It is no secret that our climate is changing - rapidly - and together with it, oceans change as well. The Intergovernmental Panel on Climate Change (IPCC), consisting of hundreds of scientists worldwide, have shown that changes in global climate have accelerated since the 1750s, causing an overall increase in temperature both on land and in the sea. The IPCC also suggests that research indicates that there is >90% chance that the change is human-mediated (IPCC, 2007). Modifications to ocean temperature, biogeochemistry, salinity, sea level, UV radiation, and current circulation patterns have all been detected within the last few decades and are expected to continue (IPCC, 2007). Increase in extreme weather is also expected, including intensification and rise in the frequency of severe storms. Less than 2 decades ago, marine ecologists could mostly speculate about the possible ecological responses of marine systems to global climate change (Lubchenco et al., 1993). Today, however, the ecological "footprint" of climate change has been observed in both terrestrial and marine ecosystems worldwide (Walther et al., 2002, 2005).

Documented ecological changes that are related, for example, to temperature alteration in the oceans include modifications to the phenology of pelagic organisms resulting in trophic "mismatches" between predators and preys (e.g., Edwards and Richardson, 2004), severe events of coral bleaching that negatively influence the structure of coral reef communities (e.g., Hughes et al., 2003), a mostly poleward shift in fish distributions in the North Sea (Perry et al., 2005), and shifts in the distributional limits of benthic organisms in temperate coastal environments (Helmuth et al., 2006b). Harley et al. (2006) provide a comprehensive review of the known and potential effects of climate change on coastal marine ecosystems. The authors demonstrate that the study of this topic is quickly accelerating, which is no surprise, given the increased rate of change in physical phenomena related to climate change in the ocean and the mounting evidence of their biological and ecological impacts. Since the publication of Harley et al.'s research, dozen more papers have been published on this issue, some with remarkable albeit worrisome findings.

In this chapter, we will illustrate some of the evidences and projections for change in the marine environment (coastal and pelagic) attributed to climate change, focusing mainly on the two most studied and experimented changes: temperature and pH. Other topics that will also be explored briefly are the predicted changes due to sea-level rise, increase of storms, and change in circulation patterns. The different aspects of climate change are expected to affect marine communities at different spatiotemporal scales and also the number of habitats impacted. For example, temperature and CO2 will most likely have basin-scale or even global effects and can potentially affect ecosystems at all depths, while sea-level rise and increased storm frequency/intensity will probably affect mostly shallow coastal environments. Climate changes are predicted to affect ocean life from the tiniest of organisms - plankton, to the largest ones - whales (Gambaiani et al., 2009).

Several lines of research are being used by investigators to identify the links between the current (and predicted) physical changes related to global climate change and their direct and indirect effects on biological and ecological patterns and processes. On large biogeographic scales, correlative studies are mostly used to find links, for example between temperature and species distribution shifts. To predict ecological impacts under different future scenarios of ocean temperature and pH, researchers use controlled laboratory or mesocosm experiments (mostly to look at one or several species). In few cases, they could also use existing manmade (e.g., outflow areas of power plants where temperatures are increased) and natural (e.g., CO2 vents) environments that today mimic predicted levels of these variables (mostly to look at the total ecosystem effects). Biophysical models and ecological food-web models can also be used to examine ecosystem-level effects of climate-induced increase or decrease of key species at the bottom or top of the food-web. Models and experiments also seek to find stabilizing forces that might modulate climate change effects.

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Guide to Alternative Fuels

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