Modern Climate Warming Research Articles

Serapeo Temple in Pozzuoli (Italy) as a unique gauge of changes in the Sea (World Ocean) level and global earth surface temperature over 2100 years

The changes in the sea level relative to the position of the Serapeo Temple in Pozzuoli (Italy) over 2100 years are discussed in the context of the well-known periods of climate cooling (Neoglacial, Little Ice Age) and climate warming (Medieval Optimum, modern warming). It is noted that the rate of sea level rise relative to the position of the Serapeo Temple in the modern phase of climate warming, which began in the late XVIII century, is about twice higher than in the previous phase of climate warming from the V to the mid-X century A.D. This indicates that not only the natural cyclic component contributes to the mechanisms of modern climate warming, but also an anthropogenic component of approximately equivalent power, which results from the release of CO2 caused by burning fossil fuels.

Alluvial responses to the changing Earth system

AbstractAlluvial systems are complex, self‐organizing and hierarchical in structure. They represent stored and transitory sediment bodies transported by rivers that have eroded their catchments and created multiscalar landforms and sedimentary architectures over a range of time‐scales. The central question we address in this paper is how environmental signals are autogenically processed and recorded by the fluvial sediment system. We compare databases of alluvial units that are well constrained in terms of dating control with direct or proxy records of environmental change. River system responses to environmental change are evaluated over three nested time periods spanning the past 200 000 years. First, focusing on Mediterranean European and African catchments, river responses to relatively abrupt and short‐term Late Pleistocene Dansgaard–Oeschger and Heinrich climate events are examined. Second, the effects of rapid and globally significant episodes of Holocene climate change on European rivers, together with anthropogenic land‐use impacts, are assessed. Last, ‘Little Ice Age’ flooding and alluvial responses to modern climate warming are reviewed with particular reference to upland Britain. These studies are shown to have significant implications for modelling local, regional and global‐scale alluvial responses to future environmental change. They highlight the necessity for numerical simulation models to be fully informed by field‐based knowledge and understanding of the memory effects of whole fluvial sediment systems, particularly those that have experienced repeated phases of environmental change. Copyright © 2008 John Wiley & Sons, Ltd.

Limits of the existence of the Kuroshio and Gulf Stream currents owing to climate trends

Based on the variational property of the energy scattering minimum, this paper presents a model of a zonal jet current applied to the Kuroshio Extension and Gulf Stream after their separation from the western boundary and their turning to the east. The model suggests the following features: (1) the condition of jet existence is the asymmetric current shape with a sharp northern boundary; (2) the dynamic current axis is located south of the convergence axis (this is one of the mechanisms of the formation of two-(multi)front structures in the ocean represented by the Subarctic Front and Kuroshio Extension); and (3) there is a critical parameter range beyond which the current is not the jet current anymore. The modern climate warming tendency is approaching a critical state, when a change in the circulation structure is expected. 1. The object of our research is the transversal structure of a geostrophic jet current applied to the Kuroshio Extension and Gulf Stream oceanic currents after their separation from the coast between 30°–40° N and their eastward turn. Jet character, permanence, and spatiotemporal stability are the properties of these currents on a climatic scale [1, 2]. The parameters of the current are as follows: width ~100 km, depth 1 km, velocity 1 m/s, and water discharge 50 × 10 6 m 3 /s. The aim of this research is to determine the limits of conservation of the jet current under variation of the external parameters owing to possible climatic trends. 2. Variation formulation. The transversal structure of a zonally uniform geostrophic jet current is modeled on a climatic scale with consideration of the detailed structure (influence of the bottom topography and meandering). The origin of coordinates is at the ocean

North Pacific Intermediate Water response to a modern climate warming shift

Oceanic observations and an isopycnal ocean model simulation are used to investigate the response of North Pacific Intermediate Water (NPIW) to atmospheric forcing associated with the well‐known 1976–1977 climate regime shift to a warm regime. The model reproduces numerous features of NPIW including distribution, depth, temperature, and salinity. Changes in NPIW associated with the climate shift in the California coastal region were strongly influenced by an anomalous poleward flow at depth (300–1100 m). This current transports old, high salinity, low oxygen intermediate waters from the northern tropics to the midlatitudes. For depths below the mixed layer, the model reproduces observed changes in salinity, nitrates, and, to some extent, oxygen, thus suggesting that advective/diffusive processes are dominant in determining their concentrations below 300 m, isolated from the surface effects of direct atmospheric forcing and biological processes. These changes are structurally similar to those induced by much larger, abrupt climate changes at the end of the last glacial episode.

Fissure calcretes in the arctic: a paleohydrologic indicator

The effects of modern climate warming are expected to be amplified in northern periglacial regions. Paleohydrological reconstructions in the arctic provide important insights into natural climatic variations during the Pleistocene and Holocene with which to compare predictions of modern impacts. Here the authors describe a new material, calcrete found in fissures in arctic carbonate terrains, which record hydrogeological and climatic conditions during climatic optimums in the north. 234U and 230Th activity ratios suggest growth during northern insolation maxima. These fissure calcretes strongly resemble biogenic calcite precipitates (endostromatolites), and grow on the external face within fissures in carbonate bedrock in periglacial environments. In thin section, samples are finely laminated and are composed of diverse fabrics including a uniformly present basal layer with regularly spaced columns from several microns to 3 cm in length. Their surface morphology is often preserved in the relief of the adjacent fissure face in a micro-lapiès texture strongly suggestive of a dissolution-reprecipitation mechanism whereby the fissure widens in lock-step with column growth. Their highly enriched δ 13C (0 to +8.4‰) composition suggests that methanogenenic bacteria, supported by a substrate of soil-derived organic matter, control growth in a network of groundwater-saturated near-surface fissures extending to a depth of 3 to 5 m. Accordingly, δ 18O holds valuable paleotemperature information.