Hot topic: what do you really know about global warming?

• Position: ENVIRONMENT

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There's a lot of talk about climate change, especially with all the extreme weather we've had recently. At the same time, polls show that fewer Americans are concerned about global warming--or even think that it's real--than just a few years ago. Whether or not you believe humans are responsible for climate change and its effects, it's clear that misconceptions about the science behind it abound. Take our pop quiz and find out how much you really know. (Answers are on p. 28.)

TRUE OR FALSE

1. The concentration of carbon dioxide in the atmosphere today is about 40 percent higher than at the start of the Industrial Revolution, around 1750.

2. Each of the past 10 years-2001 through 2010--was among the 11 warmest on record.

3. Ocean life is shielded from the effects of carbon dioxide buildup and climate change.

4. The United States currently contributes the most carbon emissions to the atmosphere.

5. Earth has been warmer in the past.

6. Some kinds of particle pollution in the atmosphere counteract global warming by reducing the amount of solar radiation that reaches Earth's surface.

7. No place on Earth is, on average, colder today than it was 100 years ago.

8. Natural phenomena, including volcanic eruptions, trap heat close to the surface of Earth and are a major cause of recent climate change.

9. Scientists derive evidence of the composition of Earth's atmosphere hundreds of thousands of years ago by studying air bubbles in ancient ice.

10. Livestock are a significant contributor of greenhouse gases.

11. As the average global temperature rises, average precipitation increases.

12. Biofuels like ethanol and biodiesel can help reduce greenhouse gas emissions.

    MULTIPLE CHOICE

13. By how much do scientists estimate that global sea levels rose in the 20th century?

    1. zero

    2. 6-9 inches

    3. 3-4 feet

    4. 21-23 feet

14. By how much do scientists estimate global sea levels would rise if all of Greenland's glacial ice melted?

    1. zero

    2. 6-9 inches

    3. 3-4 feet

    4. 21-23 feet

15. Which two of the following are not heat-trapping gases?

    1. carbon dioxide

    2. nitrogen

    3. ozone

    4. oxygen

16. In the last 50 years, the oceans have absorbed what percentage of the heat that has been added to Earth's atmosphere as a result of greenhouse gases?

    1. 50 percent

    2. 20 percent

    3. 80 percent

    4. 15 percent

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    The questions and answers come from...