This is a collection of relevant papers from Science magazine. Again, a work in progress...


Polar Ice Caps

Date	Title	Abstract
Hansen 2007	Ise Sheet Melting	Unpublished paper covering ice cap melting.
2006 Mar 24	Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise	Sea-level rise from melting of polar ice sheets is one of the largest potential threats of future climate change. Polar warming by the year 2100 may reach levels similar to those of 130,000 to 127,000 years ago that were associated with sea levels several meters above modern levels; both the Greenland Ice Sheet and portions of the Antarctic Ice Sheet may be vulnerable. The record of past ice-sheet melting indicates that the rate of future melting and related sea-level rise could be faster than widely thought.
2001 Jan 05	Atmospheric CO2 Concentrations over the Last Glacial Termination	A record of atmospheric carbon dioxide (CO2) concentration during the transition from the Last Glacial Maximum to the Holocene, obtained from the Dome Concordia, Antarctica, ice core, reveals that an increase of 76 parts per million by volume occurred over a period of 6000 years in four clearly distinguishable intervals.
2001 Jan 05	Timing of Millennial-Scale Climate Change in Antarctica and Greenland During the Last Glacial Period	A precise relative chronology for Greenland and West Antarctic paleotemperature is extended to 90,000 years ago, based on correlation of atmospheric methane records from the Greenland Ice Sheet Project 2 and Byrd ice cores. Over this period, the onset of seven major millennial-scale warmings in Antarctica preceded the onset of Greenland warmings by 1500 to 3000 years. In general, Antarctic temperatures increased gradually while Greenland temperatures were decreasing or constant, and the termination of Antarctic warming was apparently coincident with the onset of rapid warming in Greenland. This pattern provides further evidence for the operation of a "bipolar see-saw" in air temperatures and an oceanic teleconnection between the hemispheres on millennial time scales.
2002 Mar 29	Sea-Level Fingerprinting as a Direct Test for the Source of Global Meltwater Pulse IA	The ice reservoir that served as the source for the meltwater pulse 1A remains enigmatic and controversial. We show that each of the melting scenarios that have been proposed for the event produces a distinct variation, or fingerprint, in the global distribution of meltwater. We compare sea-level fingerprints associated with various melting scenarios to existing sea-level records from Barbados and the Sunda Shelf and conclude that the southern Laurentide Ice Sheet could not have been the sole source of the meltwater pulse, whereas a substantial contribution from the Antarctic Ice Sheet is consistent with these records.
2003 Mar 14	Meltwater Pulse 1A from Antarctica as a Trigger of the Bølling-Allerød Warm Interval	Meltwater pulse 1A (mwp-1A) was a prominent feature of the last deglaciation, which led to a sea-level rise of ~20 meters in less than 500 years.
2007 Mar 16	Why Is It Hard to Predict the Future of Ice Sheets?	Ice sheet retreat, hypotheses of instability could be missing important processes that limit the rate or extent of retreat, or conversely, Ice sheet behavior is strongly influenced by processes at its margin and base. Observations of rapid changes at these boundaries are helping modelers to improve predictions of future changes.
2007 Mar 30	Ice Sheet Stability and Sea-Level Rise	A wedge of sediments appears to stabilize the Whillans Ice Stream in West Antarctica, suggesting that sea-level rise may not destabilize ice sheets as much as previously feared.
2007 Jan 19	A Semi-Empirical Approach to Projecting Future Sea-Level Rise	A semi-empirical relation is presented that connects global sea-level rise to global mean surface temperature. It is proposed that, for time scales relevant to anthropogenic warming, the rate of sea-level rise is roughly proportional to the magnitude of warming above the temperatures of the pre–Industrial Age. This holds to good approximation for temperature and sea-level changes during the 20th century, with a proportionality constant of 3.4 millimeters/year per °C. When applied to future warming scenarios of the Intergovernmental Panel on Climate Change, this relationship results in a projected sea-level rise in 2100 of 0.5 to 1.4 meters above the 1990 level.

