Peruvian Glaciers Prove Little Ice Age Was Global

Despite recent attempts to revive the discredited “hockey stick” temperature graph, invented by Michael Mann and promulgated by the IPCC, new research on tropical glaciers has once again shown that supposed temperature history to be bogus. While the role of the tropics in climate change remains an open debate in climatology circles, new data suggests linkages between the tropics and the North Atlantic region. In particular, prominent glacial events and associated climatic shifts in the outer tropics during the early Holocene and late in the “Little Ice Age” period indicate that the LIA was indeed a global event.

Tropical mountain glaciers are highly sensitive to relatively small climate changes, which makes them particularly useful as indicators of past climatic fluctuations. This is one of the reasons that climate alarmists make such a big deal out of the rapid retreat of existing mountain glaciers. Because past variations for these glaciers have not occurred at precisely the same times as the historical fluctuations in Europe those fluctuations have been depreciated by some. Well documented climate events such as the Holocene Climate Maximum and the Little Ice Age have been dismissed as being local variations and not representative of Earth's climate as a whole.

Peru possesses 71% of present-day tropical glaciers, the greatest concentration in the world. In the September 25, 2009, edition of Science Joseph M. Licciardi, Joerg M. Schaefer, Jean R. Taggart, and David C. Lund have presented a new, in-depth study of moraine ages from the Cordillera Vilcabamba (13°20'S) of southern Peru that date prominent glacial events and associated climatic shifts in the outer tropics.


The location of the main study site from the report. Base maps from Google Maps.

Glacial and climatic conditions of the LIA are most thoroughly documented in northern and western Europe by extensive historical accounts, instrumental data, and proxy climate indicators. This report, entitled “Holocene Glacier Fluctuations in the Peruvian Andes Indicate Northern Climate Linkages,” provides a new glacial chronology that reinforces the notion of the Little Ice Age and other well documented Northern Hemisphere climate fluctuations were global in scope. As stated in the report:

Published chronologies of late Quaternary glacier fluctuations in the central Andes are based on a combination of radiocarbon, lichenometric, and terrestrial cosmogenic nuclide dating methods. However, robust age control of Holocene glacial deposits remains notably sparse. Here, we report high-precision cosmogenic 10Be surface exposure ages of the two most prominent Holocene glacial episodes in the Cordillera Vilcabamba of southern Peru. This new glacial chronology augments nearby ice core, lacustrine, and marine paleoclimate records.

The dating was done by examining stones taken from glacial moraines, large ridges of rock debris plowed up by advancing glaciers. Moraines are left behind when a glacier retreats during periods of warmer climate, thus marking the time of its maximum extent. The site of this investigation was located in the vicinity of Nevado Salcantay (6271 m above sea level; 13°20'S, 72°33'W), the highest peak in the Cordillera Vilcabamba. Glacial troughs emanating from Salcantay and other nearby peaks have exceptionally well-preserved moraines with many large surface boulders. The accumulation of cosmogenic nuclides in minerals at or near Earth's surface provides a basis for a number of geologic measurements, in particular surface exposure dating of landforms, which was used for this study.


Moraines in Rio Blanco Valley, Peru, were deposited by a glacier in about AD 1810. Credit: Joe Licciardi

Cosmogenic nuclides are isotopes formed by the interaction of “target” atoms with cosmic radiation. One such nuclide is the rare chemical isotope 10Be, pronounced “Beryllium ten.” The granite surface boulders were exposed to cosmic rays starting when the glaciers that deposited them retreated. By measuring the buildup of 10Be in glacial rocks, scientists can calculate when the glaciers receded. Samples were collected from 25 boulders from the moraine crests and then dated by testing the amount of 10Be present. Only the tallest boulders were used as samples to reduce the likelihood of soil and snow cover. Using this cutting edge dating technique has yielded the most accurate timing for Peruvian glacial events to date.

The resulting evidence indicates that climate swings in the northern hemisphere over the past 12,000 years have been tightly linked to changes in the tropics. Significantly, glaciers in both the tropics and North Atlantic region reached their most recent maximum extents during the so-called Little Ice Age, about 1650 AD to 1850 AD. “The results bring us one step closer to understanding global-scale patterns of glacier activity and climate during the Little Ice Age,” said lead author Joe Licciardi, a glacial geologist at the University of New Hampshire.

