Tuesday, August 25, 2015

The Evolution of Models - 12

Fig. 1 Jakobshavn Glacier, Greenland
I. Introduction

In the previous post of this series I presented some variations in software modelling which "length of doubling" produces in sea level change (SLC) projections.

"Doubling" is a description that scientists use to describe the observance of ice loss on ice sheets in the sense that if the sheet loses "x amount" of ice in one year, then a number of years later that "x amount" of ice loss per year doubles (x * 2, 2x), then that is considered a "doubling."

If it takes ten years for x to double, that is a "ten year doubling," and if it takes seven years for x to double, that is a "seven year doubling."

II. Recent Scientific Papers

One recent paper by 17 scientists, including James Hansen, indicates that with a ten year doubling, sea level rise (SLR) could be in the vicinity of ten feet by 2050 (A Paper From Hansen et al. Is Now Open For Discussion).

A more recent paper indicates that calving and melting of glaciers around the world is doubling faster than probably at any other time in recorded history:
"Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (~42 000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (~5200 since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable."
(Historically Unprecedented Global Glacier Decline, emphasis added). Later in this post (Section V) I will try to put that into the context of "doubling."

III. You Were A Naughty Scientist

Generally, when scientists publish the type of information mentioned in Section II above, they are chastened for being "alarmist" in the unspoken Jim Crow law sort of way (Blind Willie McTell News).

The psychological denial of things civilization is out of control about, such as global warming induced climate change, has now wormed its way into the institutions of science.

Scientists are treated like teenagers with an allowance that is taken away if the scientists publish things that cannot be spoken:
"I suspect the existence of what I call the `John Mercer effect'. Mercer (1978) suggested that global warming from burning of fossil fuels could lead to disastrous disintegration of the West Antarctic ice sheet, with a sea level rise of several meters worldwide. This was during the era when global warming was beginning to get attention from the United States Department of Energy and other science agencies. I noticed that scientists who disputed Mercer, suggesting that his paper was alarmist, were treated as being more authoritative.

It was not obvious who was right on the science, but it seemed to me, and I believe to most scientists, that the scientists preaching caution and downplaying the dangers of climate change fared better in receipt of research funding. Drawing attention to the dangers of global warming may or may not have helped increase funding for relevant scientific areas, but it surely did not help individuals like Mercer who stuck their heads out. I could vouch for that from my own experience. After I published a paper (Hansen et al 1981) that described likely climate effects of fossil fuel use, the Department of Energy reversed a decision to fund our research, specifically highlighting and criticizing aspects of that paper at a workshop in Coolfont, West Virginia and in publication (MacCracken 1983).

I believe there is a pressure on scientists to be conservative. Papers are accepted for publication more readily if they do not push too far and are larded with caveats. Caveats are essential to science, being born in skepticism, which is essential to the process of investigation and verification. But there is a question of degree. A tendency for `gradualism' as new evidence comes to light may be ill-suited for communication, when an issue with a short time fuse is concerned."
(Scientific Reticence & SLR, emphasis added). This is how civilizations end up damaging themselves out of existence, or as Toynbee described it "committing suicide" (Civilization Is Now On Suicide Watch).

IV. Believing Your Eyes

There is no doubt that the ice sheets of Greenland (Fig. 1) and Antarctica are, like glaciers elsewhere, "in a hurry" to melt and calve:
"Satellite images show that the world's fastest moving glacier lost a piece of ice measuring nearly 5 square miles over two days. Scientists say it is one of the most significant calving events on record.

Radar images of the Jakobshavn glacier in Greenland, taken from the European Space Agency's (ESA) Sentinel-1A and Sentinel-2A weather satellites between July 27 and Aug. 19, show the massive glacier advancing westward before its front rapidly retreated as a huge chunk fell off it front, sometime between Aug. 14 and Aug. 16.

The ESA estimates that the ice is about 1,400 meters (4,600 feet) thick, meaning that the piece lost has a volume of about 17.5 cubic km, which is enough to cover the island of Manhattan in a layer of ice almost 1,000 feet deep."
(CBS News, emphasis added). So, what does this have to do with SLC modelling software that uses a doubling scheme?

V. Believing SLC Software Models

A. The Code

I wrote a simple SLR software model that does an "oscillating doubling" of 10,7,5,3,2 year sequences, as follows.

The code below is in bold, comments are in regular text between "/** */" C++ comment markers.

The SLR program is listed between the following horizontal lines:

#include <iostream>
#include <iomanip>
#include <fstream>

using namespace std;

/** URL for "80.32" is Table 1 @: http://pubs.usgs.gov/fs/fs2-00/ */
const double maxMeanSLR = 80.32;

/** csv comma delimited header (percent is % of maxMeanSLR) */
const char *pColumnNames = "Year,SLR,Rate,Percent";

/** reoeating doubling cycle */
const int doublingYrs[5] = {10,7,5,3,2};

/** current max est. SLR per year @ East Coast (0.866141732 in.) */
const double incPerYear = 0.022;

/** number of years to project (36 for yr. 2050; 86 for yr 2100) */
const int yearsToProject = 86;

This program uses a 10,7,5,3,2 year
repeating "doubling sequence."

