28/09/2015 13:49 BST | Updated 28/09/2016 06:12 BST

Not Just a Piece of Paper

Last week in New York over 160 leaders from around the world signed an agreement that will shape all of our destinies and radically change the way we tackle poverty, inequality and climate change. In more than 25 years working in international development, this is perhaps the most pivotal moment I have had the privilege to be part of.

A decade and a half after we ushered in a new era with the Millennium Development Goals, the Sustainable Development Goals (SDGs) will come into force. There are 17 goals altogether, chosen through the most participatory process in the UN's history. If the goals are delivered we could be the first generation to end extreme poverty and hunger, end under five preventable child deaths, ensure all children not only go to school but leave being able to read and write, tackle inequality and take action on climate change.

An enormous amount is at stake. Leaders are not just signing a piece of paper - this is a moment of life and death for millions. Save the Children has calculated that on average the lives of nearly 6,500 children a day will be saved over the next 15 years if we achieve just one of the targets on child survival. In total, that's almost 35 million children - children who otherwise might not have a chance of making it past their fifth birthday. In our jobs as humanitarians, we see too many young lives pointlessly lost because they don't have enough to eat, or access to the most basic of healthcare - millions of families could be saved that heartache if governments deliver on the Goals.

The progress of every country toward reaching these targets will be closely monitored, and the Goals will shape the decision making of governments, NGOS, donors, private sector and big institutions like the World Bank on everything from use of low carbon energy to health spending. But they cannot be enforced - there is no law in place that can make governments abide by the SDGs. As such, it's up to us as citizens to make sure that they deliver.

Millions of people around the world have already made their voices heard on this, through the Action/2015 coalition and grassroots initiatives. Last week 150 events were held in more than 100 countries where citizens called on their governments to really get behind the targets and make the aims a reality. We want to make the Goals famous, so everyone around the world knows what's expected of their leaders. Billions hear our message by text, on the radio or from the pulpit.

Expectations might be high, but we know we can do it. The Millennium Development Goals show what extraordinary progress is possible when we hold ourselves and our governments to account. I've been it for myself visiting Save the Children's work around the world.

In a remote hospital in South Sudan last year, I met Sarah, who had just given birth to a tiny baby girl. She'd fled the fighting that was consuming her country at the time on foot, heavily pregnant, and arrived at the hospital just in time to give birth. There were severe complications and without the expert intervention of midwives, she would have died as too many other mothers in South Sudan have before her. The MDGs made the survival of mothers and children a priority, and helped to ensure that under-five deaths have dropped from over 12 million to nearly six million.

Now, it's time to build on that progress and make a push for lasting change that improves the lives of everyone, everywhere. Seeing the threats children face today, from hunger and disease to war and natural disasters, it's clear that there is still so much we need to do to make our world a safe and fair place for everyone to grow up. To make sure no child is left behind.

Under the Millennium Development Goals primary school enrollment improved from 83% to 90% in developing regions since 2000, and the goal on getting more girls into school has been met. But progress has not reached many of the poorest children and advances has stalled - after years of decline, the number of out of school children has been on the rise again over the last four years.

And while we made great strides on cutting child mortality, reducing the number of newborn deaths has been much slower. The advances everywhere have been inequitable, pulling some communities and countries forward while others are left behind.

This is where the SDGs promise to be different - they prioritise reducing all forms of inequality, so that no target is considered met until it's met for everyone, regardless of gender, ethnicity, location or income. As a result, over the next 15 years we can hope to eradicate some of the grossest inequalities that blight countries and keep the poor poor.

As world leaders put pen to paper and made the SDGs a reality I thought of the children I've met for whom progress will come tragically too late. I thought about Umi, who became a symbol of hope during the devastating drought in Kenya in 2011 when she pulled back from the brink of severe malnutrition - only to die two years later from pneumonia and diarrhoea because her family were too poor and too far from a clinic. I will be fighting to make sure that by 2030, children like Umi have a chance at life.