Interviewer: Earth's rising seas are some of the most visible signs of our warming planet
over the last 20 years NASA satellites, air borne missions, and field campaigns have shown
a steady rise in global sea levels as the world's polar ice sheets melt.
Here to tell us more about this is Dr. Tom Wagner from NASAs Goddard's Space Flight
Center. Start by telling us you know you have some new images. What are these new
images show us about sea level rise? Dr. Wagner: You know they show us two really
important things; you know and first thing is this, sea levels are rising around
the world and in the last 20 years they've risen by over 3 inches
on average. And we know this number really well, it's actually recorded by a number of
different satellites that go over the Earth and bounce radar signals off the ocean
to determine its height. The other amazing thing though is that the ocean has
topography. You know you can almost think of it like a mountain range with peaks and valleys.
And the coast of California in this case actually is a little bit of a valley right now
and this is caused by a combination of wind and ocean currents. But what people really
need to take away is that sea level is rising and it's going to continue to rise and it's rising enough
that it's already impacting us.
Interviewer: What's causing
sea levels to rise? Dr. Wagner: What's causing sea level to rise are two basic things. One is that
as the planet warms up the volume of the ocean expands
and that's about half of the sea level rise. The other half comes from
melting of ice that's on land. In particular the glaciers and ice caps of Alaska and
Canada and also the major ice sheets of Greenland and Antarctica.
And we have this other amazing satellite called GRACE which actually allows us to
map changes in the weight of the ice sheets. And what we found is that in the Greenland
case, we're not only losing ice but the ice loss seems to be accelerating
and that's something that we're trying to account for in our models as we move forward.
Interviewer: What is NASA doing to understand how much sea level could rise in the future?
Dr. Wagner: NASAs doing three basic things you know one is we're developing the technologies
to study sea level rise and then we're deploying them on
satellites and also on aircraft to measure how fast the oceans going up.
But we're also trying to understand the processes that are driving the ice loss and that's why
we put scientist out in the field to study what's going on with the ice itself. Both
on the ice and in the oceans around the ice cause that's an important factor. And then
finally we pull all that data together into models and those models are
important for us to understand the processes of ice loss and also to do the forecast
into the future to kind of produce those numbers that society needs to
plan for 10, 50, 100 years after. Interviewer: So where can we learn
more and see some of these images. Dr. Wagner: One of the best place to go is
nasa.gov/earth where you can learn all about the work that we're doing right
now, the data sets, that are available to see, and also learn about other NASA programs
studying the Earth.