The Rising Tide: Understanding Sea Level Rise and Its Causes
As a coastal resident, you might be questioning recent reports and observations, as the sea level has remained relatively stable for the past 62 years. However, global trends indicate a more concerning picture. Currently, the global average sea level is rising at a rate of 4 mm or 0.14 inches per year. This rate is not uniform; in some areas like the Marshall Islands, it is double this.
Global Sea Level Trends
While the Marshall Islands have experienced a notable increase in land area due to natural wave action and coral regrowth, other regions are seeing more significant effects. For example, the Bikini Atoll, a site of multiple atomic bomb tests, had data collected from a test core that drilled into the coral, revealing a submerged original volcano at one mile in depth. This geological evidence highlights the significant impact of sea level rise, equivalent to one mile of sea elevation over time.
By the year 2100, projections indicate a significant increase in sea levels. The Intergovernmental Panel on Climate Change (IPCC) projects that the global average sea level could rise by 280 mm or 11.0 inches. This could have profound implications for coastal regions, necessitating proactive measures such as sandbag preparations.
Monitoring Sea Level Changes
Accurately measuring sea level changes is a complex task, requiring ongoing and meticulous recalibration of instruments and data. Satellites, while providing valuable insights, still require periodic checks to ensure the accuracy of the data. Long-term trends show that since 1860, the average sea level has risen approximately 8-10 inches per century, or 20-23 mm per decade.
The data from the NOAA tide gauge at The Battery in Manhattan Island, one of the oldest continuous records available, provides a linear trend of about 8 inches per century. Despite the near-doubling of CO2 levels from 260 ppm to 430 ppm, the rate of sea level rise has not accelerated. This observation raises questions about the role of CO2 in exacerbating sea level rise and poses challenges to the existing climate change models.
Other Coastal Tide Gauges
It's important to note that the trends observed in the Manhattan tide gauge do align with other coastal tide gauges across the world. A thorough examination of these data points favors a consistent pattern of sea level rise, although local subsidence can sometimes complicate these measurements. The Mississippi Delta, for instance, experiences land subsidence, which can make the apparent rate of sea level rise appear higher than it actually is.
These findings raise important questions about the mechanisms driving sea level rise and the need for further research and understanding. If a near doubling of CO2 doesn't cause the predicted acceleration in sea level rise, this indeed challenges the central tenets of some climate change doctrines.
Conclusion
The evidence gathered from various sources and long-term tide gauge records suggests a steady, though not accelerating, sea level rise. This information is crucial for policymakers, planners, and coastal communities worldwide to develop adaptive measures and strategies to mitigate the impacts of rising sea levels.