We end this week with two final questions from the Wall Street Journal’s Green IQ Test. See if you know the answers to the questions below and try your hand at the entire week-long series here.

When it comes to emissions of greenhouse gases, most people know the biggest culprits: China and the U.S. Which three countries round out the top five?

A. Brazil
B. Mexico
C. South Korea
D. India
E. South Africa
F. Russia
G. Indonesia
H. Japan

ANSWER: G, A and D. Indonesia and Brazil have zoomed up the rankings due to the inclusion of tropical deforestation—not just industrial activity—in the tally. That’s one reason people from investment bankers to think-tank types are becoming tree huggers: Preventing deforestation is seen as a relatively easy and cheap way to tackle a huge chunk of global emissions, though questions loom on enforcing forest-protection plans in remote places.
Water, water everywhere, but not so much to drink. About 70% of the Earth is covered by water, and there’s more beneath the surface. But seawater is too salty to drink, and water at the poles and in glaciers is frozen. What percentage of the world’s water is fresh and liquid? And what percentage is also found above ground, in lakes and rivers?

A. 10% and 2%
B. 5% and 1%
C. 3% and 0.5%
D. 1% and 0.3%

ANSWER: D. Only 1% of the world’s water is fresh and unfrozen—and most of that is found in underground aquifers. Only 0.3% of the world’s water is fresh surface water, including huge concentrations like the Great Lakes, the Amazon and Lake Baikal. That’s one reason scientists, environmentalists, ecologists and military planners all worry that water shortages could become a source of conflict in coming decades.