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What Are the Models Predicting for Climate Change?

Prolonged drought, severe sea-level rise, dramatic flooding, raging wildfires. Climate change is having tangible impacts in regions across the country. Here’s what the models are telling us.

From sea-level rise on the coastlines to drought and wildfire inland to warmer, wetter weather in the middle of the country, it is clear that the climate is changing, and that the trends will likely continue. In fact, the global climate continues to change rapidly, outpacing the natural variations in climate that have occurred throughout Earth’s history, according to an expert interviewed for this story.

Climate change is a global phenomenon, but it impacts different regions of the U.S. differently. But if you’re on the coastline — any coastline — you can expect to experience sea-level rise as the West Coast does. The West Coast also is getting warmer and dryer and is experiencing more drought and wildfire, while the Midwest is getting wetter.

The models that project future climates are mathematical representations of interactions between the atmosphere, oceans, land surface, ice and the sun, and they are built to estimate trends but not events. For example, a model cannot predict what the weather will be like in March 2050, but it can forecast a rise in sea level or land temperature at that time.

There are many different indicators or observations that can be used to track how a climate is changing, including temperature and precipitation, Arctic sea ice, snow cover, alpine glaciers, drought, wildfires, lake levels and heavy precipitation. Some of these indicators can be traced back to the late 1800s with continual data. Satellite data goes back to the 1970s.

Models that predict future warming are tested by a process called hindcasting, according to Howard Diamond, United States Climate Science Program manager for the National Oceanic and Atmospheric Administration, via email.

Testing the models involves using the data from the past and mapping past climate change. “If they get the past right, there is no reason to think their predictions would be wrong,” Diamond wrote.
The volume of data is way too high for a human to manually process.

About a decade ago, scientists with the U.S. Geological Survey (USGS) built the Coastal Storm Modeling System (CoSMoS) to look at sea-level rise, flooding and erosion hazards along the California coast. Its use today provides data on future sea-level rise in the U.S.

“It’s meant to capture what the future climate will look like in terms of its influence on sea-level rise and storm patterns,” said Patrick Barnard, research geologist with the USGS. “It’s a physics-based model here, we’re explicitly modeling waves, the tides, the storm surge and how it all propagates and sort of combines to drive coastal flooding in that sensitive zone where all these communities are across the country.”

The practice of storm modeling, Barnard explained, has come a long way, but the way it’s communicated is far behind. The ArcGIS story maps give communities across the country the story on what’s happening with weather and the projections for the future.

AI and machine learning is beginning to come into vogue as a way to automate the processing of satellite imagery, since the quantity of data is much too great for manual analysis. “The volume of data is way too high for a human to manually process,” he said. “We’ve been using it [AI and machine learning] for satellite imagery to derive topographic features to identify where the coast is, for example, but it’s pretty early days on that.”

Barnard added that scientists are trying to enlist augmented reality and virtual reality applications to better communicate the science. “That’s another way things are headed. Figuring out innovative ways to communicate because clearly scientists haven’t been doing the best job,” he said. “We’re still arguing about where the trend is with the public and that discussion should have ended 30 years ago.”

But many communities don’t need further convincing that the climate is changing and that mitigation measures need to follow.
satellite image of the Puget Sound area
The Coastal Storm Modeling System project (CoSMoS) uses satellite imagery, like this of the Puget Sound study area, as a foundation for its climate change projections. CoSMoS is a program of the U.S. Geological Survey.


“Regardless of what people believe is directly causing it, at the end of the day, it’s occurring. It’s happening right now,” said Jonathan Lord, emergency management director for Flagler County in Florida. “Sea-level rise is going up and for us that means increased coastal flooding events, whether it’s a hurricane or our winter nor’easter events or even high tides.”

Coastal properties along the Atlantic Ocean and along the intercoastal waterways up and down the East Coast are flooding during peak tides, Lord said. “We’re seeing more frequent flooding episodes with water entering properties.”

The higher tides increase coastal erosion, which exacerbates the problem because it erodes the dunes that act as shoreline protectors. “When we have more and more of these increasingly severe events, it quickly chips away at the dune system, a multimillion-dollar protection system for the coastline,” Lord said.

There are several projections about what the area will face in 50 years and some have these same properties, which are merely flooding now, underwater.

“Nationwide we see this as well,” Lord said. “The fact is that Americans like to live on the coast. Whether it’s increased frequency of hurricanes or even non-hurricane storms or potentially stronger storms, we now have a higher population density in that at-risk area and we have to take care of them.”

Locally, that means delving into things like planning and zoning and, perhaps, requiring that any new property be elevated. But what to do with existing properties and the people living in them?

It may be a bit more dire in the short term on the East Coast, according to Barnard, who says that East Coast communities lie right at the water, whereas many coastal communities on the West Coast present a different terrain.

“There is much greater short-term risk on the East Coast,” he said. “It’s a passive margin coast, which means it’s not active tectonics — there’s not uplift and so it’s low-lying very flat gradients and so the people within that coastal zone that are in harm’s way are very vulnerable to sea-level rise in the very near term.”

These truths dramatically increase the importance of mitigation efforts and also communicate real risk going forward. “Educate them on actual risk today and then when that hurricane or nor’easter is coming, be open and honest with them,” Lord said. “When it comes to evacuations, be super clear and blunt that that wall of water is coming on top of already higher tides and although you lived through the last one, don’t count on it this time.”
sandy desert land with green plants in the western United States


When it comes to the West Coast, climate change is manifesting itself in a few ways, including prolonged periods of drought and more intense wildfire.

