Which of the following is an observed effect of human-caused atmospheric changes?

• A. More frequent heat waves
• B. More localized cooling
• C. Slightly longer winters
• D. Large floods from more powerful rainstorms and more frequent wildfires

Answer: (D)

Human-caused changes to the atmosphere are warming the planet and boosting the energy of the climate system. Warmer air can hold more water vapor, so when it rains, it often releases more moisture and falls as heavier downpours. That leads to larger floods in many regions. At the same time, higher temperatures dry out vegetation and soils, lengthening fire seasons and increasing the likelihood and intensity of wildfires. Together, these effects are consistent with what we observe as a result of human-driven climate change: more extreme rainfall running up to big floods and more frequent wildfires. The other options don’t match the broad, real-world trend of a warming climate, where extreme rainfall and fires are increasingly common, rather than localized cooling or longer winters.