When it comes to assessing housing problems that accompany overpopulation, natural disasters, political conflicts, and economic failure, Habitat for Humanity and the United Nations probably have as realistic a perspective on the situation as one can get.

UN studies indicate that more than 100 million people worldwide are homeless and millions more occupy shelters in neighborhoods without adequate sanitation, utility services, or security. Just as alarming as the squalor of these communities is the rate at which these housing deficiencies are expected to grow. The UN estimates that more than 2 million housing units will be needed each year for the next 50 years to solve the present worldwide housing crisis. But even that won’t keep pace with the actual housing needs of the global population as it expands at predicted rates: by 2060 there still may be a need for an additional 1 billion houses.

On Monday, October 5, the UN and Habitat for Humanity will be calling attention to the world’s housing crises with World Habitat Day, an annual observance that was initiated by the United Nations General Assembly in 1985 and has been marking progress and setbacks in the international community ever since.

The theme for World Habitat Day 2009 is “Planning Our Urban Future,” which is pegged to the fact that more than half the world’s population lives in urban areas, and, on average, a third of those people live in slum-like conditions.

For those motivated to improve this situation, Habitat for Humanity offers a few suggestions:

1. Let your representatives in Congress know that you want them to make affordable housing a priority. Habitat for Humanity International has a Web page (click here) featuring a prewritten message that voters can send to their representatives in both the House and Senate.

2. Become an advocate for affordable housing and neighborhood revitalization in your community. On online resource is Habitat’s Shelter Report 2008 (click here), which details the problems of “insecure tenure” – the lack of title to one’s home or land – and its connections to poverty. More generally, the organization also offers an overview of paths to community improvement on its World Habitat Day 2009 resources page (click here).

3. And, of course, you also can support Habitat for Humanity’s programs through donations (click here to reach its donations page).