California has water issues. As a state, CA currently does not have enough water to meet all of our personal, agricultural, industrial, and recreational needs. We already import water from the Colorado River, and we have already drawn down our existing reservoirs in our underground aquifers to meet these needs. Probably none of this background comes as much of a surprise? Our water woes have been well-documented and publicized for decades, dating back to the days of Mulholland. The question is, what are we doing about it--and what does the future hold?
As I mentioned before, climate change has made predicting the future much more difficult. It used to be that historical models could be counted on to accurately predict what would happen in the future. Water planners have been able to rely on the concept of "stationarity": that you can use historical water flows to plan for future water availability. Sure, there have always been unusual events that happen once every 50 or 100 years, but our weather operated in a known range. This is no longer true. "Once in a lifetime" events now happen every 10 or 20 years. New and previously unforeseen events are occurring. We're in new territory, and although we have no crystal balls, we do have computer modeling. It allows us to make reasonable decisions on what might happen, and what is most likely to happen.
For example, the Department of Water Resources is expecting the water CA gets from the annual Sierra snowmelt to decrease by 25-40% in the next 50 years. Considering that this natural resource is an important source of water for CA in the late spring and summer months, DWR must decide not only how to replace this water supply, but also whether resources can/should be dedicated to capturing and retaining precipitation that may fall as rain (and quickly runs off) rather than slow-melting snow?
Further, what about sea-level rise? Sea levels have already risen over a foot in the last 50 years. They are expected to rise another foot by 2050. However, remember that slow but profound effect I mentioned before in the last post? Sea levels are projected to rise approximately 55 inches between 2050-2100! Imagine what this will do to low-lying areas such as Venice, Florida, New Orleans--and the Sacramento River delta. Literally thousands of acres of productive farmland could be inundated, and our existing levee system is currently not ready for sea-level rise of such magnitude. Further, salt water will encrouch up river many miles further inland, affecting fresh-water availability.
There are a few easy answers. For example, golf courses use (on average) over 300,000 gallons of fresh water a day. (Is the economic and/or recreational value of a golf course worth this cost in water resources?) We currently do very little with water recycling, and many of our reservoirs, pipelines, and other delivery systems are porous, leaky, or otherwise inefficient. We have made progress with low-flow shower heads and more efficient toilets. Much can still be done to improve our water infrastructure.
Unfortunately, although these answers will help, they will not begin to solve our water problems--especially for a state with a huge agricultural industry, and a population that is expected to increase another 10 million people by 2050. The good news, if there is good news, is that DWR is no longer using modeling based on historical averages, or wishful thinking. They're using the modern computer models to base their planning on the best science available, not history or hope. They have a hard task ahead, and unfortunately things may well get worse before they get better on this front. In the meantime--don't flush that toilet!
Showing posts with label modeling. Show all posts
Showing posts with label modeling. Show all posts
Monday, October 29, 2012
Climate Change 101
If you are reading this blog, or if you have listened to the news much in the past 20 years, you are probably already aware that there is a weather phenomenon known as Climate Change. Originally often referred to as Global Warming, climate change more accurately reflects the real-world consequence to humans.
As the planet warms, weather patterns become more severe. It may lead to hotter summers and drought. It may also lead to severe winter blizzards. Hurricanes, tornadoes and monsoons have more energy and are more frequent. In fact, the entire weather cycle has more energy overall, and all weather events become more pronounced.
Of course, depending on your source of news and your political leanings, you may not believe any of this is actually happening. Fortunately, most Americans, as with the vast majority of the world, now know something is amiss with our weather. The "controversy" over whether climate change is happening is largely a product of politics and fear-mongering. When 97% of the world's climate scientists agree with the U.S. Department of Defense, any practical debate of whether climate change is actually happening is essentially over. The debate still over WHY it is happening, how much of it is caused by humans and how much is naturally occurring, and what the consequences of this change will be is another story.
For long-term planning purposes including the investment of billions of dollars in infrastructure projects, we'd be crazy not to plan for certain known eventualities. Just as our military is making critical strategic decisions about how climate change will affect our ability to defend ourselves, our State and Federal planning boards must all make key decisions. Whether it is such projects as flood control in our rivers or coastal regions, planning and allocating water supplies, making improvements to our electrical grid, siting wind farms, protecting endangered or threatened species, locating crops, eradicating or minimizing the damage from agricultural pests, enacting fire suppression in our forests, or best determining how much CO2 can be released into the atmosphere, our governmental agencies must do their best to plan for effects that will not occur for twenty, fifty, perhaps even 100 years from now.
