Ten years of measurements show a stretch of ocean takes in more carbon dioxide from the air each year than it gives back. Which term describes that ocean's role in the carbon cycle?

A power station burns coal that formed 300 million years ago, releasing that long-stored carbon into the air. Which term describes the station's role in the carbon cycle?

Cattle digestion, landfills and flooded rice fields all release the same heat-trapping gas. Each molecule of it traps far more heat than carbon dioxide, but it breaks down in about a decade. Which gas is it?

Satellite images of one region show tree cover falling from 80 percent to 35 percent over twenty years as land is cleared for cattle pasture. Which term names this change?

A station pipes steam from hot rock two kilometers underground to spin its turbines, and burns nothing at all. Which term names this energy resource?

Scientists average a year of readings from thousands of land stations, ships and ocean buoys worldwide into a single figure they compare with the same figure from past years. Which term names it?

A power plant burns wood pellets and the crop waste left after harvest, fuel that is grown again within a few years. Which term names this energy resource?

An analyst divides a country's total yearly energy use by its number of residents so countries of very different sizes can be compared fairly. Which term names the result?

An energy report reads: 'The sunlight reaching this farm's panels each day is not used up by yesterday's generation, so the resource the farm draws on is ______.' Which term fills the gap?

A utility report reads: 'Water released from the reservoir falls through turbines in the dam wall, and the ______ station supplied a fifth of the state's electricity last year.' Which term fills the gap?

A textbook reads: 'Coal, oil and natural gas all formed from the buried remains of ancient organisms over millions of years, which is why each one is called a ______.' Which term fills the gap?

A coastal plan reads: 'Taking only as many fish each year as the population can replace lets the fishery meet today's needs without reducing future catches, a practice called ______.' Which term fills the gap?

A climate summary reads: 'Sulfur dioxide thrown into the upper atmosphere reflected sunlight and cooled Earth by about half a degree Celsius for two years after ______.' Which term fills the gap?

A government report reads: 'Fresh water, timber, copper ore and fertile soil are the ______ this region draws on, materials taken from the environment and used by people.' Which term fills the gap?

Instruments on Mauna Loa have tracked one gas climbing steadily since 1958, and the rise comes mostly from burning coal, oil and natural gas. Which gas are they tracking?

Two fuels power the same town. Uranium ore took billions of years to form and is not being replaced; wood chips come from trees replanted every fifteen years. Which term describes the uranium?

A report lists methane and carbon dioxide in one column and coal and oil in another. Which term names the two substances in the first column?

A thin worldwide clay layer rich in iridium, a metal rare in Earth's crust but common in asteroids, sits exactly at the level where dinosaur fossils stop. Which event does this evidence point to?

Two plants stand in the same desert. One burns natural gas piped from a field. The other has rows of curved mirrors that turn through the day to focus heat onto pipes of water. Which term names the second plant's energy resource?

Maps of one county show farm fields replaced by streets, housing and shopping centers as people move in from the countryside. Which term names this change?