Rate of mass loss from the Greenland Ice Sheet will exceed Holocene values this century.

[NNadir]

The paper I'll discuss in this post is this one: Rate of mass loss from the Greenland Ice Sheet will exceed Holocene values this century (Jason P. Briner, Joshua K. Cuzzone, Jessica A. Badgeley, Nicolás E. Young, Eric J. Steig, Mathieu Morlighem, Nicole-Jeanne Schlegel, Gregory J. Hakim, Joerg M. Schaefer, Jesse V. Johnson, Alia J. Lesnek, Elizabeth K. Thomas, Estelle Allan, Ole Bennike, Allison A. Cluett, Beata Csatho, Anne de Vernal, Jacob Downs, Eric Larour & Sophie Nowicki, Nature volume 586, pages 70–74 (2020))

So called "renewable energy" hasn't saved the world; it isn't saving the world; it won't save the world. I have nothing more to say about the literally pyrrhic apparent triumph of the antinukes than what it says on the AAAS t-shirt distributed this year says: Facts are facts.

Since this paper which is a modeling paper, suggests, by fitting the model to the best historical data on the Greenland Ice Sheet what the future of the ice sheet will be, given that we have deliberately chosen not to do anything effective about climate change:

The abstract of the paper is available at the link.

For convenience, an excerpt:

The Greenland Ice Sheet (GIS) is losing mass at a high rate1. Given the short-term nature of the observational record, it is difficult to assess the historical importance of this mass-loss trend. Unlike records of greenhouse gas concentrations and global temperature, in which observations have been merged with palaeoclimate datasets, there are no comparably long records for rates of GIS mass change. Here we reveal unprecedented mass loss from the GIS this century, by placing contemporary and future rates of GIS mass loss within the context of the natural variability over the past 12,000 years. We force a high-resolution ice-sheet model with an ensemble of climate histories constrained by ice-core data2.

They suggest the data to which they fit their model represents a loss of ice amounting to around 6,000 billion tons of ice per century, 6 trillion tons during the Holocene, which is the current post glacial era in which civilization arose. Using their model, they predict that Greenland will lose between 8,000 billion tons to 35,000 billion tons in the 21st century, greatly exceeding any value recorded in the last 12,000 years.

For those lacking access to the full paper, I'll offer a few excerpts and graphics. From the paper's introduction:

The GIS lies within the rapidly warming Arctic, and its contribution to sea-level rise has recently accelerated1. The increased rate of GIS mass loss since the 1990s is substantial, but the lack of data on long-term GIS mass change makes it difficult to evaluate this short-term phenomenon within the context of natural variability5,7. Efforts to quantify rates of ice-mass loss through time have relied on historical climate data and image analysis, contemporary airborne and satellite observations, and numerical ice-sheet simulations5,8,9. Combined, these approaches reveal that the GIS was roughly in neutral mass balance during the nineteenth century, experienced variable mass loss in the twentieth century, and has undergone a substantial increase in mass loss in the past 20 years1,5,10. The future of GIS mass change is uncertain, but projected warming combined with feedbacks in the coupled ice-sheet–climate system will lead to continued losses9,11,12. Given plausible future climate scenarios, the GIS may be entirely gone in as few as 1,000 years13...

A few excerpts from additional sections:

The GIS’s past...

...Geological observations of GIS change are most abundant during the Holocene14. For this reason, the Holocene has been targeted as a timeframe for simulating GIS history15,16,17,18,19,20. Model simulations so far have been used to assess spatiotemporal patterns of GIS retreat and to constrain its minimum size. Simulated changes in ice volume are largely the product of climatic forcing; palaeo-mass balance is typically modelled using one of the ice-core ?18O time series from central Greenland, which is converted to temperature and precipitation, and scaled across the ice sheet15. Some approaches improve model performance with geological constraints, but climate forcing is still scaled from limited ice-core data, sometimes using prescribed Holocene temperature histories to improve model–data fit16,17. One recent study19 used data averaged from three ice-core sites to adjust palaeotemperatures from a transient climate model, and scaled precipitation from one ice-core accumulation record. All these estimates of mass-loss rates during the Holocene provide important context for projected GIS mass loss, but they have not been extended into the future, making quantitative comparisons uncertain...

