The environmental field, Brown - what academic field are you interested in?

This is the one I wrote in a rush. it would be great if someone could give this a look since the grammar is icky and I am not sure how to fix it. THANK YOU so much :)

Why are you drawn to the academic fields you indicated in the Anticipated Degree and Academic Interest questions above? (1000 characters)

Today, the world population is estimated at 6,800,000,000, and I make up for only one individual out of such an immense and growing denominator. Because one human life can seem so infinitesimal, I have set for myself the goal to find the proof of my existence. When I realized my passion for Biology, I also realized that medicine would allow me find such proof because a doctor's single decision could influence the lives of many. A career in medicine would also lead me to meet people whom I would never meet otherwise. This is especially appealing to me because I am fascinated by lives other than my own. Another field which I am equally interested in is environmental science. Being someone who holds a spiritual obsession with nature, I see it as my personal mission to combat anything that might threaten its fragile beauty. To become more learned in the environmental field would equip me with the knowledge I need to save the world one plant at a time, and encourage others to do the same.

I think the connection between the infinitesimal human life and your interests in biology and environmental science is lost somewhere in the paragraph. Maybe it would be better for you to cut that out and expand upon your specific interests for biology and environmental science.

some awkward parts:
Being someone who holds a spiritual obsession with nature - what do you mean by spiritual obsession? (obsession doesn't sound very positive)
a doctor's single decision could influence the lives of many - this is kind of a generalization

The writing is a little shaky. The last sentence needs a little work. Consider switching "learned" to educated. Get a little more personal this is the career that you have decided on for your life show them that your are passionate about the subject. Its a strong writing when to show rater than tell.

This is especially appealing to me, because I am fascinated by lives other than my own. Another field that particularly appeals to my interests is environmental science.

Being someone who holds a spiritual obsession with nature, I see it as my personal mission to combat anything that might threaten its fragile beauty.--- excellent! You write well, not icky.