The Four Corners drought of 2017 and 2018 caused $3 billion in losses and led the Navajo Nation to issue an emergency drought declaration.
Now, new research in the Bulletin of the American Meteorological Society suggests a sizable portion of the drought’s impacts stemmed from human-induced climate change.
“We’re going to keep seeing temperature rise, meaning we’re going to keep seeing these extreme events, these impacts occurring, and that makes it really important to start thinking about adaptation,” said co-author Emily Williams, a doctoral student at University of California, Santa Barbara.
In addition to UC Santa Barbara colleagues Chris Funk and Shraddhanand Shukla, Daniel McEvoy of the Western Regional Climate Center in Reno, Nevada, contributed to the research.
The Four Corners drought was intensified by the hottest regional temperatures on record, and occurred during a severe meteorological drought.
Unusually high temperatures worsen droughts in the Southwest by reducing snowpack and causing snow to melt earlier, depriving affected areas of seasonal river flows.
They also increase the amount of water the atmosphere can hold, making air “thirstier” and causing it to pull moisture from plants and soil.
According to model simulations, human-induced warming added 2.3 to 3.6 degrees Fahrenheit (1.3 to 2.0 C) to that heat—parching soil and shrinking plant coverage by 18–30 percent and making poor rangeland conditions worse.
It also drained away 20 percent of potential snowpack meltwater.
Williams said events like these reveal climate change already at work.
“And this drought, which hurt so much of the interior of the U.S., is one of those examples of what climate change looks like in the here and now,” she said.
As available water is exhausted, an additional feedback between land and water can occur: As evaporation, which absorbs latent heat and cools the area, becomes impossible, sensible heat can climb even higher.
“If this is happening in a really dry environment and there’s no more moisture in the soil that will then lead to even greater temperature rise,” said Williams.
Because the study did not model such effects, its results likely reflect a conservative estimate of the impacts of human-induced warming.
LOS ANGELES – The stretch of coast from Santa Monica to Malibu is iconic and quintessentially Californian. It’s also ridiculously beautiful — and it’s clear, based on the latest science, it could be unrecognizable by the end of the century.
As the planet warms, sea levels will continue to rise, threatening some of our most beloved stretches of coastline.
I was lucky enough to spend a lot of time on those beaches. Raised in the San Fernando Valley, I used to head over the hill in my friend’s baby blue VW bus, or my mom’s minivan, to surf Topanga or Malibu on my 9’8 Kennedy longboard. It was and still is an amazing escape from the traffic, heat and urban sprawl of the Valley.
I wanted to know exactly what climate change could mean for our beach-going experience through the end of the century, so I reached out to scientists and stakeholders to find out what they know.
Here are the challenges — and some solutions.
Seas Will Rise
First, some context.
A few feet of sea level rise might not sound very alarming, but every vertical foot could mean roughly 20 feet farther that the ocean encroaches inland (depending on a lot of factors, like the slope of the coastline), according to Patrick Barnard, a research scientist at the US Geological Survey.
And areas like Malibu could be threatened in the coming decades.
“I mean these are very, very narrow beaches. They’re already having lots of issues, and just a bit of sea level rise and they’re going to be completely gone,” said Barnard, adding that Malibu could see a major loss of its beaches in the coming decades.
Homes are sandwiched between rising water and Pacific Coast Highway at Carbon Beach in Malibu. Photographed from the air on September 9, 2019 in Malibu, California. (Video by James Bernal for LAist)
Our coastline is always changing, but as sea levels rise and intense storm surges (potentially) become more common, there’s conflict between natural processes and the parts of our coast we want to save.
“If we didn’t have anything built on the coast, the beaches in the coastal zone are incredibly dynamic and built to change. When sea level comes up, the beach moves in. When sea level goes out … the beach moves out with it,” said Kiki Patsch, who studies sediment dynamics at Cal State Channel Islands.
“But when sea level rises and we draw a line in the sand and say, ‘This is the beach and these are my homes,’ we have a problem,” she said.
When water encroaches and beaches have nowhere to go, because we decide to protect infrastructure and homes, we’re likely going to lose those beaches.
Santa Monica’s beaches are substantially wider than those in Malibu. Photographed from the air on September 9, 2019 in Santa Monica, California. (Video by James Bernal for LAist)
Beaches like Santa Monica that have been widened with massive amounts of sediment could hold up with regular additions of sand, at least for a period of time.
Here’s a visualization of what rising sea levels could theoretically look like from the pier:
Caltrans just released its vulnerability assessments for our region, and they’re particularly bleak for our coast. There’s not much area between the ocean and the hills in many spots. Really, much of it’s just homes and critical infrastructure, like PCH. Which means that in some places we’re going to have to decide between one or the other.
“There can be situations where if we’re using shoreline protection to protect private residential development, that might be coming at the expense of a public beach area. And that’s going to be a huge environmental justice issue,” said Madeline Cavaleri, statewide planning manager for the California Coastal Commission. “We don’t know how this is going to play out.”