Modeling shows that the long-term effects of climate change have three very important components. First, they tend to be slow. Our planet is currently warmed from CO2 in the atmosphere that was released decades ago, and even if we stop burning fossil fuels today, the concentration of CO2 in the atmosphere will continue to rise for many years before the concentrations start to decrease. Second, these effects are profound. Although we cannot easily see them in our daily lives, the changes that have occurred over the last fifty years are dramatic. Whether it is the warming of the Earth as a whole, the dramatic warming of the North and South Pole, the migration of species to higher altitudes or different latitudes, the acidification of our oceans, coral reef bleaching, etc., the warming of our planet is affecting ecosystems world wide.
Perhaps the most important issue is that our computer modeling is imperfect. For example, 20 simulations of rainfall predicitions for California over the next 50 years may yield 1 result where California gets twice the rainfall that it has historically, 2 results where it gets less than half, and 17 results where CA gets 10-25% less. Which model is right? If you work for the Department of Water Resources, how do you plan your infrastructure projects? Does it make sense to plan for the worst-case scenario, or the scenario that is more statistically likely to happen? In this day of limited budgets and resources, can we afford to ignore the problem entirely, or just wish it away? In my next post, I will discuss some of the steps California is currently taking to prepare for its unknown water future.
As the planet warms, weather patterns become more severe. It may lead to hotter summers and drought. It may also lead to severe winter blizzards. Hurricanes, tornadoes and monsoons have more energy and are more frequent. In fact, the entire weather cycle has more energy overall, and all weather events become more pronounced.
Of course, depending on your source of news and your political leanings, you may not believe any of this is actually happening. Fortunately, most Americans, as with the vast majority of the world, now know something is amiss with our weather. The "controversy" over whether climate change is happening is largely a product of politics and fear-mongering. When 97% of the world's climate scientists agree with the U.S. Department of Defense, any practical debate of whether climate change is actually happening is essentially over. The debate still over WHY it is happening, how much of it is caused by humans and how much is naturally occurring, and what the consequences of this change will be is another story.
For long-term planning purposes including the investment of billions of dollars in infrastructure projects, we'd be crazy not to plan for certain known eventualities. Just as our military is making critical strategic decisions about how climate change will affect our ability to defend ourselves, our State and Federal planning boards must all make key decisions. Whether it is such projects as flood control in our rivers or coastal regions, planning and allocating water supplies, making improvements to our electrical grid, siting wind farms, protecting endangered or threatened species, locating crops, eradicating or minimizing the damage from agricultural pests, enacting fire suppression in our forests, or best determining how much CO2 can be released into the atmosphere, our governmental agencies must do their best to plan for effects that will not occur for twenty, fifty, perhaps even 100 years from now.
Modeling shows that the long-term effects of climate change have three very important components. First, they tend to be slow. Our planet is currently warmed from CO2 in the atmosphere that was released decades ago, and even if we stop burning fossil fuels today, the concentration of CO2 in the atmosphere will continue to rise for many years before the concentrations start to decrease. Second, these effects are profound. Although we cannot easily see them in our daily lives, the changes that have occurred over the last fifty years are dramatic. Whether it is the warming of the Earth as a whole, the dramatic warming of the North and South Pole, the migration of species to higher altitudes or different latitudes, the acidification of our oceans, coral reef bleaching, etc., the warming of our planet is affecting ecosystems world wide.
Perhaps the most important issue is that our computer modeling is imperfect. For example, 20 simulations of rainfall predicitions for California over the next 50 years may yield 1 result where California gets twice the rainfall that it has historically, 2 results where it gets less than half, and 17 results where CA gets 10-25% less. Which model is right? If you work for the Department of Water Resources, how do you plan your infrastructure projects? Does it make sense to plan for the worst-case scenario, or the scenario that is more statistically likely to happen? In this day of limited budgets and resources, can we afford to ignore the problem entirely, or just wish it away? In my next post, I will discuss some of the steps California is currently taking to prepare for its unknown water future.
Subscribe to:
Posts (Atom)