Paleoclimate

Date	Title	Abstract
2005 Jun 10	Rapid Acidification of the Ocean During the Paleocene-Eocene Thermal Maximum	The Paleocene-Eocene thermal maximum (PETM) has been attributed to the rapid release of ~2000 x 109 metric tons of carbon in the form of methane. In theory, oxidation and ocean absorption of this carbon should have lowered deep-sea pH, thereby triggering a rapid (<10,000-year) shoaling of the calcite compensation depth (CCD), followed by gradual recovery. Here we present geochemical data from five new South Atlantic deep-sea sections that constrain the timing and extent of massive sea-floor carbonate dissolution coincident with the PETM. The sections, from between 2.7 and 4.8 kilometers water depth, are marked by a prominent clay layer, the character of which indicates that the CCD shoaled rapidly (<10,000 years) by more than 2 kilometers and recovered gradually (>100,000 years). These findings indicate that a large mass of carbon (»2000 x 109 metric tons of carbon) dissolved in the ocean at the Paleocene-Eocene boundary and that permanent sequestration of this carbon occurred through silicate weathering feedback.
2006 Jun 09	The Pliocene Paradox (Mechanisms for a Permanent El Niño)	During the early Pliocene, 5 to 3 million years ago, globally averaged temperatures were substantially higher than they are today, even though the external factors that determine climate were essentially the same. In the tropics, El Niño was continual (or "permanent") rather than intermittent.
2006 Apr 07	Evolution of the Eastern Tropical Pacific Through Plio-Pleistocene Glaciation	A tropical Pacific climate state resembling that of a permanent El Niño is hypothesized to have ended as a result of a reorganization of the ocean heat budget 3 million years ago, a time when large ice sheets appeared in the high latitudes of the Northern Hemisphere.
2000 Mar 24	Simulation of Early 20th Century Global Warming	The observed global warming of the past century occurred primarily in two distinct 20-year periods, from 1925 to 1944 and from 1978 to the present. Although the latter warming is often attributed to a human-induced increase of greenhouse gases, causes of the earlier warming are less clear because this period precedes the time of strongest increases in human-induced greenhouse gas (radiative) forcing. Results from a set of six integrations of a coupled ocean-atmosphere climate model suggest that the warming of the early 20th century could have resulted from a combination of human-induced radiative forcing and an unusually large realization of internal multidecadal variability of the coupled ocean-atmosphere system. This conclusion is dependent on the model's climate sensitivity, internal variability, and the specification of the time-varying human-induced radiative forcing.

Climate Feedbacks

Date	Title	Abstract
2005 Jun 03	Earth's Energy Imbalance	Our climate model, driven mainly by increasing human-made greenhouse gases and aerosols, among other forcings, calculates that Earth is now absorbing 0.85 ± 0.15 watts per square meter more energy from the Sun than it is emitting to space. This imbalance is confirmed by precise measurements of increasing ocean heat content over the past 10 years.
2006 Jun 16	Permafrost and the Global Carbon Budget	Climate warming will thaw permafrost, releasing trapped carbon from this high-latitude reservoir and further exacerbating global warming.
2006 Apr 14	High Natural Aerosol Loading over Boreal Forests
2004 Jul 16	The Oceanic Sink for Anthropogenic CO2	Using inorganic carbon measurements from an international survey effort in the 1990s and a tracer-based separation technique, we estimate a global oceanic anthropogenic carbon dioxide (CO2) sink for the period from 1800 to 1994 of 118 ± 19 petagrams of carbon. The oceanic sink accounts for 48% of the total fossil fuel and cement manufacturing emissions, implying that the terrestrial biosphere was a net source of CO2 to the atmosphere of about 39 ± 28 petagrams of carbon for this period. The current fraction of total anthropogenic CO2 emissions stored in the ocean appears to be about one-third of the long-term potential.

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