He said that at three feet, Malibu’s waves could get mushy. Surfers already experience that at high tide. With sea level rise it would be like it’s high tide all the time.
That said, it’s more complicated than just plunking down additional water on top of a break. How we manage our coasts and sediment flow will all impact what we experience on shore.
“Whether you are armoring the sea cliffs or damming the rivers, that’ll have ramifications all of the way down the coast, because that is where the sand is coming from,” said Patsch.
That could mean that if we decide to stick sea walls and big piles of rocks up and down our coast to protect what’s there, surf spots could suffer, too.
That could, “pull the sand offshore and downshore, so it’ll get deeper offshore. Waves break because they start to interact with the bottom, so when it’s deeper you lose your surf break,” she said.
Derek Grimes, a Ph.D. student in physical oceanography at Scripps, noted that while the transport of sediment could negatively impact Malibu’s beaches, we don’t know how it could impact other breaks up and down the coast. It’s possible that new, sought-after spots will pop up.
Grimes told me he’s seen that happen off the coast of North Carolina when the bottom of channels are dredged for ships.
What We Do Matters
The good news is that everything we love about our coast is not going to disappear overnight. And we’ll have the opportunity to decide how we want to manage things going forward.
And some people want to install armoring up and down our entire coast, which could run into big problems with California law. Some homeowners in places like Broad Beach in Malibu figured out a workaround and did it on their own.
WASHINGTON – Phoenix and Tucson were two of the fastest-warming cities in the nation over the last five decades, according to a Climate Central report based on government data.
The report looked at climate change for cities and states since the first Earth Day in 1970 and found increases in 98% of cities across the country, with four of the top five cities in the Southwest.
Tucson and Phoenix were among 10 cities that saw average annual temperatures rise more than 4 degrees over that time period, with Tucson’s increase of 4.48 degrees the third-biggest and Phoenix’s 4.35-degree rise good for fourth place.
Arizona State Climatologist Nancy Selover said the increase is even more striking at night, when she said temperatures have risen an average of 8 degrees. She and other experts attribute that in part to the fact that rapid urbanization of the desert cities has created “urban heat islands” that hold heat longer than they used to.
“If you go out 11 o’clock at night in the late spring or into the summer for sure, you’ll walk past a block wall and you will feel that heat radiating off that block wall,” Selover said. “It’ll be 2 o’clock in the morning and you’ll still be looking at temperatures in the upper 90s or the low 100s because it takes so long for that (surface) to cool.”
The Climate Central report drew on data from the National Centers for Environmental Information to determine average temperature changes in 242 cities and every state but Hawaii. In addition to the 10 cities that saw a rise of 4 degrees or more, 59 cities rose an average of more than 3 degrees. Only six cities saw their average temperature decline, it said.
Las Vegas was first on the list, with an increase of 5.76 degrees, followed by El Paso, Texas, which had a 4.74-degree rise, then Tucson and Phoenix. Rounding out the top five was Burlington, Vermont, where temperatures rose 4.13 degrees.
Among states, Arizona’s 3.23-degree change was third-largest, trailing Alaska’s average 4.22-degree rise and New Mexico’s 3.32-degree increase.
John Fleming, a staff scientist at the Center for Biological Diversity, said the Southwest’s dry climate as a whole is a contributing factor to its increase in temperature.
“The Southwest is warming faster than other regions in the U.S. because it’s already a dry region that’s becoming even drier in response to climate change,” Fleming said. “Since moisture … can store and redistribute a lot of heat, without that, due to drought or a lack of rain, additional heat goes to heating the air and ground.”
That was echoed by Selover.
“The increase in the cities is more because of how we’re changing the surfaces of the cities from natural desert or from irrigated agriculture into pavements and buildings and sidewalks,” she said. “When the sun hits those surfaces, they are heavy thermal-mass materials and they absorb that heat, and it’s conducted down into the material.”
Fleming said the report is important because it takes a conversation that often revolves around national or global temperature change and brings it down to changes at the local level.
“Often these numbers are talked about in terms of nationwide or global,” he said. “Within that average is built in that, in some places, things are going to be even worse for people than in other places.”
Selover said Arizona is doing a number of things to combat the change in temperature. Those include creating more shade to keep heat-susceptible surfaces from getting so hot and using new building materials that do not retain the heat as well.
“Whether that’s planting native vegetation and trees that will shade the ground from being able to receive that sunlight and heat up all day long, or whether it’s mechanical or artificial shade structures, they are working to shade more of the pavements,” she said.
Despite the climate challenges Phoenix and Tucson face, Selover said she believes Arizona residents will rise to the challenge.
“People have said, ‘You know, in so many years we will be uninhabitable.’ I don’t tend to buy into that argument,” she said.
“Because that would assume we are not doing anything to try and mitigate the heat,” Selover said. “We are using this opportunity to try and learn some lessons and try some things to find some strategies that will work and help us out.”