Marine Biology Assignment #4 The Ocean Conveyor Belt and Global Warming GLOBAL WARMING Global warming is one of the most pressing environmental issues for terrestrial and aquatic species, especially those in the oceans. The scientific consensus on global warming is becoming clearer every day – our global climate is changing and those changes will have long-term and widespread negative effects for all species on Earth. And humans are almost certainly responsible for those changes. The evidence that human-induced global warming is real is increasingly clear and compelling (http://www.ucsusa.org/global_environment/global_warming/index.cfm). Since the beginning of the 20th century, the mean surface temperature of the earth has increased by about 1.1º F (0.6°Celsius). Over the last 40 years, the temperature increased by about 0.5 º F (0.2-0.3°Celsius). Warming in the 20th century is greater than at any time during the past 400-600 years. Seven of the ten warmest years in the 20th century occurred in the 1990s. 1998, with global temperatures spiking due to one of the strongest El Niños on record, was the hottest year since reliable instrumental temperature measurements began. Last year was the fourth-hottest year on record. It was punctuated by four powerful hurricanes in the Caribbean, heat waves in Europe and Asia, and deadly typhoons lashing Asia. In addition, changes in the natural environment support the evidence from temperature records: mountain glaciers the world over are receding; the Arctic ice pack has lost about 40% of its thickness over the past four decades; the global sea level is rising about three times faster over the past 100 years compared to the previous 3,000 years; and there are a growing number of studies that show plants and animals changing their range and behavior in response to shifts in climate. As the Earth continues to warm, there is a growing risk that the climate will change in ways that will seriously disrupt our lives. While on average the globe will get warmer and receive more precipitation, individual regions will experience different climatic changes and environmental impacts. Among the most severe consequences of global warming are: a faster rise in sea level; disruption of oceanic circulation patterns; more heat waves and droughts, resulting in more and more conflicts for water resources; more extreme weather events, producing floods and property destruction; and a greater potential for heat-related illnesses and deaths as well as the wider spread of infectious diseases carried by insects and rodents into areas previously free from them. The purpose of this assignment is to get you to think about how global warming will affect the oceans as well as nearby land masses and human populations. THE OCEAN CONVEYOR BELT Many of the species of marine life are affected by a single ocean-circulation pattern that pulls waters from the deep ocean, brings them to the surface, and distributes them around the world. This is called the Ocean Conveyor Belt. The water that is circulated in this way also affects nearby land masses; because of its high specific heat, water has a moderating effect on climates, preventing them from heating or cooling rapidly or to extremes. Thus, if the temperature of the water in the Ocean Conveyor Belt increases, ecosystems and species in the oceans and coasts will be affected by the change. YOUR ASSIGNMENT Answer the following questions: 1. What is the Ocean Conveyor Belt? Describe what the current is like. Where does it go to? Where is it cold, where is it warm? Where does it rise to the surface, where does it sink? 2. As the water in the Ocean Conveyor Belt circulates, it redistributes nutrients. How do the warming and cooling, rising and sinking affect the distribution of nutrients in marine ecosystems on Earth? 3. As a result of global warming, the Arctic ice sheets are melting at an increasing rate. The fresh water that is produced flows into the ocean where it encounters the Gulf Stream, a major current that carries warm water from the Caribbean to the North Atlantic. Along the way, the Gulf Stream interacts with the Ocean Conveyor Belt, affecting its temperature and chemical composition. So what will happen to the Ocean Conveyor Belt if the Artic ice sheets melt and dilute the Gulf Stream? How will this affect the global circulation of nutrients? 4. In addition to interacting with the Ocean Conveyor Belt, the Gulf Stream transfers heat to the European subcontinent. Thus, it has a major effect on the climate of western Europe. What will happen to the climate in that area if global warming occurs and the Gulf Stream is diluted by water from melting Arctic ice? This assignment is due by 5:00 p.m. on Monday, February 7th.