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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.
Figure 12. Annual anomalies of global average land-surface air temperature (Jones et al., 2001).
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