By Katherine Howard
Recent news stories feature vivid pictures of record-breaking flooding across the United States. These stories make dramatic evening news coverage, because they show extreme damage in simple before and after pictures. But there is another story around flooding that is not as dramatic — at least not yet — but it is going to happen, and it is going to happen all over the world. That is the unavoidable inundation that will be caused by sea level rise.
To learn more about the potential impacts of sea level rise, I spoke with Arthur Feinstein, Sierra Club California State Conservation Chair and champion of bays and estuaries. Feinstein and a Sea Level Rise Task Force have just finished developing a set of positions for Club members to follow when addressing sea level rise issues.
Yes, climate change is causing melting glaciers and disappearing ice packs. The oceans are warming, and that leads to thermal expansion. The net result is that the levels of our oceans are definitely rising.
Sea level rise is happening every day, but it is so gradual that most people are not aware of the enormous risk that it poses to the future not only of those of us who live along the coasts, but also of the ecosystems on which we depend.
Various government and international agencies have released reports on expected sea level rise over the next 100 years. By 2050 it is expected that the oceans will rise steadily about 1.0 to 1.5 feet. Scientists say that there is nothing that can be done about this rise; it is locked in, and it is going to happen. After 2050, the amount of sea level rise will be both faster and more unpredictable. No one is certain how soon the ice in the Arctic, Antarctica, and Greenland will melt. Final predictions for sea level rise now go as high as a 10 foot rise by 2100. And this is just when the oceans are relatively calm.
Added to the impact of the rise in the static levels of the oceans is the impact of major storms with wind waves, storm surge, nearby river discharge and other events that can intensify sea level rise by contributing to the erosion of beaches and cliffs and consequent flooding. According to at least one research paper, these dynamic amplifiers can increase the impacts of flooding by up to seven times.
The coming sea level rise events will result in not only damage to the coastline and destruction of wildlife habitats, but also the loss of homes, businesses, and the infrastructure on which they have come to depend.
Let’s start with habitat. The shallow waters along our coasts are the nurseries for ocean life. According to Feinstein, the tidal marshes, mudflats, sea grass, and kelp beds support 70% to 90% of commercial fish and shellfish species. In addition to providing the food that is much of the basis for the ocean web of life, these living coastlines are effective at sequestering carbon from all those decaying plants. (Have you gotten a whiff of that intense odor at low tide? That is life in the making.) Tidal marshes also help to control flooding and inundation by slowing up storm surges. They purify water, trap impurities, and hold in mud. This in turn influences temperatures and helps cool the air.
Sea level rise threatens all of this life as these habitats drown in deeper waters. Loss of coastal habitat will impact fisheries in the deep oceans. At the same time as agriculture is impacted by rising temperatures inland due to climate change, another food source, ocean fisheries, will be depleted. And as the carbon sequestration these coastal habitats now provide is lost, Greenhouse gases will increase, resulting in further global warming.
However, if the oceans rise slowly, and if there is room for the wetlands to move inland, sea life might gradually adapt.
That is why Feinstein recommends that coastal land be set aside to allow the oceans to gradually inundate new coastal areas over the next 30 years and, with luck, the plants and other life will move inland as the oceans rise.
After 2050 other processes may have to be employed to preserve the viability of coastal waters in the face of faster changes.
The need to plan for creating new living shorelines is resulting in some interesting policy reversals. The Bay Conservation and Development Committee (BCDC) was originally formed to protect San Francisco Bay from rampant filling during the mid-twentieth century. Today, BCDC is considering rewriting its guidelines to once again allow Bay fill in order to adapt to the rising levels of the Bay. For example, at the newly recovered salt ponds, mud could be added to raise the elevation of the sea bed to allow for shoreline habitat to re-establish itself at the new coastlines.
But establishing new coastal habitat at higher elevations depends on having vacant land along the coast to inundate. In areas where there is no undeveloped land next to the existing shorelines, there is a whole other set of problems that must be faced.
Here things become sticky. In principle, we need to allow for open space inland for the rising coastal waters. This may mean saying “no” to new development. At the least, new development should plan for the eventual incursion of the ocean, and property owners should plan ahead to remove the new structures when that happens.
What happens if homes and businesses are already located in harm’s way?
There are no easy solutions for land that is already developed. One key phrase you will see in coming years is “Managed Retreat,” or permanently clearing out occupants (that’s people) and structures from coastlines that are going to be inundated. As you can imagine, proposals for Managed Retreat have already drawn storms of dissension in some communities. Homeowners are reluctant to give up a place they have lived in and loved for many years, and which may be their major financial investment.
Lots of questions to ponder here. As the oceans rise, should there be government buy-outs? Should new property owners be treated differently than those who lived along the coast before sea level rise became a possibility? Some low-income communities were forced into areas that are close to the coast but were not considered desirable at the time they were established. Their homes may be their only resource. What happens to people whose only nest-egg is their nest? Should compensation be given based on income or property values? Or would flat rate compensation be fairer to everyone?
In addition to the impacts on homes and businesses, the financial toll for sea level rise on surrounding communities will be enormous. Consider the impact on infrastructure — roads, railways, harbors, airports, power plants, wastewater facilities may all be flooded out. How will this be dealt with and paid for, on top of the need to help local homeowners and business owners?
In case you were thinking that sea level rise could be solved with sea walls, think again. Building a sea wall around your home may protect you for a few years, but in the meantime, it will increase wave action on your neighbor’s house. And, eventually, how will you get home at night? Canoeing to Trader Joe’s may feel authentic, but it will lose its appeal after awhile.
Wave action against sea walls often precludes healthy marine habitat in the nearby area. Sea walls around a city are expensive not only to build but also to maintain. And one breach means disaster — think New Orleans after Hurricane Katrina. Sea walls also require concrete; manufacturing concrete adds to greenhouse gases. And so with building sea walls the cycle of climate change builds upon itself.
As in most of the environmental challenges we now face, there are many questions and no easy answers. Feinstein advises keeping an eye on news items and attending public meetings that will be held to deal with this. Ask for a living shoreline whenever this is mentioned. Sea level rise is a problem that is very much not going away, and we will have to plan for it and adapt to it in the future.
To learn more, visit the following links:
- Sierra Club California sea level rise position paper
- San Francisco’s Sea Level Rise Action Plan is a work in process
- The USGS mapping system illustrates what may be flooded, combining the level of rising oceans with the strength of storms
- NOAA interactive maps and photos shows the impacts of sea level rise
- For the truly wonky among you, check out USGS Coastal Storm Modeling System (CoSMoS)
Katherine Howard is a local open space and environmental advocate who serves on the Executive Committee of the Sierra Club's San Francisco group. Howard writes the regular 'Environmentalk' column for the Westside Observer, where this article first appeared.
Image: Google Earth images show how San Francisco could look by 2100. The 2100 images were modeled by Climate Central using NOAA data and represent a worst-case scenario for sea level rise in San Francisco.