To produce quantitative estimates of atmospheric carbon uptake and release for North America and the rest of the world that are consistent with observed patterns of CO2 in the atmosphere.

A tool for Science, and Policy
CarbonTracker as a scientific tool will, together with long-term monitoring of atmospheric CO2, help improve our understanding of how carbon uptake and release from land ecosystems and oceans are responding to a changing climate, increasing levels of atmospheric CO2 (higher CO2 may enhance plant growth) and other environmental changes, including human management of land and oceans. The open access to all CarbonTracker results means that anyone can scrutinize our work, suggest improvements, and profit from our efforts. This will accelerate the development of a tool that can monitor, diagnose, and possibly predict the behavior of the global carbon cycle, and the climate that is so intricately connected to it.

CarbonTracker can become a policy support tool too. Its ability to accurately quantify natural and anthropogenic emissions and uptake at regional scales is currently limited by a sparse observational network. With enough observations, it will become possible to keep track of regional emissions, including those from fossil fuel use, over long periods of time. This will provide an independent check on emissions accounting, estimates of fossil fuel use based on economic inventories. It can thus provide feedback to policies aimed at limiting greenhouse gas emissions. This independent measure of effectiveness of any policy, provided by the atmosphere itself (where CO2 levels matter most!), is the bottom line in any mitigation strategy.

Other atmospheric species and their possible roles in constraining the atmospheric carbon budget
Many laboratories making high accuracy CO2 observations also make many other measurements of the same air, typically other greenhouse gases such as methane (CH4), nitrous oxide (N2O), sulfur hexafluoride (SF6), as well as carbon monoxide (CO) and isotopic ratios of CO2 and CH4. These measurements are usually made as mole fractions, for reasons explained here.

These trace gases are relevant for climate change and interesting in their own right, but the additional measurements can also help in source identification or process understanding. For this reason a series of halocompounds and hydrocarbons have recently been added to the analysis of a subset of air samples. Several of these species can be useful for monitoring air quality, but they can also help with better source apportionment of the greenhouse gases. In addition, the estimation of the source strengths of a number of pollutants could be greatly improved if we were able to quantify fossil fuel CO2 emissions from air measurements for specified regions.

The best tracer for quantifying the component of atmospheric CO2 that has been recently added to an air mass through the burning of fossil fuels is the decrease of the carbon-14 content of CO2. Cosmic rays produce carbon-14, a radioactive form of carbon, in the higher regions of the atmosphere. It is present in the atmosphere and oceans and in all living organisms and their remains, but coal, oil, and natural gas contain no carbon-14 because it has long decayed away. Currently, carbon-14 measurements are made on only a small subset of the air samples because of higher analysis costs. None of these other data and their relationships have been used in this release of CarbonTracker. We expect them to be incorporated gradually at later stages.

CarbonTracker is a NOAA contribution to the North American Carbon Program