The Vulnerability of Trees and Biomes of the Rocky Mountains to Climate Change

by Kyle Jensen

As the reality of climate change becomes ever clearer, federal land managers are becoming increasingly concerned with how climate change will affect natural resources and ecosystem services within their jurisdictions. The western US in particular is expected to warm significantly, which will have widespread effects on the distribution of forests and various species; understanding these effects is essential to developing strategies to cope with future changes. Hansen and Phillips (2015) conducted a meta-analysis of five studies assessing the vulnerability of tree species and biome types to projected future climate changes, the results of which are expected to be used by the National Park Service as it initiates climate vulnerability assessments. The studies utilized bioclimate envelope modeling, which showed a severe loss of territory for subalpine systems, especially for the white bark pine (Pinus albicaulis) and Mountain hemlock (Tsuga mertensiana). Continue reading

The Future Distribution of Harmful Algal Blooms

by Kyle Jensen

As the climate warms, algal blooms of certain harmful species are presenting an increasing threat to many biotic communities. Their introduction is often anthropogenic, and their occurrence is driven by eutrophication and changing climates. Their range may be influenced by rising temperatures, altered salinity due to runoff caused by climate change, and increasing nutrient loads due to increased development and fertilizer use containing favorable levels of nitrogen and phosphorous. Glibert et al. (2014) used a model incorporating climatic changes to predict the future distribution of these harmful algal blooms (HABs) under climate change scenarios. The study found a general increase in the distribution and presence of these HABs, though effects varied by region. Continue reading

Rising Temperatures and the Extirpation of Pika in California

by Kyle Jensen

The American pika, a cousin of rabbits and hares found in the mountains of western North America, may serve as a model organism for examining the effects of global warming on montane species. Pikas tend to live on talus slopes at higher elevations, and as their lower elevation limits are relatively high they may be especially vulnerable to climate change. Having adapted to colder climates pika are susceptible to hyperthermia in the summer, with a lethal upper body temperature occurring at only 3°C above their resting body temperature. During times of high temperature pikas reduce their foraging time to keep their body temperatures low, which also reduces their energy intake. Prolonged periods of high temperature can lead to reduced reproduction and death. Summer temperatures can thus place serious limits on the pika’s distribution. Stewart et al (2015) created a model to assess the potential risk posed to piks and other climate-sensitive mammals by climate change. Their model matched previous findings and predicted high levels of extirpation of pikas in study sites across California, with the size of talus area and summer temperatures being the best predictors of range. Continue reading

Effects of Alternative sets of Climate Predictors on Species Distribution Models and Estimates of Extinction Risk

by Kyle Jensen

As arid ecosystems have been recognized as being especially sensitive to climate change, they thus provide an appropriate system to assess the use of SDMs in estimating the threat of climate change to various species. Species distribution models (SDMs) can quantify relationships between species and environmental factors, and use this data to predict spatial distributions. SDMs are thus widely used to derive projections of species distribution under conditions of climate change. These models are correlative however, and as such are unable to identify causal species-environment relationships. They can only be used as supporting evidence for an existing hypothesis on factors affecting species distribution; as such the factors must be chosen as inputs for the SDM to function. Identifying the important climatic factors involved in determining the range of a given species is a key factor in assessing the potential effects of climate change on species distribution and extinction risk. Little research however has been done investigating the effects using alternative sets of climate predictor variables may have on the projections of SDMs. Pliscoff et al (2014) seek to examine this area of potential uncertainty, addressing the potential variability of SDM spatial projections and determination of extinction risks through the creation and analysis of several sets of environmental predictors. They found that by adjusting climate predictor variables they were able to significantly affect predictions of spatial distribution as well as, for the first time, extinction risk estimates. This implies greater variability in such studies than previously thought. Continue reading

Just Released! “Energy, Biology, Climate Change”

FrontCover6x9 white border 72dpi EBCC2015

Our newest book, published on May 6, 2015 and available at Amazon.com for $19.95.

The focus of this book is the interactions between energy, ecology, and climate change, as well as a few of the responses of humanity to these interactions. It is not a textbook, but a series of chapters discussing subtopics in which the authors were interested and wished to write about. The basic material is cutting-edge science; technical journal articles published within the last year, selected for their relevance and interest. Each author selected eight or so technical papers representing his or her view of the most interesting current research in the field, and wrote summaries of them in a journalistic style that is free of scientific jargon and understandable by lay readers. This is the sort of science writing that you might encounter in the New York Times, but concentrated in a way intended to give as broad an overview of the chapter topics as possible. None of this research will appear in textbooks for a few years, so there are not many ways that readers without access to a university library can get access to this information.

This book is intended be browsed—choose a chapter topic you like and read the individual sections in any order; each is intended to be largely stand-alone. Reading all of them will give you considerable insight into what climate scientists concerned with energy, ecology, and human effects are up to, and the challenges they face in understanding one of the most disruptive—if not very rapid—event in human history; anthropogenic climate change. The Table of Contents follows: Continue reading

Arctic Warming and the Atlantic-Pacific Fish Interchange

by Kyle Jensen

For most of the Quaternary Period the inhospitable environment north of the Arctic Circle has served as a biotic barrier between Northern portions of the Atlantic and Pacific oceans. Through it is known that interchange across the Northwest and Northeast passages has occurred, currently only 135 of over 800 fish species found above 50° of latitude are found in both oceans. Continued warming may result in the reopening of these passages resulting an accelerated interchange of species between the Atlantic and Pacific as species follow favorable conditions into higher latitudes. This may also lead to increased movement of fishing and shipping vessels through these channels, which could facilitate further interchange. This has the potential to impact the food webs and biodiversity of systems in both of these oceans, the consequences of which would affect ecosystems currently comprising 39% of global marine fish landings. To analyze potential impacts of future species interchange, Wisz et al (2015) has made forecasts of potential distributions for 515 fish species. Continue reading