California floods: What went wrong, and what’s next
Precipitation forecast for California from December 26 to January 11. source: Weather Forecast Center
California is facing severe flooding as storm after storm hits, At least 19 people were killed Nearly 100,000 people have been evacuated from their homes so far. And there is no sign that the storm will die down anytime soon.
Below, experts from all over the country Columbia Climate School Help explain this destructive weather and what it means in the broader climate change and disaster response conversation.
unusual, but not unheard of
“Flooding is caused by recurring waves in atmospheric rivers, often resulting in very high rainfall. These are not uncommon for California,” he said upmanularEngineering Professor and Director Columbia Water Center. Atmospheric rivers are air currents that carry large quantities of water vapor across the sky.
USGS Modeling predicted the devastating scenario we’re seeing now, Lall said. These forecasts are based on the 1861-62 storms that caused catastrophic flooding in California.
“A UC Santa Barbara study has sedimentary evidence that this phenomenon recurs in California about every 250 years,” Lall added.
El Niño/La Niña Effect
El Niño and La Niña — weather patterns in the Pacific Ocean — affect where and how often atmospheric rivers make landfall, Lal said.
He explained that atmospheric rivers are born in the warm waters of the tropical Pacific Ocean. During a La Niña phase, atmospheric rivers typically form in the western Pacific and make landfall on the northern U.S. West Coast. Instead, atmospheric rivers are more likely to be born in the central or eastern Pacific and make landfall in southern and central California during El Niño events.
“As the Pacific Ocean transitions from La Niña to El Niño, which may be happening, birth and landfall may shift to intermediate locations, and there’s often this chain of events that could span different parts of California,” Lall Say. “The reason this is critical for flooding is that we’ve had several of these storms within days of similar birth locations.”
Downed trees and flooding in Folsom, California, on Jan. 9. photo: Folsom Natural
Forecast and Prepare
U.S. Geological Survey models and past disasters clearly show that this kind of weather is possible, and local agencies should be prepared.
Additionally, “starting last month, U.S. government agencies have begun issuing forecasts that indicate the imminent likelihood of this happening in the near term,” Lall said. He suspects that the information does help prevent some damage — for example, actions taken by reservoir operators to prevent dams from flooding or bursting.
In terms of providing a sense of when and where heavy rain is expected, the forecast is pretty good, says Andrew CruzkiewiczSenior Associate, Columbia Climate Institute International Institute for Climate and Society. Then why do people die?
Kruczkiewicz says it comes down to a gap between science and decision-making. “How do we translate forecasts of heavy precipitation into actionable form? How do we incorporate standard operating procedures before disaster strikes, knowing that the forecast is not perfect, but making the forecast so that we can act? Even with systems, are we sure that the most underserved populations are receiving information and able to act on it?”
He said outdated governance structures were not designed to translate predictions into action, especially now that the climatic and social context around disasters is changing over time.
“Given the forecast information we have available, we could have done better. But without translating it into action, the potential value of ‘skilled’ forecasts is untapped or underutilized.”
Jeffrey SchlegelmilchPresident of the Columbia Climate Institute National Disaster Preparedness Center, echoing the need to translate predictions into actions. Analyzing disaster responses after the fact is easy, he said. “However, how can we make better use of our forward-looking data when it looks slightly different from the hazards we typically face? This is, on top of all the broader infrastructure and impact issues, an important issue for emergency managers and One of the things that elected officials should be thinking about.”
communication interruption
Kruczkiewicz thinks part of the reason people aren’t better prepared for these storms is poor communication. While the term “atmospheric river” may be catchy, it’s a dangerous oversimplification, he said. In addition to rainfall and flooding, atmospheric rivers can bring strong winds, blizzards, mudslides and rockslides.
“There are no atmospheric rivers ready for action,” he said. Instead, he argues that Californians could have benefited and saved lives by understanding hazards specific to different locations.
