Communities around the world are developing a greater sense of awareness as they are directly and indirectly affected by climate change. Though researchers have studied the potential magnitude of climate change trends for decades, relatively little is known about the rate of climate change in marine environments. Recently a group of marine scientists from around the world gathered to investigate just how quickly the world's oceans are experiencing climate-related impacts -- and their preliminary findings have taken many by surprise.
The Velocity of Climate Change
One of the primary consequences of climate change to marine ecosystems is rising ocean temperatures. To measure the rate at which these changes are occurring, scientists have coined the term "climate velocity." First used to describe the speed that plants and animals need to stay ahead of climate change on land, climate velocity has more recently been expanded to include marine ecosystems. Using temperature records, scientists calculate the rate of physical and chemical changes in a marine ecosystem as a result of climate change. On a larger scale, scientists predict that the rates of climate velocity on land and in the ocean will accelerate over the next several decades in the absence of any global mitigation measures.
Responding to Climate Velocity
Not only are marine ecosystems experiencing increased rates of climate velocity, but they are also responding more rapidly than scientists previously thought. Until recently, many scientists believed that climate-related impacts on marine ecosystems were happening more slowly than on land. However, scientists are finding increasing evidence suggesting the contrary -- leading many to think that marine plants and animals respond to climate-related change just as fast or faster than their terrestrial counterparts. In the Gulf of Maine there is an abundance of evidence suggesting that shifts in water temperature are already affecting fish productivity, size and stock structure, dispersal patterns, species interactions, and even seasonal abundance throughout the gulf.
Last year, at a Marine Climate Impacts Workshop (held by the National Center of Ecological Analysis and Synthesis), an international group of marine ecologists compiled a database of over 200 published studies on climate change to better understand just how quickly the ecosystem was responding. Not only did the group find evidence of climate change impacts in every type of marine ecosystem, at every latitude, and at every trophic level but they also found that rates of phenological (life history changes) and spatial distribution changes are occurring in some cases more rapidly in the ocean than on land. In other words, the oceans are swiftly responding on a multitude of levels.
Accounting for Rapid Change
As scientists continue to document responses to climate velocity through large-scale shifts in spatial distributions, there is a greater need for fisheries stock assessments to reflect these substantial biophysical changes -- and swiftly. Currently, annual catch limits (ACL) are based on forecasts generated from statistical models that assume static environmental conditions. This can have serious implications on the accuracy of ACLs and substantially compromise the validity of stock assessments.
Similarly, as fish species migrate from one region to another, these changes can further complicate management. For instance, how and when will regional management councils transfer management authority among each other as fish distributions shift? How will migrating fish stocks impact permits? Finally, how will these changes be reflected appropriately when calculating allocation?
Addressing the increasing pace of climate change is a formidable challenge for scientists, managers, and fishermen alike. Keeping pace with these rapid environmental changes necessitates the incorporation of environmental and ecological data into fishery management plans. Not doing so can risk the future sustainability of the world's fisheries.
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