NASA Podcasts

Science for a Hungry World: The View from Space, Pt. 3
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For other episodes in the "Science for a Hungry World" series, click here.

[Music begins]

Narrator: Imagine what the east coast of the United States looked like before the cities were built, before the sprawl of the suburbs, and before farmland dotted the countryside. Old-growth forests made up much of the landscape along the east coast. As people began developing the land, they cleared the forests for fertile planting soil and pasture. This alteration of the landscape is called land use change, and it's still happening all over the globe. University of Maryland Professor Chris Justice spends his time studying land use change through a NASA-funded satellite remote sensing project called the Land Cover Land Use Change Program.

Chris: As we are looking from space over time, we're able to see these changes. And some of them are quite astounding.

Narrator: Chris and his team monitor the Earth's surface to get an idea of where the land cover is changing, and what it is being used for.

Chris: What we see from space is the surface of the earth. Land cover could be forest or grassland, woodland, urban areas. Whereas land use is what people are doing with that surface.

Narrator: The Land Cover Land Use Change project specifically looks at agricultural land use change. Understanding where people are altering the land surface for growing food allows governments and NGOs to see which land is being converted from one type of use to another.

Chris: Not only do we have an expansion of agriculture in some parts of the world, but in others we have an abandonment of agriculture. And this, in turn, has implications in terms of both carbon sequestration but it also has impacts in terms of fire distribution.

Narrator: Whereas agricultural practices would clear and manage the fuel on active farmland, on abandoned land that fuel is much less managed, leading to some of the disastrous fires we have seen in recent years all over the world. Urban development is not the only cause for land use change. The Brazilian rain forest is being cleared at an alarming rate, as subsistence farmers convert the land for pasture and crops like sugarcane and soy.

Chris: Subsistence farmers are coming in. After a few years, due to infertile soils, those lands will be abandoned and new areas will be cut down for agriculture. And those lands will either revert to forest or can be used for pasture.

Narrator: Clearing the tropical rain forest has many negative effects on biodiversity, just as other land use practices like the application of harmful pesticides and fertilizers can have similar side effects.

Chris: From the U.S. we've seen an increasing dead zone at the mouth of the Mississippi where you have conditions where fish can't live due to the excess fertilizer. that's being put in upstream from agricultural production.

Narrator: The physical dimensions of land use change are only part of the story. Understanding the cultural, economic and social facets of land use change is important because all of these aspects are interconnected.

Chris: It takes social scientists and physical scientists working together in an integrated way to really understand the, not just the causes of land use change, but the impacts and consequences of land use change.

Narrator: As we face climate change and global population growth, NASA data continue to provide scientists with the tools they need to monitor the world's agricultural regions.

Chris: When the information that we provide by satellite is used to make management decisions that actually benefit people, then I think we've really succeeded.

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