Earth Lakes Are Under Threat Reading Answers ((top))

Introduction: The Silent Crisis Beneath the Surface Lakes cover only about 3% of the Earth’s surface, yet they harbor nearly 90% of the planet’s liquid surface freshwater. From the ancient depths of Russia’s Lake Baikal to the sprawling shallows of North America’s Lake Superior, these ecosystems have sustained human civilization, biodiversity, and climate regulation for millennia. However, a growing body of scientific evidence reveals a troubling truth: Earth’s lakes are under severe and accelerating threat.

| Word | Definition | |------|-------------| | Gigaton | Unit of mass equal to 1 billion metric tons | | Arid | Very dry, receiving little rainfall | | Glacial meltwater | Freshwater released by melting glaciers | | Exacerbating | Making a problem worse | | Diversion | Rerouting of water from its natural path | | Eutrophication | Nutrient over-enrichment causing oxygen depletion | | Hypoxia | Condition of low dissolved oxygen in water | | Feedback loops | Processes where output amplifies the original effect | | Tipping point | Threshold beyond which system change is irreversible | Understanding the reading answers to “earth lakes are under threat” is not merely an academic exercise. It equips students, policymakers, and citizens with the factual foundation needed to advocate for change. The evidence is clear: lakes are shrinking, warming, and choking on pollution. But as the recoveries of Lake Washington and Lake Biwa demonstrate, ecosystems can heal when humans act responsibly.

Paragraph 2 explains that lakes fed by glaciers reach a maximum inflow (peak water) before inflows drop permanently. This concept is critical for understanding future water security in regions like the Himalayas and Andes. Question 5: What percentage of global freshwater withdrawals is used for agriculture? Answer: 70–80%. earth lakes are under threat reading answers

Paragraph 3 notes that agricultural irrigation accounts for “70–80% of global freshwater withdrawals,” making it the dominant human use. Question 6: Name two lakes mentioned that have shrunk by over 90% of their original volume. Answer: The Aral Sea and Lake Poopó.

The final sentence of Paragraph 4 states that hypoxia and pollution threaten “the livelihoods of 40 million people” around Lake Victoria. Question 9: What two lakes are given as examples of successful recovery? Answer: Lake Washington (United States) and Lake Biwa (Japan). Introduction: The Silent Crisis Beneath the Surface Lakes

The Aral Sea is described as having shrunk to “10% of its original volume” (Paragraph 3). Lake Poopó has “virtually disappeared” (Paragraph 2), implying over 90% loss. Note that some argue the Aral Sea is not a “lake” but an inland sea; exam answers typically accept it due to common usage. Question 7: What is eutrophication, and which lake is cited as a North American example? Answer: Eutrophication is the process of nutrient pollution causing toxic algal blooms. Lake Erie is the North American example.

Paragraph 1 cites the Science study, providing this specific figure to emphasize the magnitude of loss. This is a numerical detail question, commonly tested in reading comprehension exams. Question 3: According to the passage, what is the “principal culprit” behind shrinking lakes? Answer: Rising global temperatures (climate change). | Word | Definition | |------|-------------| | Gigaton

The passage explicitly states in the introduction that lakes contain “nearly 90% of the planet’s liquid surface freshwater.” This statistic highlights the disproportionate importance of lakes relative to their small surface area. Question 2: How much water loss did the 2022 study quantify per year? Answer: Approximately 27 gigatons per year, equivalent to 27 times the annual water consumption of the United States.