This is designed to vary the ice
sheet melt/calving as different
zones are traversed and cycles of
global warming events wax and wane.

The rate of melt changes each
10 then 7 then 5 then 3 and then
2 years, and then repeats itself.
all sea level values are in meters
int main()
    /** current sea level rise since 1750 @East Coast of U.S. */
    double meanSLR = 0.4572;

    /** set initial SLR per year @East Coast (0.022 m, 0.0722 ft, 0.866 in.) */
    double incThisYear = incPerYear;

    int doublingElement = 0, doublingCount = 1;

    /** print results to a .csv text file */
    freopen("slr-lite.csv", "w", stdout);

    /** csv header: write column names and commas at top of page */
    cout << pColumnNames << endl;

    for (int year = 0; year < yearsToProject; year++)
        if (meanSLR < maxMeanSLR)
            /** simulate ice sheet melt rate of increase */
            meanSLR += incThisYear;

            /** store year to year values in csv format */
            cout << year + 2015 << ","
                 << setprecision(5)
                 << meanSLR << ","
                 << incThisYear << ","
                 << (meanSLR / maxMeanSLR) * 100
                 << endl;

            /** check doubling settings */
            if (doublingCount == doublingYrs[doublingElement])
                /** variable "incThisYear" records values in a 10,7,5,3,2 year cycle */
                incThisYear += incPerYear;

                /** test for end of 10,7,5,3,2 cycle */
                if (doublingYrs[doublingElement] == 2)
                    /** reset to beginning, repeat cycle */
                    doublingElement = 0;

                    /** reset to original doubling amount */
                    incThisYear = incPerYear;
                else /** go to next doubling value */

                /** reset the cycle counter */
                doublingCount = 1;
        else /** all ice has been depleted, so don't record data */
            cout << year + 2015
            << " - maximum SLR reached ("
            << maxMeanSLR
            << ")"
            << endl;

    return 0;

B. The Resulting Data and Graphs

When set to an ending in the year 2100, it prints the following csv ("comma separated values") file, which I used to do two graphs.

The data are on the left side, the two graphs (Fig. 2, Fig. 3) are on the right side.

Years = 2015-2100.
SLR = sea level rise in meters.
Rate is the value associated with the 10,7,5,3,2 doubling.
Percent is the percent of the total ice on Earth (equating to the 80.32 meters of potential global mean SLR) that has melted or calved by that year.

Fig. 2 2015-2050
Fig. 3 2015-2100

C. The Analysis

The csv file printout shows the "0.22" Rate repeating for 10 yrs., then the "0.44" rate following for 7 yrs., the "0.66" rate following that for 5 yrs., and so on.

Then, when the first sequence (10,7,5,3,2) completes in the yr. 2041, the sequence begins anew to repeat itself.

One effect this technique has is that in 2050 the SLR is 1.9972 meters, or 6.6 ft. instead of the 10 feet using only the 10 yr. doubling (as shown here).

The point is that projection software is probably better if it has oscillating variation, because it is not realistic to expect the same rate for each year as the old style models tend to do ("linear" projections).

The graphs reflect the sequence end, and a new beginning, in a sawtooth type of look, reflecting what the zone effect can and should look like (e.g. The Evolution of Models - 5).

That is, the graphs reflect a sawtooth look which is reflective of uneven melt rates from year to year, with an upward trend nevertheless.

VI. Conclusion

The ice sheets continue to melt and calve, with an acceleration built into that melting and calving (because of the increase in fossil fuel use and green house gas emissions).

Software models and scientific papers need to take that into consideration.

Public officials also need to take that into consideration (You Are Here - 5).

In fact, everyone else needs to take that reality into consideration.

The next post in this series is here, the previous post in this series is here.

01:30 Warming is concentrated in the Arctic ... this pattern has been evident for decades
02:45 These same models that began development in the late 60's always had an Arctic amplified warming because the physics of that reflectivity is simple.
02:55 Removal of reflective cover absorb more sunlight. The primitive models got that and its of course validated by observation.
04:32 Within our lifetimes we will bear witness to this story unfolding rather rapidly.
04:40 The red line shows observations of sea ice area. It depicts how sea ice is retreating at twice the rate [doubling] that our best model projections show.
05:05 The models still don't get the true fidelity of climate, the rapidity of sea ice loss ...
05:30 ... retreating at a rate four times [doubling * 2] what model projections currently get ... the models are if anything underestimating ...
06:28 Greenland is absorbing an additional amount of solar energy that equals twice the energy use of the U.S. each year
07:53 Just in the past ten years science reveals more sensitive response than was previously encoded in models.

Researcher sweating it out at an Economic Summit:


  1. It ain't like makin' model air-planes.

  2. Honing in on reality - that it's happening at all is the scare of course (because we're powerless to stop it) - but this gives us a good idea of where things are going (you could run the models with various doubling values at different times to get a range that the measured reality of sea level at any time might occur between). Nice work Dredd.


    1. Yep.

      Copy the code, put it into your compiler, and generate many hypothetical scenarios.