It is no coincidence that the rate of glacial melting in Greenland also doubled over the last decade; rapid global warming traces directly to the increasing consumption of fossil fuels by an expanding world population. The resulting carbon dioxide and other greenhouse gases trap excessive heat, warming the planet.

Reversing global warming requires drastically reducing the consumption of fossil fuels. This means switching to sustainable sources of energy (wind, solar, biomass) and deploying more efficient technologies in transportation (hybrid cars and light rail), climate control (passive solar and better construction techniques), agricultural and manufacturing sectors of the economy.

But we must also recognize that the swelling world population is the ultimate driver of global warming and exacerbates all of the other environmental problems we now face. Over-population promotes deforestation, air and water pollution, the production of carcinogens and toxins, soil erosion and the collapse of fisheries.

Jesus shared the earth with no more than 400 million other souls, Thomas Jefferson with about 1 billion contemporaries, and at projected population growth rates, our children will live with 9 billion others by mid-century. Such rapid population growth can not go on endlessly. Humans, like all other species, can only populate up to the carrying capacity of the environment. Carrying capacity is set by availability of resources (food, water, places to live) and sometimes by the build-up of toxic metabolic wastes. However, as populations approach their carrying capacity, growth often slows as a consequence of increased mortality and lower birth rates due to disease, competition and malnutrition. And for humans we can add the scourge of wars fought for controlling limited resources.

Our children will live in a much better world if human population growth is checked by the rational decision to reduce family size, rather than by famine, epidemics and war.