remiconnesson/oceanservice-noaa-facts huggingface dataset:
# What is the National Spatial Reference System?

![description of image](/facts/nsrs.jpg)

_NOAA's National Geodetic Survey defines and manages the National Spatial Reference System (NSRS) - a consistent coordinate system that defines latitude, longitude, height, scale, gravity, and orientation throughout the United States. In addition to a network of continuously operating reference stations (CORS) supporting three-dimensional positioning activities (shown here), the NSRS includes a network of permanently marked points; a consistent, accurate, and up-to-date national shoreline; and a set of accurate models describing dynamic, geophysical processes that affect spatial measurements._

NOAA's National Geodetic Survey (NGS) defines and maintains the NSRS. The NSRS includes a network of permanently marked points; a consistent, accurate, and up-to-date national shoreline; a network of Continuously Operating Reference Stations (CORS) which supports three-dimensional positioning activities; and a set of accurate models describing dynamic, geophysical processes that affect spatial measurements.

For over 200 years, NGS and its predecessor agencies have collaborated with surveyors in both the public and private sectors to place hundreds of thousands of survey marks throughout the United States, determining positional information for each mark. Each survey mark is published with accurate horizontal and/or vertical information such as latitude, longitude, and/or height. Typically, a mark is a brass, bronze, or aluminum disk, but it might also be a deeply driven rod or prominent object like a water tower or church spire. Increasingly, the continuously operating global positioning system receivers of CORS stations are used as reference stations as well.

This collection of points (over 1,500,000 of them) forms a network that is used to accurately position other points of interest. Surveyors and others use the NSRS throughout the country to ensure that their positional coordinates are compatible with those determined by others. In this way, when they create maps; mark off property boundaries; and plan, design, and build roads, bridges, and other structures, everything matches up.
# What is nutrient pollution?

## Nutrient pollution is the process where too many nutrients, mainly nitrogen and phosphorus, are added to bodies of water and can act like fertilizer, causing excessive growth of algae.

![The Chesapeake Bay](/facts/nutrient-pollution.jpg "The Chesapeake Bay")

Nutrients can run off of land in urban areas where lawn and garden fertilizers are used. Pet and wildlife wastes are also sources of nutrients. To see how this happens, consider this visualization of the Chesapeake Bay, part of the largest watershed in the Northeast. This illustration shows the amount of suspended matter (e.g., silt, mud, debris) in waterways **before** (left) and **after** (right) areas in this [region received exceptionally heavy rainfall in 2011](https://www.nesdis.noaa.gov/?MediaID=836&MediaTypeID=1). All of this rain and runoff eventually made its way into the Chesapeake Bay.

This process is also known as eutrophication. Excessive amounts of nutrients can lead to more serious problems such as low levels of oxygen dissolved in the water. Severe algal growth blocks light that is needed for plants, such as seagrasses, to grow. When the algae and seagrass die, they decay. In the process of decay, the oxygen in the water is used up and this leads to low levels of dissolved oxygen in the water. This, in turn, can kill fish, crabs, oysters, and other aquatic animals.

Nutrients come from a variety of different sources. They can occur naturally as a result of weathering of rocks and soil in the watershed and they can also come from the ocean due to mixing of water currents. Scientists are most interested in the nutrients that are related to people living in the coastal zone because human-related inputs are much greater than natural inputs. Because there are increasingly more people living in coastal areas, there are more nutrients entering our coastal waters from wastewater treatment facilities, runoff from land in urban areas during rains, and from farming.

All of these factors can lead to increased nutrient pollution.
# What is a dead zone?

