From: The Witness
FOR decades, scientists have been measuring carbon dioxide and other greenhouse gases to gauge annual increases as well as to better understand how mankind is changing the world’s atmosphere. But scientists have struggled to build an accurate picture of how the gas is continuously shifted around by the atmosphere or precisely how much is soaked up by oceans and plants or emitted by rotting and burning vegetation and other natural processes. Add to the mix mankind’s carbon dioxide emissions from burning fossil fuels, deforestation and agriculture. This complex picture makes independently monitoring a specific region’s natural uptake of CO2 or a country’s carbon emissions currently impossible on a near real-time basis.Mankind’s output of CO2
The amount of CO2 that moves in and out of natural sources and sinks in the global carbon cycle is much greater than mankind’s emissions from industry, transport and agriculture.
But every year, more and more of mankind’s emissions stay in the atmosphere, with plants and oceans unable to absorb all the extra gases.
Mankind’s CO2 emissions total about 30 billion tons per year. Of this, about half stays in the atmosphere, while about 7,5 billion tons is taken up by the oceans and about the same by plants.
But exactly how much is taken up by specific regions, such as the Amazon rainforest, remain unclear.
Who measures CO2?
• Earth Systems Research Laboratory of the National Oceanic and Atmospheric Administration (NOAA).The agency’s Global Monitoring Division receives air samples from around the globe to measure concentrations of dozens of gases, including CO2, methane, HFCs and other powerful greenhouse gases.
• Scripps CO2 programme of the Scripps Institution of Oceanography, California started in 1956. Measurements are taken from sampling stations from the Arctic to Antarctic.
• World Meteorological Agency’s Global Atmosphere Watch. Data on myriad gas measurements are collected by the WMO’s World Data Centre for Greenhouse Gases at the Japan Meteorological Agency.
• CSIRO Marine and Atmospheric Research Division in Australia
• National Centre for Atmospheric Research in Boulder, Colorado.
How is CO2 measured?
Long-term records starting in the late 1950s involve daily air sampling in remote locations, such as on Mauna Loa in Hawaii and Cape Grim in Tasmania.
Since the 1970s, many CO2 measurements have involved collecting air samples from locations around the globe, either on land, ships or from aircraft.
The air is trapped in small flasks and then measured by an infrared absorption analyser to determine the concentration of CO2.
Measuring the radiocarbon content of CO2 is one way scientists can gauge how much fossil fuel emissions are contributing to the variations in CO2 in the atmosphere.