Melting Antarctic Ice Part of Natural Cycle
Historical records for the western Antarctic Peninsula (WAP) show that it is particularly prone to rapid climate change—change that occurs in cycles of ~200 years and ~2500 years. By studying major transitions in plankton productivity in the western Antarctic, scientists have shown that “spectacular” ice-cover losses have happened many times in the past. In other words, the “unprecedented rapid loss of ice” from parts of Antarctica that global warming alarmists make so much of are a normal part of nature's cycles.
According to the latest report in the journal Science, this is how it works: Less ice in the northern zone causes more cloud cover, reducing the amount of light reaching the plankton. A loss of light, together with less ice-melt freshwater and stronger winds means fewer large plankton blooms. By contrast, in the south, the skies stay cloudless for longer and the Antarctic current increases its flow rate, pulling up more nutrients. Both factors contribute to greater primary productivity. These physical changes explain the striking shifts recently observed in krill and the vertebrate communities of the western Antarctic.
For those who take their science straight, here is the abstract of the paper titled “Recent Changes in Phytoplankton Communities Associated with Rapid Regional Climate Change Along the Western Antarctic Peninsula,” by Martin Montes-Hugo, et al, as it appears in Science:
“The climate of the western shelf of the Antarctic Peninsula (WAP) is undergoing a transition from a cold-dry polar-type climate to a warm-humid sub-Antarctic–type climate. Using three decades of satellite and field data, we document that ocean biological productivity, inferred from chlorophyll a concentration (Chl a), has significantly changed along the WAP shelf. Summertime surface Chl a (summer integrated Chl a ~63% of annually integrated Chl a) declined by 12% along the WAP over the past 30 years, with the largest decreases equatorward of 63°S and with substantial increases in Chl a occurring farther south. The latitudinal variation in Chl a trends reflects shifting patterns of ice cover, cloud formation, and windiness affecting water-column mixing. Regional changes in phytoplankton coincide with observed changes in krill (Euphausia superba) and penguin populations.”
What this means is that, by measuring amounts of the chemical chlorophyll-a, scientitsts can figure out living conditions in the Antarctic ocean, from which they can infer what was going on with ice cover and other climate conditions. What they found was that the recent period of rapid ice melting in the WAP fits normal climate cycles that have been detected by other scientists. Previous studies have reported similar oscillations in sea ice extent and rate of change during the Holocene—the relatively warm interglacial period we have been in for the past 15,000 years. One such study was by Amy Leventer, et al, reported in the Geological Society of America Bulletin, in December 1996.
In a paper titled “Productivity cycles of 200–300 years in the Antarctic Peninsula region: Understanding linkages among the sun, atmosphere, oceans, sea ice, and biota,” Leventer and colleagues report the results of a multiproxy record from a sediment core retrieved from a deep basin on the western side of the Antarctic Peninsula. The report reveals “a dramatic perspective on paleoclimatic changes over the past 3700 yr. Analyses completed include measurement of magnetic susceptibility and granulometry, bed thickness, particle size, percent organic carbon, bulk density, and microscopic evaluation of diatom and benthic foraminiferal assemblages and abundances.” Their conclusion was that “variability of these parameters demonstrates the significance of both short-term cycles, which recur approximately every 200 yr, and longer term events (~2500 yr cycles) that are most likely related to global climatic fluctuations.”
In other words, ice in the Antarctic region undergoes periodic episodes of rapid melting—and it is all entirely natural, not because of human activity. The new paper echos these findings: “Paleo-records show that analogous climate variations have occurred in the past 200 to 300 years, and over longer 2500-year cycles, with rapid (decadal) transitions between warm and cool phases in the WAP. In this study (~30 years), the Chl a trend evidenced in the southern subregion of the WAP presented similar characteristics to those trends detected during typical interneoglacial periods (~200 to 300 years) (i.e., high phytoplankton biomass, and presumably productivity, due to less area covered by permanent sea ice).”
Science is marvelous, it never rests and never accepts any simple answer at face value. Here we see confirmation of an alternate explanation for rapid ice melting in Antarctica. The latest paper cites thirty supporting references and cross referencing the older paper provides links to eighteen others—this paper's conclusions are not from a single group of “fringe” scientists. Yet have you heard this well documented explanation for rapid ice melting from any media outlet reporting on global warming? Of Course not! What is reported is “more unprecedented melting!”
To have reported that the melting ice could be explained more accurately by a scientific theory other than anthropogenic global warming would muddy the water, not to mention confuse the news anchor doing the reporting. This is what makes other scientists, myself included, so angry about the climate change clique—their lack of open mindedness, their willful disregard for any facts counter to their preconceived ideas, their out right lies. When the dust finally settles on the great global warming debate there will be a number of climate scientist with much to account for.
Meanwhile, enjoy the interglacial and stay skeptical.