A new study published in Nature Climate Change suggests that the megadrought that persists in the American West is the new normal as wildfires ravage the Southwest and continue to threaten the West Coast nearly year-round.

Regardless of what people believe is directly causing it, at the end of the day, it’s occurring. It’s happening right now.
But as harrowing as continuous drought and the continued threat of devastating wildfire is, the West Coast is far more threatened by the effects of sea-level rise, economically speaking. “What we found in California is that sea-level rise impacts in the future for California are going to likely be far greater than wildfire impacts in terms of dollars,” Barnard said.

By a factor of about 10, Barnard said. “The biggest fires, last time I checked cost the state about $20 billion. Looking out at the end of the century at sea-level rise [damage], it’s on the order of $200 billion, not factoring in that fires may be more intense and the impacts may be greater than present-day numbers.”

Although California has high terrain, there are still millions of people living at sea level along estuaries in San Francisco, San Diego Bay and throughout San Diego and Orange County. These areas are already risky to home dwellers even without sea-level rise.

A similar situation exists farther north, although more of those living at sea level in Oregon and Washington tend to be underserved communities and tribes that are living on very low-lying river delta areas along the coast. These regions are being threatened by salt-water intrusion and more frequent flooding.

California has already experienced about eight inches of sea-level rise over the last century and the expectation is that the rise is going to continue at about the same pace over the next 30 years.
flooded streets in Davenport, Iowa
Experts attribute increased flooding in the Midwest, including places like Davenport, Iowa, to fewer but more intense rainstorms than several decades ago.


The Midwest has seen warmer, wetter weather over the last few decades, accompanied by unprecedented flooding events, and the projections call for more of the same. The National Climate Assessment projects that the top 5 percent of rainiest days will experience a 10 percent increase in rain quantity by the middle of this century and a 20 percent increase by the end of the century.

So by 2050, the rainiest day will produce 5.5 inches of rain instead of 5, and by 2100 it becomes 6 inches of rain. “That’s an additional 33 percent of runoff,” said Dr. Larry Weber, from the Iowa Flood Center.

“From the climate change perspective, it’s the intensification of rainfall in fewer and fewer storms at greater magnitude that’s going to result in more flooding.”

What Weber has witnessed over the last 25 years is consistent with what climatologists forecasted 25 years ago, namely more extreme weather. “And that we would see the intensification of rainfall and flood events interspersed with drought events, and that’s been true.”

“When you look at the average rainfall over the last 30 to 40 years, it’s been creeping up slowly,” Weber said. “But as it creeps up, what we see is that the average rainfall is coming in fewer but more intense storms.”

Pat Guinan, professor of climatology at the University of Missouri Extension, said that period has coincided with an unprecedented warm period. Four of the five wettest years going back to 1895 have occurred since 1970.

In Missouri, the recent unprecedented floods prompted the creation of a hydrology office. A drought in 2018 was followed by floods in 2019 that led officials to the conclusion that the status quo was unacceptable. The office will be a hub for information sharing for stakeholders and the public to glean information about the vulnerabilities and hazards of the area when it comes to drought and flooding.

Education is becoming a theme in Iowa as well, and the public is catching on.

Weber meets with various groups in Iowa, including agricultural groups, and city, state and federal officials. “The biggest benefit has been we’ve increased the overall literacy or understanding of these issues across those sectors of Iowa,” he said. “We used to have to explain the hydrologic process and we don’t have to do that anymore. It’s water literacy. We can have more meaningful conversations and get more meaningful work done.”

The Northeast:
Milder winters and earlier springs are altering ecosystems and environments in ways that adversely impact tourism, farming and forestry. The region’s rural industries and livelihoods are at risk as less distinct seasons continue to lead to changes to forests, wildlife, snowpack and stream flow.

Extreme weather events like heat waves and river flooding, along with sea-level rise, will negatively impact the social, economic as well as physical health of residents, especially disadvantaged populations.

The Southwest: Snowpack and streamflow amounts are projected to decline in parts of the Southwest, decreasing surface water supply reliability for cities, agriculture and ecosystems.

The Southwest produces more than half of the nation’s high-value specialty crops, which are irrigation-dependent and particularly vulnerable to extremes of moisture, cold and heat. Reduced yields from increasing temperatures and increasing competition for scarce water supplies will displace jobs in some rural communities.

Increased warming, drought and insect outbreaks, all caused by or linked to climate change, have increased wildfires and impacts to people and ecosystems in the Southwest. Fire models project more wildfire and increased risks to communities across extensive areas.

The Northern Great Plains: Montana, Nebraska, North Dakota, South Dakota and Wyoming, home to just 5 million people, are a key part of the nation’s food supply as much of the area is used for dry land and irrigated crops and livestock grazing. It’s also a central flyway for migratory birds in spring and fall.

Noted for its highly variable climate, temperatures are increasing, producing a wide range of impacts depending on location with some positive results and some negative. In recent years, the region has experienced drought and flooding, both heat and cold waves, and blizzards and extreme weather.

Source: U.S. Climate Resilience Toolkit
Jim McKay is the editor of Emergency Management magazine.