Predicting climate change effects on subarctic–Arctic populations of Atlantic salmon ( Salmo salar ) (original) (raw)
Related papers
Studies of climatic change with zonally averaged models
1991
En este artículo se incluye un breve repaso a la clasificación de modelos climáticos basados en grados de libertad, mencionando las ventajas deles que se aplican a promedios zonales (ZACM). Concretamente, los dos modeles que se describen, uno cuasi-geostrófico (QG) y otro más completo de ecuaciones primitivas (PE), se utilizan para realizar experimentos numéricos sobre el cambio climático inducido por anomalías en la temperatura de la superficie del mar (SST) y por alteraciones en las características de los suelos. Los experimentos relativos a anomalías en la SST consideran las situaciones correspondientes a los conocidos fenómenos de El Niño y La Niña. Los resultados muestran que durante El Niño, tanto la corriente en chorro subtropical como la circulación de l-ladley se intensifican y la temperatura superficialdel mar aumenta en la región perturbada. En el caso de La Niña se observa la situación opuesta. Por otra parte, en el experimento correspondiente a alteraciones en las características del suelo se consideran los efectos inducidos por procesos geobotánicos (deforestación y desertificación) en el clima. Los resultados muestran que la alteración en la temperatura del suelo se debe más al cambio en el ritmo de evapotranspiración que en el del albedo.
Possible regional consequences of global climate changes
Russian Journal of Earth Sciences, 2008
The present article deals with possible global and regional changes of climate in the 21st century with different scenarios of natural and anthropogenic impacts given in comparison to the estimates of contemporary changes according to observations data. The results of analysis of numerical simulations with global climatic models and of the more detailed regional simulations are described. Possible changes are analyzed, taking into account the carbon cycle in climatic models, including the methane cycle. Together with temperature the changes of precipitation, river runoff, bioproductivity of terrestrial ecosystems are estimated. Moreover, the article describes the characteristics of extreme regimes, including extreme precipitation, droughts and fires. The relative contribution of natural (solar and volcanic activity) and anthropogenic factors, for the entire globe and for the regions with considerable temperature changes over the last decades are also evaluated.
1993
The main theme of this research project is to explore the behavior of a class of climate models by use of classical statistical estimation techniques and to examine the broader applicability of the techniques themselves. In particular, the authors study a class of energy balance climate models including a crude representation of the deep ocean and with stochastic forcing at the surface. These models include an explicit representation of the land-sea geography so that regional products are generated (although crude at best). The authors view the exercise as preliminary to the same techniques being applied to coupled ocean/atmosphere general circulation models and the solutions they generate can be thought of as benchmarks against which the more detailed simulations can be compared.
2009
In this paper we use a coupled ocean-atmosphere model to investigate the impact of the interruption of Agulhas leakage of Indian ocean water on the Tropical Atlantic, a region where strong coupled ocean atmosphere interactions occur. The effect of a shut down of leakage of Indian ocean water is isolated from the effect of a collapse of the MOC. In our experiments, the ocean model is forced with boundary conditions in the southeastern corner of the domain that correspond to no interocean exchange of Indian ocean water into the Atlantic. The southern boundary condition is taken from the Levitus data and ensures a MOC in the Atlantic. Within this configuration temperature (cold) and salinity (fresh) anomalies of southern ocean origin propagate into the South Atlantic and eventually reach the equatorial region, mainly in the thermocline. This set up mimics the closure of the "warm water path" in favor of the "cold water path". As part of the atmospheric response, there is a northward shift of the Intertropical Convergence Zone (ITCZ). The changes in Trade Winds lead to reduced Ekman pumping in the equatorial region. This leads to a freshening and warming of the surface waters along the equator. Especially in the Cold Tongue region, the cold and fresh subsurface anomalies do not reach the surface due to the reduced upwelling. The anomaly signals are transported by the Equatorial undercurrent and spread away from the Equator within the thermocline. Part of the anomaly eventually reaches the Tropical North Atlantic, where it affects the Guinea Dome. Surprisingly, the main effect at the surface is small on the equator and relatively large at the Guinea Dome. In the atmosphere, the northward shift of the ITCZ is associated with a band of negative precipitation anomalies and higher salinities over the Tropical South Atlantic.