While the LIA maximum occurred across Europe within the past 500 years, records show asynchronous maxima in Scandinavia (~1750AD) and the Swiss Alps (~1860AD). That temperature variations did not even take place uniformly across Europe during times of change shows the simultaneous event argument to be meaningless. Indeed, this report correlates data from a number of different studies to provide a clear image of the LIA period at several different locations around the world.

Figure 3 from the Science report: Comparison of climate and proxy records spanning the last millennium. (A) Fluctuations of Nigardsbreen, Norway, and Great Aletsch and Gorner glaciers, Swiss Alps, with black triangles indicating maximum extension; lichenometrically dated glacial maxima in the Cordillera Blanca, Peru (CB), and eastern Cordilleras, Bolivia (BOL); 10Be-dated glacial maxima in New Zealand, with vertical bars schematically showing decreasing amplitudes of events. (B) Volume transport of the Florida Current. (C) Surface water δ18Ow in two Dry Tortugas cores, with higher values reflecting higher Florida Current surface salinity. (D) Titanium percentages in Cariaco Basin sediments, with lower values implying greater aridity in northern Venezuela and a more southerly mean latitude of the ITCZ. (E and F) Quelccaya Ice Cap δ18O and accumulation data, with inferred colder and wetter intervals shaded in gray. (G) Glacial maxima from this study [For the sources of the data from other locations shown in the figure above please refer to the report].

As can be seen from the figure, climate change from Norway to New Zealand and from the Dry Tortugas to Peru all indicate that the Little Ice Age was not a localized anomaly but a world wide event. But then, this is only the most recent study to affirm this fact. In a 1986 paper, entitiled “The Little Ice Age as Recorded in the Stratigraphy of the Tropical Quelccaya Ice Cap,” L. G. Thompson et al., after analyzing more than 1000 years of ice core data from another tropical glacier, reported similar results. In fact, this study provided the data in sections E and F of the figure above. The authors of this study, performed two decades earlier, concluded: “The fact that the Little Ice Age (about A.D. 1500 to 1900) stands out as a significant climatic event in the oxygen isotope and electrical conductivity records confirms the worldwide character of this event.”

So why do climate alarmists continue to resurrect the infamous hockey stick, which implies that the LIA did not happen on a world wide basis? The story of Michael Mann's hockey stick climate reconstruction, its statistical bias and the influence of the bristlecone pines is well known. The work of Steve McIntyre in debunking the original graph is also widely known. What is less well known is that there have been several recent attempts to re-establish this bit of statistical flimflam as scientifically valid.


The bogus “hockey stick” inspired graph in UNEP's 2009 publication.

Recently, Steve McIntyre, writing on his Climate Audit blog, reported the discovery of a Wikipedia “hockey Stick” graphic by “Hanno” being used in an official UNEP document. The UNEP Climate Change Science Compendium 2009, on page 5, used the graph from Wikipedia as shown above. Evidently the offending graph was expunged from the document and a new version quickly published (see “United Nations Pulls Hockey Stick from Climate Report”). This incident underscores how horribly slipshod the “science” behind the IPCC/UNEP reports truly is. If an undergraduate student dared to use a Wikipedia graph in a paper they would find themselves in deep trouble, yet these UN agencies, and a number of journals that keep publishing papers supporting this sort of tripe, blithely continue to palm scientific trash off on an unsuspecting public.

For years, the IPCC and its supporters have been trying to rewrite Earth's climate history, at least the history of the Holocene. They do this to try and strengthen their claims that Earth's temperature is rising abnormally and that the rise is due to human CO2 emissions. People who are aware of what has happened to Earth's climate since the end of the last glacial period, ~12,000 years ago, understand that the slight warming trend of the last century (now reduced to only 0.7°C even by global warming cheerleaders) is well within normal variation. There is no crisis, no imminent catastrophe, just the climate changing as it always does.

Licciardi et al. have reinforced what had already been reported by many others—the Little Ice Age and all of the other well documented warm and cold periods that have occurred during the Holocene were real and global in nature. The revived attempts to rewrite Earth's climate history have been shown to be fraudulent and anthropogenic global warming has once again proven to be a theory built on bad data and statistical quicksand.

Be safe, enjoy the interglacial and stay skeptical.

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