A sinking of the oceanic crust could have caused the sea level to drop by 30 meters. – Evidence Network

Report on Tectonic Influences on Global Sea Level and Sustainable Development Goals

1.0 Introduction: A Paleo-Perspective on Climate and Ocean Health

A recent study published on the AGU scientific platform provides critical insights into long-term sea-level dynamics, offering a geological context for current environmental challenges outlined in the Sustainable Development Goals (SDGs). Research conducted by Colleen A. Dalton and colleagues reveals that a significant slowdown in oceanic crust formation between 15 and 6 million years ago caused a global sea-level fall of 26 to 32 metres. This historical analysis of Earth’s systems directly informs our understanding of SDG 13 (Climate Action) and SDG 14 (Life Below Water) by demonstrating the profound impact of geological processes on the planet’s oceans and climate, contrasting sharply with today’s anthropogenic sea-level rise.

2.0 Primary Causal Factor: Reduced Seafloor Spreading

The study’s central finding identifies a 35% decrease in oceanic crust production during the specified period. This reduction in the rate of new rock formation at ocean ridges had cascading effects on the global environment.

2.1 Deepening of Ocean Basins and Sea-Level Fall

The primary consequence of slowed tectonic activity was the gradual cooling and sinking of the oceanic crust, which led to a deepening of ocean basins. This structural change is the direct cause of the estimated sea-level drop. Understanding such large-scale fluctuations is vital for developing resilient coastal infrastructure and planning for SDG 11 (Sustainable Cities and Communities).

1. Mechanism: Reduced production of new, buoyant oceanic crust at ridges allowed older, denser crust to dominate, increasing average ocean depth.
2. Quantification: Calculations incorporating crust age, surface area, and destruction rate indicate a sea-level fall between 26 and 32 metres.
3. Relevance to SDGs: This data provides a crucial baseline for long-term climate models, reinforcing the scientific foundation for SDG 13 (Climate Action).

3.0 Associated Environmental Impacts and SDG Linkages

The slowdown in crustal production triggered significant changes in global energy and chemical cycles, with direct implications for multiple SDGs.

3.1 Altered Geothermal Heat Flow and Ocean Chemistry

The Earth’s internal heat, a key component of the planet’s energy system, was significantly affected. This has direct relevance to SDG 14 (Life Below Water), as ocean chemistry is fundamental to marine ecosystem health.

• A reduction in heat dissipation from the Earth’s mantle, averaging 8% globally and up to 35% at ocean ridges, was observed.
• This thermal change would have altered hydrothermal interactions and the dissolution of minerals, impacting the biogeochemical balance of the oceans.
• This highlights the sensitivity of marine environments to geological-scale changes, underscoring the urgency of protecting them from modern stressors as targeted by SDG 14.

3.2 Reduced Volcanic CO₂ Emissions and Climate Feedback

The decrease in submarine volcanic activity led to a reduction in natural carbon dioxide (CO₂) emissions, a key driver of the period’s global cooling. This provides a powerful paleo-analogue for understanding the climate dynamics central to SDG 13 (Climate Action).

• Lower atmospheric CO₂ levels contributed to global cooling, which in turn promoted the expansion of continental ice caps.
• This expansion sequestered vast amounts of water on land, creating a positive feedback loop that caused an additional sea-level drop of over 60 metres.
• This interplay between the carbon cycle and the global water cycle provides critical knowledge for managing Earth’s resources, a theme related to SDG 6 (Clean Water and Sanitation).

4.0 Conclusion: Geological Insights for a Sustainable Future

The study’s findings, supported by stratigraphic data from New Jersey and Nova Scotia, represent a significant advancement in scientific innovation, aligning with the principles of SDG 9 (Industry, Innovation, and Infrastructure). By elucidating the powerful influence of natural geological cycles on sea level, climate, and ocean chemistry, this research provides an invaluable long-term perspective. It underscores the profound sensitivity of the Earth’s systems and reinforces the critical importance of achieving the Sustainable Development Goals to mitigate the impacts of current, unprecedented anthropogenic change.

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

   The article’s discussion on historical climate change, ocean dynamics, and geological processes connects to the following Sustainable Development Goals:

   • SDG 13: Climate Action: The article directly discusses factors influencing global climate, such as a decrease in CO₂ emissions from submarine volcanic activity leading to “global climate cooling.” It also contrasts this historical event with modern “rising sea levels… mainly attributed to global warming,” placing the study’s findings within the broader context of climate science.
   • SDG 14: Life Below Water: The core of the article focuses on oceanographic changes. It describes the “deepening of ocean basins,” alterations in “ocean chemistry,” and the impact of heat dissipation from the Earth’s mantle on “hydrothermal interactions and the dissolution of minerals in seawater.” These topics are central to understanding the physical and chemical state of the oceans.

2. What specific targets under those SDGs can be identified based on the article’s content?

   Based on the article’s focus on scientific research and understanding Earth’s systems, the following targets can be identified:

   • Target 13.3: Improve education, awareness-raising and human and institutional capacity on climate change mitigation, adaptation, impact reduction and early warning. The study itself, published on a “scientific platform,” contributes to the fundamental scientific knowledge required to build capacity and awareness. Understanding past climate events, like the “global climate cooling” mentioned, is crucial for refining climate models and improving our understanding of the Earth’s climate system.
   • Target 14.3: Minimize and address the impacts of ocean acidification, including through enhanced scientific cooperation at all levels. The article’s mention of changes in “ocean chemistry” and “dissolution of minerals” due to geological processes is directly related to the chemical balance of the oceans. The study is an example of “enhanced scientific cooperation” that deepens the understanding of factors affecting marine environments.
   • Target 14.a: Increase scientific knowledge, develop research capacity and transfer marine technology… in order to improve ocean health and to enhance the contribution of marine biodiversity to the development of developing countries. The entire article is a summary of a scientific study that increases knowledge about long-term ocean dynamics. It details how researchers used data on “oceanic crust production,” “heat flow from the Earth’s mantle,” and “submarine volcanic activity” to understand historical sea-level changes, directly fulfilling the goal of increasing scientific knowledge about the ocean.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

   Yes, the article mentions or implies several indicators that are used to measure the phenomena discussed, which align with monitoring progress towards the identified targets:

   • Global Sea Level: This is a primary indicator mentioned throughout the article. Specific measurements are provided, such as a “sea levels to fall by 26 to 32 metres” and an “additional sea level drop of more than 60 metres.” Monitoring sea level is a key indicator for both climate change (SDG 13) and ocean health (SDG 14).
   • Carbon Dioxide (CO₂) Emissions: The article explicitly links a decline in submarine volcanic activity to a “decrease in CO₂ emissions.” While the source is geological rather than anthropogenic, the measurement of atmospheric CO₂ is a fundamental indicator for tracking climate change under SDG 13.
   • Ocean Chemistry Parameters: The article implies the use of indicators related to ocean chemistry by mentioning its alteration, including “hydrothermal interactions and the dissolution of minerals in seawater.” This relates to indicators like ocean acidity (pH), which is used to track progress on Target 14.3.
   • Rate of Oceanic Crust Production: The study’s central premise is based on measuring a “35% decrease in oceanic crust production.” This geological metric serves as an indicator for understanding the tectonic forces that influence both climate and ocean basin shape.

SDGs, Targets, and Indicators Table

Source: evidencenetwork.ca