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What you need to know about the latest National Climate Assessment
There’s still time to adapt, report authors said
Brittney J. Miller
Nov. 28, 2023 3:06 am
This month, the federally created U.S. Global Change Research Program released its Fifth National Climate Assessment — an in-depth look at how different parts of the country are experiencing, addressing and adapting to climate change.
Since the Industrial Revolution, humans have been emitting greenhouse gases into the atmosphere through sectors like transportation, electricity production, industry and agriculture. Those gases — including carbon dioxide, methane and nitrous oxide — trap heat and make the Earth grow warmer than it naturally would be. As a result, the climate is changing, sending rippling impacts worldwide.
The Fifth National Climate Assessment and its Interactive Atlas Explorer map those impacts across 10 U.S. regions, including the Midwest. About 750 authors contributed to the report, which is mandated by Congress roughly every four years.
“I'm happy to say that this assessment is not just another climate report to gather dust on your shelf,” said Allison Crimmins, director of the assessment, during a Nov. 15 press call. “We really want people to think of (it) as a guide to climate change in the United States … to inform climate decisions.”
Here’s what you need to know about the assessment’s findings for Iowa and the Midwest:
Temperatures creeping higher
Earth is about 2 degrees warmer than it was in the late 1800s before emissions began to spike. Even so, the number of very hot days has actually decreased across the central United States compared with the early 20th century, according to the assessment.
On average, the Midwest is seeing at least five fewer days a year that surpass 95 degrees.
That doesn’t mean the Midwest isn’t affected: Annual average temperatures in the upper Midwest are more than 2 degrees warmer than they were a century ago. When heat waves do roll in, they’re hotter, larger and lasting longer. If global temperatures continue rising, heat waves will likely grow more severe.
The Midwest also now sees five fewer days a year colder than 32 degrees. Extreme cold events, like last year’s Winter Storm Elliott, are becoming less frequent and more mild. Warm nights, on the other hand, are growing more frequent, giving humans, animals and crops less time to recover from hotter days.
Average annual temperatures are projected to increase across all of Iowa — between 2 and 9 degrees over time, depending on the county and climate scenario, according to the assessment’s Interactive Atlas Explorer. Just in this last summer’s hottest heat wave, feels-like temperatures in Eastern Iowa reached 120 degrees and broke records.
“We do know very clearly — and the science supports this — that every increment of warming matters, and therefore every action matters,” said Heidi Roop, a University of Minnesota climate science assistant professor and assessment contributing author. “And we have no time to waste.”
Quick climate change facts
According to the Fifth National Climate Assessment:
• Global temperature has increased faster in the past 50 years than at any time in the past 2,000 years.
• The rate of sea level rise in the 20th century was faster than in any other century in at least the last 3,000 years.
• Present-day levels of greenhouse gases in the atmosphere are higher than at any time in at least the past 800,000 years, with most of these emissions occurring since 1970.
Extremes — from rain to drought
Changing temperatures send ripple effects through Earth’s weather systems, impacting the severity and frequency of extreme events, the authors wrote. The heaviest precipitation events, for instance, have grown more frequent and severe across most of the United States.
From 1992 to 2021, annual precipitation increased between 5 and 15 percent across much of the Midwest. The region has seen a 45 percent increase in the number of days with extreme precipitation, or the top 1 percent of precipitation events.
As a whole, annual precipitation in Iowa is projected to slightly increase, according to the assessment’s Interactive Atlas Explorer. The wettest day of the year may grow even more wet in most counties, particularly in Northern Iowa. The entire state is likely to see more days with extreme precipitation.
These trends have contributed to increased flooding in the Midwest. Earlier this year, melting snowpacks in Minnesota and Wisconsin flooded Iowa communities along the Mississippi River, with several locations reaching in their top three highest crests on record.
Even with more precipitation expected, drought risks may also rise as global temperatures climb. Along with much of the United States, the Midwest is vulnerable to flash droughts that rapidly intensify. The region also experiences rapid shifts between wet and dry periods — which are tricky to predict but jolting to economies and ecosystems, the authors wrote.
Wide-ranging impacts
Climate change leaves its mark on industries, ecosystems and communities — and its impact is increasing.
In the 1980s, the United States experienced one billion-dollar weather disaster about every four months. Now, adjusting for inflation, there is one about every three weeks. In 2022 alone, the country suffered 18 such disasters — four of which impacted Iowa.
Climate change puts the Midwest’s agriculture at risk. Excessive spring rains may delay planting; droughts may reduce yields; rising temperatures could reduce crop productivity; extreme heat stresses livestock. Between 2001 and 2022, Iowa ranked No. 4 in the country for its drought- and flood-related insurance payouts, according to a recent report.
The changing climate also strains Midwestern infrastructure, including its energy distribution and generation systems, dams, bridges, roads, wastewater facilities and water sources and distribution systems. Since 1980, the region has suffered between $49 billion and $109 billion in damages due to flooding alone — losses sure to increase with climate change.
Iowans are growing more exposed to climate hazards like increased extreme heat, flooding and poor air quality. Just this summer, smoke from Canadian wildfires painted Midwestern skies gray and prompted air quality alerts. In 2022, there were 1,037 emergency department visits in Iowa due to heat-related illness, according to state data. Forty-nine people were hospitalized.
If climate change stays its course, Midwestern populations will see an increase in climate-related deaths, injury and disease, the assessment authors said. Those impacts disproportionately affect vulnerable groups like older adults and people of color.
Midwest climate mitigation
The data in the Fifth National Climate Assessment spells out the need to reduce greenhouse gas emissions. The United States is making some progress: Its annual emissions fell 12 percent between 2005 and 2019, largely due to the decline of non-renewable energy production.
That’s not enough, the authors contended. Emissions would have to decline by more than 6 percent each year on average to meet the country’s goals and appease international temperature goals.
“The good news is that the assessment finds that the benefits of taking climate action right now far outweigh the costs,” Crimmins said.
As of March, more than $36 billion has been allocated for infrastructure projects in the Midwest through the Infrastructure Investment and Jobs Act, according to the authors. And, with billions of dollars in funding, agriculture is integrating more climate smart practices, including cover crops, no-till and nutrient management, the report authors wrote.
“There has been an astounding amount of federal funding that has been applied to agriculture in the Midwest and across the U.S. that is just being implemented,” including money from the Inflation Reduction Act, said Dennis Todey, director of the U.S. Department of Agriculture’s Midwest Climate Hub and an assessment contributing author.
Renewable energy production in the Midwest has grown by more than 275 percent in the last decade. Iowa now ranks second in the nation for its wind energy production and leads the country in its megawatt capacity per capita.
Community-level initiatives also are improving local resilience to climate change. Tree planting — like ReLeaf Cedar Rapids — helps reduce climate-related health and community impacts. Improved coordination in times of emergency, like Linn County’s resiliency hubs, can help communities better recover from climate disasters. And, to mitigate flood impacts, more jurisdictions are turning to natural flood infrastructure to protect themselves.
Brittney J. Miller is the Energy & Environment Reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.
Comments: (319) 398-8370; brittney.miller@thegazette.com