GIS modelling

We place today’s rates of ice loss into the context of the Holocene and the future using a consistent framework, by simulating rates of GIS mass change from 12,000 years ago to AD 2100. We use the high-resolution Ice Sheet and Sea-level system Model (ISSM), which resolves topography as finely as 2 km (refs. 21,22,23). Our simulations are forced with a palaeoclimate reanalysis product for Greenland temperature and precipitation over the past 20,000 years2. This reanalysis was derived using data assimilation of Arctic ice-core records (oxygen isotopes of ice, and snow accumulation) with a transient climate model (Methods). We account for uncertainty in the temperature and precipitation reconstructions by creating an ensemble of nine individual ISSM simulations that have varying temperature and precipitation forcings2 (Methods). Sensitivity tests using a simplified model in the same domain24 suggest that the range in plausible palaeoclimate forcing, which we use, has a larger influence on simulated rates of ice-mass change than do model parameters such as basal drag, surface-mass-balance parameters and initial state. We compare our simulated GIS extent against mapped and dated changes in the position of the GIS margin3,4...

Some pictures from the text:

Fig. 1: Domain for the ice-sheet model and moraine record of past GIS change in SW Greenland:



The caption:

a, Map of the present-day GIS, showing commonly used domains (as labelled) and our model domain (outlined in red). NO, north; NE, northeast; NW, northwest; CW, central–west; SE, southeast; SW, southwest. b, WSW Greenland (boxed in a), showing widely traceable moraine sequences3. JI, Jakobshavn Isbræ; KNS, Kangiata Nunaata Sermia. c, Cosmogenic–nuclide exposure-age chronologies of all moraines between the ocean and the GIS4 (boxed in b); 1? age uncertainties are listed; moraine lines are dashed where uncertain. Base-map topography from BedMachine37.

Fig. 2: Increased and variable GIS mass loss during the Holocene.



The caption:

a, Simulated cumulative change in WSW GIS ice mass from 12,000 years ago to AD 1850, for nine model simulations (Methods). b, Simulated position of the WSW GIS margin in the Holocene, for the transect shown in Fig. 1c. Black circles represent independent observations of ice-margin position based on mapped and dated moraines (with one-standard-deviation age uncertainty); the red circle is the present-day GIS margin. c, Bar plot showing the mean rate of ice-mass loss from 12,500 to 7,000 years ago; vertical lines and shading show moraine age and one-standard-deviation uncertainty for every moraine between Baffin Bay and the present-day ice margin4; asterisks mark the five centuries with the highest rates of mass loss.

In figure 3, notice the vertical line on the extreme right of the large graphic. This would be an excellent time to tell me all about how many "Watts" of solar cells are installed in California. Please avoid, since we live in the age of the celebration of the lie, using units of energy, GigaJoules - which matter - in favor of units of peak power - which mean zero at midnight in California.

The annual weekly minimum for carbon dioxide concentrations as measured at Mauna Loa was likely reached last week. The data hasn't been posted, but as I follow these data points weekly, I expect it will come in at about 411.0 ppm +/- 0.2 ppm. In 2010, the annual minimum was reached in the week beginning September 26, 2010. At that time, the concentration of the dangerous fossil fuel waste carbon dioxide in the planetary atmosphere was 386.77 ppm. Read the caption and choose your dot on the vertical line that represents the 21st century, the age of "renewable energy will save us" aka, in my mind, the age of the lie.

Fig. 3: Exceptional rates of ice-mass loss in the twenty-first century, relative to the Holocene.



The caption:

The mean rate of ice-mass change each century, from 12,500 years ago to AD 2100, is shown by the black line. The light grey bars indicate the ice-mass change in each of the nine simulations. For the 1900s, simulated rates are shown in dark grey. For the 2000s, rates of ice-mass change for various RCP2.6 and RCP8.5 simulations are shown as blue and red circles (see legend in inset). The histogram on the right incorporates all (n = 1,125) Holocene rates of ice-mass change. The inset shows simulated rates of ice-mass change in annual timesteps from AD 1850 to AD 2100.

