Earth system scientists ask questions about many spheres: the biosphere (life on Earth, from tiny microbes to giant redwood trees), the atmosphere (the gases surrounding Earth), the hydrosphere (water), and the geosphere (the solid parts of the planet). How do the respiration and photosynthesis of plants in tropical forests affect the rest of the planet? What destroys ozone gas 32 miles above Earth’s surface, in the stratosphere, above the North and South Poles? How do salty oceans respond to fresh meltwater from receding glaciers? What role do the frozen parts of the geosphere, known as the cryosphere, play in climate change? Earth System and Computer Scientist Charles Zender uses math to create models that help predict how these different spheres interact to produce Earth’s climate.