Oregon researcher says West tides increasing

An Oregon researcher says the tides are getting bigger along the West Coast, possibly speeding up erosion.Portland State University engineering professor David Jay says the amplitude of tides from Alaska to Mexico has increased - meaning the change between the highest and lowest tides is bigger.Jay says global climate change is likely to blame - along with rising sea levels.But scientists had previously believed the tides remained constant because they are driven by gravitational forces between the Earth and the moon.The Portland State study showed one of the biggest changes in the tides has been in Astoria - with the range increasing by nearly a foot a century.