Fig. 4: Substantial change in surface elevation of the GIS over the twenty-first century.



The caption:

a–c, Simulated change in surface elevation of WSW GIS (metres per century; colour scale) for the centuries in the Holocene with the highest mass-loss rate (a, c) and during the cold event 8,200 years ago (b), from model experiment 9. d–f, Simulated change in surface elevation (metres per century; colour scale) over the twenty-first century under the MIROC RCP2.6 (e) and RCP8.5 (f) scenarios, compared to the twentieth century (d). g, Comparison of the mass-loss rate for WSW GIS (right axis, red) and for the entire GIS (left axis, black), from AD 1972 to AD 2018, based on observations5 (r2 = 0.82, where r is the correlation coefficient). h, Comparison of the mass-loss rate for WSW GIS (right axis, red) and for the entire GIS (left axis, black), from AD 2015 to AD 2100, from our simulation using the MIROC RCP8.5 climate forcing (r^(2) = 0.97).

Some additional text from the paper:

The substantial increase in rates of GIS mass loss in the past two decades is exceptional in the context of estimates of mass loss in the historic interval5,8,9,35. If the rates of mass loss observed over the past two decades were to remain constant for the rest of the twenty-first century, the total rate of mass loss over the twenty-first-century would be around 6,100 Gt per century for WSW Greenland5. This value is within the low end of our simulated range of mass-loss rates during the early Holocene. However, 6,100 Gt per century may vastly underestimate the rate of mass loss for the twenty-first century, because climate is projected to become increasingly unfavourable for maintaining even the current levels of GIS mass balance6. Our simulations of twenty-first-century WSW GIS mass loss, using an identical model and model set-up, address the limitation of extrapolating observed rates of mass loss and yield century-average mass-loss rates of 8,800–10,600 Gt per century for RCP2.6 scenarios and 14,000–35,900 Gt per century for RCP8.5 scenarios (Methods, Fig. 3).

As of 2018, the humanity was consuming 599.34 exajoules of primary energy per year. 81% of that energy came from dangerous fossil fuels, as opposed to 80% of 420.19 exajoules that were being consumed in the year 2000. Things are getting worse, not better.

Every year, quantities of carbon dioxide added to the atmosphere as dangerous fosssil fuel waste amounts to more than 35 billion metric tons. Land use changes, including those involved in providing so called "renewable energy" - for example the destruction of the Pantanal for ethanol farms - add about another ten billion tons.

To provide about 600 exajoules of primary energy each year, would require, assuming 190 MeV/fission, ignoring neutrinos, completely fissioning about 7.5 thousand tons of plutonium each year. The density of plutonium, in at least one allotrope, is about 19.9 g/ml, depending on the isotopic vector. The size of a cube containing 7.5 thousand tons of plutonium - which could never be assembled as such owing to criticality constraints - is less than 8 meters on a side.

I am often informed by people that "nobody knows what to do with (so called) 'nuclear waste.'" In saying this, it is very clear that these people have never in their wildest imagination ever considered what to do with hundreds of billions of tons of dangerous fossil fuel waste, which is choking the planet literally to death. Of course, their considerations are weak, because the best evidence is that these people can't be bothered to open a scientific paper or a science book on the subject of any kind of waste. Somehow people expect me to be impressed by rote statements reflecting, to my mind, a total lack of attention or at least a very lazy selective attention to statements from equally lazy and equally misinformed people, often journalists or "activists" of a type that have never passed a college level physical science course. Ignorance, we know, runs in circles, scientific and engineering ignorance as well as political ignorance.

I have been opening science books and reading scientific papers for the bulk of my adult life. A huge percentage of them are about waste and so called "waste." Perhaps, I'm the "nobody" about whom these people speak, since I know perfectly well what to do with so called "nuclear waste." It contains, I'm convinced, enough plutonium (as well as americium and neptunium) to save the Greenland Ice Sheet, and in fact, the world.

Tears in Rain.

I wish you a safe and pleasant weekend.