The Integrated Public Alert and Warning System (IPAWS) will give the U.S. the ability to send out urgent public alerts over many different media at once.  IPAWS envisions radio, TV, satellite and cable, cellular telephone alerts, alerting weather radios, and various other warning technologies, all delivering a coordinated message, simultaneously and consistently.

But why bother?  There are obvious reasons, and others that might be less obvious.

Certainly there are the simple mechanical benefits of reach and reliability.  By using multiple warning channels in parallel we minimize the number of people who might miss an alert sent over only a single system.  By putting our warning eggs in more than one basket we also hedge against the possibility that one or more of systems might fail us; humankind has yet to invent a technology that doesn’t break down at least occasionally.

We also improve the odds that an accurate warning will get out in time.  Officials who issue public warnings rarely get to work under ideal conditions.  Time is always in short supply, and there are competing demands on their attention.  The last thing they need is a grab bag of computer screens and checklists for activating different warning systems.  A “write it once” approach to originating alerts lets the emergency official do it once, do it right, and get on with her other urgent duties.

But wait.  “Was that an alert I just heard?  Hmmm… probably not.  I don’t see anything unusual happening.  I’ll just wait and see if I hear anything else.”  Sound typical?  Fifty years of research say it is.  The scientists tell us people almost never take protective action based on a single warning message.  Nobody wants to overreact—or be perceived by others as overreacting!

The most we can hope for, the research tells us, is that people who receive an initial alert will become vigilant, sensitive to confirming evidence.  So corroborating an alert through multiple delivery channels isn’t just more reliable technically, it’s also more likely to trigger protective action in humans.

Even once people decide a threat is real, they generally don’t act alone.  This leads to the “milling” phenomenon identified by warning scientist Dennis Mileti.  “Milling involves people discussing the information with other people…and discussing the options that are available to them.”  To move people to effective protective action in an emergency, it’s not enough to deliver corroborated alerts to individuals.  We also need to achieve a “critical density” of awareness and belief in the reality of a threat among the families, groups and communities at risk.

(Mileti and his colleague Jeanette Sutton at the University of Colorado have done some interesting work (PDF) on how emerging “social media” can augment official warning systems by, among other things, their effect on this milling process.)

So IPAWS is more than just a technological advance.  It’s also, and more importantly, a practical application of state-of-the-art policy and science in public safety and homeland security.