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Rising Tides, Sinking Shores: Coastal Flooding and Climate Change

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  30-Jan-2024 | Arifa Nadeem

This blog addresses the critical issue of coastal flooding and its connection to climate change. Human activity in coastal locations is being impacted by rising and falling sea levels. Rising sea levels inundate low-lying wetlands and dry land, erode shorelines, contribute to coastal flooding, and increase the flow of salt water into estuaries and surrounding freshwater and groundwater. Additionally, coastal infrastructure is more susceptible to storm damage as sea levels rise.

Coastal Flooding

Flooding is becoming more common as sea levels rise and the difference between average sea level and land height narrows. This form of tidal flooding is likely to grow in size and frequency. Many coastal cities have set "nuisance" flooding (also known as high tide flooding) thresholds. When water rises over this level, minor flooding usually occurs.

Recurrent coastal flooding can have serious consequences, including frequent road closures, limited storm-water drainage capacity, and deterioration of infrastructure that was not designed to resist recurrent inundation or saltwater exposure. Coastal flooding can also impact human health, such as increasing the risk of drinking water and wastewater infrastructure failure, and exposing people to diseases and harmful substances.

Rising Sea Levels

One of the repercussions of climate change is rising sea levels. Since 1880, average sea levels have risen by more than 23 cm, with the last 25 years accounting for almost three of those inches. Every year, the sea rises by 3.2 mm. According to research published in February 2022, sea level is rising and is expected to increase by 1 foot by 2050. Most of the observed sea-level rise is caused by melting water from land-based ice sheets and mountain glaciers, which contributes to the ocean's volume as well as thermal expansion.

While the absolute sea level has consistently climbed over time, particularly in recent years, regional trends differ, and the absolute sea level has declined in some places. Relative sea level has not risen consistently due to regional and local shifts in land movement, as well as long-term changes in coastal circulation patterns. Sea level rises and falls as the Earth's temperature changes. There are two basic reasons why temperature and sea level are linked:

• Changes in the volume of water and ice on land (glaciers and ice sheets) can raise or lower the volume of water in the ocean.
• Water expands slightly when it heats, a phenomenon that occurs throughout the ocean's depths.

Understanding the Causes

As humans continue to emit greenhouse gases into the atmosphere, oceans have mitigated the effects. The world's waters have absorbed more than 90% of the heat from these gases, but it's having an impact on our oceans: 2021 established a new record for ocean warming.

Coastal flooding and rising sea levels result from a combination of natural processes and human activities. Here are the primary causes of these phenomena:

• The Earth's average temperature is rising due to human-induced climate change. This warming contributes to the melting of glaciers and ice sheets in Polar Regions, releasing freshwater into the oceans and causing sea levels to rise.
• As the atmosphere warms, the ocean absorbs heat. This warming causes seawater to expand, leading to an increase in sea level. Thermal expansion is a significant contributor to rising sea levels.
• The burning of fossil fuels releases greenhouse gases (such as carbon dioxide) into the atmosphere, trapping heat and causing global temperatures to rise. This warming effect contributes to the melting of ice and thermal expansion of seawater.
• The sinking or subsidence of land, whether due to natural geological processes or human activities (such as excessive groundwater extraction or oil and gas extraction), can amplify the impact of rising sea levels by lowering local elevations.
• Intense tropical storms, hurricanes, and cyclones generate powerful winds and low atmospheric pressure, leading to storm surges. These surges can cause temporary and localised increases in sea level, resulting in coastal flooding.
• The gravitational pull of the moon and the sun causes tides. During certain lunar phases, such as spring tides, high tides are more extreme. When combined with other factors, such as storm surges, it can lead to coastal flooding.
• Coastal ecosystems, including mangroves, marshes, and coral reefs, act as natural buffers against storm surges and flooding. Human activities that degrade or remove these natural barriers contribute to increased vulnerability.
• Underwater landslides and earthquakes can displace large volumes of water, causing tsunamis and localised changes in sea levels that lead to coastal flooding.
• Removing natural vegetation can impact the ability of ecosystems to absorb and slow down water, exacerbating flooding.
• Natural climate variations, such as El Niño and La Niña events, can influence sea levels and precipitation patterns, leading to short-term variations in coastal flooding.

These complex and multifaceted challenges require a comprehensive approach that integrates environmental science, policy-making, community engagement, and innovative solutions.

Key Aspects and Strategies for Navigating These Challenges

Environmental Science and Monitoring

• Using advanced meteorological data to predict and understand extreme weather events contributing to flooding.
  • Implementing robust monitoring systems for tracking sea level rise and assessing its impact on coastal areas.
• Flood monitoring systems provide real-time data and insights into numerous aspects such as flood levels, velocity, and rainfall, enabling early warnings and rapid response.
  • They assist authorities, communities, and organisations in making informed decisions, thereby decreasing the loss of life and property.
• Investing in research and development of innovative technologies for flood prediction, mitigation, and adaptation.
  • Exploring sustainable and eco-friendly technologies to address coastal challenges without further harming the environment.

Policy and Planning

• Development and implementation of the policies that integrate climate resilience into coastal management plans.
  • Establishing stringent zoning regulations to guide responsible development in vulnerable coastal areas.
• Adopting adaptive planning strategies that account for changing climate conditions and uncertainties.
  • Supporting communities in developing diverse and resilient economies to reduce dependence on vulnerable sectors.
  • Exploring insurance and financial mechanisms to assist communities in recovering from the economic impacts of flooding.
• Establishing and strengthening legal frameworks that ensure responsible environmental stewardship and protect vulnerable coastal areas.
  • Implementing liability mechanisms to hold entities accountable for activities that contribute to coastal degradation.

Infrastructure and Engineering Solutions

• Promoting the use of natural infrastructure such as wetlands and mangroves to act as buffers against storm surges.
• Exploring innovative engineering solutions like seawalls, levees, and stormwater management systems.
  • Encouraging resilient building design and retrofitting of existing infrastructure to withstand flooding.

Community Engagement

• Raising awareness about the impacts of climate change and flooding among local communities.
  • Involvement of the communities in the planning and decision-making processes to ensure their needs and concerns are considered.
• Establishing effective communication and early warning systems to alert communities about imminent flood risks.

International Collaboration

• Encouraging collaboration between countries to share knowledge, technology, and resources for tackling trans boundary issues related to coastal flooding.
• Advocate for international agreements that address the root causes of climate change and its impact on coastal regions.

Conclusion

Addressing the challenges of these rising tides and sinking shores requires a holistic and collaborative effort from governments, communities, scientists, and businesses. By combining scientific understanding, effective policies, community engagement, and innovative solutions, it is possible to navigate these challenges and build a more resilient and sustainable future for coastal regions.

Sources:

https://www.epa.gov/climate-indicators/climate-change-indicators-coastal-flooding

https://www.epa.gov/climate-indicators/climate-change-indicators-sea-level

https://sealevel.nasa.gov/faq/12/what-causes-sea-level-rise/#:~:text=Most%20of%20the%20observed%20sea,roughly%201%20mm%20per%20year).

https://www.nationalgeographic.com/environment/article/sea-level-rise-1

https://ysi.com/applications/flooding#:~:text=Flood%20monitoring%20systems%20offer%20real,loss%20of%20life%20and%20property.