Human Impact Activities Practice Test

A region added many new natural-gas power plants between 2010 and 2020.

Evidence:

• CO₂ emissions: 22 million tons/year (2010) → 31 million tons/year (2020)
• Average number of days with “unhealthy” air quality: 12 days/year → 20 days/year
• Electricity produced: 40 TWh/year → 68 TWh/year

If the same trend in energy use continues for another 10 years without additional controls, what environmental change is most likely based on the evidence? (Impacts can be positive or negative depending on context.)

A student reads this claim: “The fish population in Lake Orion dropped, but humans probably had nothing to do with it.”

Evidence collected over 8 years:

• A factory upstream increased water use for cooling from 5 million L/day to 18 million L/day.
• Average summer water temperature in the lake rose from 22°C to 26°C.
• Dissolved oxygen near the lake bottom dropped from 7 mg/L to 4 mg/L.
• Fish counts during surveys dropped by about 35%.

Which claim is incorrect because it ignores human influence shown by the evidence? (Impacts can be positive or negative depending on context.)