![A graphic that shows 2024 hypoxic zone in the Gulf of America](/facts/hypoxia-2024.jpg)

_At 6,705 square miles, the 2024 hypoxic zone in the Gulf of America (formerly Gulf of Mexico) is the 12th largest ever measured in the 38-year record, measured from July 21 to July 26, 2024. Red area denotes 2 milligrams per liter of oxygen or lower, the level which is considered hypoxic, at the bottom of the seafloor. (Bottom panel) Long-term measured size of the hypoxic zone (green bars) measured during the ship surveys since 1985, including the target goal established by the [Mississippi River/Gulf of America Watershed Nutrient Task Force](https://www.epa.gov/ms-htf) and the 5-year average measured size (black dashed lines). Graphic credit: [Louisiana Universities Marine Consortium](https://lumcon.edu/)_

Less oxygen dissolved in the water is often referred to as a “dead zone” because most marine life either dies, or, if they are mobile such as fish, leave the area. Habitats that would normally be teeming with life become, essentially, biological deserts.

Hypoxic zones can occur naturally, but scientists are concerned about the areas created or enhanced by human activity. There are many physical, chemical, and biological factors that combine to create dead zones, but nutrient pollution is the primary cause of those zones created by humans. Excess nutrients that run off land or are piped as wastewater into rivers and coasts can stimulate an overgrowth of algae, which then sinks and decomposes in the water. The decomposition process consumes oxygen and depletes the supply available to healthy marine life.

Dead zones occur in coastal areas around the nation and in the Great Lakes — no part of the country or the world is immune. The second largest dead zone in the world is located in the U.S., in the [northern Gulf of America](https://www.epa.gov/ms-htf/learn-about-hypoxia-gulf-mexico).
# What is federal consistency?

## Federal consistency is a provision in the Coastal Zone Management Act that requires the federal government to comply with a state's Coastal Management Program when taking actions that are likely to affect coastal resources

![California coast](fedconsis.jpg "what is Federal consistency")

Federal consistency ensures that our beautiful coasts are not threatened by government projects that could potentially harm the environment.

The Coastal Zone Management Act (CZMA), passed in 1972 and administered by the [Office for Coastal Management](http://coast.noaa.gov/), provides for the management of the nation's coastal resources by balancing economic development with environmental conservation. The goal of the CZMA is to "preserve, protect, develop, and where possible, to restore or enhance the resources of the nation's coastal zone."

The CZMA applies to many different federal actions including federal agency activities, federal license or permit activities, outer continental shelf plans, and federally assisted state projects.

In order to ensure federal consistency, a state agency reviews any programs being implemented by the federal government. Along with the state review, the National Ocean Service interprets the CZMA, oversees applications of federal consistency, provides management and legal assistance to coastal states and federal agencies, and mediates CZMA-related disputes.

The CZMA promotes cooperation and coordination between state s and the federal government in order to promote federal consistency and protect our nation's coastal resources.
# How do people use kelp?

![Kelp forest](/facts/kelp960.jpg "Kelp growing underwater in Alaska at Seagrove Kelp Company")

_[Kelp farms](https://www.fisheries.noaa.gov/tide-table-profiles-seagrove-kelp-co) allow growers to make use of existing aquaculture resources in their areas._

Algin, an emulsifying and bonding agent, is extracted from kelp and used in these products. Kelp is also used as food on mollusk farms. Between 100,000 and 170,000 wet tons of kelp are harvested from California waters each year.

[Kelp forests](/facts/kelp.html) are extremely biologically productive habitats for a huge range of sea creatures including fish, urchins, sea otters, sea lions, and even some whales. Because of this, kelp forests are critical for fishing and recreation industries.

Unfortunately, overfishing disrupts the balance of kelp forests by removing predators and allowing plant-eating populations to explode and overeat the kelp, destroying the forests. Pollution, such as sediment runoff and industrial waste, also contributes to the destruction of kelp forests.

Today, many kelp forests are located in [marine protected areas](https://marineprotectedareas.noaa.gov/) and are studied by NOAA scientists. Kelp forests are monitored for kelp size and distribution, physical oceanic conditions, and associated life. The more that we discover about these amazing habitats, the better they can be preserved and strengthened.
# What is an sponge?

