Physical Sciences and Mathematics Commons^™

Climatic Changes In Mountain Regions Of The American Cordillera And The Tropics: Historical Changes And Future Outlook, Henry F. Diaz, Raymond S. Bradley, Liang Ning

Raymond S Bradley

We review some recent work regarding climatic changes in selected mountain regions, with particular attention to the tropics and the American Cordillera. Key aspects of climatic variability and trends in these regions are the amplification of surface warming trends with height, and the strong modulation of tempera¬ture trends by tropical sea surface temperature, largely controlled by changes in El Niño–Southern Oscillation on multiple time scales. Corollary aspects of these climate trends include the increase in a critical plant growth temperature threshold, a rise in the freezing level surface, and the possibility of enhanced subtropical drying. Anthropogenic global warming projections indicate …

The Influence Of Land Use And Climate Change On Forest Biomass And Composition In Massachusetts, Usa, J. R. Thompson, D. R. Foster, R. Scheller, David B. Kittredge

David B. Kittredge

Land use and climate change have complex and interacting effects on naturally dynamic forest landscapes. To anticipate and adapt to these changes, it is necessary to understand their individual and aggregate impacts on forest growth and composition. We conducted a simulation experiment to evaluate regional forest change in Massachusetts, USA over the next 50 years (2010–2060). Our objective was to estimate, assuming a linear continuation of recent trends, the relative and interactive influence of continued growth and succession, climate change, forest conversion to developed uses, and timber harvest on live aboveground biomass (AGB) and tree species composition. We examined 20 …

Where Do We Stand On Global Warming?, Raymond S. Bradley

Raymond S Bradley

Global temperatures have risen by ~0.8°C since the end of the 19th century. This increase has not been linear, as there have been periods when temperatures were stable for short periods before rising once again. The reasons for these changes in the rate of temperature rise are related to anthropogenic factors (sulphate aerosol pollution versus greenhouse gas inputs to the atmosphere) as well as to natural factors (volcanic eruptions, solar irradiance variations, El Ni.o/Southern Oscillation [ENSO] fluctuations, etc). Over the last decade or so, temperatures have not risen at the same rate as in previous decades, and this has led …

Natural Archives, Changing Climates, Raymond S. Bradley

Raymond S Bradley

Climatic changes have occurred throughout human history, but instrumental measurements do not provide us with a very long perspective on climate variations. In many regions, instrumental records only extend back a century or two. To understand the longer-term variability of the climate system, we rely on natural archives— sediments, ice caps, peat bogs, cave deposits, banded corals and tree rings—in which a record of past changes in climate has been preserved. They are a treasure trove of the climatic and environmental history of the planet and provide information about factors that may have caused the climate to change, such as …

Local Surface Water Policy Under Conditions Of Climate Change, Elizabeth Brabec, Elisabeth Hamin, Chingwen Cheng

Elizabeth Brabec

Climate change means two things for local stormwater managers – that storm events will become more severe, and rainfall will, in many instances, become more erratic, causing enhanced periods of drought and flood. Two approaches are needed to deal with the eventualities: mitigation and adaptation.

While urbanization increases stormwater runoff and decreases the lag time of stormwater discharge, there is also a resulting lack of infiltration and reduction in evapotranspiration (Brunke and Gonser 1997). Stormwater detention, retention and infiltration have attempted to compensate, resulting in the concentrated point location infiltration of stormwater, which replenishes groundwater and baseflow. Equally important to …

Changes In Extreme Climate Indices For The Northeastern United States, 1870-2006, Paula J. Brown, Raymond S. Bradley, Frank T. Keimig

Raymond S Bradley

The northeastern United States is one of the most variable climates in the world, and how climate extremes are changing is critical to populations, industries, and the environment in this region.Along-term (1870–2005) temperature and precipitation dataset was compiled for the northeastern United States to assess how the climate has changed. Adjustments were made to daily temperatures to account for changes in mean, variance, and skewness resulting from inhomogeneities, but precipitation data were not adjusted. Trends in 17 temperature and 10 precipitation indices at 40 stations were evaluated over three time periods—1893–2005, 1893– 1950, and 1951–2005—and over 1870–2005 for a subset …

Threats To Water Supplies In The Tropical Andes, Raymond S. Bradley, Mathias Vuille, Henry F. Diaz, Walter Vergara

Raymond S Bradley

Climate models predict that greenhouse warming will cause temperatures to rise faster at higher than at lower altitudes. In the tropical Andes, glaciers may soon disappear, with potentially grave consequences for water supplies.

Adaptation And Sustainability In A Small Arctic Community: Results Of An Agent-Based Simulation Model, Matthew Berman, Craig Nicolson, Gary Kofinas, Joe Tetlichi, Stephanie Martin

Craig Nicolson

Climate warming and resource development could alter key Arctic ecosystem functions that support fish and wildlife resources harvested by local indigenous communities. A different set of global forces—government policies and tourism markets—increasingly directs local cash economies that communities use to support subsistence activities. Agent-based computational models (ABMs) contribute to an integrated assessment of community sustainability by simulating how people interact with each other and adapt to changing economic and environmental conditions. Relying on research and local knowledge to provide rules and parameters for individual and collective decision making, our ABM generates hypothetical social histories as adaptations to scenario-driven changes in …