Fear or Fail: about the melting Greenland ice sheet
Summary: Climate scientists have, as a group, learned little or nothing from ClimageGate. While the professional literature continues on track, many participate in gross exaggerations — often doomseter-like speculation that diminishes their credibility. This post provides examples.
Today’s scary news: “Weighing Greenland“, Seth Shulman, Union of Concerned Scientists (UCS), 15 May 2010 — “Spotlight: Scott Luthcke, NASA’s Goddard Space Flight Center”. Opening:
According to the latest scientific evidence, Greenland’s vast ice sheet is melting at a dramatic rate. Over the past six years, Greenland has lost an average of 183 gigatons (or 200 cubic kilometers) of ice annually. That’s a third of the volume of water in Lake Erie every year. Greenland’s shrinking ice sheet offers powerful evidence that global warming is underway.
For those who like facts in context (rather than straight agitprop), the rest of the story appears in “On Being the Wrong Size“, Willis Eschenbach, WUWT, 23 May 2010:
Now, that sounds pretty scary, it’s losing a third of the volume of Lake Erie every year. Can’t have that. But what does that volume, a third of Lake Erie, really mean? … there is only one thing to which we should compare the ice loss, and that is the ice volume of the Greenland Ice Cap itself. So how many cubic kilometres of ice are sitting up there on Greenland?
… that the annual loss is around 200 km^3 lost annually out of some 3,000,000 km^3 total. This means that Greenland is losing about 0.007% of its total mass every year, seven thousandths of one percent lost annually … And if that terrifying rate of loss continues unabated, of course, it will all be gone in a mere 15,000 years. That’s my pet peeve, that numbers are being presented in the most frightening way possible. The loss of 200 km^3 of ice per year is not “some of the most powerful evidence of global warming”, that’s hyperbole. It is a trivial change in a huge block of ice.
… As the article points out, we’ve only been measuring Greenland ice using the GRACE satellites for six years now.
This UCS article combines the classic propaganda tropes of global warming hysteria. Numbers with no context, forecasts based on immature theory and short periods of data, doom-laded adjectives — and no mention of contrary evidence in the scientific literature.
What does the literature show?
Fortunately, despite the intense propaganda in the general media — often abetted by scientists grossly exaggerating their findings — the slowly working mills of science continue to work. Here is a selection of recent articles. Note the emphasis on the tiny current changes in polar melting, the short period of accurate data, and the large uncertainties about past conditions, current dynamics, and future projections. Red emphasis added.
(1) “Sea level in Roman time in the Central Mediterranean and implications for recent change“, Kurt Lambecka et al, Earth and Planetary Science Letters, 15 August 2004 — Abstract:
Instrumental records indicate that ocean volumes during the 20th century have increased so as to raise eustatic sea level by ~ 1–2 mm/year and the few available records suggest that this is higher than for the previous century. Geological data indicate that ocean volumes have increased since the main phase of deglaciation about 7000 years ago but whether this continued into the recent past remains unclear. Yet, this is important for establishing whether the recent rise is associated with global warming or is part of a longer duration non-anthropogenic signal.
Here, we present results for sea-level change in the central Mediterranean basin for the Roman Period using new archaeological evidence. These data provide a precise measure of local sea level of 1.35 F0.07 m at 2000 years ago. Part of this change is the result of ongoing glacio-hydro isostatic adjustment of the crust subsequent to the last deglaciation. When corrected for this, using geologically constrained model predictions, the change in eustatic sea level since the Roman Period is 0.13 ± 0.09 m.
A comparison with tide-gauge records from nearby locations and with geologically constrained model predictions of the glacio-isostatic contributions establishes that the onset of modern sea-level rise occurred in recent time at f100F53 years before present.
(2) “Greenland warming of 1920-1930 and 1995-2005″, Geophysical Research Letters, 13 June 2006 — Abstract:
We provide an analysis of Greenland temperature records to compare the current (1995–2005) warming period with the previous (1920–1930) Greenland warming. We find that the current Greenland warming is not unprecedented in recent Greenland history. Temperature increases in the two warming periods are of a similar magnitude, however, the rate of warming in 1920–1930 was about 50% higher than that in 1995–2005.
