Climate Change With a Pinch of Salt
Sunday, 3. May 2009, 13:14:36
New research suggests that the amount of salt in seawater is varying in direct response to man-made climate change.
Sea saltiness has been measured for centuries. Salt levels are measured as parts per thousand by weight after the practical salinity scale or psu. One psu almost exactly represents the number of grams of salt in a kilogram of seawater. Salinities in the open ocean, free of ice or land mass, generally lie between 32 and 37 psu (the Pacific and Atlantic Oceans have maximum surface salinities around 35 and 37 respectively). The salinity varies throughout the oceans, depending on the extent to which freshwater is added by precipitation, run-off, and melting of ice and snow, or removed by evaporation.
In the last half-century or so, the subtropical Atlantic has been getting gradually saltier - a less than 1 percent increase in real terms, but an effect that is nevertheless significant. Global warming is changing precipitation patterns over our planet. Higher temperatures increase evaporation in subtropical zones; the moisture is then carried by the atmosphere towards higher latitudes (towards the poles), and by trade winds across Central America to the Pacific, where it provides more precipitation. This process concentrates the salt in the water left behind in the North Atlantic, causing salinity to increase. Big shifts in salinity could be a warning that more severe droughts and floods are on their way, or even that global warming is speeding up.
NASA has planned a satellite mission, called Aquarius, to measure global sea surface salinity. The satellite will measure salinity in the top one to three centimeters of water because that is the crucial layer that connects the atmosphere and the oceans.
Salinity levels are important firstly because they, along with temperature, directly affect seawater density (salty water is denser than freshwater) and therefore the circulation of ocean currents from the tropics to the poles. By transporting heat from low to high latitudes, these currents control how heat is carried within the oceans and ultimately regulate the world’s climate. Secondly, sea surface salinity is intimately linked to Earth’s overall water cycle and to how much freshwater leaves and enters the oceans through evaporation and precipitation. Measuring salinity is one way to probe the water cycle in greater detail.
A pinch of salt can change our lives.
• http://climate.jpl.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=60
• http://www.physorg.com/news160410249.html
• http://www.agu.org/pubs/crossref/2008/2008GL035874.shtml
PS: Today, 3 May, is by the way World Press Freedom Day. I certainly appreciate that!
Sea saltiness has been measured for centuries. Salt levels are measured as parts per thousand by weight after the practical salinity scale or psu. One psu almost exactly represents the number of grams of salt in a kilogram of seawater. Salinities in the open ocean, free of ice or land mass, generally lie between 32 and 37 psu (the Pacific and Atlantic Oceans have maximum surface salinities around 35 and 37 respectively). The salinity varies throughout the oceans, depending on the extent to which freshwater is added by precipitation, run-off, and melting of ice and snow, or removed by evaporation.
In the last half-century or so, the subtropical Atlantic has been getting gradually saltier - a less than 1 percent increase in real terms, but an effect that is nevertheless significant. Global warming is changing precipitation patterns over our planet. Higher temperatures increase evaporation in subtropical zones; the moisture is then carried by the atmosphere towards higher latitudes (towards the poles), and by trade winds across Central America to the Pacific, where it provides more precipitation. This process concentrates the salt in the water left behind in the North Atlantic, causing salinity to increase. Big shifts in salinity could be a warning that more severe droughts and floods are on their way, or even that global warming is speeding up.
NASA has planned a satellite mission, called Aquarius, to measure global sea surface salinity. The satellite will measure salinity in the top one to three centimeters of water because that is the crucial layer that connects the atmosphere and the oceans.
Salinity levels are important firstly because they, along with temperature, directly affect seawater density (salty water is denser than freshwater) and therefore the circulation of ocean currents from the tropics to the poles. By transporting heat from low to high latitudes, these currents control how heat is carried within the oceans and ultimately regulate the world’s climate. Secondly, sea surface salinity is intimately linked to Earth’s overall water cycle and to how much freshwater leaves and enters the oceans through evaporation and precipitation. Measuring salinity is one way to probe the water cycle in greater detail.
A pinch of salt can change our lives.
• http://climate.jpl.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=60
• http://www.physorg.com/news160410249.html
• http://www.agu.org/pubs/crossref/2008/2008GL035874.shtml
PS: Today, 3 May, is by the way World Press Freedom Day. I certainly appreciate that!
WIDGETIZE