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SPECIAL REPORT:CLIMATE OF OPPORTUNITY
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Awareness about climate change is at an all-time high. Will this surge of attention translate into more jobs for climate scientists?
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Aerosols heat up
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Solid particles suspended in the atmosphere have long played second fiddle to greenhouse gases as agents of climate change. A study of atmospheric heating over the Indian Ocean could provoke a rethink.
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Scientific reticence and sea level rise
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I suggest that ‘scientific reticence’, in some cases, hinders communication with the public about dangers of global warming. If I am right, it is important that policy-makers recognize the potential influence of this phenomenon.
Scientific reticence may be a consequence of the scientific method. Success in science depends on objective skepticism. Caution, if not reticence, has its merits. However, in a case such as ice sheet instability and sea level rise, there is a danger in excessive caution. We may rue reticence, if it serves to lock in future disasters.Barber (1961) describes a ‘resistance by scientists to scientific discovery’, with a scholarly discussion of several sources of cultural resistance.There are aspects of the phenomenon that Barber discusses in the ‘scientific reticence’ that I describe, but additional factors come into play in the case of global climate change and sea level rise.
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Projections of Future Drought in the Continental United States and Mexico
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Using the Palmer drought severity index, the ability of 19 state-of-the-art climate models to reproduce ob- served statistics of drought over North America is examined. It is found that correction of substantial biases in the models’ surface air temperature and precipitation fields is necessary. However, even after a bias correction, there are significant differences in the models’ ability to reproduce observations. Using metrics based on the ability to reproduce observed temporal and spatial patterns of drought, the relationship between model per- formance in simulating present-day drought characteristics and their differences in projections of future drought changes is investigated. It is found that all models project increases in future drought frequency and severity. However, using the metrics presented here to increase confidence in the multimodel projection is complicated by a correlation between models’ drought metric skill and climate sensitivity. The effect of this sampling error can be removed by changing how the projection is presented, from a projection based on a specific time interval to a projection based on a specified temperature change. This modified class of projections has reduced intermodel uncertainty and could be suitable for a wide range of climate change impacts projections.
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THE SPATIAL AND TEMPORAL VARIABILITY OF RAIN-ON-SNOW
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Snow melt during rainfall causes large-scale flooding and avalanching. These rain-on- snow events are most well-documented in the coastal mountain ranges of western North America. To determine what role they play in interior mountains, we analyzed flood frequencies in the Columbia River basin and modeled rain-on-snow potential from daily temperature and precipitation data. Applying the model with geographically distributed weather data allowed maps of rain-on-snow potential at 2km spatial resolution to be generated for characteristic climate years of 1982 (cold and wet), 1988 (warm and dry), and 1989 (average). It was found that rain-on-snow events are more likely during cool, wet years (such as 1982). A greater number of events and more widespread distribution of events occur during this type of climate. The cool temperatures allow low-elevation snow to accumulate and frequent storms bring the possibility of mid-winter rain. Warm, dry years (1988) are less likely to experience rain-on-snow events. There is little low-elevation snow at these times and only occasional precipitation. During all years, areas most susceptible to rain-on-snow are those where topography allows incursion of relatively warm, moist marine air that flows from the Pacific Ocean into the Columbia Plateau and up the Snake River Valley. These areas include the Cascade mountains; northern Idaho, northeastern Washington, and northwestern Montana where valleys open into the Columbia plateau; the Blue Mountains of northeastern Oregon; and western Wyoming and central Idaho adjacent to the Snake River.
KEYWORDS: snow, avalanches, rain-on-snow, floods
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RAIN-ON-SNOW EVENTS IN THE WESTERN UNITED STATES
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Severity of rain on snow depends on a number of factors, and an overall decrease in these events appears to be driven, in part, by changes in El Niño–Southern Oscillation.