Excerpt of conclusions:
We have analyzed temperature time series from available Greenland locations and we have found that …
iv. Greenland warming of the 1995-2005 period is similar to the warming of 1920-1930, although the rate of temperature increase was by about 50% higher during the 1920-1930 warming period.
v. There are significant differences between the global temperature and the Greenland temperature records within the 1881-2005 period. While all the decadal averages of the post-1955 global temperature are higher (warmer climate) than the pre-1955 average, almost all post-1955 temperature averages at Greenland stations are lower (colder climate) than the pre-1955 temperature average.
An important question is to what extent can the current (1995-2005) temperature increase in Greenland coastal regions be interpreted as evidence of man-induced global warming? Although there has been a considerable temperature increase during the last decade (1995 to 2005) a similar increase and at a faster rate occurred during the early part of the 20th century (1920 to 1930) when carbon dioxide or other greenhouse gases could not be a cause. The Greenland warming of 1920 to 1930 demonstrates that a high concentration of carbon dioxide and other greenhouse gases is not a necessary condition for period of warming to arise. The observed 1995-2005 temperature increase seems to be within a natural variability of Greenland climate. A general increase in solar activity [Scafetta and West, 2006] since 1990s can be a contributing factor as well as the sea surface temperature changes of tropical ocean [Hoerling et al., 2001].
The glacier acceleration observed during the 1996-2005 period [Rignot and Kanagaratnam, 2006] has probably occurred previously. There should have been the same or more extensive acceleration during the 1920-1930 warming as well as during the Medieval Warm period in Greenland [Dahl-Jensen et al., 1998; DeMenocal et al., 2000] when Greenland temperatures were generally higher than today. The total Greenland mass seems to be stable or slightly growing [Zwally et al., 2005].
To summarize, we find no direct evidence to support the claims that the Greenland ice sheet is melting due to increased temperature caused by increased atmospheric concentration of carbon dioxide. The rate of warming from 1995 to 2005 was in fact lower than the warming that occurred from 1920 to 1930. The temperature trend during the next ten years may be a decisive factor in a possible detection of an anthropogenic part of climate signal over area of the Greenland ice sheet.
(3) “Recent Greenland Ice Mass Loss by Drainage System from Satellite Gravity Observations“, Scott Luthcke et al, Science, 24 November 2006 — Abstract
Mass changes of the Greenland Ice Sheet resolved by drainage system regions were derived from a local mass concentration analysis of NASA–Deutsches Zentrum für Luft- und Raumfahrt Gravity Recovery and Climate Experiment (GRACE mission) observations. From 2003 to 2005, the ice sheet lost 101 ± 16 gigaton/year, with a gain of 54 gigaton/year above 2000 meters and a loss of 155 gigaton/year at lower elevations. The lower elevations show a large seasonal cycle, with mass losses during summer melting followed by gains from fall through spring. The overall rate of loss reflects a considerable change in trend (–113 ± 17 gigaton/year) from a near balance during the 1990s but is smaller than some other recent estimates.
The Greenland mass loss contributes 0.28 ± 0.04 mm/year to global sea level rise, which is nearly 10% of the 3 mm/year rate recently observed by satellite altimeters.
(4) “How Fast Are the Ice Sheets Melting?“, Anny Cazenav, Science, 24 November 2006 — “Remote-sensing data suggest that ice sheets currently contribute little to sea-level rise. However, dynamical instabilities in response to climate warming may cause faster ice-mass loss.” Excerpt:
If the ice sheets covering Greenland and Antarctica were to melt completely, they would raise sea level by about 65 m. … For the past 3000 years, global sea level has remained stable, but since the end of the 19th century, tide gauges have detected global sea-level rises [~1.8 mm/year on average over the past 50 years. Satellite altimetry data document a rate of ~3 mm/year since 1993. However, it remains unclear whether the recent rate increase reflects an acceleration in sea-level rise or a natural fluctuation on a decadal time scale.
