10/13/2014 03:34 pm ET Updated Dec 13, 2014

Celebrating the International Day of the Girl: Why Adolescent Girls Are a Smart Investment

On Friday, the Nobel Prize Committee recognized Malala Yousafzai for her fearless advocacy on behalf of girl's education. Her award is a cause for celebration -- but it is also a call for action, especially as we paused this October 11 to recognize the annual International Day of the Girl. This year, the international community's attention is focused on an issue that could not be more timely or important, especially in light of Malala's work: empowering adolescent girls: ending the cycle of violence.

The fact is we have made a lot of progress when it comes to girls. More girls than ever are enrolled in school. In some countries, girls are actually outperforming boys and graduating in greater numbers. And more families, communities and leaders are recognizing their value as important and equal members of society. Everywhere I go, I have been encouraged that momentum and enthusiasm around empowering adolescent girls -- supporting their health, well-being and autonomy -- continues to build.

But despite the vast potential they represent, adolescent girls confront a unique set of vulnerabilities, including the increased threat of violence, in their communities, at their schools or in their homes. UN Women estimates that 150 million girls worldwide experience sexual violence each year, and nearly half of all sexual assaults are committed against girls younger than 16 years of age. Adolescent girls face the threat of early and forced marriage, which is a form of gender-based violence. In fact, one in nine girls is married by the age of 15. Brides who are barely out of childhood are more likely to suffer early pregnancy, maternal mortality, and transmission of HIV/AIDS. In addition, every year, more than three million girls are at risk of female genital mutilation/cutting, which can lead to devastating physical and mental health problems.

Conflict increases the risk of gender-based violence. In some countries, terrorist groups view educated girls as a threat and intimidate or harm girls who are pursuing an education, as evidenced by Boko Haram's kidnapping of girls in Nigeria, including more than 200 girls from their school dormitories. A few weeks ago, I wrote about how the brutal treatment and dehumanization of women and girls by the Islamic State of Iraq and the Levant (ISIL) is central to its campaign of terror, contributing to the destabilization of an entire region.

Fortunately, the world is starting to realize that allowing this violence to continue is not just a tragedy for the individual girl, but for her entire family, community and society. And more countries now recognize that this violence carries real economic costs. Globally, conservative estimates of lost productivity resulting from just one form of violence -- intimate partner violence -- range from 1.2 to 2 percent of gross domestic product. To put this number in context, it represents approximately the same share as most governments in developing countries spend on primary education. And these figures do not include costs associated with other factors, such as long-term emotional impact.

However, if we invest in girls, keep them safe, and allow them to continue their education, we will not only allow girls to realize their full potential, but also help their communities and countries thrive. This is why the United States strongly supports a focus on gender equality and the empowerment of women and girls as part of the Post-2015 Development Agenda. Ensuring that girls receive an education beyond the primary level is critical to realizing these gains.

A girl with secondary schooling is up to six times less likely to be married as a child than a girl with no education. When she herself has children, each extra year that she is educated reduces her children's mortality risk by five to 10 percent. Secondary education also promotes civic participation: while primary education may give a girl the literacy she needs to vote or read, it is secondary education that enables her to meaningfully participate in the civic life of her country. Investing in girls also increases economic growth. Plan International estimates that the cost to 65 low- and middle-income and transitional countries that fail to offer girls the same secondary school opportunities as boys is a staggering $92 billion each year.

These statistics convey the transformative power of adolescent girls. But that power is crystal clear in the girls I meet both at home and abroad. One girl I met recently, Memory, left me particularly inspired and hopeful for the future.

Memory is from Malawi, where many young girls are married very early. She shared with me the story of her younger sister, who was married at 11 and had three children by the age of 16. Memory vowed not to let social norms in her community dictate her future. And now she is in college and committed to finishing her education, while working to help other girls in her community stay in school.

This past Thursday, October 9, I hosted a Google+ Hangout at the State Department to commemorate the International Day of the Girl. After the discussion, one girl from Afghanistan -- a place where, not too long ago, girls were not even allowed to attend school -- summed up why continued investment in girls is so critical. She said, "We can do anything we want. Girls can be heroes and role models for many to follow."

As Malala and I discussed at the Girls Summit in London this past summer, girls are critical to solving the world's problems. Empowering adolescent girls -- specifically by freeing them from violence and ensuring them an education--is key to building the future we all want. Today, as we celebrate Malala and girls everywhere, we recommit ourselves to that future.