It is a fundamental necessity for everybody to try to do something in order to preserve the health of our planet.

preserve 是动词，由前缀 pre-（表示"预先、提前"）和词根 serve（"保持、维护"）组成，字面意思是"提前采取措施来维护"。在这里表示"保护、维护"，指采取行动防止地球环境恶化。