“I think sometimes these terms [like atmospheric river], yes, they’ll get clicks and raise awareness somewhat,” Kruczkiewicz said, “but they do create confusion. In a disaster situation, chaos means time, and time means potentially increased impact. Often, when we have this kind of delay and increased impact, what we see is the prioritization of more affluent populations, and the deprioritization of low-income and traditionally underserved populations. “
Kruczkiewicz believes the media missed an opportunity to highlight how underserved communities are disproportionately affected by such incidents. People with money and power may experience chaos, but overall they can ride out the storm or move if needed, while people with less money and privileges have fewer options to protect themselves from disasters and recover from them. .
“Low-income people may have their homes destroyed, and/or may be forced to miss work for weeks, and/or may suffer physical and mental harm, requiring medical care they cannot afford,” he said. “These types of effects are likely to last much longer than those in wealthier regions and regions with higher economic activity.”
complicating factors
For more than 20 years, the southwest region has been in the severe drought. It is possible that these dry conditions contributed to the deadly flooding in California, he said Kay CohenhuberAdjunct Research Associate at Columbia Climate Institute Lamont-Doherty Earth Observatory.
“If you have very dry soil and it’s raining, of course the water won’t be absorbed as quickly, which often exacerbates flooding,” he explained. “The extent to which this plays a role needs to be assessed on a regional scale.”
In addition, Kornhuber said, wildfires exacerbated by drought could exacerbate the storm’s impact.By removing trees and leaving bare soil, wildfires have been known to Increased risk of landslidesHowever, he cautioned, “It’s very early days, so there’s no data – there’s a lot of speculation at the moment.”
where is the drought
Are Atmospheric River Conditions Helping California’s Drought Conditions?
“Certainly, water quality conditions will improve in some parts of the West as a result of this atmospheric river event,” Kruczkiewicz said. They process those rainfalls. So there might be some overall benefits in some areas.”
However, many areas that need water won’t benefit because they won’t be able to absorb the volume of water that’s raining, and the negative effects of mudslides, landslides and flash floods will far outweigh any positive effects, he said.
Some areas are getting heavy snowfall, which could benefit water supplies in the long run; during warmer months, melting snow and ice help replenish depleted streams and aquifers.
“But what is the price we pay in the short term in terms of socioeconomic impact, loss of life and damage to infrastructure?” Kruczkiewicz asked.
The role of climate change
What role does climate change play in this seemingly never-ending storm sweeping through California?
“As the climate warms in many parts of the world, extreme precipitation is becoming more frequent,” Kornhuber said. “A sort of A recent study This suggests that climate change is increasing the frequency and intensity of such storm sequences affecting California. “
However, for atmospheric rivers in general, he said, “it’s hard to say how much climate change has changed their frequency,” in part because don’t know How atmospheric circulation will change as the climate continues to warm.
A flooded walnut orchard in Chico, California. photo: Frank Schulenburg
looking to the future
Researchers at the Columbia Climate Institute are working to better understand the climate phenomena we see in California and to translate the data into real-world action and adaptation.
Kruczkiewicz said he plans to see where the flash floods occurred when more data on the disaster becomes available. With many areas experiencing flash flooding from downpours for the first time ever, he wants to understand these trends to better communicate risk and inform government policy.
Lal and his colleagues at the Columbia Water Center are exploring whether they can actually steer atmospheric rivers by pushing them with small amounts of energy.
“The basic idea is that the system is chaotic, i.e. it’s very sensitive to small perturbations, so if we push it at the right time and place, the final landing location can change significantly,” Lall said. “If successful, one could direct an atmospheric river from a potentially flooded to arid place. So far, we have explored this idea mathematically in an idealized model and established its plausibility.” Resilience. Research on how this can actually be done is an open question. If this is possible, then we will open a new chapter in adaptation, significantly reducing the impact of floods and droughts, and actively managing water futures.”
A major takeaway from this disaster is that climate impacts are becoming more common and more complexstacked on top of each other in time and space—disaster recovery, preparedness, and response need to be aligned accordingly.
“Planning for extreme events needs to become the norm,” Schlegelmilch said. “Both how we build our towns and the underlying infrastructure has a lot to do with the severity of the impacts. We therefore need to rethink the value of more resilient buildings in the face of climate change and how equity affects disaster vulnerability and recovery imbalance.”
