If the "books" wasn't a plural, it would be "his" but since it isn't singular, it would be "their"
Answer:
In certain situations, it can be affirmed that science causes damage to nature through its actions. It is that, although science in general at present seeks to improve the quality of life of people (and, therefore, improve the conditions of the natural environment), in many situations scientific action generates the opposite effect. Thus, for example, scientific advances in the exploitation of resources, while optimizing their use, harm nature by being invasive means for it (for example, fracking to extract oil).
That would be present tense in 3rd person view :)
