Search

Just over 40 years ago, I wrote a paper entitled 'Climate change: Are we on the brink of a pronounced global warming?' In it, I attempted to explain why despite a rise in the atmosphere's CO2 content there had been no significant warming. I predicted that a natural cooling was about to give way to a warming, and that industrial emissions of CO2 would amplify this warming. The paper published in Science in 1975. Warming did follow in 1976-1977. However, a retrospective look shows that my analysis was flawed. What is more-and to my chagrin-based on the words 'global warming' in my Science paper, I was given the title 'Father of Global Warming.' Not only did I not like this title, I had done little to merit it. [ABSTRACT FROM AUTHOR]

Measurements on fluid inclusions (Timofeeff and others, 2006) indicate that over the last 110 million years, the Mg to Ca ratio in seawater has risen by at least a factor of four. Those by Zachos and others (2003) on planktic foraminifera suggest that about half of this rise occurred during the last 55 million years. Although Coggon and others' (2010) measurements on ridge-flank basalts are consistent with a rise of this magnitude, they indicate that it occurred after 46 million years ago and perhaps even as recently as the last 15 million years. Based on the Mg to K trend in 36 million-year-old halite-hosted fluid inclusions, Brennan and others (2013) confirm Zimmerman's (2000) conclusion that the Mg content of sea salt was about 35 percent lower than now at that time. Hence, if the Coggon and others' (2010) results are to be believed, then the rise in Mg must have been accompanied by a drop in calcium. When account is taken that the C02 content of the atmosphere 35 million years ago was about five times larger than it is today, then perhaps at that time, the dissolution rate of limestone was greater than today's. If so, then the large increase in Mg to Ca ratio could be explained by a combination of a decrease in sea level which slowed the rate of dolomite formation and a drop in atmospheric CO2 content which slowed the delivery by rivers to the sea of Ca derived from limestone weathering. Unfortunately, as the deposition of gypsum prior to halite formation removed virtually all the calcium from the brine pools in which the halite subsequently formed, there is no record of Ca in Cenozoic-age fluid inclusions. Hence, in order to resolve the difference between the large Mg/Ca rise over the last 40 million years suggested by ridge-plank calcites and, the smaller one suggested by planktic foraminifera, an additional proxy for Ca is needed. As I suggested many years ago (Broecker, 1970), one such candidate is the uranium content of corals. [ABSTRACT FROM AUTHOR]

Abstract: Lake Estancia''s transition from a Big Dry episode during the first half of the Mystery Interval to a Big Wet episode during the second half has equivalents in records from across the planet. At the time of this transition, Chinese monsoons experienced pronounced weakening, closed-basin lakes in both the Great Basin of the western United States and in the southern Altiplano of South America underwent a major expansion, mountain glaciers in Southern Hemisphere middle latitudes had retreated, and the rates of increase of CO2 and of δ18O in Antarctic ice underwent a decrease. Finally, the precipitous drop in dust rain over Antarctica and the Southern Ocean terminated as did a similar drop in the 13C to 12C ratio in atmospheric CO2. These changes are consistent with a southward shift of the thermal equator. The cause of such a shift is thought to be an expansion of sea ice caused by a shutdown in deep water production in the northern Atlantic. This creates a dilemma because a similar southward shift is an expected consequence of the Heinrich event #1 which initiated the Mystery Interval. [Copyright &y& Elsevier]

Deep-ocean carbonate ion concentrations ([CO32-]) and carbon isotopic ratios (δ13C) place important constraints on past redistributions of carbon in the ocean-land-atmosphere system and hence provide clues to the causes of atmospheric CO2 concentration changes. However, existing deep-sea [CO32-] reconstructions conflict with one another, complicating paleoceanographic interpretations. Here, we present deep-sea [CO32-] for five cores from the three major oceans quantified using benthic foraminiferal boron/calcium ratios since the last glacial period. Combined benthic δ 13C and [CO32-] results indicate that deep-sea-released CO2 during the early deglacial period (17.5 to 14.5 thousand years ago) was preferentially stored in the atmosphere, whereas during the late deglacial period (14 to 10 thousand years ago), besides contributing to the contemporary atmospheric CO2 rise, a substantial portion of CO2 released from oceans was absorbed by the terrestrial biosphere. [ABSTRACT FROM AUTHOR]

Illustrates the events of Earth climate experiencing oscillations between glacial and interglacial conditions. Observation of discreet layers of sediment rich in ice-rafted debris; Suggestion of the binge-purge hypothesis for the climatic change; Significance of the Heinrich and Dansgaard-Oeschger events.

The article presents an abstract of comments written on the article "Deep-Sea Temperature and Ice Volume Changes Across the Pliocene-Pleistocene Climate Transitions," by S. Sosdian and Y. Rosenthal in the July 17, 2009 issue.

Abstract We measured U/Ca ratios, 4He concentrations, 234U/238U, and 238U/235U in a subset of well-preserved aragonitic scleractinian fossil corals previously described by Gothmann et al. (2015). Comparisons of measured fossil coral He/U ages with the stratigraphic age demonstrate that well-preserved coral aragonite retains most or all of its radiogenic He for 10's of millions of years. Such samples must be largely or entirely free of alteration, including neomorphism. Measurements of 234U/238U and 238U/235U further help to characterize the fidelity with which the original U concentration has been preserved. Analyses of fossil coral U/Ca show that the seawater U/Ca ratio rose by a factor of 4–5 between the Early Cenozoic and today. Possible explanations for the observed increase include (1) the stabilization of U in seawater due to an increase in seawater [CO 3 2−], and a resulting increase in UO 2 -CO 3 complexation as originally suggested by Broecker (1971); (2) a decrease in the rate of low-temperature hydrothermal alteration from Early Cenozoic to present, leading to a diminished U sink and higher seawater [U]; or (3) a decrease in uranium removal in reducing sediments, again leading to higher seawater [U]. [ABSTRACT FROM AUTHOR]