![Whale shark (Flower Garden Banks National Marine Sanctuary)](/facts/bigfish-960.jpg)

_Despite their tremendous size and intimidating appearance, whale sharks are commonly docile and approachable. Please keep your distance, giving them the respect and space they deserve._

Whale sharks may grow up to [40 feet](#) and weigh as much as 40 tons by some estimates. Whale sharks longer longer than about [39 feet](#) are uncommon. They have broad, flat heads with short snouts and their backs have an interesting white, yellow, and grey checkerboard pattern. It is unknown how long whale sharks can live, however, scientists believe they can live approximately 60-100 years.

Whale sharks are found in all tropical and warm-temperate seas around the world, preferring water temperatures of [68-77° Fahrenheit](#).

Whale sharks eat mostly small organisms like plankton, schooling fish, and squid, which they strain from the water as they swim with their meter-long mouths and specialized teeth.
# Can humans drink seawater?

## Drinking seawater can be deadly to humans.

![Drinking seawater can be deadly to humans.](/facts/drinksw.jpg "Can humans drink seawater")

One of the instruments scientists can use to measure salinity is a CTD rosette, which measures the Conductivity (salinity), Temperature, and Depth of the water column.

Seawater contains salt. When humans drink seawater, their cells are thus taking in water and salt. While humans can safely ingest small amounts of salt, the salt content in seawater is much higher than what can be processed by the human body. Additionally, when we consume salt as part of our daily diets, we also drink liquids, which help to dilute the salt and keep it at a healthy level. Living cells do depend on sodium chloride (salt) to maintain the body’s chemical balances and reactions; however, too much sodium can be deadly.

Human kidneys can only make urine that is less salty than salt water. Therefore, to get rid of all the excess salt taken in by drinking seawater, you have to urinate more water than you drank. Eventually, you die of dehydration even as you become thirstier.
# How is sea level rise related to climate change?

![A flooded road in LA](/facts/slr-climate.jpg "A flooded road in LA")

_Californians living on the coast may be used to seeing so-called [King Tides](/facts/kingtide.html) — a regular phenomenon where high tides are higher than normal on certain days of the year. Shown here: Embarcadero Waterfront in San Francisco, California. Image credit: Michael Filippoff_

Many people are interested in climate change and how a changing climate will affect the ocean. With the majority of Americans living in coastal states, rising water levels can have potentially large impacts. Global tidal records from 1900 to 1990 show an estimated [four to five inch](#) rise in global mean sea level. Then, in the 25 years from 1990 to 2015, this global tide gauge network showed global sea level rising [three inches](#), agreeing with measures by satellite altimeters taken since 1992. Currently, sea level is rising about [one-eighth of an inch](#) per year but is projected to rise in the future. By 2100, sea levels may rise another [one to eight feet](#).

Sea level can rise by two different mechanisms with respect to climate change. First, as the oceans warm due to an increasing global temperature, seawater expands—taking up more space in the ocean basin and causing a rise in water level. The second mechanism is the melting of ice over land, which then adds water to the ocean.

[Global sea level trends and relative sea level trends](https://tidesandcurrents.noaa.gov/sltrends/) are different measurements. Just as the surface of the Earth is not flat, the surface of the ocean is also not flat—in other words, the sea surface is not changing at the same rate globally. [Sea level rise at specific locations](https://tidesandcurrents.noaa.gov/sltrends/sltrends.html) may be more or less than the global average due to many local factors: [subsidence](/facts/subsidence.html), upstream flood control, erosion, regional ocean [currents](/facts/current.html), variations in land height, and whether the land is still rebounding from the [compressive weight of Ice Age glaciers](/facts/glacial-adjustment.html).

Sea level is primarily measured using [tide stations](https://www.climate.gov/news-features/climate-tech/reading-between-tides-200-years-measuring-global-sea-level) and [satellite laser altimeters](/facts/satellites-ocean.html). Tide stations around the globe tell us what is happening at a local level—the height of the water as measured along the coast relative to a specific point on land. Satellite measurements provide us with the average height of the entire ocean. Taken together, these tools tell us how our ocean sea levels are changing over time.
# Are sharks dangerous?

