V.6 Conservation and Global Climate Change
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V.6 Conservation and Global Climate Change Diane M. Debinski and Molly S. Cross OUTLINE 1. Introduction 2. How climate is changing 3. Environmental responses to climate change 4. Consequences of climate change for conservation 5. The missing links One of the most challenging issues for conservation during the coming decades will be preserving biodiversity in the face of climate change. It has become increasingly apparent that the climate is changing because of human activities —the chemical composition of the atmosphere has been modified,record-breakingtemperaturesarebecomingmore common on an annual basis, and polar ice caps are melting. Ecosystems will respond to these changes in a variety of ways; some may be deemed beneficial and others detrimental . The question for ecologists and conservationists then becomes how do we conserve ecosystems, ecological processes, and species under conditions of a changing climate? GLOSSARY assisted migration. Directed dispersal or translocation of organisms across the landscape bioclimatic envelope models. Models that use statistical methods to correlate species occurrences with environmental predictor variables to define a species’ environmental niche and predict the species’ occurrence across a broader landscape greenhouse gases (GHGs). Gases such as carbon dioxide , methane, nitrous oxide, tropospheric ozone, or chloroflorocarbons that absorb solar radiation and reflect it back down to earth, creating a ‘‘greenhouse effect’’ that warms the earth’s surface interannual. Between years lake turnover. The mixing of deep anoxic (oxygenpoor ) and shallow oxygen-rich water in lakes that occurs in fall and spring when water hits the threshold temperature of 48C oceanic conveyor belt. Ocean circulation pattern driven by temperature and salinity gradients across the globe that moves warm and cold water around the globe, moderating temperatures and salinity patterns phenological changes. Timing of life cycle events that are related to seasonality of the organism such as hibernation, bud burst, flowering, egg laying, etc. Quaternary period. The geologic time period beginning roughly 1.8 million years before present stepping stones. Small, unconnected portions of suitable habitat that an organism uses to move from one place to another trophic cascades. Changes at one level of the food chain that percolate through many other levels of the food chain, causing both direct and indirect effects on species composition vagility. An organism’s ability to move through the landscape 1. INTRODUCTION In this chapter, we describe how climate is changing , including both paleoclimatic and anthropogenic changes. We then discuss how the Earth is responding, both from an abiotic perspective (including atmospheric changes, temperature fluctuations, and ocean circulation patterns) and from the perspective of biotic communities. We describe some of the research approaches that have been used to examine and anticipate the types of responses of ecological communities to climate change and how scientists might prioritize and manage areas for conservation under conditions of a changing climate. Finally, we end with a discussion of the missing links—the need for research that will allow us to better predict responses and to manage for change in the coming decades. 2. HOW CLIMATE IS CHANGING Paleoclimatic Changes Changes in the Earth’s climate over the past thousands of years can be reconstructed using a combination of direct measurements from land and ocean weather stations and indirect proxy methods, which include tree rings and pollen and plankton from lakes and ocean sediment cores. These records indicate that the Earth’s climate has cycled through many warming and cooling periods over geologic times. Ancient samples of atmospheric gases from ice cores reveal that the concentration of greenhouse gases (GHGs) in the atmosphere has also fluctuated in the past, with high GHG levels being correlated with warmer global temperatures. Cycles in temperature and GHG concentrations over geologic time scales have been caused by natural fluctuations in incoming solar radiation and the chemical composition of the atmosphere. Anthropogenic Climate Changes The 2007 Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) details the unequivocal warming of the Earth’s climate over the last 50 years, most of which is very likely a result of increases in anthropogenic GHG emissions. There has been a rapid 35% rise in atmospheric GHG concentrations since preindustrial times, and in 2005, atmospheric GHG concentrations were higher than any levels recorded or estimated for the previous 650,000 years. Although the magnitude of warming has varied across the Earth’s surface, globally averaged temperature has risen *0.68C over the last 50 years. It is likely that average Northern Hemisphere temperatures during the last 50 years were warmer than during...