Global warming is rocking the world harder — literally!

Much like a shiver announcing a fever, the Earth has been demonstrating various pangs to warn us of the bleak crisis-riddled future ahead. From intensifying natural disasters to worsening pandemics, the planetary symptoms are only getting worse every passing day. And now, scientists have discovered that the effects of climate change are literally rocking the world we live in!

A new study has found that climate-induced changes have been affecting the behaviour of ocean waves, especially those driven by storms. Over the past four decades, these waves have not just caused sea levels to rise, but are also shaking the Earth — literally.

Seismologists use instruments called seismographs to monitor and study earthquakes. However, these sensitive machines also record a wide range of natural and human-caused seismic phenomena, from volcanic eruptions and meteor strikes to even human activities and environmental changes. Interestingly, seismographs noted a decrease in human-caused seismic noise due to COVID-19 lockdown measures worldwide in 2020.

While seismographs spike during certain strong events, they also have a constant background thrum of shakiness, which scientists have been able to identify as driven by storm-driven ocean waves. These global microseisms provide unique insights into the state of our oceans and the broader climate system.

In general, ocean waves are gently shaking the planet in two ways. The primary microseism is where the ocean waves directly push and pull on the seafloor, prominently in regions where the depth is less than 1,000 feet. The other method, termed secondary microseism, is when waves interact with each other, applying a variety of pressures on the seafloor.

This study, in particular, focused on the primary variant, looking back at the history of such jolts since the 1980s. Out of 52 seismograph sites around the world with extensive records, 79% of these stations showed that the waves are beginning to turn more energetic, and thus imparting a stronger background hum to the Earth.

The team also found that the ocean wave energy has been increasing at a median rate of 0.27% per year since the late 20th century. However, since 2000, this increase rate has risen to 0.35% per year. While the change might seem small, it reflects a worrying trend of intensifying ocean wave activity. With the oceans absorbing 90% of the excess heat from human activities, the added energy is translating into more damaging and powerful ocean waves.

The regions experiencing the most significant microseism energy are found in the Southern Ocean near the Antarctica peninsula, a generally stormy part of the world. However, the study also highlighted that North Atlantic waves have seen the fastest intensification in recent decades. This aligns with research indicating an increase in storm intensity and coastal hazards in the North Atlantic.

If this trend continues, it spells further disaster for coastal communities, which are already prone to rising sea levels. Soaring ocean wave heights can pose a considerable threat, causing damage to infrastructure and eroding coastlines. When combined with ongoing sea level rise and subsidence, these impacts become even more pronounced.

The seismic data also reveals the seasonal variations in strong winter storms between the Northern and Southern hemispheres and their connections to phenomena like El Niño and La Niña. These findings underscore the complex relationship between climate change and ocean dynamics. Climate change is not just affecting our environment; it's literally shaking the Earth beneath our feet, demanding our attention and action. It's time we reciprocate.