While the're putting the finishing touches on the controversial fence along the southern border between the U.S. and Mexico, the outrage is far from over. The multi-billion dollar plan to build some 700 miles of fencing has been billed as the way to stem the flow of undocumented immigrants and provide security from potential terrorism. NOW senior correspondent Maria Hinojosa travels to Texas to meet border families who fear losing their property, their safety, and their way of life. Many question if the fence can keep people from sneaking in at all. An even greater worry may be the virtual fence the Obama administration is planning for the remaining 1,300 miles of border, at an estimated cost of nearly $7 billion. The problem? The new technology to complete the virtual fence has not been proven to work in the field.

Also this week, global warming is front and center in Washington with the passage of the climate bill in the House. We look below the surface at a growing body of evidence that suggests climate change is affecting the chemistry of the seas, which could have potentially catastrophic results on the way we live. NOW travels deep into our oceans with a scientist from the Woods Hole Oceanographic Institution and help from other researchers for a first hand look at this stunning sea change, and what we can do about it.