"It's definitely a bad report. We did pick up little bit from last year, but this is over 30 percent below what used to be normal...."
- "Normal" for what period? Arctic ice cover has oscillated greatly over recorded time. Is ice cover less than 30 years ago... sure, no argument... we were at at the end of a cold period thirty years ago. Is it less than during the 1850s or the 1920s-30s warming periods... no one knows.
"Scientists have monitored sea ice conditions for about 50 years with the help of satellites"
- Fifty years ago is 1958. Sputnik was launched in October of 1957. No satellites were used to study Arctic ice conditions until the mid-to-late 1970s... thirty years ago.
Quote:
...In an article recently appearing in the Journal of Geophysical Research, Dmitry Divine and Chad Dick (2006) of the Norwegian Polar Institute report on their use of historical observations of ice cover in the Nordic Seas region to construct time series of warm season ice edge position dating back to 1750. Their particular search for a climate change signal is important for three reasons. First, as an insulator between the ocean and the atmosphere, as an effective reflector of solar radiation, and as a modifier of atmospheric and oceanic circulation, sea ice cover has a significant impact on global climate. Second, the Nordic Seas region, which is inclusive of the Iceland, Greenland, Norwegian, and Barents seas, is a focal point for the global climate due to its primary role in driving the global oceanic thermohaline circulation. It is in this region that excess fresh water from melting ice in association with global warming is theorized to impact the thermohaline circulation enough to generate significant climate changes worldwide. (Alarmists hope that this evokes in your mind scenes from the movie Day After Tomorrow.) Third, Divine and Dick use data generated through direct observation of ice conditions, which allowed them to construct a historical record of a length that far surpasses those of sea ice studies that rely on satellite-derived ice cover products. Divine and Dick note that many studies “have revealed a dramatic retreat of ice extent over the past decades in almost all regions where sea ice exists as a seasonal or perennial phenomenon.” However, (and this is a big caveat) Divine and Dick point out that “debate continues over whether the recent shrinkage of ice cover gives direct evidence of global warming caused by human activity or is mainly a part of a secular cycle.” The 30-year record of satellite sensing of sea ice “has shed light on the spatial and temporal patterns of seasonal and interannual variability in ice extent and concentrations, but is still too short for resolving the multi-year variability in ice cover.”
Records of ice extent in the Nordic Seas region date to the mid-17th century, primarily in the form of ship logs and diaries early in the record and airborne and satellite observations later in the record. The data are sparse until the latter half of the 19th century when sealing and whaling in the region became popular. Data from 1850 to present are considered to be rather complete and the sea ice data for this period collectively represent one of the few data sets with direct measurements of climate conditions dating back more than a century. Divine and Dick note the importance of the period from a climate change perspective, as the 150+ years include well-known “Arctic cooling (1880s–1910s, 1960s–1970s) and warming (1920s–1930s, 1980s–1990s) events as well as the recent significant reduction of ice extent.”
The researchers used data from the Arctic Climate Systems Study Historical Ice Chart Archive to extend the historical record back to 1750. These data were complimented with Soviet aircraft reconnaissance ice charts for the period 1950 through 1965 to help fill a gap in data for the Barents Sea within the Ice Chart Archive. Data from two passive microwave sensors aboard satellites were used to also represent ice concentration within the region across the period 1978 through 2002. Divine and Dick simply define ice extent as a single line or “ice edge” separating “close pack ice from loose drift ice.” Data from the three sources were merged to produce a complete series of monthly ice charts representing the mean position of the ice edge. Based on oceanographic and geographical considerations the region was divided into seven sectors for analysis and data interpretation.
The researchers focused on the annual period from March through September, which represents the annual warm season that is conducive to hunting, and thereby associated with a much greater data density than the cold winter months. The period includes the typical timing of the annual ice cover maximum (April) and minimum (September), but in their analysis, Divine and Dick emphasized the months of April, June, and August, where June represents an approximate mid-point between ice maximum and minimum, and August is characterized by greater data density than during the time of minimum ice cover in September.
In agreement with the findings of previous work, Divine and Dick found a persistent ice retreat within the region since the second half of the 19th century. However, their analysis also indicates that the decreasing trend is being superimposed on multidecadal oscillations in ice edge position. Their work suggests the presence of a 60-80 year variability and two- to three-decadal oscillations in ice extent. Divine and Dick associate the multidecadal oscillations “with the so-called low-frequency oscillation found in Arctic climate and possibly associated with the North Atlantic thermohaline circulation variability.” The researchers further conclude that since the last Arctic cold period occurred in the late 1960s, it is likely that the Arctic ice pack is now at the height of its low frequency variability.... Reference
"So, just how much ice is disappearing?
Less than 30 years ago, there would still be 7 million square kilometers or 2.5 million square miles of ice left at the end of an Arctic summer. That's now dropped by almost 40 percent."
- Thirty years ago puts us at the end of a known Arctic cold period (through the 1960s into the 1970s), where ice cover would have been at its greatest. We know we have been in a warming trend. We also know that that warming trend has flattened out over the last ten years, and we know that the last couple years show declining temperatures.
"The Arctic sea ice melt is a disaster for the polar bears," according to Kassie Siegel, staff attorney for the Center for Biological Diversity. "They are dependent on the Arctic sea ice for all of their essential behaviors, and as the ice melts and global warming transforms the Arctic, polar bears are starving, drowning, even resorting to cannibalism because they don't have access to their usual food sources."
- A wee touch of hyperbole here... polar bears have been around (as a distinct species) for roughly 200,000 years. They have survived all kinds of changes in ice coverage just fine, and measured population levels are at all time highs.
Even though arctic ice cover has been declining for thirty years, worldwide polar bear population estimates have increased over the past 50 years and are relatively stable today (20,000-25,000).
This directly contradicts forecasts relating expected declines in population with what is actually being measured (i.e., the forecasts are not backed up by the results). Starving, drowning and even cannibalism are all "normal" behaviors for polar bears... and for all other bears as well.
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