Tidal wetland sediment accretion might keep up with sea level rise in one location. Maybe.

I attended our annual Santa Clara County Creeks Conference last Saturday, with an even better than usual program that included a panel on tidal wetlands restoration in South San Francisco Bay, where we're bringing back 16,000 acres of tidal wetlands from former saltponds (will post a video link when it's online).

The restoration has barely begun, but the land that sank after being separated from tidal flows has gained sediment rapidly, something that's necessary to create a complex environment of open water, partially submerged, and emergent tidal environments. While it's slowed more after the first few years that individual ponds have been opened to the the tides, they're still adding sediment, two inches annually, far more than the worst projections for sea level rise.

So, good for us. Except that California is a geologically young area with lots of gradients, erosion, and sediment flow. Our particular part of San Francisco Bay might also disproportionately benefit from the "backwash" of sediment from the rest of the Bay.

Our tidal wetlands can keep up where they are, for now, but whether that will work in other places is less clear.  Still, it's one small piece of good news that demonstrates the value of restoring tidal wetlands, which have been lost to a far greater extent in the US than even freshwater wetlands have.

I'm trying not to porkbarrel, but it's complicated

I haven't written much about my glamorous life as an international spy water district director, but I thought about it today as I spent my Saturday politely sparring with officials from other agencies.

I got elected on an environmental agenda but have spent as much or more time dealing with money and budget issues. That's appropriate - the public doesn't want the Water District dollars wasted.

So here's the real tricky part - I often try to help our taxpayers and ratepayers by fighting with other agencies over who's going to pay for what, but if we're just transferring costs amongst ourselves, are there any real savings?

I think the answer is partly yes - an efficient allocation of resources depends on the communities that receive the benefits being the ones that pay for them (adjusting for any transfers done to fix social problems). Agencies and communities that want our resources without pitching in comparably will demand more than they should, and our community will be willing to pay less than they should.

In today's example, we have a creek flooding issue that crosses two counties, and since more flooding happens on our side, it's somewhat appropriate that we've been paying more. At the same time we also have tidal flooding that will get worse from sea level rise that's partially integrated with our creek flooding (someone tell Roger about that) but is also more evenly spread between the two counties. I supported beginning plans to rebuild the levees to address the tidal flooding, but also said that if damages are more equal between counties then we have to revisit cost allocations. I want the problem addressed and the costs addressed appropriately.

So how does this fit a Stoat post on the failings of politicians? I guess we need to structure elected government so that the ability to win elections derives more from the competence values. If I fight for Water District cost reductions, including some real reductions, maybe that will be rewarded. We'll see.

I also want to see campaign finance reform for our little district, but that's another issue....

Lomborg misunderstands city subsidence and sea level rise

Maybe I should ignore this Bjorn Lomborg Op-Ed like everyone else has, but one part got a rise out of me. He compares subsidence that's happened in certain cities due to groundwater depletion to the long-term, multi-century sea level rise of 15 feet (actually it could be more than that), and says that we've handled "large relative sea-level rises without much difficulty." In other words, adaptation is no big deal.

I don't know the cities he's talking about, but I do know about subsidence in San Jose along San Francisco Bay. Contrary to Lomborg's statement, it's a big deal and a serious problem, especially when combined with other potential flooding problems that usually exist because cities are normally located near rivers.

The other point Lomborg misses is that city subsidence is geographically limited. The only area that needs to be protected from relative sea level rise is a small stretch of shoreline. And cities are the most economically valuable land on the planet, so the cost of protecting them relative to their value constitutes the best possible scenario.

Sea level rise, even minor sea level rise, is a much bigger deal. Here in Santa Clara County, we're going to have to deal with it, and it's already costing taxpayers money. Flood projects for near-sea-level creeks are right now being designed to handle sea level rise, which is the only intelligent way to construct these long-term structures. Adaptation is already here, it's a significant problem, and the question is who should pay for the costs. Seems like greenhouse gas emissions would be a good place to look for a tax to pay for greenhouse gas costs.

Scientists overselling or underselling climate change risks?

Kevin Vranes wrote a while back that he felt that scientists may feel like they've almost accidentally oversold their certainty about climate change and associated risks, particularly their confidence in climate model results.

On the other side, James Hansen says this about the risk of a 5 meter sea level rise in a century:

a 'scientific reticence' is inhibiting the communication of a threat of a
potentially large sea level rise. Delay is dangerous because of system inertias
that could create a situation with future sea level changes out of our control.
I argue for calling together a panel of scientific leaders to hear evidence and
issue a prompt plain-written report on current understanding of the sea level
change issue.

So who's right? Wish I knew. But, both of them could be right - scientists could be overselling 85% certainty as 95% certainty, while refusing to discuss a 10% risk of catastrophe. Or maybe just one is, or neither.

Hansen does add, "scientists preaching caution and downplaying the dangers of climate change fared better in receipt of research funding." Pointing out that something could be considered a risk at the current state of science, when it is likely (but far from certain) that the improved science will eliminate the risk, isn't going to make the scientist look all that prescient. Hansen's argument makes some intuitive sense to me, and we'll just have to see if Kevin Vranes is right or not.