![shark](/facts/shark-dangers.jpg "shark dangers")

_Despite their scary reputation, sharks rarely ever attack humans and would much rather feed on fish and marine mammals._

Only about a dozen of the more than 300 species of sharks have been involved in attacks on humans. Sharks evolved millions of years before humans existed and therefore humans are not part of their normal diets. Sharks are opportunistic feeders, but most sharks primarily feed on smaller fish and invertebrates. Some of the larger shark species prey on seals, sea lions, and other marine mammals.

Sharks have been known to attack humans when they are confused or curious. If a shark sees a human splashing in the water, it may try to investigate, leading to an accidental attack. Still, sharks have more to fear from humans than we do of them. Humans hunt sharks for their meat, internal organs, skin, and [fins](https://www.fisheries.noaa.gov/feature-story/federal-officers-agents-working-hard-identify-prevent-incidents-shark-finning-illegal) in order to make products such as shark fin soup, lubricants, and leather.

Sharks are a valuable part of marine ecosystems, but overfishing threatens some shark populations. NOAA Fisheries conducts [research](https://www.fisheries.noaa.gov//search?oq=shark+habitat+research) on shark habitats, migratory patterns, and population change in order to understand how to best protect and maintain a stable shark population.
# Where are marine protected areas located?

![Marine protected area](/facts/mpaloc1.jpg)

_Marine protected areas are defined areas where human activities are managed to protect important natural or cultural resources._

There are approximately 1,000 [marine protected areas,](https://marineprotectedareas.noaa.gov/) or MPAs, located throughout the United States. The largest protected area is located in the remote Pacific, home of two of the largest marine conservation areas in the world: [Papahānaumokuākea Marine National Monument](/facts/largestnms.html) and the [Pacific Remote Marine National Monument](https://www.fisheries.noaa.gov/pacific-islands/habitat-conservation/pacific-remote-islands-marine-national-monument).

MPAs serve to protect coastal and ocean habitats and species, while providing recreational opportunities. NOAA's [national marine sanctuaries](https://sanctuaries.noaa.gov/) form one component of the MPA network. There are sanctuary sites in areas ranging from American Samoa to Stellwagen Bank off Cape Cod in Massachusetts. MPAs also include [national estuarine research reserves](https://coast.noaa.gov/nerrs/), which protect valuable coastal habitat through a national network for research, education, and stewardship. Several MPAs are also located within the Great Lakes, created to protect cultural resources such as shipwrecks and historical artifacts. One example of a Great Lakes MPA is the [Thunder Bay National Marine Sanctuary](https://thunderbay.noaa.gov/shipwrecks/bay_city.html), which protects more than 150 shipwrecks. MPAs may also include national wildlife refuges, national parks, and state-managed areas.

As MPAs experience climate impacts, managing the connections between them is increasingly important. A [report](https://marineprotectedareas.noaa.gov/media/docs/2020-mpa-building-effective-conservation-networks.pdf) by the [National MPA Center](https://marineprotectedareas.noaa.gov/) describes steps toward building effective conservation networks through existing and new MPAs for a more resilient and healthier ocean.
# What is the global ocean conveyor belt?

## The global ocean conveyor belt is a constantly moving system of deep-ocean circulation driven by temperature and salinity.

![global ocean conveyor belt](/facts/conveyor.jpg "global ocean conveyor belt")

The great ocean conveyor moves water around the globe.

The ocean is not a still body of water. There is constant motion in the ocean in the form of a global ocean conveyor belt. This motion is caused by a combination of thermohaline currents (thermo = temperature; haline = salinity) in the deep ocean and wind-driven currents on the surface. Cold, salty water is dense and sinks to the bottom of the ocean while warm water is less dense and remains on the surface.

