Part 2. Greenhouse gases and global warming

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Picture 1. Left: Naturally occurring greenhouse gases — carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) — normally trap some of the sun’s heat, keeping the planet from freezing. Right: Human activities, such as the burning of fossil fuels, are increasing greenhouse gas levels, leading to an enhanced greenhouse effect. The result is global warming and unprecedented rates of climate change.

(Figure source: National Climate Assessment)

 

a. The greenhouse effect, combined with increasing levels of greenhouse gases and the resulting global warming, is expected to have profound implications, according to the near-universal consensus of scientists.

b. These greenhouse gases include water vapour, carbon dioxide (CO₂), methane, nitrous oxide (N₂O) and other gases, according to the Environmental Protection Agency (EPA). Since the dawn of the Industrial Revolution in the early 1800s, the burning of fossil fuels like coal, oil and gasoline have greatly increased the concentration of greenhouse gases in the atmosphere, especially CO₂, National Oceanic and Atmospheric Administration (NOAA). " Deforestation is the second largest anthropogenic source of carbon dioxide to the atmosphere ranging between 6 percent and 17 percent," said Daley.

c. If global warming continues unchecked, it will cause significant climate change, a rise in sea levels, increasing ocean acidification, extreme weather events and other severe natural and societal impacts, according to NASA, the EPA and other scientific and governmental bodies.

d. "Gas molecules that absorb thermal infrared radiation, and are in significant enough quantity, can force the climate system. These type of gas molecules are called greenhouse gases," Michael Daley, an associate professor of Environmental Science at Lasell College told Live Science. Carbon dioxide (CO₂) and other greenhouse gases act like a blanket, absorbing IR radiation and preventing it from escaping into outer space. The net effect is the gradual heating of Earth's atmosphere and surface, a process known as global warming.

e. Atmospheric CO₂ levels have increased by more than 40 percent since the beginning of the Industrial Revolution, from about 280 parts per million (ppm) in the 1800s to 400 ppm today. The last time Earth's atmospheric levels of CO₂ reached 400 ppm was during the Pliocene Epoch, between 5 million and 3 million years ago, according to the University of California, San Diego's Scripps Institution of Oceanography.

Can the greenhouse effect be reversed?

Many scientists agree that the damage to the Earth's atmosphere and climate is past the point of no return or that the damage is near the point of no return. "I agree that we have passed the point of avoiding climate change," Josef Werne, an associate professor at the department of geology & planetary science at the University of Pittsburgh told Live Science. In Werne's opinion, there are three options from this point forward:

1. Do nothing and live with the consequences.

2. Adapt to the changing climate (which includes things like rising sea level and related flooding).

3. Mitigate the impact of climate change by aggressively enacting policies that actually reduce the concentration of CO₂ in the atmosphere.

 

v Task 1.4 for Student B. Vocabulary work. After you complete reading and ordering paragraphs, select synonyms out of the box for the following words in bold type:

thick covering lying decreasing pH very serious uncontrolled fumes  early days consequences unrenewable sources of energy  disappearance of all trees

1. to have profound implications

2. water vapour

3. the dawn of the Industrial Revolution

Fossil fuels

Deforestation

6. ranging between 6 and 17 percent

7. to continue unchecked

8. ocean acidification

9. severe natural and societal impacts

10. act like a blanket

v Task 1.5. Speaking. Student A, retell your text to your partner, outlining the main facts and using all the target vocabulary. Answer your partner’s questions. Then listen to your partner’s story and ask him/her questions to clarify the following:

1. the historic period when the concentration of the greenhouse gases began to increase steadily

2. current amount of parts per million of CO₂

3. types of events caused by global warming

4. the optimal ways to deal with climate change

Student B, listen to your partner’s story and ask him/her questions to clarify the following: