Carbon Loss from an Unprecedented Arctic Tundra Wildfire

As increased frequency and severity of wildfires in historically fire-prone areas pose one set of threats to our ever-more concerning climate situation, scientists have identified a new threat to rising global atmospheric CO₂ levels. Not since the early Holocene epoch has there been any significant wildfire activity or the presence of typical fire regimes within the Arctic tundra biome. As global temperatures rise, changing climatic conditions have introduced wildfire-induced carbon (C) releases in the Arctic tundra that have not been observed in many millennia (perhaps 10,000 years or more). Mack et al. (2011) examined the Anaktuvuk River fire that burned 1,039 km2 of Arctic tundra on the North Slope of the Brooks Range in Alaska, USA, in 2007; this single fire burned more than double the cumulative area burned in the region over the past half-century. They concluded that the C released from this one fire supports the hypothesis that tundra fires have the potential to significantly amplify global warming through the release of concentrated C pools into the atmosphere that in some cases are thousands of years old. –Lindon Pronto

Mack, Michelle C., Bret-Harte, M. Syndonia, Hollingsworth, Teresa N., Jandt, Randi R., Schuur, Edward A. G., Shaver, Gaius R., Verbyla, David L., 2011. Carbon Loss from an Unprecedented Arctic Tundra Wildfire. Nature 475, 489–492.

Asia’s Five Major Watersheds’ Resources Threatened by Climate Change

Asia’s has five major water basins all above 2,000m above sea level: the Indus, Brahmaputra, Ganges, Yangtze, and Yellow river basins. Together, these basins provide for rivers that provide water supply for more than 20% of the global population. Climate Change will bring changing trends in temperature and precipitation which will affect the amount of water available for people. The hydrolic affects leading to a change in water availability will vary greatly from watershed to watershed, but overall, there will be a decrease in water equivalent to a supply for 4.5% of the total population served. The Indus and Brahmaputra basins will have the highest water discharge decreases, and due to increased rainfall, the Yellow is projected to have a slight increase in discharge.–Darien Martin

Immerzeel, W., Beek, L., Bierkens, M., 2010. Climate change will affect the asian

water towers. Science AAAS 328, 1382–1385.

Negative Effects of Increased Temperature and O3 Offset Positive Effects of CO2 in Oilseed Rape (Brassica napus L.)

CO₂ in the atmosphere is steadily increasing and is predicted to be 500–1000 ppm by the end of the century. Emissions of other greenhouse gases are also increasing and are expected to raise the surface temperature 1.8–4.0^o C, along with increasing emissions of ozone (O₃) from human activity. These forces, and many others, naturally act together and have an important effect on agricultural productivity and climate change. It is more useful and practical to study the effects of multiple, layered factors of climate change than to study one factor in isolation. For example, increased CO₂ alone will increase the photosynthetic rate in plants, increasing biomass production, and result in positive growth for plants. However, this increase in biomass does not necessarily lead to an increase in crop yield. It is important to combine and test the effects of various factors of climate change on crops to determine potential crop yield because with a growing human population, maximizing crop yield is highly desirable. Plants do not have many natural adaptations for living in conditions with increased CO₂, so it is important to study how they react in order to better breed and genetically prepare plants for climate change.—Taylor Jones

Frenk, G., Van der Linden, L., Mikkelsen, T. N., Brix, H., Jorgensen, R. B., 2011. Increased [CO₂] does not compensate for negative effects on yield caused by higher temperature and [O₃] in Brassica napus L. European Journal of Agronomy 35, 127–134.

Drought and Other Driving Forces behind Population Change in Six Rural Counties in the United States

Although population change in the United States has been widely researched, most studies have focused on social and economic reasons for population shifts. The research that does exist on environmental factors for the most part has looked at temperature and seasonal relationships. To provide more depth to known impact of environment on US population shifts, Maxwell et al. (2011) set the primary research goal of identifying the main reasons for population shifts in six counties in three geographic regions. Secondarily, the researchers were interested in finding the relationship between drought from the 1800s to the present and population change. Furthermore, the study sought to assess the spatial variability between the six locations in the study. The study found that traditional variables for population change–unemployment, education, technological advancement, etc.–had the largest impact on population change. Through correlation and regression analysis drought was determined to cause a small variance in population change with significance in three of the six counties. Spatially, without other measures of climatic variables, counties in the same region tended to experience similar results. –Adriane Holter

Maxwell, Justin T., Soule, Peter T., 2011. Drought and Other Driving Forces behind Population Change in Six Rural Counties in the United States. Southeast Geographer 51, 133 – 148

Genetically Modified Crops Benefit Biodiversity and Human Sustainability

The use of genetically modified crops in commercial agriculture has been in debate for many years now, and there exists a worry of how these crops may adversely affect humans, as well as other species. Carpenter (2011) reviews journal articles related to the effect of genetically modified crops on biodiversity, focusing the review on crop diversity, effect on non-target soil organisms, effect on target pests, changes in farming practices, weed diversity, use of pesticides and herbicides, and several other topics. The overall findings of Carpenter are that genetically modified crops have near negligible effects on non-targeted species, while being successful at reducing targeted species populations. There is also evidence that genetically modified crops are already aiding biodiversity by increasing farming yields, reducing the amount of land needed to convert from natural habitat to agricultural land. The increased yields, due to successful reduction of pests, has also resulted in more beneficial farming practices, including more conservative tillage practices and decreases in pesticide and herbicide use. The introduction of genetically modified crops has the potential to be extremely beneficial to both humans and our efforts in preserving biodiversity. –Mathew Harreld

Carpenter, J.E. 2011. Impacts of GM crops on biodiversity. Landes Bioscience 2:1, 1–17.

Rethinking Biofuels: Alternative Feedstocks Switchgrass and Miscanthus Predicted to Outperform Corn Grain

            Concerns over the potential effects of climate change on energy and food production in the last ten years have created a new market for alternative fuels.  In the United States, corn-based ethanol, likely due to the political clout of the US corn lobby, has dominated biofuels research to date.  However, corn may be ill-suited for ethanol production because oil is used in the production, transport, and application of the large amounts of nitrogen fertilizer necessary to boost corn yields.  The nitrogen fertilizers have a detrimental effect on the environment by decreasing soil productivity and leaching into neighboring soils and water tables.  With the advent of the US Energy Independence Act of 2007, the US government created demand for up to 15 billion gallons of corn derived ethanol per year, mandating any amount beyond that be produced from other feedstock sources.  Although high in energy yield, corn's dependence on oil makes it less efficient overall if environmental damage and GHG emissions are considered.  The cap on corn ethanol production initially stimulated research into alternative feedstock, with preliminary research showing great promise from perennial grasses like switchgrass and miscanthus.  The initial studies on the relative energy yield efficiency of corn and alternative feedstock prompted Parton et al. to develop a model capable of estimating the benefits of switching ethanol feedstock from corn to perennials.  By using regression analysis of the DAYCENT model, they found that by substituting miscanthus and switchgrass for corn on lands already designated for ethanol production food productivity would increase by 4% and available feedstock for ethanol by 82% all while avoiding the GHG releases associated with the conversion of uncultivated land for agricultural production (known as ILUC, indirect land-use change).—Michael Gazeley-Romney

Davis, S., Parton, W., Del Grosso, S., Keough, C., Marx, E., Adler, P., DeLucia, E., 2011. "Impact of second-generation biofuel agriculture on greenhouse-gas emissions in the corn-growing regions of the US". Frontiers in Ecology and the Environment; doi:10.1890/110003

Disproportional Risk for Habitat Loss of High-Altitude Endemic Species Under Climate Change

Scientists project that climate change will alter the distributions and range shifts of biota, ultimately causing an increase in terrestrial species’ extinction rates. In many mountainous areas, warming temperatures have already generated an upward shift of tree lines. Therefore, range-restricted, high-altitude, endemic species inhabiting mountain ranges are particularly at risk since the upward shift of the tree line may significantly reduce these endemic species’ habitat areas. Using a Potential Climate Tree Line (PCT) model and statistical analyses, Dirnbock et al. (2011) analyzed the loss of available habitats for high-altitude endemics of five Austrian Alps taxonomic groups (vascular plants, snails, spiders, butterflies, and beetles). Habitat loss was attributed to the upward shift of forest species. Additionally, the authors investigated whether hotspots of endemics would be disproportionally affected by habitat loss. Dirnbock et al. found that even under the weakest climate change scenario (+1.8 °C by 2100), above tree line area was reduced by 77%. The results also demonstrated that areas with high endemic species richness showed the largest losses of suitable habitat. Therefore, endemic species richness was positively related to above tree line area loss. These results suggest that endemic hotspots in the Alps will be disproportionally affected by habitat loss caused by climate change induced forest expansion. Combined with these species’ range restrictions, their ability to persist in the face of climate change may be greatly reduced.—Megan Smith.

Dirnbock, T., Essl, F., Rabitsch, W., 2011. Disproportional risk for habitat loss of high-altitude endemic species under climate change. Global Change Biology, 990–996, doi: 10.1111/j.1365-2486.2010.02266.x