NATURE
1. Water risk as world warms
Nature 505, 10-11 (02 January 2014) doi: 10.1038/505010a
Initial results from the Inter-Sectoral Impact Model Intercomparison Project, aiming to produce a set of harmonised global-impact reports based on the same set of climate data thereby allowing models to be directly compared, suggest that even modest climate change might drastically affect the living conditions of billions of people.
2. Climate science: Clouds of uncertainty
Hideo Shiogama and Tomoo Ogura
Nature 505, 34-35 (02 January 2014) doi: 10.1038/505034a
Evaluation of atmospheric convective mixing and low-level clouds in climate models suggests Earth’s climate will warm more than was thought in response to increasing levels of carbon dioxide. Higher climate sensitivities are more likely than lower ones.
3. Extrasolar planets: Cloudy with a chance of dustballs
Julianne Moses
Nature 505, 31-32 (02 January 2014) doi: 10.1038/505031a
Observations of planets GJ 1214b and GJ436b have shown them to be archetypes of super-Earth and Neptune-class planets. They collectively represent a populous type of extrasolar planet which may have exotic hydrogen-poor, dust-shrouded atmospheres that have no true analogues in the Solar System.
4. Increasing subtropical North Pacific Ocean nitrogen fixation since the Little Ice Age
Owen A. Sherwood, Thomas P. Guilderson, Fabian C. Batista, John T. Schiff and Matthew D. McCarthy
Nature 505, 78-81 (02 January 2014) doi: 10.1038/nature12784
The long-lived deep-sea Hawaiian gold coral Kulamanamana haumeaae provides a unique geochemical time-series in its proteinaceous coral skeleton. Primary productivity in the North Pacific subtropical gyre has increased in recent decades despite a decline in nutrient supply. An ecosystem shift towards nitrogen-fixing plankton communities has been put forward as a possible explanation, but the cause for this shift remains unclear. Sherwood et al. use nitrogen isotopic (δ15N) records from K. haumeaae corals to establish that the increase in nitrogen fixation had already began around 150 years ago, and that it may have been linked to Northern Hemisphere climate change since the end of the Little Ice Age.
SCIENCE
5. A question of balance
H. Jesse Smith
Vol. 343 no. 6166 (03 January 2014)
Nat. Clim. Change doi: 10.1038/NCLIMATE2058 (2013)
Lupascu et al. report that in High Arctic tundra—an important subset of permafrost terrain, which is experiencing a complex combination of rising temperatures, increasing precipitation, and permafrost degradation—warming alone increases the summertime CO2 sink strength by up to 55%, but warming combined with wetting increased the CO2 sink strength by an order of magnitude. Thus, the High Arctic has the potential to remain a strong carbon sink even if the rest of the Arctic permafrost region becomes a net carbon source due to future global warming.
6. EPA science report signals start of wetlands battle
Erik Stokstad
Vol. 343 no. 6166 p. 15 (03 January 2014) doi: 10.1126/science.343.6166.15
A recent report by Environmental Protection Agency (EPA) states that ephemeral water bodies deserve the same protections against pollution and development the Clean Water Act offers to larger rivers and lakes. This will provide key scientific backing for a new stream and wetland protection rule in preparation by the Obama administration; however, landowners and industry groups are lining up to block it.
PNAS
7. Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth
Alan D. Rooney, Francis A. Macdonald, Justin V. Strauss, Francis O. Dudas, Christian Hallmann and David Selby
Vol. 111 no. 1 p. 51-56 doi: 10.1073/pnas.1317266110
New Re-Os geochronology which, together with existing U-Pb ages, reveals that the glacial period in northwest Canada lasted for around 55My. An original method to track tectonic influences on climatic perturbations using a high-resolution Os-Sr isotope curve across the transition from an ice-free world to a Neoproterozoic Snowball Earth was developed. The data indicated that increases in mantle-derived, juvenile material emplaced onto continents and subsequently weathered into the oceans led to enhanced consumption and sequestration of CO2 into sediments.