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Influence of Timber Harvest on Rain-On-Snow Runoff: A Mechanism for Cumulative Watershed Effects
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Rain-on-snow dominates many geomorphological processes in the Pacific Northwest. Wind-aided transfers of heat to snow during rain-on-snow comprise the largest source of heat for snowmelt during rainfall.␣ Recent field research in western. Oregon and western Washington has shown that timber harvest and thinning can increase both snow accumulation and the wind-aided transfers of heat, resulting in higher rates of water delivery to soil during rain-on-snow conditions.␣ Increased rates of water delivery to soil can lead to higher streamflows and to landslides on marginally stable slopes. Because of the magnitude of increase in water delivery to soils during common rain-on-snow conditions and a hydrologic recovery period that may require 40 years, rain-on-snow runoff is
an important mechanism␣ whereby forest management activities might cumulatively affect water resources.
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Rain on Snow: Little Understood Killer in the North
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n October 2003, a severe rain-on-snow (ROS) event killed approximately 20,000 musk-oxen (Figure 1) on Banks Island, which is the westernmost of the Canadian Arctic islands (approximately 380 kilome- ters by 290 kilometers in size). The event reduced the isolated herd by 25% and sig- nificantly affected the people dependent on the herd’s well-being. Because of the sparsity of weather stations in the Arctic and the lack of routinely deployed weather equipment that was capable of accurately sensing the ROS event, its detection largely was based on reports from hunters who were in the affected areas at the time.Such events can significantly alter a fro- zen ecosystem—with changes that often persist for the remainder of a winter—by creating ice layers at the surface of, within, or below the snowpack. The water and ice layers are known to facilitate the growth of toxic fungi, significantly warm the soil surface under thick snowpack, and deter large grazing mammals.
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Simulating snowmelt process during rain-on-snow over a semi-arid mountain basin
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In the Pacific Northwest of North America, significant flooding can occur during mid-winter rain-on-snow events. Warm, wet Pacific storms caused significant floods in the Pacific Northwest in February 1996, January 1997 and January 1998. Rapid melting of the mountain snow cover substantially augmented discharge during these flood events. An energy-balance snowmelt model is used to simulate snowmelt processes during the January 1997 event over a small headwater basin within the Reynolds Creek Experimental Watershed located in the Owyhee Mountains of southwestern Idaho, U.S.A. This sub-basin is 34% forested 12% fir, 22% aspen and 66% mixed sagebrush primarily mountain big sage- brush)). Data from paired open and forested experimental sites were used to drive the model. Model-forcing data were corrected for topographic and vegetation canopy effects. The event was preceded by cold, stormy conditions that developed a significant snow cover over the sub- basin. The snow cover at sites protected by forest cover was slightly reduced, while at open sites significant snowmelt occurred. The warm, moist, windy conditions during the flooding event produced substantially higher melt rates in exposed areas, where sensible- and latent- heat exchanges contributed 60^90% of the energy for snowmelt. Simulated snow-cover devel- opment and ablation during the model run closely matched measured conditions at the two experimental sites. This experiment shows the sensitivity of snowmelt processes to both climate and land cover, and illustrates how the forest canopy is coupled to the hydrologic cycle in mountainous areas.
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Protecting Wildlife Migration Corridors and Crucial Wildlife Habitat in the West
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BACKGROUND
1. Large intact and functioning ecosystems, healthy fish and wildlife populations, and abundant public access to natural landscapes are a significant contributing factor to the West's economic and in-migration boom as well as quality of life. Critical wildlife migration corridors and crucial wildlife habitats are necessary to maintain flourishing wildlife populations. .
2. The Western States are particularly and uniquely affected by activity occurring in wildlife migration corridors and crucial wildlife habitats. Western States must also contend with an inter-connected mixture of private, state and federal lands. Migration corridors cross all political boundaries and States need to protect migration corridors on federal land through various state planning documents.
3. Natural resource development, urban development, and maintenance of the existing infrastructures of the West impact wildlife species, their habitats and migration corridors. Western States are increasingly expending limited state funds to participate in federal public land resource management planning as a result of the growing national focus on energy production and independence. States continue to expend scarce funds to protect or mitigate impacts to wildlife resources by energy development.
4. States possess broad trustee, police powers and primacy over fish and wildlife within their borders. With the exception of marine mammals, states retain concurrent jurisdiction even where Congress has directed specific federal authority of fish and wildlife speci
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