Whatever happened to climate change? With a global financial crisis, unrest in the Middle East, and a pending U.S. election,the concern our nation once expressed over climate change seems to have faded into the background. However, the same observable trends and implications that once instilled anxiety and in some cases precipitated action around the world in the era of Al Gore’s Inconvenient Truth still persist.
Water levels are rising at an increasing rate in San Francisco Bay, and although scientists are observing noticeable changes, it is difficult for the casual observer to pick up on these changes as they occur gradually. This tendency to overlook subtle changes is referred to as creeping normalcy. Author Jared Diamond calls this same phenomenon “landscape amnesia,” but I think it is overly disparaging to label Bay Area residents as amnesiacs. In fact, I think that many Bay Area citizens are well aware of the potential threats facing the Bay, even if it’s difficult to directly observe them.
In the past month, I’ve fielded some very astute questions about climate change and wetlands while running Save The Bay restoration programs. Frustrated by my inability to provide complete answers to the questions posed by our inquisitive and concerned community volunteers, I decided to dig a little deeper into current research on sea level rise in the San Francisco Bay. Here are some answers to the most common questions:
We know that sea levels are rising, but how much rise will San Francisco Bay experience in the next century?
Water levels in the Bay are influenced by rises in ocean water levels, changes in the timing and quantity of precipitation and runoff events in the San Francisco Bay Watershed (which drains 40% of the state), and an increasing frequency of severe weather events. Estimates vary greatly depending on the scenario; however, a recent study put Bay level rise at 96 – 125cm within the next century. Earlier this month, the San Francisco Bay Conservation and Development Commission (BCDC) amended its policies to address sea level rise.
Will rising Bay water levels simply flood the marshes?
For tidal marsh vegetation to remain sustainable and functioning under sea level rise scenarios, the marsh must accrete significant amounts of sediment to maintain marsh surface. The ability to increase surface elevation is partially dependent on the ability of the marsh to incorporate organic matter in the root zone. Specifically in ecotone habitat within the marsh, native vegetation is imperative to sediment accretion within the marsh system.
Under current landscape, most of San Francisco bay’s tidal marshes upland is restricted by development, levees and other obstacles. Marsh elevations can adjust to changes in seal level rise if native vegetation is established.
Do wetlands help to mitigate climate change?
Yes! This is why the policy and restoration work we do is so important. Wetlands act as sponges, slowing down and soaking up large quantities of water runoff and sediment from rainstorms and high tides. Besides acting as absorbent buffers, tidal salt marshes capture and store carbon from greenhouse gases in the air efficiently and effectively, helping to counter global warming. As we all know, carbon dioxide is a leading driver of global warming , so trapping this carbon in the ground is an important means of climate change mitigation.