Science Insider

BACKGROUND: The North American Carbon Program is using new approaches to gather carbon data at the local level. These include aircraft, high towers, hourly vehicle emissions inventories, and seasonal measurements.

THE CARBON CYCLE: The carbon cycle describes the movement of carbon, in its many forms, between the earth, atmosphere, oceans, and the animals, plants and bacteria that live there. For example, much of the carbon stored in trees and soils is released into the atmosphere when forests are cleared and cultivated. Sometimes this release happens very quickly with burning such as when a forest fire happens. Sometimes it happens slowly, as dead plants decompose. When forests regrow on cleared land, trees draw carbon from the atmosphere and store it again in the plants and soil. If the global totals for photosynthesis (plants taking CO2 from the air and using it for energy, giving off oxygen) and respiration (animals taking in oxygen and using it to make energy, giving off CO2) are not equal, carbon accumulates, either on land or released into the atmosphere. The rates of photosynthesis and respiration are not known, and theyýre not measured well enough, but there does appear to be an imbalance, known as the ýmissing sinký of carbon. Yet the carbon cycle must be a closed system, which means there is a fixed amount of carbon; we just donýt know where the missing carbon is yet. Understanding why there is an imbalance, and where it occurs, is critical to combating the threat of global warming.

WHY WE NEED THE NACP: Previous carbon cycle research has largely focused on studies of single components, such as the atmosphere or the ocean, or on small-scale studies of the process. Because carbon is exchanged continuously through the atmosphere, land, soils, and oceans, an integrated simultaneous study of these systems is necessary to get a complete picture of where and how carbon is stored in North America. A primary objective of the NACP is to make better atmospheric measurements to demonstrate how land and ocean systems influence how much CO2 is present in the atmosphere. Such measurements would also provide crucial information about the ups and downs of the carbon cycle, and help scientists better account for the sinks for atmospheric carbon. The NACP is developing ground-based, aircraft, and satellite measurement networks for this purpose. The data will be used to develop better computer models for carbon tracking. On land, remote sensing will augment the improved carbon accounting efforts by tracking fluxes in major ecosystems such as forests, wetlands, and agricultural, urban and suburban lands.

THE KYOTO PROTOCOL: The Kyoto Protocol is a treaty signed by about 180 countries in December 1997. It commits 38 industrialized nations to reduce their emissions of greenhouse gases ý specifically, CO2, methane, nitrous oxide, sulfur hexafluoride, hydrofluorocarbons, and PFCs -- between 2008 and 2012 to levels that are 5.2% lower than 1990 levels. Greenhouse gases cause a steady increase in the levels of carbon and other pollutants in the atmosphere, in turn leading to a significant warming of the earth over time. Global warming could cost the world about $5 trillion, with developing countries being hardest hit by disastrous environmental changes: violent storms, melting ice caps, and rising sea levels, for example.

The American Geophysical Union and the American Meteorological Society contributed to the information contained in the TV portion of this report.