What Would Be the Estimated Sea Level Rise Without Tidal Influences?

The often-misunderstood relationship between tides and sea level rise is a common point of confusion in discussions about climate change and ocean levels. While tides do play a significant role in the daily variability of ocean heights, they do not directly impact the long-term measurement of sea level rise.

The Role of Tides in Sea Level Monitoring

Tides, caused by the gravitational pull of the moon and the sun, cause the rise and fall of the ocean twice a day. Sea level rise, on the other hand, is measured from a constant point of reference, typically from the daily low tide mark or the high tide mark. These reference points change throughout the year due to the cyclical nature of the gravitational impacts of the sun and moon. Therefore, when we measure sea level rise, we are not accounting for the day-to-day tidal variations.

Understanding Sea Level Rise

Current scientific measurements show that global sea level rise is approximately double what it was forty years ago. More than half of this rise is attributed to the thermal expansion of ocean waters, which occurs as the oceans warm due to increased greenhouse gas concentrations. The melting of ice sheets, particularly those in Greenland, also contributes significantly to sea level rise.

Thermal Expansion and Ice Melt

Thermal expansion is the dominant factor today, and this is expected to continue as long as global temperatures remain elevated. Greenland's ice sheet is currently the largest contributor to ice melt, but other factors like temperature changes and ocean currents will continue to influence this trend. It's important to note that even if fossil fuel use is phased out, thermal expansion and ice melt may not immediately slow down, given the inertia of the climate system.

Global Sea Level Balance

The global sea level is a balance between rising and falling areas. Without tidal influences, the sea level rise we experience would be measured from the point where the seas would naturally settle if not for these forces. Other significant factors that influence sea level, such as hurricanes and typhoons, also contribute to the rise through their powerful winds and storm surges.

Planetary Gravitational Influences

While the moon and sun cause the most prominent tidal effects, other planetary bodies like Saturn and Jupiter exert minor gravitational forces that also impact ocean levels. However, these effects are not significant enough to be a primary consideration in measuring sea level rise.

Time-Dependent Factors in Sea Level Rise

Your question is incomplete without specifying a time frame. Sea level rise is not a static process. It has varied over geological time scales and is expected to continue as long as climate conditions persist. The rate of rise can also vary over shorter periods due to natural and human-induced factors like El Ni?o events.

Conclusion

Without tidal influences from the sun and moon, the sea level rise we would measure would be similar to the average of the flood and ebb tide at any specific location. However, the dominant forces driving this rise are thermal expansion and melting ice. While the replacement of fossil fuels with renewable energy could potentially slow down thermal expansion, other factors like temperature changes and ice melt will continue to impact sea level rise.