For centuries, the word population remained stable, not rising above 500 million people. When the Industrial Revolution began in the 18th century, the world population stood at one billion. Within one generation it doubled, and in the next half-century it doubled again, reaching 4 billion by the end of the 19th century. Today our planet is home to 7 billion people and counting. In other words, the world population grew sevenfold in two centuries.

The critical question in the eyes of ecologists and demographers is how large a human population the planet can sustain. Air and water pollution, as well as depletion of the earth's fresh water, arable land and non-renewable energy sources such as natural gas and oil, are all side effects of the burgeoning world population. Furthermore, a balance must be maintained between the needs of the human population and wildlife, on land or in the seas or skies.

Ironically, fears for the survival of Planet Earth have intensified just as the human population is flourishing as never before. We have figured out how to utilize the earth's resources to our advantage, to afford a luxurious standard of living, by harnessing the sources of energy buried deep within the earth. But this standard of living comes with a heavy price: The more we use up the earth's resources now, the less remains for future generations to enjoy.

What is the Torah's view on the balance between the benefits to the expanding human population and the possible long-run costs to the planet? In the very first portion of the Torah, Bereishit, G-d commands mankind: "Be fruitful and multiply and fill the earth and subdue it, and rule over the fish of the sea and over the fowl of the sky and over all the beasts that tread upon the earth. " We have a responsibility to fill and subdue the earth, but at the same time we must rule over it benevolently, in a way that ensures its continued existence.

Renewable energy and sustainable agricultural practices are two of the many ways that we can use our divinely granted intelligence to fulfill our dual mandate: to populate the world and to rule over it with concern and compassion for the all the earth's inhabitants.

Very soon, we will witness an incredible, unimaginable expansion of the world’s population: After the revelation of Moshiach will come the era of the resurrection of the dead. Not only will death be eradicated, but all the past inhabitants of this earth will come to life. How will the earth sustain them all? That is a question that will be answered in time, when this prophecy is fulfilled. For now, it is our responsibility to prepare ourselves for that time, both physically and spiritually. Our spiritual preparations include studying Torah sources on the topic of Moshiach and Redemption, and living our lives in its spirit, through increasing in acts of goodness and kindness.