When it is a proven fact that girls matter more to the health of families than boys, why do we persist in helping them less?
When women are recognised to be the lynchpins of successful communities, why do we continue to tolerate the sex discrimination and exploitation that has left 500 million in abject poverty and another one billion on the edge of it?
And when "Girl Power" has been such a massive driver of change in western societies, why have the past 50 years seen global movements to liberate women, and men, from colonialism, apartheid, black discrimination and prejudice against gays, but no civil rights struggle to liberate girls from oppression?
2016 must be the year of girl empowerment globally - the beginnings of a worldwide civil rights movement that focuses on freeing girls from the worst persecution in some of the poorest, most remote and most dangerous places in the world?
As we enter 2016, more than 68 million girls under the age of 14 are child labourers working in slave conditions, in domestic service, unsafe factories and even down mines.
This year, 15 million girls will be married off before the age of 18 - one child bride every two seconds. These numbers are rising even faster in conflict zones. One example is that of Syrian girls in Jordan where the rate of child marriage has doubled.
Today an astonishing 17 million girls each year become mothers before they are legally able to be married. More than 720 million women alive today were married or entered into a union before their 18th birthday. The rights of girls to a childhood are so routinely trampled upon that in the next few decades it is expected that child brides will not fall in number but rise to a staggering one billion.
And because so many children are caught up in conflict, the trafficking of girls is on the increase with an estimated half a million sent into slavery this year.
And as report after report on Iraq, Syria, Libya, Afghanistan and Myanamar has revealed, thousands more are subjected to rape, molestation and conscription into child militias - all in breach of the Rome Statutes of the International Criminal Court that define such practises as crimes against humanity and a reason for indictment and prosecution.
Girls form the majority of children who are out of school and denied the opportunity to plan their own future. More than 30 million girls never enjoy a first day at school or drop out before they finish primary education. One estimate suggests that as many as 500 million girls worldwide will never complete their schooling despite the Millennium Development goal promise of universal primary education by 2015.
Century is too long
It will take until 2086 before every girl goes to primary school. And while the world recently approved sustainable development goals to achieve universal secondary education by 2030, the best estimate is that it will take until 2111 before every girl completes lower secondary school - 70 years behind the richest boys who are projected to achieve that milestone in 2041.
We know children born today will live longer than generations past, but a century is too long for an infant today to wait for her basic right to be upheld.
In Africa and the Indian subcontinent, girls' chances of reaching university are so slender that it is estimated that while in 2050, 80 percent of Taiwanese, Singaporean and Japanese girls will be university graduates, the figure will be three, four or at most five per cent for girls in the world's poorest countries.
We spend an average of $400 on an African girl's education but more than $100,000 on that of a Western child aged three to 16. The truth is that, in the delivery of opportunity, many countries are 100 years behind their richer neighbours, and as rich countries continue to expand higher education for girls, we cannot comfort ourselves in the knowledge that the gap between rich and poor is narrowing. It continues to widen.
I once heard Nelson Mandela say that promises made to children are so sacred that they should never be broken, but as the author JK Rowling has reminded us: No one is easier to silence than a child. Fortunately the silent majorty will remain silent no more.
From my vantage point as chairman of the Global Citizenship Commission - reviewing the first 70 years of the universal declaration of human rights - the most eagerly-anticipated and exciting development in 2016 will be the growth of civil rights activism among girls themselves.
The wedding busters
Starting in 22 communities of Bangladesh, brave girls have formed child marriage-free zones. Nicknamed by some "the wedding busters", they come together as one - defying their fathers if necessary - to prevent any one of their schoolmates being married off as children. Supported by Plan International, their success has inspired child marriage-free zones in Pakistan, India and parts of Africa.
Under the banner of the Global March against Child Labour, led by Nobel prize winner Kailash Satyarthi, child labourers are literally on the march to demand their freedom.
And inspired not just by fellow Nobel prize winner Malala Yousafzai but also by the Bring Back Our Girls campaign to free the 200 Chibok girls abducted a year ago by Boko Haram in Nigeria, there are now 1,000 global youth ambassadors and they are to be found on Facebook and Twitter under the banner of A World At School.
This year many established charities will shift their priorities to make girls' rights even more central to their campaigns and this year in support of UNICEF's State of the Worlds Children report, THEIRWORLD charity will work with others to set out a clear agenda.
This autumn the report of the Commission on Global Educational Opportunity to Bank Ki Moon UN Secretary General will set out a plan for how in one generation - over the next 40 years - the education attainments of girls in poorer countries can converge with that of girls and boys in rich countries.
Urgent need for action
But there is an urgent need for action to support 15 million displaced girls now in conflict zones by establishing what I call HOPE - the Humanitarian Operation for the Provision of Education in Emergencies - to get them into education.
In 2005, Security Council Resolution 1612 established a monitoring mechanism to expose grave violations of children's rights during armed conflict. But as the new head of the International Criminal Court has said, girls will see things change only when there are well publicised prosecutions and indictments.
And while there is a legal right, in theory, to take cases of child abuse to the UN Human Rights Committee under the Optional Protocol to the Convention on the Rights of the Child, only 14 countries have signed the Protocol - with, sadly, those most likely to infringe it least likely to sign. So we also need a new political mechanism to force countries to act on the abuse of girls' rights.
I suggest that each year the Security Council should meet at least once as a Children's Rights Council to speak up for the half of humanity who represent our future.
The long-term goal is simple: girl power is not just for the comfortable West and "leaning in" is not just for the comfortably off. Girl power will achieve its goals only when the rights of the world's most vulnerable and the most desolate girls are championed and made real.
By Gordon Brown
Gordon Brown is the UN Secretary-General's Special Envoy for Global Education and the former Prime Minister and Chancellor of the Exchequer of the United Kingdom.
The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.
Source: Al Jazeera