1 of 5 | The burned-out remains of the Pioneer Cafe off Main Street smolder in the downtown area of Greenville, Calif., after the Dixie fire destroyed the town in August. File Photo by Peter DaSilva/UPI | License Photo
Dec. 29 (UPI) -- Researchers and activists sometimes describe global warming, or climate change, as "settled science."
The evidence that greenhouse gases emitted by human activities have and continue to warm the planet and alter Earth's climate is overwhelming, but science never is settled.
And each year, scientists learn more about the climatic disruptions caused by atmospheric greenhouse gas.
In 2021, scientists gained new insights into the impacts of climate change on extreme weather, including wildfires, hurricanes and deadly winter storms -- as they all got worse.
The year began with one of the deadliest winter storms in history.
While initial estimates suggested the freezing temperatures and lengthy, widespread power outages triggered by February's polar vortex, a low-pressure expanse of cold air, killed 151 people, subsequent investigations showed the catastrophe claimed 700 lives.
The stratospheric polar vortex typically holds a tight circle, keeping frigid Arctic air trapped around the top of the globe.
But as the Arctic has warmed rapidly, the temperature difference between the middle and far northern latitudes has diminished, destabilizing the polar vortex and allowing frigid Arctic to occasionally spill as far south as Texas.
Research published in 2021 showed the phenomenon is fueled by global warming.
As the Arctic continues to warm, researchers predict, extreme winter weather in North America will strike more frequently in the short term, even as winters get warmer on average.
That's bad news for places like Texas, where critics -- despite assurances from the state's policy makers -- say energy systems remain both insufficiently weatherized and regulated. Texas' energy system is highly privatized and independent, meaning it's isolated from regional grids.
"Markets are good at allocating resources during normal operations, but not for extreme events in which public safety is at risk," Carey King, a research scientist at the University of Texas and assistant director at the Energy Institute, told UPI in an email.
King said better regulations must be developed to ensure gas generators funnel increased revenues into grid stabilization efforts and infrastructure upgrades. He said he also would like to see rules designed to prevent price gouging during emergencies.
"[Policy makers] can learn the limits of markets to incentivize behavior that suits the public good in terms of safety and financial ramifications, particularly in times of emergencies," he said. "Effective oversight is needed."
No state produces more green energy than California, but all that sustainable power wasn't enough to avoid summertime in 2021.
Over the summer, the state's three largest investor-owned utilities once again were forced to cut the lights for thousands of homes as the threat of wildfire spread.
While climate change could bring increased precipitation to parts of California, rising temperatures and prolonged droughts yield bigger and more intense fires across the West. According to research published early this year, wildfires are crippling the carbon storage abilities of Earth's forests.
Even when woodlands in California avoid fire, one recent study found, the state's most-drought-resistant tree species, the blue oak, is left vulnerable by prolonged dry periods.
The near-five-year drought that dehydrated much of California between 2012 and 2016 led to significant tree cover declines and die-offs among stands of blue oak, Quercus douglasii, the hardy trees found among the foothills of the Sierra Nevadas.
"Fire seasons in areas with an active fire regime are getting longer, snowpack is dwindling, springs are coming earlier, summers later, winter temperatures are warming and total annual precipitation is not keeping pace with warming," Paul Hessburg, a forest ecologist with the Forest Service's Pacific Northwest Research Station, told UPI.
"The effect is that during fire seasons, fuels become available to burn earlier, and they stay available to burn longer most years," Hessburg said.
But according to Hessburg, the West isn't suffering for lack of trees. In fact, more combustible fuel exists now than 200 years ago, when lightning-triggered fires regularly thinned forests and indigenous populations routinely burned forestland to grow crops and attract game.
Today, authorities suppress almost all wildfires. When fires do escape containment at the height of wildfire season, when conditions are especially hot and dry, they have a plethora of fuel to burn.
Climate patterns are worsening the effects of West's fire deficit, leaving the region's carbon storage increasingly vulnerable.
"Research shows that in all countries with an active fire season that a warming and drying climate is driving fire sizes, that is annual burned area," Hessburg said. "Some countries are experiencing active fire regimes for the first time in recent memory, too."
The barrage of tornadoes that scarred parts of the South and Midwest in early December was perhaps the year's most shocking weather story.
The outbreak, which featured at least 35 confirmed twisters, killed 93 people across five states. Kentucky suffered the most fatalities, with 78 dead.
While the links between climate change and extreme weather have become clearer in recent years, the impacts of the global warming on tornadoes are not well understood.
Tornadoes form when rapidly rising warm air hits cooler, denser air above, yielding wind shear and promoting the formation of supercells and spinning funnels.
Some scientists estimate that a great supply of warm air -- fueled by global warming -- will provide more fuel for tornado-producing storm systems.
But other researchers suggest the same phenomenon driving an increase in extreme winter weather -- the Northern Hemisphere's diminished temperature gradient -- will limit the strength of high-altitude winds that help shape and energize funnel cells in tornadoes.
Preparing for extremes
"We know that the climate is getting warmer and drier, and until we get a handle on greenhouse gas emissions, that's going to remain the case," Hessburg said. "There isn't going to be a new normal -- these trends are going to continue through at least the end of the century."
The Earth's natural systems are exceedingly complex, making it difficult to identify the precise ways in which climate change impacts weather, but numerous studies have revealed a strong link between global warming and extreme weather.
Research suggests that the sooner carbon emissions are reduced, the better the chance humans can avoid the most catastrophic effects of climate change.
In the meantime, officials, experts and advocates have said governments must start to prepare more strategically for consequences of global warming.
"To avoid what happened in Texas, there needs to be a recognition that more severe and unusual weather will be the norm in the future," Maine state Rep. Seth Berry told UPI earlier this year.
Berry is part of a growing group of policy makers pushing for greater public control of utilizes, as well as decentralized energy solutions.
"We need to anticipate bizarre and extreme weather and be ready for it. Building more fortified infrastructure is important," he said. "That can look like taller and stouter poles. It can be insulated tree wire, which is stronger and doesn't short out when a tree is leaning on the wire."