Carbon and oxygen isotopes in mummified wood reveal warmer and wetter winters in the Siberian Arctic 3000Â years ago.

Paleoclimate reconstructions from the Holocene are important for defining baseline conditions in order to interpret and contextualize the effects of modern climate change. Such records are particularly lacking for Siberia, a region that represents ~ 50% of the Arctic. In addition, the majority of proxy-based paleoclimate reconstructions for the Holocene represent mean annual conditions, and few quantify winter temperature, which is particularly important for predicting the effects of global warming in Arctic environments.

Plant growth chamber design for subambient pCO and δ C studies.

Rationale: Subambient pCO has persisted across the major Phanerozoic ice ages, including the entire late Cenozoic (ca 30 Ma to present). Stable isotope analysis of plant-derived organic matter is used to infer changes in pCO and climate in the geologic past, but a growth chamber that can precisely control environmental conditions, including pCO and δ C value of CO (δ C ) at subambient pCO , is lacking.

Methods: We designed and built five identical chambers specifically for plant growth under stable subambient pCO (ca 100 to 400 ppm) and δ C conditions.

Temperature-induced water stress in high-latitude forests in response to natural and anthropogenic warming.

The Arctic is particularly sensitive to climate change, but the independent effects of increasing atmospheric CO2 concentration (pCO2 ) and temperature on high-latitude forests are poorly understood. Here, we present a new, annually resolved record of stable carbon isotope (δ(13) C) data determined from Larix cajanderi tree cores collected from far northeastern Siberia in order to investigate the physiological response of these trees to regional warming. The tree-ring record, which extends from 1912 through 1961 (50 years), targets early twentieth-century warming (ETCW), a natural warming event in the 1920s to 1940s that was limited to Northern hemisphere high latitudes.

Large-scale plant growth chamber design for elevated pCO2 and δ13C studies.

Rationale: Throughout at least the next century, CO(2) fertilization and environmental stresses (e.g. nutrient, moisture, insect herbivory) are predicted to affect yields of economically important crop species.

Characterization of ancient DNA supports long-term survival of Haloarchaea.

Bacteria and archaea isolated from crystals of halite 10(4) to 10(8) years old suggest long-term survival of halophilic microorganisms, but the results are controversial. Independent verification of the authenticity of reputed living prokaryotes in ancient salt is required because of the high potential for environmental and laboratory contamination. Low success rates of prokaryote cultivation from ancient halite, however, hamper direct replication experiments.

Reconciliation of marine and terrestrial carbon isotope excursions based on changing atmospheric COâ‚‚ levels.

Negative carbon isotope excursions measured in marine and terrestrial substrates indicate large-scale changes in the global carbon cycle, yet terrestrial substrates characteristically record a larger-amplitude carbon isotope excursion than marine substrates for a single event. Here we reconcile this difference by accounting for the fundamental increase in carbon isotope fractionation by land plants in response to increasing atmospheric CO₂ concentration (pCO₂). We show that for any change in pCO₂ concentration (ΔpCO₂), terrestrial and marine records can be used together to reconstruct background and maximum pCO₂ levels across the carbon isotope excursion.

Practical considerations for the use of pollen δ13C value as a paleoclimate indicator.

Rationale: Workers have shown a correlation between temperature and the pollen δ(13)C value, and therefore suggested using pollen δ(13)C values to reconstruct paleotemperature. To evaluate the potential for pollen δ(13)C values to be used as a paleotemperature proxy, it is essential to quantify the variability in pollen δ(13)C values and to evaluate the effect of temperature on pollen δ(13)C values, in isolation, under controlled environmental conditions.

Methods: Pollen was isolated from 146 Hibiscus flowers from 26 plants within a single climate environment to evaluate isotopic variability in pollen δ(13)C values.

Corn content of French fry oil from national chain vs. small business restaurants.

Several issues, ranging from sustainability to health, may interest the consumers in the corn content of their food. However, because restaurants are excluded from the Nutrition Labeling and Education Act of 1990, national chain restaurants provide nonspecific ingredient information and small businesses supply none. We measured the carbon isotope composition of fry oil in French fries purchased from 68 (67%) of the 101 national chain fast food restaurants on Oahu (i.

Halophilic Archaea cultured from ancient halite, Death Valley, California.

Halophilic Archaea cultured from ancient fluid inclusions in a 90-m-long (0- to 100,000-year-old) salt core from Death Valley, California, demonstrate survival of bacterial cells in subsurface halite for up to 34,000 years. Five enrichment cultures, representing three genera of halophilic Archaea (Halorubrum, Natronomonas and Haloterrigena), were obtained from five surface-sterilized halite crystals exclusively in one section of the core (13.0-17.

Microscopic identification of prokaryotes in modern and ancient halite, Saline Valley and Death Valley, California.

Primary fluid inclusions in halite crystallized in Saline Valley, California, in 1980, 2004-2005, and 2007, contain rod- and coccoid-shaped microparticles the same size and morphology as archaea and bacteria living in modern brines. Primary fluid inclusions from a well-dated (0-100,000 years), 90 m long salt core from Badwater Basin, Death Valley, California, also contain microparticles, here interpreted as halophilic and halotolerant prokaryotes. Prokaryotes are distinguished from crystals on the basis of morphology, optical properties (birefringence), and uniformity of size.