The conventional method for assessing sea level rise has relied on tide gauges, which might seem straightforward. Collecting data on high and low tides along coastlines, analyzing it, and publishing results appears simple.

However, the reality is much more complex.

Challenges with Tide Gauges

There are inherent issues with relying solely on tide gauge data; without proper context, the readings can be misleading. The simplistic notion that water levels rise uniformly is flawed.

Tide gauges are fixed on land, meaning they are susceptible to shifts in the Earth's crust, influenced by both natural events and human actions. For example, the melting of glaciers can cause land to rise, while earthquakes and human activities like groundwater extraction and dam construction also play a role.

Furthermore, tide gauges provide localized data rather than a comprehensive global picture. Our planet is not flat but rather a self-gravitating, compressible sphere, which results in significant global variations.

The situation is further complicated by the fact that melting ice is not the sole contributor to rising sea levels.

Heating water leads to increased kinetic energy among water molecules, causing them to spread apart. Thus, as ocean temperatures rise, the water expands, and approximately half of the current sea level rise can be attributed to thermal expansion.

This raises questions about the reliability of our measurements and the confidence we have in understanding sea level rise.

Advancements in Measurement Tools

For the past three decades, satellites have provided us with a far more accurate means of measuring sea levels.

The journey began on August 10, 1992, with the launch of TOPEX/Poseidon, which has led to continuous monitoring since then, including:

1. TOPEX/Poseidon (1992 to 2006)
2. Jason-1 (2001 to 2013)
3. The Ocean Surface Topography Mission/Jason-2 (2008 to 2019)
4. Jason-3 (2016 to present)
5. Sentinel-6 Michael Freilich (2020 to present)

The principle is straightforward: satellites emit microwave pulses that bounce off the ocean's surface. The time it takes for these pulses to return allows for precise calculations of sea surface height. While the concept is simple, the execution is complex, requiring precise positioning of the satellites.

The data generated by these satellites vastly surpasses earlier tide gauge readings. With three decades of continuous operation, we now possess insights that extend beyond seasonal and decadal fluctuations.

Key Insights

The most significant findings include:

• Sea levels are indeed rising.
• The rate of this rise is accelerating.

In the 1990s, the average annual rise was 2.5 mm, which has now escalated to 3.9 mm per year.

You may wonder, what does 3.9 mm mean? While it may seem trivial, it accumulates over time, and given the accelerating rate, it is a cause for concern.

Since 1992, the global average sea level has increased by 10.1 cm (approximately 3.98 inches).

Looking Ahead

A report from February 2022 predicts that by 2050, the US coastline could see an increase of 10 to 12 inches above current levels. Notably, 2050 is just around the corner, less time away than the interval since the launch of the first satellite.

This is not a gradual rise; events like King Tides and storm surges will become more frequent and intense.

What happens beyond 2050? The projections are alarming. By 2100, sea levels could potentially rise by as much as 1.1 meters.

This rise will affect hundreds of millions, possibly close to a billion people.

Our previous emissions have already ensured a rise that cannot be avoided. A recent paper in Nature indicates that we are locked into a minimum sea-level rise of 27 cm (10.6 inches) from Greenland alone, even if fossil fuel emissions ceased immediately.

The term "minimum" is crucial here.

Dr. William Colgan from Geus states, "The minimum of 27 cm is the sea-level rise deficit that we have accrued to date and it’s going to get paid out, no matter what we do going forward. Whether it’s coming in 100 years or 150 years, it’s coming."

Colgan also noted that if years like 2012 become the norm, the committed rise could escalate to 78 cm. This stark difference highlights the importance of the Paris Agreement and the potential to mitigate damage.

Are We Out of Options?

The short answer is no.

Immediate actions we can take include:

• Addressing the root causes by reducing emissions now. We will have to make these reductions, either voluntarily or under pressure from nature. It’s better to choose now.
• Constructing flood defenses. Understanding future risks enables proactive planning, which may include strategic retreats in vulnerable areas.
• Protecting carbon sinks like forests and grasslands.

Why This Matters Now

Institutions monitoring sea levels are collaborating to raise awareness through a joint initiative. Here are some reputable sources:

• NASA Earth Observatory (Aug 11, 2022): Tracking 30 Years of Sea Level Rise
• World Economic Forum (Aug 25, 2022): 30 years of sea level rise in 2 charts

What Else Is at Stake?

It's not just Greenland at risk. The East Antarctic ice sheet could collapse if global temperatures rise beyond 2°C, which is alarmingly close. If all Antarctic ice melted, sea levels could rise by 52 meters.

While such a scenario would unfold over centuries, the implications are dire. Exceeding 2°C could lead to a rise of 1.5 to 3 meters by 2300, and potentially up to 5 meters by 2500.

Currently, these outcomes represent the "do nothing" scenarios, but we still have choices that can mitigate the worst effects.

Oceanic Impact

Heat waves also affect oceans, which have absorbed over 90% of excess heat from climate change. Since around 1990, ocean heat content has been increasing rapidly, with the upper layers containing more thermal energy than the entire atmosphere.

Final Thoughts: The Urgency to Reduce CO2 Emissions

Your voting choices matter. We need leaders who will take decisive action.

One critical graph to consider is the Keeling Curve, which illustrates the CO2 emissions we are generating and where we currently stand. This is the curve we must work to bend downward.

What Lies Ahead?

I hope for a resolution to these challenges. With sufficient political will, we could indeed succeed.

However, I worry that the necessary depth of commitment is lacking. We may continue to respond reactively, with some individuals doing their best while others assume someone else will manage the situation.

As events unfold, we will take action, but by then, we may already be facing many consequences. The best we might achieve is to slow down the pace of change, buying time to adapt.

I sincerely hope to be proven wrong.

Can We Act Now?

Yes, we can. Consider the following actions:

• Accelerating the adoption of electric vehicles to replace internal combustion engines.
• Utilizing renewable energy sources such as solar, wind, nuclear, and geothermal to meet our energy needs without fossil fuels.
• Transitioning to green steel production, which accounts for about 10% of global emissions.
• Exploring green hydrocarbon fuels for air travel.
• Investigating CO2 capture technologies.

Yes, these initiatives require investment.

However, the cost of inaction will far exceed the expenses of taking meaningful steps.

As we hesitate, sea levels will continue to rise at an alarming rate.

Am I putting my own resources into action? Absolutely. I have solar panels and batteries on the way. The investment pays off more quickly than one might think, especially compared to costs from just a few years ago. So, I’m committed to action, not just words.

Please consider how you can contribute to a greener future.