GEOLOGY
8. Middle Miocene climate cooling linked to intensification of eastern equatorial Pacific upwelling
Ann Holbourn, Wolfgang Kahnt, Mitch Lyle, Leah Schneider, Oscar Romero and Nils Andersen
Vol. 42 no. 1 p. 19-22 doi: 10.1130/G34890.1
High resolution benthic stable isotope data was integrated with X-ray fluorescence scanner-derived biogenic silica and carbonate accumulation estimates in an sedimentary archive and used to reconstruct eastern equatorial Pacific productivity variations and to investigate temporal links between high- and low-latitude climate change over 16-13 Ma. Climatic optimum was characterised by high-amplitude climate variations. Two massive increases in opal accumulation ca. 14.0 and ca. 13.8 Ma occurred just before and during the final and most prominent cooling step, supporting the hypothesis that enhanced siliceous productivity in the eastern equatorial Pacific contributed to CO2 drawdown.
9. Amino acid ratios in reworked marine bivalve shells constrain Greenland Ice Sheet history during the Holocene
Jason P. Briner, Darrell S. Kaufman, Ole Bennike and Matthew A. Kosnik
Vol. 42 no. 1 p. 75-78 doi: 10.1130/G34843.1
Amino acid geochronology in ice sheet-reworked marine bivalve shells was used to constrain the history of the western Greenland Ice Sheet margin during intervals of relative warmth in the middle Holocene. Ice margin changes in western Greenland are tightly linked with oceanographic conditions and thus the distribution of reworked bivalve ages provides important information about relative ice margin position during smaller-than-present ice sheet configurations.
NATURE GEOSCIENCE
10. Warming early Mars with CO2 and H2
Ramses M. Ramirez, Ravi Kopparapu, Michael E. Zugger, Tyler D. Robinson, Richard Freedman and James F. Kasting
Nature Geoscience 7, 59-63 (2014) doi: 10.1038/ngeo2000
Ancient valleys suggest a warm early Mars where liquid water flowed, but a greenhouse effect strong enough to offset a dim early Sun has been difficult to explain. Climate simulations suggest that sufficient concentrations of the greenhouse gases CO2 and H2 — outgassed during volcanic eruptions — could have warmed Mars above water’s freezing point.
11. Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks
Yoko Ohtomo, Takeshi Kakegawa, Akizumi Ishida, Toshiro Nagase and Minik T. Rosing
Nature Geoscience 7, 25-28 (2014) doi: 10.1038/ngeo2025
The Archaean rocks of Isua, West Greenland, contain graphite, but its origins are debated. Geochemical and microscopic analyses suggest that the graphite was formed from biologically formed carbon that was deposited at least 3.7 billion years ago.
12. Planetary science: Flow of an alien ocean
Jason Goodman
Nature Geoscience 7, 8-9 (2014) doi: 10.1038/ngeo2034
Liquid water may lurk beneath the frozen surfaces of Jupiter's moon Europa and other icy worlds. Extending ocean science beyond Earth, planetary oceanographers are linking Europa's ocean dynamics to its enigmatic surface geology.
NATURE COMMUNICATIONS
13. Persistent 400 000 year variability of Antarctic ice volume and the carbon cycle is revealed throughout the Plio-Pleistocene
B. de Boer, Lucas J. Lourens and Roderik S. W. van de Wal
Nature Communications 5, Article no. 2999 (02 January 2014) doi: 10.1038/ncomms3999
Global ice volume over the past 5 million years was simulated with a coupled system of four three-dimensional ice-sheet models. The 400 000 year long eccentricity cycles of Antarctica vary coherently with δ13C data during the Pleistocene, suggesting that they drove the long-term carbon cycle changes throughout the past 35 million years. The 400,000-year response of Antarctica was eventually suppressed by the dominant 100,000-year glacial cycles of the large ice sheets in the Northern Hemisphere.
