Since the late 1980s, modern seismic stations around the world have been taking the pulse of the planet. The dull, steady sound of ocean waves, once thought of by seismologists as background noise, has been getting louder since the late 20th century, echoing off deeper seas, according to a study led by the University of Colorado. The climate is warming. The ocean floor in coastal areas experiences constant push and pull from these waves, and these pressure changes create increasingly intense seismic waves.  As ocean waves rise and fall, they exert forces on the seafloor, creating seismic waves. These seismic waves are so strong and widespread that they show up as regular noise on seismographs. ,  the same instruments used to monitor and study earthquakes. Study published in Nature Communications examines data from 52 seismic stations that record Earth's movements once a second for more than 35 years. The decades of data confirm findings from independent climate and ocean research that suggest storms are not only becoming more intense as the climate warms, but that they are also shaking the ocean. (ALEXANDRA AGETA)