C temperature rise is a dangerous and erroneous assumption.
We are about halfway to a 2°C temperature rise already, and the dangers presented already are killing millions of people and thousands of species of life on Earth (Oil-Qaeda: The Indictment).
Not to mention that we have already seriously damaged the Global Climate System, fresh water sources, farming soils, the oceans, and many other human habitat necessities.
Since the general, normalcy-biased press corps have not considered the serious dangers that SLR presents to current civilization, I have been doing so.
That is, I have been pointing out the dangers to the world's sea ports which an SLR of only 1m / 3 ft. presents.
Since the world's ports are essential to current civilization, many Dredd Blog posts have addressed the issue from many vantage points (e.g. Greenland & Antarctica Invade The United States, 2, 3; The 1% May Face The Wrath of Sea Level Rise First; Why The Military Can't Defend Against The Invasion; Weekend Rebel Science Excursion - 44; Why Sea Level Rise May Be The Greatest Threat To Civilization, 2, 3, 4).
Those posts, and others, point out that Petroleum Civilization is based in the main on delivery of commodities such as crude oil, coal, gas, foodstuffs, etc. via sea ports.
Sea ports were built at sea level decades or centuries ago, because that is where sea ports are built (at sea level).
When SLR takes place, those sea ports are thereby rendered below sea level.
Which presents very serious problems that, upon further analysis, are dangerous to current civilization:
"We suggest that this viewpoint ["2°C is ok"] fails to appreciate the nature of the threat posed by ice sheet instability and sea level rise. If the ocean continues to accumulate heat and increase melting of marine-terminating ice shelves of Antarctica and Greenland, a point will be reached at which it is impossible to avoid large scale ice sheet disintegration with sea level rise of at least several meters. The economic and social cost of losing functionality of all coastal cities is practically incalculable. We suggest that a strategic approach relying on adaptation to such consequences is unacceptable to most of humanity, so it is important to understand this threat as soon as possible."(Hansen Paper Introduction, Section I above, emphasis added). And those are problems which threaten to convert current civilization into a civilization absent the sea trade essential to its existence (Weekend Rebel Science Excursion - 44).
There is no realistic denial of that, instead, the resistance to comprehending it comes from pondering when it will happen (find "the law of when" here).
III. Some Arithmetic Concerning SLR
The Hansen et al. paper indicates "sea levels rising as much as 10 feet in the next 50 years," so it is a departure from the IPCC position of 3 ft in the next 85 years.
If we apply linear arithmetic to the paper, it means 5 ft. of SLR per decade (50 ÷ 10 = 5), which would mean 1m / 3 ft. of SLR @ 6 years from now, or the year 2021 (5/10 = 3/x; x=6).
In non-linear arithmetic, i.e. a "doubling" or "an acceleration" of the annual rate, the first 10 year SLR would be less than the second 10 year rate, and so forth.
In contrast, my SLR calculation model indicates a 1m / 3 ft. SLR by 2031, or 16 yrs. from now (The Question Is: How Much Acceleration Is Involved In SLR - 5?).
IV. Surge or Pulse SLR Is Historically Real
What both my SLR calculation model and the Hansen et al. model leave out is surges in SLR.
Scientists call them "pulses" rather than "surges," and they add a number and letter to further identify those events of history (e.g. "Pulse 1B", "Pulse 3C", "Pulse 2A").
I have been considering "pulse 1C" of about 8k years ago, which resulted in a 1m / 3ft. SLR in a few years or less (see NASA GISS here and here).
The "pulse 1C" was not directly related to climate alone, but rather was related to some of the dynamics that take place when ice sheets melt over land during a warming climate.
Sometimes, as in the case of pulse 1C, the meltwater is dammed up by obstructions.
This can take place either down under the surface of the ice sheet, on top of the ice sheet, or around the edges of the ice sheet.
We are talking about meltwater that is still over land, i.e., meltwater that has not reached the sea yet.
