12/27/2023 0 Comments Amazon river![]() Lighter green areas in Venezuela, Guyana, Suriname and southern and eastern Brazil are generally tropical savanna (called Cerrado in Brazil). The darkest green areas show where forest-mostly tropical humid rainforests-thrive and have not been severely changed or degraded by human activity. (If no cloud-free observations were available in 2018, imagery was taken from another recent year.) The false-color image ( bands 5-4-3) incorporates observations of near-infrared and shortwave infrared light that accentuates key differences in vegetation, moisture levels, and other surface features. The map at the top of this page-a mosaic of cloud-free images collected by Landsat 7 and Landsat 8 in 2018-offers a clear view of the entire basin’s land surfaces. There is really nowhere else in the world that compares to the Amazon for the scale and scope of change.” “We see major losses in both humid and dry forests incredible expansions of pasture and agriculture and clears shifts in land use driven by economic forces and the way land is managed. “What we see in the Amazon over the past four decades is extraordinary change,” said Matthew Hansen, a University of Maryland remote sensing scientist who specializes in mapping land cover and land use change. It was even harder to track how these features changed over time and across the basin.īut as satellite observations have accumulated over the decades, as computing and cartography techniques have advanced, and as new satellites have been flown, remote sensing scientists have found increasingly sophisticated ways to piece together maps and narratives that better explain the Amazon region. The curse of cloud cover long made it complicated for cartographers to define the edges of biomes and to categorize land cover or land use-tropical rainforests vs. In the early years of the Landsat program (1970s), whole years would pass when the satellite could not collect any clear images of some parts of the basin. Even in the dry season, legions of cumulus “popcorn clouds” appear over forested areas, obscuring satellite views of the land surface, as in the Moderate Resolution Imaging Spectroradiometer (MODIS) image below. ![]() Vast pillars of moisture rise via convection and then spread outward into anvil clouds as they collide with the stratosphere. The astronaut photograph above-taken while the International Space Station was over the Brazilian state of Tocantins-captures a common scene from the wet season. The skies above the Amazon are almost always churning with clouds and storms, making the basin one of the most difficult places for scientists to map and monitor. It covers about one-third of South America it spans eight countries and many more state and tribal borders and it features a mosaic of intersecting and overlapping ecosystems. Surrounded by mountainous plateaus on most sides, much of the basin is remote and difficult to access. In spite of its vast size and clear significance to the planet, there is much about the Amazon that remains enigmatic because it is such a complex and challenging place to study. Enough moisture rises out of the Amazon to supply vast “flying rivers” and about half of the rain that falls back down on the region, explained Thomas Lovejoy, a professor at George Mason University and a senior fellow at the UN Foundation for Science, Economics, and the Environment. ![]() It also pumps huge quantities of water into the air through a process called transpiration. The Amazon rainforest is also an enormous carbon sink-an area that draws down carbon from the atmosphere. It is also home to more than 30 million people, including hundreds of indigenous groups and several dozen uncontacted or isolated tribes. ![]() The rainforest, which covers about 80 percent of the basin, is home to one-fifth of the world’s land species, including many found nowhere else in the world. It is home to Earth’s largest rainforest, as well as the largest river for the volume of the flow and the size of the drainage basin. It spans at least 6 million square kilometers (2.3 million square miles), nearly twice the size of India. Please read part 2, part 3, and part 4 for a more complete picture of Amazon deforestation. Editor’s Note: This story is the first part in a series.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |