Earth's+Changing+Oceans

Name: Date: 8th Grade Science – STEM Middle Academy – Mr. Condon Block: Earth’s Changing Oceans The italics and bolded lettering is from an on-line article from science daily. Read the article and answer the questions to prepare for an end of class discussion. 1. In the space below Diagram a typical water cycle showing Precipitation, Condensation, Evaporation, and Run Off.
 * Massive Salinity Changes In Oceans **by Kate Melville,
 * // Tropical ocean waters have become dramatically saltier over the past 40 years, while oceans closer to Earth's poles have become fresher, scientists report in the journal Nature. These large-scale, relatively rapid oceanic changes suggest that recent climate changes, including global warming, may be altering the fundamental planetary system that regulates evaporation and precipitation and cycles fresh water around the globe //**
 * // "This study is important because it provides direct evidence that the global water cycle is intensifying," said Elise Ralph, associate director of the National Science Foundation's (NSF) physical oceanography program, which funded the research. "This is consistent with global warming hypotheses that suggest ocean evaporation will increase as Earth's temperature does. These issues are particularly important as pressure on freshwater resources has become critical in many areas around the world." //**

2. Ocean circulation Results from the movement of water in surface currents and deep water upwelling. Upwelling occurs when less dense water rises through parts of the ocean with higher density water. What might cause ocean water to have higher density? 3. From your work yesterday, what is the density of fresh water? 4. Adding salt to the water caused the density of water to increase. A concern for oceans is that global warming will cause glaciers in Alaska, Greenland, and Antarctica to melt. These “melt waters” will flow into the oceans. Because of their lower density, will they sink or float on the already salty ocean water? 5. Draw a diagram of what the ocean’ waters might look like as this run off is added. Be sure to include the density of the waters.
 * // An acceleration of Earth's global water cycle can potentially affect global precipitation patterns that govern the distribution, severity and frequency of droughts, floods and storms. It would also exacerbate global warming by rapidly adding more water vapor - itself a potent, heat-trapping greenhouse gas - to the atmosphere. And it could continue to freshen North Atlantic Ocean waters to a point that could disrupt ocean circulation and trigger further climate changes. //**
 * // If the North Atlantic becomes too fresh, its waters would stop sinking and the Conveyor (ocean currents and upwelling) could slow down. Analyses of ice cores, deep-sea sediment cores, and other geologic evidence have clearly demonstrated the Conveyor has abruptly slowed down or halted many times in Earth's history. That has caused the North Atlantic region to cool significantly . //**
 * // Melting glaciers and Arctic sea ice, another consequence of global warming, are other sources of additional fresh water to the North Atlantic. An accelerated water cycle also appears to be increasing precipitation in higher latitudes, contributing to the freshening of North Atlantic waters and increasing the possibility of slowing the Conveyor. //**
 * // A cooling of the North Atlantic region would slow the melting process, curtail the influx of fresh water to the North Atlantic. The Conveyor would again begin to circulate ocean waters. But global warming and an accelerated water cycle would continue to bring fresh water to high latitudes. Monitoring Earth's hydrological cycle is critical, the scientists said, because of its potential near-term impacts on Earth's climate. //**

6. Imagine that you are a fish adapted to the normal salinity (saltiness) of the ocean. What might you have to do to survive this change? 7. Now imagine that you are a microscopic organism. You need sunlight to survive, but you also need normal ocean salinity. Could you survive? How or Why Not? 8. How might the survival of organisms in question 7 affect the survival of ocean fish populations? 9. The scientists from the article you read have made some claims about how global warming might affect the oceans. What type of evidence would you want to see to be convinced that we should stop global warming?