It’s getting close to that time of year when weather watchers and water managers start wringing their hands and wondering whether it will be a boy or a girl. The boy is none other than El Niño – that Pacific weather pattern characterized by warm ocean temperatures and heavy precipitation. Last year, we heard all about the monster El Niño that would refill California’s reservoirs. But it never actually materialized. Now, the National Weather Service projects a different winter visitor – La Niña. She’s the opposite of her brother – a weather pattern characterized by dry conditions. Get ready for the headlines: Miserly La Niña steals our water!
But here’s the real story: come El Niño or La Niña, climate change is La Madre (the Mother) of weather systems and she will be playing the lead role in California’s water supply drama in the years ahead. Climate change is truly a game changer when it comes to our water supply, and dealing with it will require a seismic shift in how we manage this precious resource. It’s a shift we are only beginning to understand. Our current approach to water management doesn’t adequately integrate climate change projections into estimates of future water supply or designs for new water infrastructure, yet climate change will have a bigger impact on water availability than any single El Niño or La Niña cycle.
Climate change is such a destabilizing force because of the way our water system is engineered. For more than a century, Californians have relied on snowmelt-fed reservoirs, rivers and streams for much of our freshwater. Drought and climate change are depleting those traditional supplies. Global warming means hotter temperatures, which lead to less snow and more evaporation. In fact, the statewide average temperature during the winter of 2014–15 was the warmest ever recorded, at 50.5 degrees Fahrenheit (10.3 Celsius) – more than 5 degrees warmer than the average for the 20th century. And, even more disturbing, warming has been most severe in the Sierra Nevada, where much of our state’s water supply originates. In 2015, average minimum winter temperatures were above freezing for the first time, and the snowpack was the lowest ever recorded.
Snowpack decline is projected to continue as more winter precipitation falls as rain rather than snow. Projections indicate that if we stay on the current track of rising temperatures, we can expect to see snowpack declines of 73–90 percent by late century. (This is during the expected lifetime of my child, which makes it seem much less far away.) In addition, the snow that does fall will melt much sooner. (Snow is already melting as many as 30 days earlier than during the mid-20th century.) Thus, timing of water supply will be increasingly out of sync with demand, which is highest in the summer.
To date, dams, canals and aqueducts – the systems that store and distribute snowmelt – have been the major focus of water management. Yet, as surface water becomes less reliable, Californians are turning to underground aquifers to supply water. In fact, more than half of our water supply came from groundwater during the last year. Until recently, the aquifers beneath the ground have been mostly unmanaged or mismanaged. As more and more people have tapped into the groundwater, drinking water wells have run dry. In some places, the land is actually subsiding (or sinking) as much as 1ft (30cm) a year due to rapidly falling groundwater tables. All in all, the state has designated 21 groundwater basins as “critically overdrafted” or severely depleted.
Therefore, the shift to groundwater isn’t quite as simple as turning a new tap; rather, we must create new physical and, likely more importantly, institutional infrastructure to manage this finite resource. And that is exactly what we are beginning to do. Following passage of the Sustainable Groundwater Management Act, new governing bodies called groundwater sustainability agencies must be formed in less than a year, and these agencies have unprecedented requirements for public participation and transparency, the likes of which have never before been seen in the traditional, closed-door circles of water management. Truly achieving sustainability will require not only greater transparency and inclusion of diverse interests (not just large water users or surface water rights holders, as in the past) but also better information. In particular, information about both climate impacts on water resources and climate emissions from water uses is needed to guide water management decisions.
And yet much of this is happening with no fanfare, no catchy headlines and little public scrutiny. So, skip the El Niño or La Niña stories, and focus on La Madre: coming to a watershed near you.