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Nenana Ice Classic 2019

Filed under: — gavin @ 14 April 2019

Wow.

Perhaps unsurprisingly given the exceptional (relative) warmth in Alaska last month and in February, the record for the Nenana Ice Classic was shattered this year.

The previous official record was associated with the exceptional conditions in El Niño-affected winter of 1939-1940, when the ice went out on April 20th 1940. Though since 1940 was a leap year, that was actually a little later (relative to the vernal equinox) than the ice out date in 1998 (which wasn’t a leap year). 

Other records are also tumbling in the region, for instance the ice out data at Bethel, Alaska:

 

 

While the trend at Nenana since 1908 has been towards earlier ice-out dates (by about 7 days a century on average), the interannual variability is high. This is consistent with the winter warming in this region over that period of about 2.5ºC.  Recent winters have got close (2012/14/15/16) (3 to 4 days past the record),  but this year’s April 14th date is an impressive jump (and with no leap year to help calendrically).

As usual, I plot both the raw date data and the version adjusted to relative to the vernal equinox (the official time of breakup was ~12:21am).

  [As usual, I predict that there will be no interest from the our favorite contrarians in this]

 

 

 

 

 

 

 

 

 

 

 

First successful model simulation of the past 3 million years of climate change

Filed under: — stefan @ 3 April 2019

Guest post by Matteo Willeit, Potsdam Institute for Climate Impact Research

A new study published in Science Advances shows that the main features of natural climate variability over the last 3 million years can be reproduced with an efficient model of the Earth system.

The Quaternary is the most recent geological Period, covering the past ~2.6 million years. It is defined by the presence of glacial-interglacial cycles associated with the cyclic growth and decay of continental ice sheets in the Northern Hemisphere. Climate variations during the Quaternary are best seen in oxygen isotopes measured in deep-sea sediment cores, which represent variations in global ice volume and ocean temperature. These data show clearly that there has been a general trend towards larger ice sheets and cooler temperatures over the last 3 million years, accompanied by an increase in the amplitude of glacial-interglacial variations and a transition from mostly symmetry cycles with a periodicity of 40,000 years to strongly asymmetric 100,000-year cycles at around 1 million years ago.  However, the ultimate causes of these transitions in glacial cycle dynamics remain debated.

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Unforced variations: April 2019

Filed under: — group @ 2 April 2019

This month’s open thread on climate science issues. Remember that discussions about climate solutions go here.