By John Seager, Source: TreeHugger

World Population Day was July 11. Why should you care? Unlike Slurpee Day (also July 11) or National Hot Dog Day (July 21), population growth has a direct effect on you, your children, your future and the health of our planet.

Let’s put population growth into terms any baseball fan can understand. Every hour, the world population increases by about 9,100 people. At that rate, it would take less than five hours to fill up Wrigley Field. It would be loud. It would be crowded. A lot of Slurpees and hot dogs would be needed to feed everyone.

And while crowded stadiums can be great fun, a crowded world isn’t. Our population is growing rapidly. Our Earth is not. Something has to give.

Adding 80 million people a year to the Earth’s population puts incredible strain on our natural resources. Experts project that in less than 50 years, we might add another 2 billion to 4 billion people to our planet. All of those people need food, water, clean air and space—necessities that are already running in short supply in many areas.

Lester Brown gives a great example of this in his book “Plan B 4.0: Mobilizing to Save Civilization.”

Beginning in the 1970s, Saudi Arabia used powerful pumps to extract water from a fossil aquifer deep under the desert. These wells allowed Saudi Arabia to grow much of its own grain. But turning the desert green comes at an incredibly high cost. These ancient aquifers are now running dry, and by 2016, Saudi Arabia will end wheat production altogether. Food for 30 million people will have to come from somewhere else. What will this do to prices at your grocery store? How will the one billion people who struggle to live on less than $1 per day be able to afford even the basics?

So what’s the world to do? Access to voluntary family planning for all women is a great start.

According to a new report from the Guttmacher Institute, about 222 million women around the globe want to delay or end their childbearing but have no access to modern contraception. Universal access to contraception would slow population growth, give women and girls more power over their own futures and help communities and nations build a better quality of life for all of their people.

Sound expensive? It’s not. Providing the current level of contraceptive use in the developing world costs $4 billion—and saves $5.6 billion—each year.  If the world doubled that amount—spending $8.1 billion per year—we could fully meet the need for modern contraception. We’d see 54 million fewer unintended pregnancies, 26 million fewer abortions, 21 million fewer unplanned births, 79,000 fewer pregnancy-related deaths and 1.1 million fewer infant deaths. We’d also save an additional $5.7 billion. Contraception pays for itself.

Unfortunately, while we know that giving women the power to control their own futures is the solution, powerful interests are willing to do anything to keep that from happening. House Republicans have fought at every turn to prevent access to contraception, both at home and abroad. And at the recent Rio+20 United Nations Conference on Sustainable Development, the Vatican was successful in removing references to gender equality and reproductive rights from the final document, despite Secretary of State Hillary Clinton’s best efforts. We can expect the same intransigence in response to the London summit on family planning. If we want to achieve women’s rights, a stable population and a healthier planet, we must keep fighting.

So go ahead and enjoy that Slurpee and celebrate National Hot Dog Day, if you’re so inclined. But don’t forget to mark World Population Day, too. Because when it comes to the health of our planet, the quality of our lives and the future of our children, population counts.

John Seager is president of Population Connection, America’s largest grassroots population organization.