Ocean Temperatures – Changing Planet

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The world’s oceans cover more than 70 percent of Earth’s surface. Millions of creatures, great and small, call the oceans home. These massive bodies of water play a crucial role in maintaining the planet’s delicate environmental balance, from supporting a complex food chain, to affecting global weather patterns. But rising air temperatures are warming the oceans and bringing dramatic impacts felt around the globe. Dr. TONY KNAP (Bermuda Institute of Ocean Sciences): One of the things warming does in, say areas off the United States, it creates a much bigger pool of warm water in the surface of the ocean that lends a huge amount of energy to hurricanes and tropical cyclones. THOMPSON: Dr. Tony Knap is the director of the Bermuda Institute of Ocean Sciences, or BIOS. Famous for its luxurious golf courses and pink sand beaches, Bermuda is also home to one of the world’s leading institutes for ocean studies, with a focus on water temperatures.

KNAP: Here off Bermuda, we have probably a better view of it then many other people are going to have over time. THOMPSON: Bermuda is located over 600 miles, or almost 1,000 kilometers, from the coast of North Carolina, in an area of the Atlantic Ocean called the Sargasso Sea. KNAP: We like to think of the Sargasso Sea in the North Atlantic as the canary in the coalmine. It’s the smallest ocean, it’s between North America and Europe and we think if we are going to see changes, we will see them first here in the ocean off Bermuda. THOMPSON: Scientists at BIOS have been measuring the temperature of the ocean since 1954, making it one of the world’s longest ongoing studies of ocean data. KNAP: Well you measure the temperature of the ocean in many ways. In the old days you used to do it with buckets and thermometers. Now you use sophisticated instruments called conductivity, temperature and depth recorders. THOMPSON: These recorders, called CTDs, are large measuring instruments lowered deep into the water at specific locations in the ocean. On this day, Knap and his team are headed to “Station S.

” QUENTIN LEWIS, Jr. (Captain, R/V Atlantic Explorer): The weather is not going to be our friend today, unfortunately. The winds out of the west, it’s 35-40 and some higher gusts. The seas are anywhere from 14 to 16 feet or higher. THOMPSON: Lowered to a depth of three kilometers, or just under two miles, the CTD records temperature, salinity, carbon dioxide levels, and captures water samples. KNAP: This is a screen for the output on the CTD. The temperature will be in red, blue is salinity or the saltiness, and yellow is the oxygen content. THOMPSON: At BIOS, all of the data is then carefully logged and analyzed. Dr. NICK BATES (Bermuda Institute of Ocean Sciences): With this instrument we can see changes that happen over the season, over the year. And then from year to year.

THOMPSON: Using ocean temperature data going back several decades, BIOS research can trace the warming trend. In the past 56 years, it has risen half a degree Celsius. KNAP: Since 1954 we’ve seen, on average, the temperature increasing by a small amount, an equivalent to what is really a half a watt per year which is, doesn’t seem like a lot but over the whole of the ocean, it’s a lot. THOMPSON: What’s a half a watt? KNAP: It’s not much. It’s about a 100th of a degree per year. It’s not a lot. THOMPSON: But that small a difference can make, have a huge impact? KNAP: Yeah. THOMPSON: Really? KNAP: Yeah, because it’s going on every year. You think about how big the ocean is, and how deep it is, and how much energy it has, I mean it’s a tremendous source of heat. THOMPSON: So where is that warming coming from? KNAP: The warming we believe is to due to changes in CO2 in the atmosphere, the atmosphere getting warmer and the surface of the ocean getting warmer.

And that transfer of heat is being made into the ocean. THOMPSON: So what is the impact of a warmer ocean? The rising temperature causes the ocean to expand, and raises sea levels. KNAP: The tides going up by 3.2 millimeters a year. Half of that is attributed to the ocean warming down to 700 meters. The oceans on average 4,000 meters deep so it has a lot more to expand. THOMPSON: Warming temperatures also impact the growth rates of certain organisms at the very bottom of the ocean food chain, like phytoplankton. And so if you see changes in phytoplankton, does that mean that we are going to see changes in the food chain at the ocean? KNAP: If the organisms that eat those organisms, OK, eat the plankton, for example, can’t eat those plankton, then yes you’ll see changes. THOMPSON: And the small changes being recorded could bring even stronger storms.

This report published in 2005 in Science Magazine shows the gradual rise of the number of Category 4 and 5 hurricanes over recent years. An increase in storm intensity like this many scientists believe is the result of the warming of the oceans. KNAP: You think about how big the ocean is, and how deep it is, and how much energy it has. Even if you look at difference in hurricanes intensity, etc., one, one and a half degree centigrade in the water column of one hundred meters makes a massive amount of difference. THOMPSON: Small changes with big consequences for the creatures in the sea and all the people who live along the coasts..

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