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The Effects of Global Warming
Figure 1. Projected surface temperature changes by 2099. ("Climate Change 2001: The Scientific Basis," 2001)
Over the past century or so, the earth has seen a significant rise in average global temperatures (see Figure 1). Studies show that average surface temperatures have risen at the rate of approximately 0.1°C/decade, which is significant when compared to estimates of historical values (IPCC, 2001). Regardless of whether this temperature increase is primarily a result anthropogenic causes, such as as emission of greenhouse gases, or natural fluctuations, global warming will have a profound effect upon the oceans and should therefore be of great concern to anyone in charge of managing global fisheries. It is also very likely that global warming will accelerate in the near future due to positive feedback mechanisms, including the lowering of the Earth's albedo due to melting of polar caps (IPCC, 2001). Climate change is quite difficult to monitor, and even more difficult to predict accurately (see Figure 2). Despite this, research on current systems as well as research into past global warming events provides a general idea of what can be expected in future years. Knowledge of these general trends will allow us to better understand the effects and, consequently, better manage fisheries.
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One possible method of reacting to a specific negative effect of climate change - decreasing natural phytoplankton levels and debasing the ocean food chain - is "ocean fertilization" with finely powerdered. This allows high levels of phytoplankton growth in areas deficient in this nutrient (Jones & Young, 1997). There are significant technical problems related to this approach. Also, the large-scale effectiveness of iron fertilization is extremely speculative (Chisholm, Falkowsi, & Cullen, 2002). Hence, we do not advise this method until significantly more research has been conducted.
Figure 23. Range of future temperature predictions made by different models (IPCC, 2001)
Figure 3. Projected surface temperature changes by 2099. ("Climate Change 2001: The Scientific Basis, " 2001)
There is a large amount of uncertainty in the future of climate change (See . Figure 3 )shows the variation between the predictions of the average global temperature by different models. Although predictions can be made about what will happen, there is no way to know for certain how global warming will effect the oceans and fish populations. However, the climate is an important factor in the formulation of a plan for fishery management. It is important to be aware that climate will not change uniformly over the entire globe. For instance, the effects of global warming are likely to be more pronounced in the high latitude regions. Thus, any recommendations must be made specific to region of the ocean. Due to the importance of climate change to fisheries, we propose that we should set up a system for better collecting and analyzing data as global warming progresses. Many types of biological, physical, and geological data are needed to better predict the future climate of various regions. In particular, we advocate the monitoring of temperature, salinity, pH, gas solubility, biomass, species population, and current strength and direction in order to look for trends that would allow us to better predict the future climate of various regions. Also, in particular, more work has to be done to quantitatively determine how fish populations react to climate change. As these data are monitored and studied over longer time periods, more concrete trends should be discovered.
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