Atmosphere-Ocean, 2001
A new earth system climate model of intermediate complexity has been developed and its climatology compared to observations. The UVic Earth System Climate Model consists of a three-dimensional ocean general circulation model coupled to a thermodynamic/dynamic sea-ice model, an energy-moisture balance atmospheric model with dynamical feedbacks, and a thermomechanical land-ice model. In order to keep the model computationally efficient a reduced complexity atmosphere model is used. Atmospheric heat and freshwater transports are parametrized through Fickian diffusion, and precipitation is assumed to occur when the relative humidity is greater than 85%. Moisture transport can also be accomplished through advection if desired. Precipitation over land is assumed to return instantaneously to the ocean via one of 33 observed river drainage basins. Ice and snow albedo feedbacks are included in the coupled model by locally increasing the prescribed latitudinal profile of the planetary albedo. The atmospheric model includes a parametrization of water vapour/ planetary longwave feedbacks, although the radiative forcing associated with changes in atmospheric CO 2 is prescribed as a modification of the planetary longwave radiative flux. A specified lapse rate is used to reduce the surface temperature over land where there is topography. The model uses prescribed present-day winds in its climatology, although a dynamical wind feedback is included which exploits a latitudinally-varying empirical relationship between atmospheric surface temperature and density. The ocean component of the coupled model is based on the Geophysical Fluid Dynamics Laboratory (GFDL) Modular Ocean Model 2.2, with a global resolution of 3.6°( zonal) by 1.8°(meridional) and 19 vertical levels, and includes an option for brine-rejection parametrization. The sea-ice component incorporates an elastic-viscous-plastic rheology to represent sea-ice dynamics and various options for the representation of sea-ice thermodynamics and thickness distribution. The systematic comparison of the coupled model with observations reveals good agreement, especially when moisture transport is accomplished through advection.
Climate changes affect aquatic ecosystems by altering temperatures and precipitation patterns, and the rear edges of the distributions of cold-water species are especially sensitive to these effects. The main goal of this study was to predict in detail how changes in air temperature and precipitation will affect streamflow, the thermal habitat of a cold-water fish (the brown trout, Salmo trutta), and the syn-ergistic relationships among these variables at the rear edge of the natural distribution of brown trout. Thirty-one sites in 14 mountain rivers and streams were studied in central Spain. Models of streamflow were built for several of these sites using M5 model trees, and a non-linear regression method was used to estimate stream temperatures. Nine global climate models simulations for Representative Concentration Pathways RCP4.5 and RCP8.5 scenarios were downscaled to the local level. Significant reductions in streamflow were predicted to occur in all of the basins (max. −49 %) by the year 2099, and seasonal differences were noted between the basins. The stream temperature models showed relationships between the model parameters, geology and hydrologic responses. Temperature was sensitive to streamflow in one set of streams, and summer reductions in streamflow contributed to additional stream temperature increases (max. 3.6 • C), although the sites that are most dependent on deep aquifers will likely resist warming to a greater degree. The predicted increases in water temperatures were as high as 4.0 • C. Temperature and streamflow changes will cause a shift in the rear edge of the distribution of this species. However, geology will affect the extent of this shift. Approaches like the one used herein have proven to be useful in planning the prevention and mitigation of the negative effects of climate change by differentiating areas based on the risk level and viability of fish populations.
Hydrological Sciences Journal, 2004
By use of a coupled ocean-atmosphere-land model, this study explores the changes of water availability, as measured by river discharge and soil moisture, that could occur by the middle of the 21st century in response to combined increases of greenhouse gases and sulphate aerosols based upon the "IS92a" scenario. In addition, it presents the simulated change in water availability that might be realized in a few centuries in response to a quadrupling of CO 2 concentration in the atmosphere. Averaging the results over extended periods, the radiatively forced changes, which are very similar between the two sets of experiments, were successfully extracted. The analysis indicates that the discharges from Arctic rivers such as the Mackenzie and Ob' increase by up to 20% (of the pre-Industrial Period level) by the middle of the 21st century and by up to 40% or more in a few centuries. In the tropics, the discharges from the Amazonas and Ganga-Brahmaputra rivers increase substantially. However, the percentage changes in runoff from other tropical and many mid-latitude rivers are smaller, with both positive and negative signs. For soil moisture, the results of this study indicate reductions during much of the year in many semiarid regions of the world, such as the southwestern region of North America, the northeastern region of China, the Mediterranean coast of Europe, and the grasslands of Australia and Africa. As a percentage, the reduction is particularly large during the dry season. From middle to high latitudes of the Northern Hemisphere, soil moisture decreases in summer but increases in winter.