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MODIS Data Product Non-Technical Description - MOD 12

Earth’s land surfaces form an ever-changing patchwork of land cover types: desert, tundra, pastureland, forest, swamp, etc. As our uses of them change, so too do the land types themselves. As boreal forests in North America give way to human development, so too do rain forests in South America, savannahs in Africa, and deserts in Asia. With the climate changing, worldwide resources dwindling, and human populations dramatically swelling, keeping track of those different land types is becoming more and more important. To help meet this need, MODIS scientists developed the Land Cover Type / Land Cover Change product (MOD 12).

Just 100 years ago, there were only 1.7 billion humans on Earth. Today the total stands at over 6 billion, and by the year 2025, that number is expected to increase by almost two billion. Keeping all those people fed and housed is a problem that every nation faces, but the problem is especially critical to those nations where resources are scarce and populations high (like Japan). Thus, keeping track of those resources that are available and how they are changing in response to human development and climate change is important.

Conservation efforts are also dependant upon and sensitive to changes in and amounts of different types of land cover. Many species’ natural habitats are shrinking at an alarming rate, and many habitats have completely disappeared. Conservation and rehabilitation efforts rely heavily on knowing where and how much of suitable land cover types exist. Wolves are one of a number of species undergoing a habitat rehabilitation effort, particularly in North America, where most of the wolf population was systematically exterminated in the last two centuries. Now that they are a protected species, there are many programs underway to increase their numbers and find land suitable for their reintroduction: mostly forest with little or no urban or farmland areas, covering anywhere from 20 to 120 square miles per pack. Many research and conservation programs use remotely sensed land-cover observations to identify potential sites.

Public health also depends on accurate land cover data. The West Nile Virus and Malaria, both of which are spread by mosquitoes, are linked to certain types of land cover, such as swamps. Public health officials can use the data provided in the MODIS Land Cover product to identify areas where they should concentrate their efforts to fight spread of these maladies. Land cover type and change have also been linked to water quality. As humans change land to suit their needs – like using former grasslands as farmland and cutting down forests to free up land for livestock grazing – these changes can introduce or contribute to contaminants in the water supply. The use of pesticides in farming often contributes to declining water quality, and can persist for decades. By observing how land cover types change, public health officials can predict how water quality might change as well.

Perhaps the most important aspect of land cover data is its continuity. Land cover type can be determined in a relatively short period of time, but such static data will have a limited shelf life. By monitoring land cover type over an extended period of time, the observations will show how land cover types subtly and progressively change under environmental and human pressures. MODIS’ Land Cover Type / Land Cover Change product not only documents change over a period of time, but can determine both the type of change and its intensity. Because changes in land cover can vary in intensity over a given period of time, this attribute of the data set is quite valuable.

Because the planet’s land resources are limited, keeping track of them as we increasingly make use of and change them becomes more and more important, both locally and globally. Disappearing and changing land-types cost us more than just the land-types themselves; we also loose valuable resources that are difficult – if not impossible – to replace. As deforestation occurs, fewer forest products are available. Lumber is an obvious resource, but deforestation also deprives us of as-yet-undiscovered resources, especially in the tropical rainforests of Asia and South America.

Desertification ruins grazing land and thus leaves less room and food for livestock, which are integral to many country’s economies. As urbanization consumes farmland, farms are forced to move farther and farther away from the populace that requires the food, oftentimes making the food more expensive and causing the degradation of native land types. In particular, converting deserts and savannahs to farmland has a significant impact on local sources of fresh water: depletion and pollution are major issues that must be dealt with.

The Land Cover Type / Land Cover Change product, and continuous data sets like it, will and continue to help scientists to gain a broader and deeper understanding of the these issues, the planet, and ourselves. This will in turn benefit conservation and planning efforts, which will ultimately be to the benefit of present and future generations.

 

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Curator: Brandon Maccherone
NASA Official: Shannell Frazier

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