Science of dating events using ice

Here we model this event and its atmospheric effects and compare it to extensive ice core data.

In two short decades, we have learned so much about when glaciers and ice sheets retreated that it's hard to imagine a world where glacial boulders were not targets for dating.

Yet, children born when the first paper using cosmogenic nuclides to date such erratics was published (Phillips et al., 1990) are still not old enough to vote. took a simple and oft-used approach for characterizing the vertical extent of now-vanished ice.

They have also identified a spike representing fallout from stepped-up atmospheric testing that took place just prior to the 1963 Test Ban Treaty, which allowed for underground tests only. This graph, which combines results from cores taken in both Antarctica and Greenland, tracks sodium levels over the past 1,200 years. (Winds are generally stronger in springtime, meaning more dust gets blown into the atmosphere.) In this photograph of an ice core drilled in the Kunlun Mountains of western China, the thick, lighter bands indicate heavy snowfall during the monsoon season in the year 1167 AD, while the thinner, darker strips show layers of dust blown into the snowfield during the dry season.

Sporadic solar energetic particle (SEP) events affect the Earth’s atmosphere and environment, in particular leading to depletion of the protective ozone layer in the Earth’s atmosphere, and pose potential technological and even life hazards.

No longer should it be considered a major player in postglacial sea-level rise.

Until just 20 years ago, when pioneering work in accelerator mass spectrometry (Elmore and Phillips, 1987), cosmogenic isotope systematics (Lal, 1988), and geologic applications (Craig and Poreda, 1986; Kurz, 1986) hit the presses, such conclusions were unreachable because many hypotheses regarding rates and dates of glacial processes were simply unfalsifiable.p .main-container #login input[type=text], .main-container #login input[type=password] .main-container #login input[type=text] .main-container #login input[type=password] .main-container #login div .main-container .remember-forgot .main-container .main-container .main-container #login div label .main-container button .main-container #social .main-container #social span .main-container #social span.facebook .main-container #social .main-container #social span.twitter .main-container #social .main-container .main-container .Attribution: You must attribute the work in the manner specified by the author or licensor (but no in any way that suggests that they endorse you or your use of the work).Using state-of-the-art cosmic ray cascade and chemistry-climate models, we successfully reproduce the observed variability of cosmogenic isotope Be, around 775 AD, in four ice cores from Greenland and Antarctica, thereby validating the models in the assessment of this event.We add to prior conclusions that any nitrate deposition signal from SEP events remains too weak to be detected in ice cores by showing that, even for such an extreme solar storm and sub-annual data resolution, the nitrate deposition signal is indistinguishable from the seasonal cycle.The greatest SEP storm known for the last 11 millennia (the Holocene) occurred in 774–775 AD, serving as a likely worst-case scenario being 40–50 times stronger than any directly observed one.

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