INTRODUCTION
In 2010, the Food and Agriculture Organization of the United Nations verified Peru as the second largest fishing industry in the world based on 7.4 million tones fish catch annually. Due to its strategic position, upwelling process has been occurring in Peru's ocean. This process, which happens due to extensive wind system and the Coriolis Effect, is the main reason why ocean in Peru provides fishermen with higher successful rate in fishing. As illustrated by figure 1, the trade wind from the Southeast that is parallel to the coast pushes warm surface water away from the coast and being replaced by deep water, this process is known as upwelling. The deep water is rich in nutrients which support a phytoplankton bloom. Moreover, according to Dr. David Eggleston, a faculty advisor in department marine, earth, and atmospheric science, Anchovy eats phytoplankton as a result it would increase anchovy's capacity during upwelling.
Furthermore, the amount of nutrients at the coast depends on El NiĂąo and La NiĂąa. National Oceanic and Atmospheric Administration states that Peruvian fishermen realize they had higher catches during La NiĂąa conditions compared to El NiĂąo. El NiĂąo, was originally used by the Peruvian fishermen, means the sea water becomes warmer prior to Christmas and causes the fishing outcome to be poorer than normal. In contradiction, La NiĂąa occurs when the sea water turns colder and improved the fishing outcome. These phenomena teach Peruvian fishermen that the temperature does affect fishing outcome. Figure 2 (next page) shows the record of the United Nation's Intergovernmental Panel on Climate Change (IPCC), the global average temperature has changed one degree Celsius in the past 150 years. Although it sounds like a small number, but it has great impact on the Peruvian Anchovy industry.
This paper will cover how climate change effect fishing industry in Peru. Furthermore, this paper will focus specifically on how climate change causes changes in trade wind pattern, amount of fresh water input, and the frequency and intensity of El Nino and La Nina.
CLIMATE CHANGE CAUSED TRADE WIND TO WEAKEN
Climate change caused trade winds to weaken which would diminish the capacity of the Anchovy. According to NBC, trade winds, which sweep around half of the globe, are weakening. This is identified by using combination of observations and computer modeling. Consequently, it can be concludes that Walker Circulation has weakened by about 3.5 percent since mid 1800s (Than, 2006). Since trade wind is part of the Walker Circulation, consequently trade wind is decreasing in strength (Than, 2006).
The weakening of Walker Circulation can also be shown through Figure 4. In the figure 4, the graph shows the sea surface graph temperature on May 13, 1992, which indicates the absence of the cold tongue. Cold tongue has been used to know the strength of Walker Circulation and ENSO condition. Due to the absence of the cold tongue, we can conclude that there is a weakening on the Walker Circulation.
The phenomenon of decreasing in magnitude of trade wind is called El- Nino-Southern Oscillation (ENSO). ENSO will cause the water being up-welled is much warmer and low in nutrition resulting in a decrease in the productivity of fishing.
The wind along the equator influences how intense is the upwelling. For example, Figure 5a when there is a strong wind from the eastern side, as a result, there will be upwelling of cold water along the equatorial pacific. The surface water will chilling the air above it and make it too dense to rise high enough for water vapour, and condense to form cloud formation. Once the cloud reaches the low pressure zone, it will become precipitation or what we call rain. As a result, the eastern part will be free of cloud while the equatorial pacific will be raining. But when the wind come from the east weaken, the upwelling will be weaken as it is shown in Figure 5b, and also the changes in ocean temperatures could cause the raining equatorial pacific part to shift to the eastern part.
CLIMATE CHANGE EFFECT THE NUMBER OF FRESH WATER INPUT
Climate change increases the number of input of fresh water. Higher global temperature caused the glacier to melt. The United Nations Intergovernmental Panel on Climate Change states that "The Cordillera Blanca mountain range which is the largest and highest tropical glacier chain in the world" has diminished 112 square kilometers in 7 years and it lost 15.5 percent of its ice mass in 27 years (2007). The melting of the glacier will decrease the salinity because it will increase the fresh water supplies.
Due to the increase in average of sea temperature, the sea water temperature is warmer compared to normal. Decreasing in salinity and warmer surface water will make the thermocline located deeper as shows by figure 6. In order for upwelling to occurs, the thermocline should be shallow enough for the wind to mix the deep water with the mixed layer. However, increasing in the fresh water input, will caused thermocline to located deeper which means it requires stronger wind in order for the deep water to mixed with the mixed layer.
CLIMATE CHANGE EFFECTS THE FREQUENCY AND INTENSITY OF EL NINO AND LA NINA
Larry west, a writer in about, stated that some climatologist believed that climate change will have an impact on the frequency, and intensity of El NiĂąo and La Nina events . As we can see from the figure 7, it represents how the magnitude of La NiĂąa and El NiĂąo related to increase in sea water temperature. The red color will represent the magnitude of the El NiĂąo and inversely, the blue color will represent the magnitude of La NiĂąa. As we can see, when there is increase in temperature, iwill increase the magnitude of El NiĂąo. For example, in year 1930 it has the highest increase in temperature and it also has the largest magnitude of the El NiĂąo. The same thing happens for La NiĂąa, in 1950, the highest decreasing in temperature was recorded which caused the largest magnitude of the La Nina. From this, it can be conclude that, Change in temperature has an impact on magnitude of both the El NiĂąo and La NiĂąa.
Water is a good heat capacitor therefore an increase in the global temperature, will caused water to absorb more the heat to the ocean. This increases the ocean water temperature and would probably increase the frequency of El NiĂąo happening as shows in figure 7.
CONCLUSION
The climate change has caused the walker circulation to weaken, which will also caused the trade wind to weaken. Weakening in trade wind will decrease the intensity of upwelling.
The climate change has caused the global land temperature to increase. Due to increase in temperature, it has effect on the melting rate of The Cordillera Blanca mountain range to increasing rapidly. Melting Glacier will increase the amount of fresh water input which has a direct impact on upwelling.
Lastly, increase in the land surface temperature will also increase the sea surface water temperature. The changes in the sea surface water temperature will have an
impact on the intensity and the frequency of La NiĂąa and El NiĂąo. The occurrence of El NiĂąo and La Nina has an impact on upwelling.
From the above discussion, we can conclude the following: weakening Walker Circulation, the rate of Cordillera Blanca Mountain is melting rapidly and increase the ocean surface temperature have an impact on upwelling. In Peru upwelling is a huge major effect of their productivity in fishing. Decreasing in the upwelling will cause the productivity of anchovy in Peru to decrease.
