Changes, linked to the rapid increases in atmospheric greenhouses gases, are already affecting global climates and the oceans, and such changes are expected to accelerate in coming decades. The most widespread change at present is that of warming, not only of the air but also of oceanic surface waters. These temperature changes in turn drive changes in precipitation, and in the patterns of storms and ocean currents. River flows may also be changed. Sea level rise is a further direct consequence of warming – it arises from the natural expansion of water as it warms, and from the increasing volume of water driven by the melting of large ice-caps. A second major influence in coastal areas is likely to come through ocean acidification.
Storms, rainfall and rivers. The exact patterns of changes in the weather are often hard to predict at local scales, but increases in storm intensity and frequency are likely in many areas. Storms are among the major drivers of change in coastal areas, often causing flooding and rapid erosion, but in some cases releasing very large volumes of sediment. Gradual changes in climate and precipitation will also cause changes in growing conditions for plants and animals. Likewise increases or reductions in the flow of freshwater from the land to the sea will greatly influence the survival and growth of critical coastal ecosystems such as mangroves and salt marshes.
Sea level rise. Sea levels have already risen by 20 cm or more in many areas, and rise rates appear to be accelerating, although there remains little consensus as to how fast such changes will be in the future. Estimates of global sea level rise hide a diverse range of changes at local scales, which are driven by regional atmospheric and oceanographic drivers, as well as by the influence of natural changes in elevation of the land itself. Where seas are rising, the threat to adjacent coastal lands is not simply that of gradual inundation of low-lying areas, but also of increased rates of erosion even along higher shorelines.
The result of these combined factors will likely be more devastating coastal storm events, combined with ongoing increased coastal erosion and flooding, gradual inundation of low-lying lands, and, in many areas, the salinization of groundwater. Even under the most optimistic mitigation scenarios, impacts are likely to be considerable and will continue increasing over the next decades.
Ecosystem impacts. The ecosystems on which natural coastal protection depends are themselves likely to be influenced by climate change and future planning needs to account for this. Rising temperatures are at least partly to explain for expansion of mangroves in higher latitudes in Australia, New Zealand and the Gulf of Mexico. Loss of ice-scour is equally likely to enable expansion of salt marshes in polar regions. By contrast warming waters have clearly had negative impacts on coral reefs through coral bleaching. Increasing concentrations of carbon dioxide may have positive effects on growth rates of coastal vegetation, but the impact of ocean acidification is also predicted to be severe on coral reefs and other calcifying organisms.
For more resources on climate change visit NOAA Climate.gov. NOAA Climate.gov is a source of timely and authoritative scientific data and information about climate.
Risk and vulnerability assessments are an integral component of the Coastal Resilience approach and help identify who or what is at risk and which characteristics of these human or ecological systems make them more or less susceptible to the damaging effects of coastal hazards and sea level rise.
A Risk Assessment Framework includes the following components:
Risk = Exposure * Vulnerability
Vulnerability = Susceptibility * Coping Capacity * Adaptive Capacity
Exposure describes the who or what is exposed to the hazard while vulnerability describes the characteristics and circumstances of a community, system or asset that make it susceptible to the damage. This follows a framework consistent with many site-based risk and vulnerability estimates locally, regionally and globally.
We have built upon the Risk Assessment Framework to develop tools and resources to help coastal communities and decision makers understand where natural coastal protection can help to reduce risk.
Tools & Apps
There are a number of tools and applications built into the Coastal Resilience decision support system that address risk and vulnerability. Below is a list of those features:
The Community Planning app is the location where resilient communities host their locally specific data to inform their decisions and track their successes. It is also where the community comes to view their information alongside and with the other Coastal Resilience data layers. This app provides information for a community-level engagement process over time.
Flooding is increasing along the coast and certain rivers. Use this app to view areas affected today and in the future due to increased sea level rise, surge from storms and hurricanes, and inland flooding.
Certain ecosystems like coastal wetlands have the ability to move landward as sea level rises. This depends on several factors including the rate of land accretion or the amount of sediment accumulating in the coastal area, the rate sea level is rising, and whether or not there are physical obstacles preventing wetlands from moving landward. The Future Habitat app categorizes various tidal marsh advancement scenarios from spatial model outputs.
The Risk Explorer is organized by state and permits users to easily visualize coastal hazards exposure, social vulnerability and overall risk. The app allows users to explore where people and properties benefit most from the risk reduction benefits provided by habitats.