Transcript of Rising_Seas


  The ice is melting. The seas are rising. Little by little, in most parts of the world, the ocean is overtaking the land. Most of us don't think much about sea level rise, but it's one of the biggest signs that humans are affecting the Earth's climate. And it's something worth watching. So the big question is, are we facing a doom and gloom scenario? I prefer not to think about climate change and global warming in terms of doom and gloom scenarios, so much as a change in our planet. Our planet's definitely changing, and we're definitely causing it. So we're going to have learn to deal with some of these changes. But in addition, we're going to have to learn how to make a slightly smaller footprint on our planet. Sea level is rising effectively because of global warming. As the planet heats up, two things happen to the ocean. One is that the temperature of the water increases. And as that happens, the water actually expands and takes up more room. The other thing that happens is that ice that was on land in the form of glaciers and ice sheets begins to melt and as that runs off into the ocean, it increases the water in the ocean, and it actually raises sea level as well. It's important to understand how the world's ice sheets form, how they change over time, and how fast they are moving into the sea. That's where researchers like NASA's Lora Koenig come in. She recently spent three months in Greenland studying the composition of those ice sheets. All ice sheets and glaciers start as snowfall. Those tiny flakes get compressed by the weight of more snow above, and eventually become dense masses of ice. What we're seeing right now on the ice sheets and glaciers is that they are shrinking in size. And as glaciers on land are shrinking overall, that contributes a little bit to sea level rise. And we are worried that as we see warming over the ice sheets, and increased melting over the ice sheets, that they are going to start contributing much more to sea level rise. Two thids of the fresh water on Earth is frozen in the world's ice fields. If that ice melts, seas will rise. If all of that ice were to melt, sea level would rise worldwide by 70 meters. No one expects all of that ice to melt anytime soon, but even the meter of sea level rise that many scientists predict in the next century, could have dramatic consequences. Even though the polar regions seem very far from a lot of people's day to day life, they are very important. Because they are regions that cool our earth. And as they change, they're going to cause larger changes throughout the rest of the globe. A lot of people live in coastal areas. Coastal places that have beaches. As sea level rises, then beaches begin to erode and we begin to lose wetlands -- a lot of different ecologically-sensitive regions lie along the coastline, and as sea level rises, these get flooded, ecosystems, of course, change. So all of this can have big consequences for people and especially people who live along the coast. As the great ice sheets of Antarctica and Greenland begin to melt and break up to global warming, we really might experience very rapid sea level rise; three or four times as fast as the rate that we see today. So predicting this rate is very tricky because we really don't know when the ice sheets might break up and how fast they will go when they do. So predicting future sea level rise is one of the great scientific problems of the future.