Posted by greg2213 on June 2, 2013
Alarmists love to call the modern warming “unprecedented.” This is pretty hysterical given that number of much larger and more abrupt changes over the years. The .5 to .8C over the last 150 years just doesn’t compare.
And all of those other changes (warming and cooling) were without benefit of significant CO2 changes. Thi sis another nail in the coffin of the “CO2 is the primary cause of CC” argument.
On, WUWT, the conclusion:
(1) The ice core isotope data were hugely significant because they showed that the Younger Dryas, as well as the other late Pleistocene warming and cooling events, could not possibly be caused by human emissions of CO2 because they occurred thousands of years before such emissions had any effect on atmospheric CO2.
(2) The magnitude and intensity of multiple climatic fluctuations has been up to 20 times larger than warming during the past century.
(3) Single events, i.e., volcanic activity or cosmic impacts, cannot have caused the abrupt Dansgaard/Oerscher warming and cooling events because of the multiplicity of warm/cold events over periods of thousands of years.
(4) The absence of a time lag between the N and S Hemisphere glacial fluctuations precludes an oceanic cause and is not consistent with the North Atlantic Deep Ocean Water hypothesis for the cause of the Younger Dryas.
(5) The abruptness of the climate changes and their multiplicity could not have been caused by slow, Croll-Milankovitch orbital forcing, which occurs over many tens of thousands of years. Since fluctuations to and from full glacial climates occurred over short periods of time, clearly a cause other than the Croll-Milankovitch theory is capable of causing the Ice Ages .
The whole article is here.
The modern warming compared to prior warmings:
(see the full article for details.)
Posted in Cycles, Temerature Records | Tagged: Bond, Carbon Dioxide, Dansgaard, Ice Age, Younger Dryas | 1 Comment »
Posted by greg2213 on January 28, 2011
Update 3/12/13: New paper confirms Greenland is resistant to thaw
No, Greenland isn’t Melting
From a WUWT comment: (excerts added are mine)
Greenland air temps of the past:
“…the rate of warming in 1920–1930 was about 50% higher than that in 1995–2005.”
Petr Chylek et. al.
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.
“The annual whole ice sheet 1919–32 warming trend is 33% greater in magnitude than the 1994–2007 warming.”
Jason E. Box et. al.
Meteorological station records and regional climate model output are combined to develop a continuous 168-yr (1840–2007) spatial reconstruction of monthly, seasonal, and annual mean Greenland ice sheet near-surface air temperatures. Independent observations are used to assess and compensate for systematic errors in the model output. Uncertainty is quantified using residual nonsystematic error. Spatial and temporal temperature variability is investigated on seasonal and annual time scales. It is found that volcanic cooling episodes are concentrated in winter and along the western ice sheet slope. Interdecadal warming trends coincide with an absence of major volcanic eruptions. Year 2003 was the only year of 1840–2007 with a warm anomaly that exceeds three standard deviations from the 1951–80 base period. The annual whole ice sheet 1919–32 warming trend is 33% greater in magnitude than the 1994–2007 warming. The recent warming was, however, stronger along western Greenland in autumn and southern Greenland in winter. Spring trends marked the 1920s warming onset, while autumn leads the 1994–2007 warming. In contrast to the 1920s warming, the 1994–2007 warming has not surpassed the Northern Hemisphere anomaly. An additional 1.0°–1.5°C of annual mean warming would be needed for Greenland to be in phase with the Northern Hemispheric pattern. Thus, it is expected that the ice sheet melt rates and mass deficit will continue to grow in the early twenty-first century as Greenland’s climate catches up with the Northern Hemisphere warming trend and the Arctic climate warms according to global climate model predictions.
“We found that northern hemisphere temperature and Greenland temperature changed synchronously at periods of ~20 years and 40–100 years. This quasi-periodic multi-decadal temperature fluctuation persisted throughout the last millennium, and is likely to continue into the future.”
Takuro Kobashi et. al.
Future Greenland temperature evolution will affect melting of the ice sheet and associated global sea-level change. Therefore, understanding Greenland temperature variability and its relation to global trends is critical. Here, we reconstruct the last 1,000 years of central Greenland surface temperature from isotopes of N2 and Ar in air bubbles in an ice core. This technique provides constraints on decadal to centennial temperature fluctuations. We found that northern hemisphere temperature and Greenland temperature changed synchronously at periods of ~20 years and 40–100 years. This quasi-periodic multi-decadal temperature fluctuation persisted throughout the last millennium, and is likely to continue into the future.
“The warmest year in the extended Greenland temperature record is 1941, while the 1930s and 1940s are the warmest decades. Two distinct cold periods, following the 1809 (‘‘unidentified’’ volcanic eruption and the eruption of Tambora in 1815 make the 1810s the coldest decade on record.”
B. M. Vinther et. al.
“Particulars are given regarding the big rise of winter temperatures in Greenland and its more oceanic climate during the last fifteen years.”
Posted in Temerature Records | Leave a Comment »