… Improved mass-balance estimates from remote-sensing observations, such as those reported by Luthcke et al., will inform on the ongoing behavior of the ice sheets and help to validate models. This goal requires long time series of satellite observations, and hence continuity of space missions
(5) “Recent Sea-Level Contributions of the Antarctic and Greenland Ice Sheets“, Andrew Shepherd et al, Science, 16 March 2007 — Abstract:
After a century of polar exploration, the past decade of satellite measurements has painted an altogether new picture of how Earth’s ice sheets are changing. As global temperatures have risen, so have rates of snowfall, ice melting, and glacier flow. Although the balance between these opposing processes has varied considerably on a regional scale, data show that Antarctica and Greenland are each losing mass overall. Our best estimate of their combined imbalance is about 125 gigatons per year of ice, enough to raise sea level by 0.35 millimeters per year. This is only a modest contribution to the present rate of sea-level rise of 3.0 millimeters per year. However, much of the loss from Antarctica and Greenland is the result of the flow of ice to the ocean from ice streams and glaciers, which has accelerated over the past decade. In both continents, there are suspected triggers for the accelerated ice discharge — surface and ocean warming, respectively — and, over the course of the 21st century, these processes could rapidly counteract the snowfall gains predicted by present coupled climate models.
The discovery that particular ice streams and glaciers are dominating ice sheet mass losses means that today our ability to predict future changes is limited. Present numerical models capture neither the details of actual ice streams nor, in Greenland, those of hydraulic connections between the surface and the bed. In addition, the detailed mechanics at the grounding line still remain to be fully worked out. In consequence, the view that the changing sea-level contribution of the Antarctic and Greenland ice sheets in the 21st century will be both small and negative as a result of accumulating snow in Antarctica [e.g., –0.05 mm year−1 in is now uncertain.
(6) “Towards a re-assessment of the surface mass balance of the Greenland ice sheet“, M van den Broeke et al, presented at ECRA 2008: Human Dimensions of Global Environmental Change — Abstract:
At present, the mass balance and especially the surface mass balance of the Greenland Ice Sheet (GrIS) are poorly known. Current methods to determine GrIS surface mass balance as well as the inherent uncertainties are discussed. Special emphasis is placed on the increasingly important role of regional atmospheric climate models, which explicitly calculate the individual components of the surface mass balance: (solid) precipitation, melt and subsequent runoff, sublimation/deposition and refreezing in the snow. Especially the latter term is very uncertain, and poses a great challenge to modellers. Some recent advances in these fields of research are presented.
(7) “Recent Changes of the Earth’s land ice from GRACE: methods, signals and errors“, Scott Luthcke et al, Meeting of the American Geophysical Union, Fall 2009
Recent changes in the cryosphere highlight the importance of methods for directly observing the complex spatial and temporal variation of the ice sheets and glacier systems. The NASA/DLR Gravity Recovery and Climate Experiment (GRACE) mission has been acquiring ultra-precise inter-satellite K-band range and range-rate (KBRR) measurements providing new observations of the complex evolution of the Earth’s land ice. The fidelity of the ice mass flux solutions depends on many factors including solution method, parameterization and processing of the GRACE level 1B data including forward modeling of various non-ice mass signals (e.g. hydrology, oceans, atmosphere).
In this talk we present the latest GRACE derived ice mass solutions for the Gulf of Alaska glaciers, Greenland and Antarctica. We compare solutions derived from various techniques including those that estimate the mass flux directly from the GRACE observations (regional high-resolution mascon and global mascon solutions), as well as regional averaging kernel techniques applied to spherical harmonic solutions estimated from the GRACE data. We also explore the impact of forward modeling and parameterization on the final solutions. Solution results as well as errors and limitations will be discussed.
