More than seven billion people live on Earth today, and that number is expected to reach nearly 10 billion by 2050, according to a new projection from the United Nations.
As Earth's population continues to grow, humans have an increasingly negative effect on Earth's environment. Warming global temperatures are melting ice caps and glaciers and global sea levels are expected to rise at a higher level than during the past 50 years, according to the Environmental Protection Agency. If these rates continue, New York City sea levels are expected to rise 2.3 feet, reports the EPA.
These reports raise the question of whether the Earth has a limit to how many people it can hold, especially as resources become more scarce.
On July 11, World Population Day, that question comes into even closer focus.
The growth rate is highest in poorer countries like Nigeria.
"Not too many years ago, the UN demographers thought Nigeria would have about 290 million people in the middle of the century," said Robert Engelman, President of the Worldwatch Institute. "They’re now projecting 440 million people for the middle of this century. That’s a huge uptick."
Nigeria, which has a GDP in the bottom 20 percent worldwide, is expected to surpass the United States in population by 2050.
Experts attribute the higher rates to increasing life expectancy and inadequate contraceptive resources.
In the United States, more than half of all pregnancies were unintended, according to the Center for Disease Control and Prevention. The 2011 study found that four out of five pregnancies were unintended among women 19 years and younger.
The U.S. spends $615 million annually to provide family planning support in foreign countries, but has often wavered over the conditions of support.
"There’s a significant division nationally on abortion clearly, but the fact that it affects whether we want to make contraception as widely available as possible to anyone who wants to use it, is really fairly surprising for a modern developed country in the early 21st century," Engelman said.
Under Republican leadership, the United States has restricted access to contraceptives based on whether a family planning provider gives advice on or supports abortion.
In 2009, President Barack Obama repealed former-President George W. Bush's policies of restricting aid to organizations that support abortion.
“For the past eight years, they have undermined efforts to promote safe and effective voluntary family planning in developing countries,” President Obama wrote in an official statement. “For these reasons, it is right for us to rescind this policy and restore critical efforts to protect and empower women and promote global economic development.”
Still, some critics have called for the United States to increase their funding of foreign contraception efforts.
"I think the public is really interested in this issue, but politicians don’t seem to be hearing that message, and it would be good if they did," Engelman said.