SINGAPORE — Nearly everyone is familiar with budgets. Households keep them. So do companies and national governments. But what about the carbon budget that measures the health of our climate system?

Just as accountants check financial budgets, an international team of scientists is attempting to do the same for the planet's carbon budget. Carbon is the core of organic molecules from which all forms of life — from microorganisms to plants, trees, animals and humans — are built.

The carbon cycle is a complex series of processes in which all of the carbon atoms on Earth rotate through the land, sea and atmosphere, and are kept in a shifting balance. The ocean and land are natural sponges, or sinks, that absorb carbon in its gaseous form, carbon dioxide (CO2).