About 34 million years ago, Earth's climate cooled and an ice sheet formed on Antarctica as atmospheric carbon dioxide (CO2) fell below ~750 parts per million (ppm). Sedimentary cycles from a drill core in the western Ross Sea provide direct evidence of orbitally controlled glacial cycles between 34 million and 31 million years ago. Initially, under atmospheric CO2 levels of ≥600 ppm, a smaller...

Maize (Zea mays) seedlings were exposed to elevated atmospheric pressures while growing in moist sand in open plastic envelopes to evaluate the effects of directly applied atmospheric pressure on ethylene production and root growth. Effects were evaluated after 24 h. The threshold pressures necessary to promote ethylene production and decrease root elongation were about 600 and 400 kPa, respect...

Different ad hoc threshold functions associated with the autoconversion process have been arbitrarily used in atmospheric models. However, it is unclear how these ad hoc functions impact model results. Here systematic investigations of the sensitivities of climatically-important properties: CF (cloud fraction), LWP (liquid water path), and AIE (aerosol indirect effect) to threshold functions ha...

1875-9637/$ see front matter 2009 Elsevier B.V. A doi:10.1016/j.aeolia.2009.07.002 * Corresponding author. Tel.: +1 208 220 6571; fax E-mail addresses: [email protected], jbsankey@hotm [email protected] (M.J. Germino), [email protected] (N.F. G 1 Tel.: +1 208 282 3285; fax: +1 208 282 4570. 2 Tel.: +1 208 345 1994; fax: +1 208 345 8353. Aeolian transport is an important contemporary geomorphic process ...

Congress has mandated the detection of 90 percent of 140 meter diameter and larger Near Earth Objects (NEOs). While a dedicated satellite would be the preferred method of detection, ground-based telescopes are the current detection technology available. With current detection techniques, 140 meter diameter NEOs at 1 astronomical unit or more away from Earth are difficult to detect. In order to ...

Since the CALUX (Chemically Activated LUciferase gene eXpression) bioassay is a fast, sensitive and inexpensive tool for the analysis of a high number of samples, the use of this technique in routine analysis of atmospheric deposition samples may be a valuable alternative for GC-HRMS. In this study, a validated CALUX method was used for the analysis of PCDD/Fs and dioxin-like PCBs in more than ...

Linear and nonlinear analyses are performed on a generic carbon cycle model, exploiting available empirical information and avoiding detailed physics as far as possible. It is shown that the ability to reproduce atmospheric CO2 historical data of past decades is neither necessary nor sufficient to establish credibility for the century-timescale predictions. This is because the relevant historic...

Modelling simulations of palaeoclimate and past vegetation form and function can contribute to global change research by constraining predictions of potential earth system responses to future warming, and by providing useful insights into the ecophysiological tolerances and threshold responses of plants to varying degrees of atmospheric change. We contrasted HadCM3LC simulations of Amazonian fo...