co2 is the main greenhouse gas which urban forests have a high potential to absorb and sequestrate it. the air pollution of tehran is one of the most important environmental problems of the iran. to do this research 40 years old stands of robinia pseudoacacia and fraxinus rotundifolia and the surrounding barren land ( as blank) were selected in chitgar forest park of tehran and the amount of ca...

The equilibrium carbon storage capacity of the terrestrial biosphere has been investigated by running the Lund-Potsdam-Jena Dynamic Global Vegetation Model to equilibrium for a range of CO2 concentrations and idealized climate states. Local climate is defined by the combination of an observation-based climatology and perturbation patterns derived from a 4×CO2 warming simulations, which are line...

Anthropogenic climate change is now well established as a global issue of scienti!c and political importance. One of the principal impacts of the gradual change associated with anthropogenic climate warming comes from a shi" in, or an exaggeration of, pre-existing natural variability. For example, if the average distribution of precipitation shi"s to higher or lower values, this can mean that t...

Evidence from high-sedimentation-rate South Atlantic deep-sea cores indicates that global and Southern Ocean carbon budget shifts preceded thermohaline circulation changes during the last ice age initiation and termination and that these were preceded by ice-sheet growth and retreat, respectively. No consistent lead-lag relationships are observed during abrupt millennial warming events during t...

BACKGROUND Global warming and shifted precipitation regimes increasingly affect species abundances and distributions worldwide. Despite a large literature on species' physiological, phenological, growth, and reproductive responses to such climate change, dispersal is rarely examined. Our study aims to test whether the dispersal ability of a non-native, wind-dispersed plant species is affected b...

Understanding recent biogeographic responses to climate change is fundamental for improving our predictions of likely future responses and guiding conservation planning at both local and global scales. Studies of observed biogeographic responses to 20th century climate change have principally examined effects related to ubiquitous increases in temperature - collectively termed a warming fingerp...

[1] A consistent weakening and poleward expansion of the Hadley circulation is diagnosed in the climate change simulations of the IPCC AR4 project. Associated with this widening is a poleward expansion of the subtropical dry zone. Simple scaling analysis supports the notion that the poleward extent of the Hadley cell is set by the location where the thermally driven jet first becomes baroclinic...

in this paper, according to the data of 17 weather stations in khuzestan during 1951–2012, the trend of climate changes and its severity were evaluated. a consistent correlation was highlighted for trends of de martonne index as indicator of climate and temperature index in some stations. based on the results of the temperature analysis, 88.31% of the province became warmer, 6.3% became colder,...

The terrestrial biosphere is currently a strong carbon (C) sink but may switch to a source in the 21st century as climate-driven losses exceed CO2-driven C gains, thereby accelerating global warming. Although it has long been recognized that tropical climate plays a critical role in regulating interannual climate variability, the causal link between changes in temperature and precipitation and ...