Trace amounts of other gases play a critical role in regulating climate. Which statement is true?

• A. They have no impact
• B. They regulate climate
• C. They cause weather extremes only
• D. They only trap heat in the stratosphere

Answer: (B)

Trace gases regulate climate because they control how much infrared energy is absorbed and retained in the atmosphere. Even in tiny amounts, they are very effective at trapping heat, shaping the Earth's energy balance. Their impact depends on how strongly they absorb infrared radiation and how long they remain in the air. For example, methane is a very potent greenhouse gas with a relatively short lifetime, while nitrous oxide lasts much longer; ozone can warm or cool depending on whether it's in the upper atmosphere or lower down. Water vapor acts as a feedback: as air warms, it holds more moisture, which amplifies warming. Taken together, these gases influence the overall climate system through radiative forcing and atmospheric chemistry, so they do regulate climate. The other statements misstate their role by claiming no impact, that they only cause weather extremes, or that they trap heat only in the stratosphere.