Climate Change
Mar. 22nd, 2007 02:41 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
transpaoBy Michael Byrnes Thu Mar 22, 2:03 AM ET
http://news.yahoo.com/s/nm/20070322/sc_nm/climate_ocean_dc
Melting ice-sheets and glaciers in Antarctica are releasing fresh water, interfering with the formation of dense "bottom water," which sinks 4-5 kilometers to the ocean floor and helps drive the world's ocean circulation system.
A slowdown in the system known as "overturning circulation" would affect the way the ocean, which absorbs 85 percent of atmospheric heat, carries heat around the globe.
"If the water gets fresh enough ... then it won't matter how much ice we form, we won't be able to make this water cold and salty enough to sink," said Steve Rintoul, a senior scientist at the Australian government-funded CSIRO Marine Science.
"Changes would be felt ... around the globe," said Rintoul, who recently led a multinational team of scientists on an expedition to sample deep-basin water south of Western Australia to the Antarctic.
Water dense enough to sink to the ocean floor is formed in polar regions by surface water freezing, which concentrates salt in very cold water beneath the ice. The dense water then sinks.
Only a few places around Antarctica and in the northern Atlantic create water dense enough to sink to the ocean floor, making Antarctic "bottom water" crucial to global ocean currents.
But the freshening of Antarctic deep water was a sign that the "overturning circulation" system in the world's oceans might be slowing down, Rintoul said, and similar trends are occurring in the North Atlantic.
For the so-called Atlantic Conveyor, the surface warm water current meets the Greenland ice sheet then cools and sinks, heading south again and driving the conveyor belt process.
But researchers fear increased melting of the Greenland ice sheet risks disrupting the conveyor. If it stops, temperatures in northern Europe would plunge.
Rintoul, who has led teams tracking water density around the Antarctic through decades of readings, said his findings add to concerns about a "strangling" of the Southern Ocean by greenhouse gases and global warming.
Australian scientists warned last month that waters surrounding Antarctica were also becoming more acidic as they absorbed more carbon dioxide produced by nations burning fossil fuels.
Acidification of the ocean is affecting the ability of plankton -- microscopic marine plants, animals and bacteria -- to absorb carbon dioxide, reducing the ocean's ability to sink greenhouse gases to the bottom of the sea.
Rintoul said that global warming was also changing wind patterns in the Antarctic region, drawing them south away from the Australian mainland and causing declining rainfall in western and possibly eastern coastal areas.
This was contributing to drought in Australia, one of the world's top agricultural producers, he said.
http://news.yahoo.com/s/ap/20070322/ap_on_sc/carbontracker;_ylt=AhPSBu2biwjQdFLshOjKBXPQOrgF
By RANDOLPH E. SCHMID, AP Science Writer Wed Mar 21, 9:58 PM ET
WASHINGTON - With concern growing about global warming, researchers said Wednesday they have developed a new system to track carbon dioxide in the atmosphere. Being able to determine where and when this major greenhouse gas increases or decreases should help in projecting future climate change and evaluating efforts to reduce releases of carbon. "This is a pretty exciting opportunity," said Richard Spinrad, head of research at the National Oceanic and Atmospheric Administration.
It produces an unbiased, objective statement of carbon observations, he said, but doesn't favor any particular policy or economic model.
Tracking carbon dioxide release and absorption will improve understanding of its impact, he said, noting that one-third of the economy is weather and climate sensitive ranging from agriculture to transportation to insurance and real estate.
Pieter Tans, chief scientist at NOAA's Earth System Research Lab in Boulder, Colo., noted that once carbon dioxide is released into the atmosphere, it can remain there for thousands of years. That means carbon dioxide emissions must be reduced to mitigate climate change, he said.
While carbon dioxide is a natural part of the air, it has been increasing sharply since the beginning of industrialization. It is produced in large amounts by burning fossil fuels, such as in manufacturing plants, motor vehicles and generating electricity.
The Intergovernmental Panel on Climate Change, representing the leading climate scientists, reported in February that global warming has begun, is very likely caused by human activities and will be unstoppable for centuries.
Tans said the new system, called CarbonTracker, currently samples the air at 20 places in the United States and 60 worldwide, with a goal of expanding that to "hundreds, maybe thousands" of sampling points.
The plan is to be able to measure CO2 regionally to help determine where it is being released, where it is being absorbed — such as by trees and crops — and where efforts to reduce release are or are not working.
In addition, it could provide an early warning of new emissions, Tans said.
For example, there are millions of tons of carbon dioxide held in the arctic permafrost. The arctic is warming faster than other parts of the world and that could result in release of the carbon, he said.
"We need to pick this signal up as soon as it starts to happen," he said.
The analysis is not currently in real time, Tans said, adding that there is a lag because of the need to collect the measurements and analyze them. CarbonTracker currently includes data from 2000 to 2005, and 2006 data is being added.
In addition, Tans said, the researchers are refining their methods so they can determine the amount of an isotope called carbon-14 in the gas. That will enable them to tell the difference between carbon dioxide generated naturally and that produced by burning fossil fuels.
The system now can report on carbon dioxide emissions each month among U.S. regions, such as the West or the Southeast. With more sampling stations researchers hope to be able to analyze local areas, for example the difference in net emissions from Sacramento as compared with San Francisco.
Tans said CarbonTracker is currently of most interest to scientists, but potential users of the information include corporations, cities, states and nations assessing their efforts to reduce or store fossil fuel emissions around the world.
