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Paleoclimate proxy records reveal a pervasive cooling event with a Northern Hemispheric extent approximately 9300 years ago. Coeval changes in the oceanic circulation of the North Atlantic imply freshwater forcing. However, the source, magnitude, and routing of meltwater have remained unknown. Located in central North America, Lake Superior is a key site for regulating the outflow of glacial meltwater to the oceans. Here, we show evidence for an approximately 45-meter rapid lake-level fall in this basin, centered on 9300 calibrated years before the present, due to the failure of a glacial drift dam on the southeast corner of the lake. We ascribe the widespread climate anomaly approximately 9300 years ago to this freshwater outburst delivered to the North Atlantic Ocean through the Lake Huron-North Bay-Ottawa River-St. Lawrence River valleys.

ObjectiveTo compare voice-activated internet searches by smartphone (two digital assistants) with laptop ones for information and advice related to smoking cessation.DesignResponses to 80 questions on a range of topics related to smoking cessation (including the FAQ from a NHS website), compared for quality.SettingSmartphone and internet searches as performed in New Zealand.Main outcome measuresRanked responses to the questions.ResultsGoogle laptop internet searches came first (or first equal) for best quality smoking cessation advice for 83% (66/80) of the responses. Voiced questions to Google Assistant (“OK Google”) came first/first equal 76% of the time vs Siri (Apple) at 28%. Google and Google Assistant were statistically significantly better than Siri searches (odds ratio 12.4 and 8.5 respectively, p<0.0001 in each comparison). When asked FAQs from the National Health Service website, or to find information the Centers for Disease Control has made videos on, the best search results used expert sources 59% (31/52) of the time, “some expertise” (eg, Wikipedia) 18% of the time, but also magazines and other low quality sources 19% of the time. Using all three methods failed to find relevant information 8% (6/80) of the time, with Siri having the most failed responses (53% of the time).ConclusionGoogle internet searches and Google Assistant were found to be significantly superior to the Siri digital assistant for smoking cessation information. While expert content was returned over half the time, there is still substantial room for improvement in how these software systems deliver smoking cessation advice.

Os isotopes ͉ platinum group elements ͉ Clovis ͉ Pleistocene extinction ͉ meteorite P roxy records of millennial-scale climate variations during the most recent deglaciation from polar ice cores (1-3) as well as deep-sea and lacustrine sediments (4-10) display abrupt changes that are typically attributed to internal forcing of Earth's climate system. A striking example is the Younger Dryas (YD) cooling episode from 12.896 Ϯ 0.138 thousand years (ka) to 11.703 Ϯ 0.099 ka calendar years before AD 2000 (11) after the interstadial warming event Bølling-Allerød (BA) (14.692 Ϯ 0.186-14.075 Ϯ 0.169 ka). High-resolution stable ␦ 18 O and ␦D in H 2 O and the glaciochemical record from Greenland ice cores show that both the onset and the termination of the YD occurred abruptly, the former lasting slightly more than two centuries, whereas the latter transitioned into a new state in a few years (12). The most widely accepted interpretations of Earth's recent climate history place the origin and termination of the YD within Earth's complex network of feedback mechanisms (13-15). Proxies and model results favor a significant freshwater input into the North Atlantic reducing the formation of deep waters and weakening or shutting down of the meridional overturning circulation (16) as the primary cause of the YD cooling regardless of its source, timing, duration, volume, and path of melt water (17-21).

Despite recent interest in the North American fire record, paleoecological evidence for the deliberate burning of grassland by hunter–gatherers has not previously been sought. Through the analysis of grass phytoliths preserved in a sequence of buried soil horizons in the Lauder Sandhills, southwestern Manitoba, Canada, this article reconstructs a local grassland fire record for the past 5,000 years. I propose that an apparent peak in fire frequency shortly after 2,500 14C years b.p. corresponds to the deliberate burning of prairie by Sonota–Besant (Plains Woodland) hunter–gatherers, rather than climatic “forcing.” This practice, which is clearly documented in the historic record, may have functioned as a means of making bison–herd movements more predictable and may have enabled higher human carrying capacities in the Plains Woodland period. This hypothesis is meant to stimulate multidisciplinary discussion on a significant, but neglected, topic.