(8) “Why the Greenland and Antarctic Ice Sheets are Not Collapsing“, Cliff Ollier and Colin Pain, AIG News (Australian Institute of Geoscientists),August 2009 — Abstract:
Global warming alarmists have suggested that the ice sheets of Greenland and Antarctica may collapse, causing disastrous sea level rise. This idea is based on the concept of an ice sheet sliding down an inclined plane on a base lubricated by meltwater, which is itself increasing because of global warming.
In reality the Greenland and Antarctic ice sheets occupy deep basins, and cannot slide down a plane. Furthermore glacial flow depends on stress (including the important yield stress) as well as temperature, and much of the ice sheets are well below melting point. The accumulation of kilometres of undisturbed ice in cores in Greenland and Antarctica (the same ones that are sometimes used to fuel ideas of global warming) show hundreds of thousands of years of accumulation with no melting or flow. Except around the edges, ice sheets flow at the base, and depend on geothermal heat, not the climate at the surface. It is impossible for the Greenland and Antarctic ice sheets to ‘collapse’.
(9) “Projections of future sea level becoming more dire“, Jonathan T. Overpecka and Jeremy L. Weiss, Proceedings of the National Academy of Science (PNAS), 22 December 2009 — Excerpt:
The Fourth Assessment of the Intergovernmental Panel on Climate Change (IPCC) was unable to provide a strong constraint on estimates of sealevel rise likely to occur by the end of this century. Their projection of 0.26- to 0.59-m sea-level rise by 2100 (under the business as usual A1FI greenhouse gas emissions scenario; ref. 1) represents a lower-bound estimate because it excludes sea-level change caused by rapid dynamical changes in the flow of Greenland and Antarctic ice. The IPCC excluded this information because the quantitative understanding of the dynamics internal to the Earth’s great ice sheets was too incomplete.
… The observed acceleration in the decline of polar ice sheet mass provides all the more reason to take the new results from Vermeer and Rahmstorf (2) seriously. Their work provides a significant update of previous work (8) and uses the relationship between observed past temperature and global sea level to project a sea-level rise of 0.75–1.90 m for the period 1990–2100. Empirically, this relationship is nonlinear and reflects the evolution of a sea-level rise currently dominated by the warming of the oceans to one dominated by the melting of polar ice sheets.
- “Greenland Ice Sheet surface mass-balance modelling and freshwater flux for 2007, and in a 1995–2007 perspective“, Sebastian H. Mernild et al, Hydrological Processes, 15 August 2009
- “A new view on sea level rise“, Stefan Rahmstorf, Nature Reports Climate Change, April 2010 — “Has the IPCC underestimated the risk of sea level rise?”
- “Back to the future: Greenland’s contribution to sea-level change“, Antony J. Long, GSA Today ( The Geological Society of America), June 2009 – Predictions suggest that the Greenland Ice Sheet could contribute >0.5 m of global sea-level rise by the end of this century…”
Other posts about Climate propaganda on the FM website
- The media doing what it does best these days, feeding us disinformation, 18 February 2008
- An example of important climate change research hidden, lest it spoil the media’s narrative, 22 May 2009
- More attempts to control the climate science debate using smears and swarming, 19 October 2009
- About those headlines of the past century about global cooling…, 2 November 2009
- Important News, still breaking, about Climate Science propaganda, 21 November 2009
- About Wikipedia’s handling of controversial topics…like climate science, 20 December 2009
- The floodgates slowly open and the foreign news media debunk climate change propaganda, 24 January 2010
- Hot news about climate change. The picture rapidly changes as the curtains open on things long hidden., 25 January 2010
- An important step to take before we spend a trillion dollars to save the planet from global warming, 31 January 2010
- Successful propaganda as a characteristic of 21st century America, 1 February 2010
- More propaganda: the eco-fable of Easter Island, 4 February 2010
- Quote of the day – hidden history for people who rely on the mainstream media for information, 12 February 2010
- The hidden history of the global warming crusade, 19 February 2010
- A real-time example of the birth and spread of climate propaganda, 9 March 2010