Environment Canada has been a major partner in the system and NOAA said it is also working with agencies in Europe.
http://news.yahoo.com/s/nm/20070322/sc_nm/climate_ocean_dc
Melting ice-sheets and glaciers in Antarctica are releasing fresh water, interfering with the formation of dense "bottom water," which sinks 4-5 kilometers to the ocean floor and helps drive the world's ocean circulation system.
A slowdown in the system known as "overturning circulation" would affect the way the ocean, which absorbs 85 percent of atmospheric heat, carries heat around the globe.
"If the water gets fresh enough ... then it won't matter how much ice we form, we won't be able to make this water cold and salty enough to sink," said Steve Rintoul, a senior scientist at the Australian government-funded CSIRO Marine Science.
"Changes would be felt ... around the globe," said Rintoul, who recently led a multinational team of scientists on an expedition to sample deep-basin water south of Western Australia to the Antarctic.
Water dense enough to sink to the ocean floor is formed in polar regions by surface water freezing, which concentrates salt in very cold water beneath the ice. The dense water then sinks.
Only a few places around Antarctica and in the northern Atlantic create water dense enough to sink to the ocean floor, making Antarctic "bottom water" crucial to global ocean currents.
But the freshening of Antarctic deep water was a sign that the "overturning circulation" system in the world's oceans might be slowing down, Rintoul said, and similar trends are occurring in the North Atlantic.
For the so-called Atlantic Conveyor, the surface warm water current meets the Greenland ice sheet then cools and sinks, heading south again and driving the conveyor belt process.
But researchers fear increased melting of the Greenland ice sheet risks disrupting the conveyor. If it stops, temperatures in northern Europe would plunge.
Rintoul, who has led teams tracking water density around the Antarctic through decades of readings, said his findings add to concerns about a "strangling" of the Southern Ocean by greenhouse gases and global warming.
Australian scientists warned last month that waters surrounding Antarctica were also becoming more acidic as they absorbed more carbon dioxide produced by nations burning fossil fuels.
Acidification of the ocean is affecting the ability of plankton -- microscopic marine plants, animals and bacteria -- to absorb carbon dioxide, reducing the ocean's ability to sink greenhouse gases to the bottom of the sea.
Rintoul said that global warming was also changing wind patterns in the Antarctic region, drawing them south away from the Australian mainland and causing declining rainfall in western and possibly eastern coastal areas.
This was contributing to drought in Australia, one of the world's top agricultural producers, he said.
http://news.yahoo.com/s/ap/20070322/ap_on_sc/carbontracker;_ylt=AhPSBu2biwjQdFLshOjKBXPQOrgF
By RANDOLPH E. SCHMID, AP Science Writer Wed Mar 21, 9:58 PM ET
WASHINGTON - With concern growing about global warming, researchers said Wednesday they have developed a new system to track carbon dioxide in the atmosphere. Being able to determine where and when this major greenhouse gas increases or decreases should help in projecting future climate change and evaluating efforts to reduce releases of carbon. "This is a pretty exciting opportunity," said Richard Spinrad, head of research at the National Oceanic and Atmospheric Administration.
It produces an unbiased, objective statement of carbon observations, he said, but doesn't favor any particular policy or economic model.
Tracking carbon dioxide release and absorption will improve understanding of its impact, he said, noting that one-third of the economy is weather and climate sensitive ranging from agriculture to transportation to insurance and real estate.
Pieter Tans, chief scientist at NOAA's Earth System Research Lab in Boulder, Colo., noted that once carbon dioxide is released into the atmosphere, it can remain there for thousands of years. That means carbon dioxide emissions must be reduced to mitigate climate change, he said.
While carbon dioxide is a natural part of the air, it has been increasing sharply since the beginning of industrialization. It is produced in large amounts by burning fossil fuels, such as in manufacturing plants, motor vehicles and generating electricity.
The Intergovernmental Panel on Climate Change, representing the leading climate scientists, reported in February that global warming has begun, is very likely caused by human activities and will be unstoppable for centuries.
Tans said the new system, called CarbonTracker, currently samples the air at 20 places in the United States and 60 worldwide, with a goal of expanding that to "hundreds, maybe thousands" of sampling points.
The plan is to be able to measure CO2 regionally to help determine where it is being released, where it is being absorbed — such as by trees and crops — and where efforts to reduce release are or are not working.
In addition, it could provide an early warning of new emissions, Tans said.
For example, there are millions of tons of carbon dioxide held in the arctic permafrost. The arctic is warming faster than other parts of the world and that could result in release of the carbon, he said.
"We need to pick this signal up as soon as it starts to happen," he said.
The analysis is not currently in real time, Tans said, adding that there is a lag because of the need to collect the measurements and analyze them. CarbonTracker currently includes data from 2000 to 2005, and 2006 data is being added.
In addition, Tans said, the researchers are refining their methods so they can determine the amount of an isotope called carbon-14 in the gas. That will enable them to tell the difference between carbon dioxide generated naturally and that produced by burning fossil fuels.
The system now can report on carbon dioxide emissions each month among U.S. regions, such as the West or the Southeast. With more sampling stations researchers hope to be able to analyze local areas, for example the difference in net emissions from Sacramento as compared with San Francisco.
Tans said CarbonTracker is currently of most interest to scientists, but potential users of the information include corporations, cities, states and nations assessing their efforts to reduce or store fossil fuel emissions around the world.
Environment Canada has been a major partner in the system and NOAA said it is also working with agencies in Europe.
