(CNN) It took thousands of years for the global population to hit 5 billion, which happened in 1987. Some 32 years later, we're closing in on 8 billion.

This explosive growth concerns leaders at the United Nations, who created World Population Day in 1989 to raise awareness about the problems caused by overpopulation. The holiday is observed annually on July 11.

The planet's population today is 7.7 billion. How mind-bogglingly huge is that number? If you started now and ticked off 7.7 billion seconds, you wouldn't be done until the year 2263.

And by 2050, the world is projected to add another 2 billion people.

If we have issues with overpopulation now, just image the future impact on the planet. Here's a closer look at some global population trends.

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