Final answer:
The statement is true; without greenhouse gases, Earth's average surface temperature would be well below the freezing point of water, resulting in a global ice age with all surface water frozen.
Step-by-step explanation:
The statement is true. The greenhouse effect plays a critical role in maintaining the Earth's surface temperature. Greenhouse gases, such as water vapor and carbon dioxide, trap heat in the atmosphere, preventing it from escaping to space too quickly. Without these gases, the Earth's average surface temperature would be about -18°C, rather than the current average of approximately 15°C. This would result in Earth's water being frozen, plunging our planet into a global ice age. It's due to the delicate balance of the greenhouse effect that Earth can sustain liquid water, which is essential for life as we know it.
Our neighbor planets, Mars and Venus, illustrate the consequences of having too little or too much greenhouse effect. Mars, having lost its substantial greenhouse gas atmosphere, became too cold, freezing its remaining water. Venus, on the other hand, has a runaway greenhouse effect causing extremely high surface temperatures and the permanent loss of water. Earth's atmosphere contains the right amount of greenhouse gases to sustain a favorable climate for life.