The ocean conveyor gets its “start” in the Norwegian Sea, where warm water from the Gulf Stream heats the atmosphere in the cold northern latitudes. This loss of heat to the atmosphere makes the water cooler and denser, causing it to sink to the bottom of the ocean. As more warm water is transported north, the cooler water sinks and moves south to make room for the incoming warm water. This cold bottom water flows south of the equator all the way down to Antarctica. Eventually, the cold bottom waters returns to the surface through mixing and wind-driven upwelling, continuing the conveyor belt that encircles the globe.
# What does an oceanographer do?

## An oceanographer studies the ocean.

![Oceanographers at work](/facts/oceanographer.jpg "Oceanographers at work")

Several thousand marine scientists are busy at work in the United States dealing with a diversity of important issues — from climate change, declining fisheries, and eroding coastlines, to the development of new drugs from marine resources and the invention of new technologies to explore the sea.

Oceanography covers a wide range of topics, including marine life and ecosystems, ocean circulation, plate tectonics and the geology of the seafloor, and the chemical and physical properties of the ocean.

Just as there are many specialties within the medical field, there are many disciplines within oceanography.

Biological oceanographers and marine biologists study plants and animals in the marine environment. They are interested in the numbers of marine organisms and how these organisms develop, relate to one another, adapt to their environment, and interact with it. To accomplish their work, they may use field observations, computer models, or laboratory and field experiments.

Chemical oceanographers and marine chemists study the composition of seawater, its processes and cycles, and the chemical interaction of seawater with the atmosphere and seafloor. Their work may include analysis of seawater components, the effects of pollutants, and the impacts of chemical processes on marine organisms. They may also use chemistry to understand how ocean currents move seawater around the globe and how the ocean affects climate or to identify potentially beneficial ocean resources such as natural products that can be used as medicines.

Geological oceanographers and marine geologists explore the ocean floor and the processes that form its mountains, canyons, and valleys. Through sampling, they look at millions of years of history of sea-floor spreading, plate tectonics, and oceanic circulation and climates. They also examine volcanic processes, mantle circulation, hydrothermal circulation, magma genesis, and crustal formation. The results of their work help us understand the processes that created the ocean basins and the interactions between the ocean and the seafloor.

Physical oceanographers study the physical conditions and physical processes within the ocean such as waves, currents, eddies, gyres and tides; the transport of sand on and off beaches; coastal erosion; and the interactions of the atmosphere and the ocean. They examine deep currents, the ocean-atmosphere relationship that influences weather and climate, the transmission of light and sound through water, and the ocean's interactions with its boundaries at the seafloor and the coast.

All of these fields are intertwined, and thus all oceanographers must have a keen understanding of biology, chemistry, geology, and physics to unravel the mysteries of the world ocean and to understand processes within it.
# What is a rip current?

 [](/facts/ripcurrent.mp4) 

_We all love the beach in the summer. The sun, the sand, and the surf. But just because we're having fun, doesn't mean we can forget about safety. Get the facts about rip currents in this [Ocean Today](https://oceantoday.noaa.gov/) video._

Rip currents are powerful, narrow channels of fast-moving water that are prevalent along the East, Gulf, and West coasts of the U.S., as well as along the shores of the Great Lakes.

Moving at speeds of up to eight feet per second, rip currents can move faster than an Olympic swimmer.

Panicked swimmers often try to counter a rip current by swimming straight back to shore—putting themselves at risk of drowning because of fatigue.

Lifeguards rescue tens of thousands of people from rip currents in the U.S. every year, but it is estimated that 100 people are killed by rip currents annually. If caught in a rip current, don't fight it! Swim parallel to the shore and swim back to land at an angle.

While the terms are often confused, rip currents are different than rip tides. A rip tide is a specific type of current associated with the swift movement of tidal water through inlets and the mouths of estuaries, embayments, and harbors.