This letter was submitted by Richard Blewitt, chief executive of HelpAge International, to the editor of the Herald Tribune.

Wednesday [October 1st] is the UN International Day of Older People–a time to celebrate and recognize the contribution of older people to global society.

In the developing world, this contribution could not be clearer. Older people are at the frontline of the battle against HIV, caring for the sick and for grandchildren orphaned by the pandemic. In disaster situations, it’s the wisdom and experience of older people that enable communities to rehabilitate and rebuild. Older people also make a huge economic contribution, working long into old age to support themselves and their extended families.

Yet 100 million older people still struggle to survive on less than $1 per day. Their economic and social potential is both unrecognized and unsupported. For the sake of older people, their families and communities, and global development, this cannot continue.

On Wednesday, older people in 36 countries will join together under the banner of Age Demands Action, a global campaign to press for change. They will meet with their national governments to call for improved aging policies and practices in their countries. They will call on the international community to recognize and include older people in responses to tackle poverty, HIV and abuses of human rights.

By 2050, one in five of the world’s population will be over the age of 60, with over three quarters in developing countries.

In an aging world, investing in older people has never been more crucial.