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The timing and origins of Alpine gorge formation are controversial. A high-resolution analysis of the inner gorges of the Swiss Alps suggests that these landforms were carved over successive interglacial periods, and survived the intervening glaciations.
The existence of a microbial community in the ocean crust has long been hypothesized. Isotopic evidence indicates that a deep biosphere of microbes both scrubs oceanic fluids of organic matter and produces new, yet old, organic carbon in situ.
Unusual wind patterns and the albedo feedback effect played crucial roles in the rapid reduction of Arctic sea-ice cover in recent years. Evidence is now building that a warmer ocean has also contributed to the thinning of Arctic ice.
Bromine facilitates the oxidation of elemental mercury in the lower atmosphere in polar and subpolar regions. Measurements over the Dead Sea suggest that bromine also generates large quantities of oxidized mercury in the mid-latitudes.
Climate models suggest that deficits in soil moisture can lead to more frequent and severe hot summer temperatures. Observations confirm this effect, but only for relatively dry regions, where evaporation is limited by available moisture.
Controversy has surrounded projections of tropical temperatures aloft in a changing climate. An analysis of sea surface temperatures and rainfall over the past decades suggests amplified warming in the upper atmosphere, consistent with theory and models.
The Palaeocene–Eocene Thermal Maximum 55 million years ago was triggered by the sudden release of carbon to the ocean–atmosphere system. The carbon may have been removed almost as abruptly 100,000 years later, in the form of organic carbon.
Model projections of future climate are highly sensitive to the assumed response of organic matter decomposition to changes in temperature. Incubation experiments on North American soils suggest that the decisive factors lie at the molecular level.
Magma from the mantle meets the ocean at seafloor spreading centres. At young rifts, basalt sills may heat overlying sediments and induce natural carbon release; basalt flows elsewhere may offer secure reservoirs for sequestration of anthropogenic carbon.
Evidence for the sedimentary carbonate rocks proposed to be prevalent on Mars has generally been lacking. Carbonate-bearing rocks found in the Leighton Crater may be associated with the formation of methane detected in the martian atmosphere.
The Haiti earthquake ruptured one or more buried faults, generated tsunamis and caused extensive structural damage in Port-au-Prince. Investigations in the epicentral region quantify seismic hazards but offer no clear views of Haiti's seismic future.
Wetlands are home to microorganisms that produce and emit methane. Very small wetlands, tucked into unexpected places, might be making a larger contribution to the global methane budget than previously thought.
The gradual expansion of Northern Hemisphere glaciation about 3.6 million years ago followed a period of prolonged warmth. An analysis of ancient sea surface temperatures fuels the debate surrounding the roles of atmospheric carbon dioxide and global circulation in the cooling.