When that obstruction or dam eventually gives way, there is a surge in SLR that is not directly related to either the linear or the accelerating melt that is ongoing at that time (the dammed up, obstructed meltwater is from ice that melted earlier on).
That is, there can be a surge or pulse in SLR without there having to be an isolated surge or pulse in global temperature or in global atmospheric CO2 content.
An example would be the surges or pulses in the N.E. U.S. sea level in very recent years (Will This Float Your Boat - 5).
The SLR in such a case is caused by a debris or ice "dam" type of obstruction finally giving way, which allows the older meltwater to then flow into the sea.
I have posted several times indicating that such obstructions currently take place on both the Greenland Ice Sheet and on the Antarctic Ice Sheet (The Surge: A Forgotten Aspect of Sea Level Rise, Weekend Rebel Science Excursion - 45).,
V. Risk Management
We can't calculate, by models, exactly when those types of obstructions will give way to thereby allow dammed up older meltwater to then surge or pulse, and flow to the sea unexpectedly.
So, instead, it is a matter of dealing with chaotic happen-stance, and therefore utilizing "better safe than sorry" risk management as the way to go (New Climate Catastrophe Policy: Triage - 13).
VI. The Odds By The Numbers
It is instructive to remember that SLR catastrophe involves only a tiny percentage (1.14%) of the ice sheets of the Earth melting or otherwise finding a way to the sea:
To spark our interest, and bind ourselves to a sober view of this phenomenon which is called "The Biggest Story in the World" (according to a worldwide circulation news source), first consider the following quote from the video below:(Why Sea Level Rise May Be The Greatest Threat To Civilization - 3). The threat to the infrastructure of current world civilization is far more imminent (assuming no nuclear war) than the extinction of the human race is.
2:43 - "One meter [of SLR] would be a global catastrophic event, 3 meters would remap the world as we know it?"(emphasis added). This allows us to focus our attention on 1m / 3ft. of SLR, because it would be "a global catastrophic event."
2:50 - "Yes, absolutely."
The delicacy of the issue can be seen ... by realizing that only 1.14% of the global ice volume needs to melt to get us there (3 ft ÷ 263.5 ft. = 0.011385 = 1.14%).
The overall invader needs to use only 1.14% of its forces to accomplish the invasion.
If a small portion of one glacier (the Totten Glacier) in East Antarctica melts, or otherwise slides into the sea, the same will happen:
"How little it will take can also easily be seen by a statement from a scientist who is studying those locations closely and regularly:(Why Sea Level Rise May Be The Greatest Threat To Civilization). That is a slim margin, because the Totten Glacier and all other ice sheets are showing signs of decomposition (Nature).
'One of them, Totten glacier, holds the equivalent of seven metres of global sea level.' [a lower estimate is "at least" 3.3 metres here](Dr. Rignot East Antarctica glaciers, cf. Totten Glacier Melting). The percentage of that one glacier which needs to melt to cause 3 ft. / 1 m. of SLR is: 1÷7 = 0.142857143 = 14.3%."
The NEGIS is 16% of the entire GIS, JI is 8%, while KG & HG at ~2% each.
These four entities make up 28% of the total ice in the GIS.
The entire GIS represents 21.49 ft. of SLR (Fig. 2), so 28% of that is (21.49 × .28) 6.02 feet.
Which means that only half of that amount (14%) is needed to reach "3 ft. / 1 m. of SLR."
One can only hope that the clueless minions currently herded by Oil-Qaeda will suddenly freak out and get down to business, calling for a world wide effort never before considered seriously.
An effort that I and others would gladly rejoice in performing ... putting our energy into whatever it takes to LEAVE THE CIVILIZATION-POISONING FOSSIL FUELS IN THE GROUND !!
I would work like a slave to help with that, after Oil-Qaeda is brought to justice.
The next post in this series is here.
Paul Beckwith, on The Hansen et al. Paper