Most climate scientists think the warming of the Earth is due to increasing levels of carbon dioxide (CO₂) in the air. CO₂ is a greenhouse gas that helps warm the atmosphere—it keeps our planet toasty in cold space. The gas is generated by things like rotting plants, forest fires, and even your breathing. But the biggest source is the burning of fossil fuels such as coal, oil, and natural gas.

Knowing how CO₂ enters and leaves the atmosphere—called the carbon cycle—is important for understanding and predicting Earth's future climate. Several years ago Inez made a big contribution to her field. She created the first mathematical model of the carbon cycle.

What makes Inez's work so special is that she doesn't just look at CO₂ in the atmosphere. She studies it in the oceans and on land and asks questions about how trees and other living things help change CO₂ levels. She looks at the total CO₂ picture!

Inez's research earns her another reward.

Today Inez is the director of the Center for Atmospheric Studies at the University of California, Berkeley. Her continuing work on climate models is helping put together the many puzzle pieces of climate change.

In 2007 NASA will launch the Orbiting Carbon Observatory (OCO). It will orbit Earth to measure and map the CO2 in the atmosphere. Scientists will use the data to learn more about how natural cycles and people's actions affect CO2 levels—and climate change. Inez is one of the lucky scientists helping to plan the OCO mission. She's also going to help analyze the data that the satellite beams back to Earth.