It’s a question that follows any natural disaster, especially brutal hurricanes like Ian: Was this due to climate change?
When scientists like Kevin Reed are asked, they usually push back. Most researchers agree that it is incorrect to refer to a single storm and to say that it is “caused” by global warming. Too many variables.
This is a really difficult question to answer. There is no “What would September 2022 look like without climate change?” said Reed, assistant professor in the School of Marine and Atmospheric Sciences at Stony Brook University.
But there is a growing consensus that sea-level rise and warming in the past 100 years have already affected storms like Ian, which swept through Florida last week, and may continue to do so in the future. At the very least, hot weather means the oceans are warming, fueling the strength of hurricanes.
“We live in a world one degree (centigrade) warmer, and there is no doubt that hurricanes have been altered in some ways by climate change,” he said.
Tom Knutson, a NOAA senior scientist who studies climate and hurricanes, said scientists are more confident in noticing what has changed about storms in the modern world. But less so in terms of being able to link these changes to climate change. Predicting what the future might hold is even more difficult.
That’s because hurricanes and global weather patterns are very complex. Some changes in the atmosphere and storms can be attributed, for example, to high levels of physical air pollution, other than greenhouse gases, being emitted into the atmosphere.
Storm tracking technology has also greatly improved in recent centuries. Scientists agree that we are now capturing more “unwanted storms” – short-lived, weak hurricanes – than ever before. This can skew the data, which is why most scientists are careful when drawing a direct line between the Earth’s hottest numbers and hurricanes.
“It’s a very complicated picture and it gets more and more complicated, we’re inferring many of these things from climate models that are themselves uncertain,” Knutson said. “We have to be careful.”
Here science stands on several fronts:
The probability of a storm occurring is higher than a storm
Sea levels near southern Florida have already risen about eight inches since 1950, according to NOAA tidal gauge data. This means that the water starts at a higher base level, allowing more hurricanes to reach a height of a few inches and cover more ground.
Researchers expect sea level rise to accelerate because rising temperatures are causing the polar ice sheets to melt faster. Over the next century, South Florida can expect a sea level rise of more than three feet, according to estimates by the United Nations’ Intergovernmental Panel on Climate Change (IPCC).
This will push storms higher as hurricanes stream through coastal communities. One 2020 study modeled what 21 hurricanes that struck between 2000 and 2013 might look like under projected weather conditions in the year 2100. The researchers estimated that, on average, floods could have been about 30% worse and covered about a quarter of the Earth. .
heavy rain
One of the most direct links between climate change and hurricanes is rain. As anyone who struggles with humidity knows, warmer air holds more moisture.
For every 2°F of warming, there is about 8% more water in the atmosphere, and the world has warmed at least 2°F since pre-industrial times.
So, perhaps not surprisingly, one study conducted in the 2020 hurricane season found an 8% increase in average three-day precipitation rates for hurricanes, and a 5% increase in tropical storms.
The lead author, Stony Brook Reed, said they also discovered that a warming planet increased the rate of precipitation. In the 2020 season, three-hour precipitation rates will increase by 10% or more due to tropical storms and hurricanes.
“If we experience a similar storm in the future, it will rain more because of climate change,” he said. “If you had 30 inches of rain, you could say that more than 2.5 inches of that rain was due to climate change, which means it wouldn’t rain as much if we didn’t warm the planet.”
Reed and colleagues also produced a rapid study of Hurricane Ian on Thursday that suggested a 10 percent increase in extreme precipitation rates due to human-caused climate change.
This research group, known as attribution science, looks to answer the question of how climate change affects a particular storm. In Reed’s case, he and his colleagues loaded a powerful weather model onto a supercomputer with the exact track and data from a modern-day storm, then reset the clock to temperature and weather conditions in the 1850s.
The most obvious change they see is that storms are less wetter when they occur in the past.
Get stronger faster
One of the most dangerous features of hurricanes is rapid intensification, which is when a storm’s maximum wind speeds increase 35 miles per hour or more in a single day. It’s also hard to predict, as when a storm suddenly intensifies near shore, coastal communities don’t have enough time to prepare or evacuate.
Early studies suggest that climate change has made rapid intensification more common. A 2021 IPCC report found that “the global frequency of rapid intensification events (tropical cyclone) has likely increased over the past four decades” and added that researchers had “medium confidence” that “none of these changes can be explained by Natural contrast alone.”
The researchers can say with more certainty that conditions that lead to rapid densification are becoming more common. Sea surface temperatures are rising at a rate of 0.14 degrees Fahrenheit per decade, according to NOAA, and air humidity is increasing between 1% and 2% every decade, according to the Intergovernmental Panel on Climate Change. Both of these factors may give future hurricanes more fuel to fuel their growth.
Meanwhile, NOAA and Columbia researchers predict that climate change will weaken vertical wind shear, an atmospheric feature that can pump the brakes on rapid intensification.
Kiran Bhatia, a former climate researcher at Princeton University, who is now vice chair of the climate change risk advisory group at insurance broker Jay Carpenter, said.
Less hurricanes but stronger
Climate change may make hurricanes more severe but less frequent.
Reliable global records of hurricane intensity go back only about four decades, when weather satellites began to help scientists estimate storm strength accurately. In the years since, hurricanes appear to be getting stronger, according to a 2020 research paper from researchers at NOAA and the University of Wisconsin. They found that the probability of a hurricane reaching Category 3 wind speeds — the threshold for which it would be classified as a “major hurricane” — has risen by about 25% since 1979, as extra heat in the oceans and atmosphere gives storms more fuel to grow.
But even as climate change is making storms stronger, scientists believe it is weakening the ocean currents that help hurricanes form in the first place — notably the AMOC, which pulls warm surface water from the tropics across the Atlantic. The 2021 IPCC report says the AMOC, which also operates the Gulf Stream, is “very likely” to weaken during the 21st century.
As a result, the frequency of hurricanes may decrease. A research paper published in July in Nature Climate Change estimated that tropical cyclones formed 13% less in the 20th century than they did between 1850 and 1900. Although pre-satellite hurricane data is spotty, the international team of researchers Combine real world observations and simulation. from climate models to fill in the gaps and estimate the number of hurricanes that may have formed from 1850 to 2012.” “A series of back-to-back seasons with Category 5, and that’s something more in line with what we would expect in a warmer climate… as opposed to a greater number of storms,” Brian said. Soden, professor of atmospheric sciences at the University of Miami’s Rosenstiel College of Marine and Atmospheric Sciences, told The Herald in 2020.
Slower, Wet Storms Jim Kosin, a climate scientist at the Collaborative Institute for Meteorological Satellite Studies in NOAA, in Madison, Wisconsin, published a paper in 2018 that suggested tropical storms and hurricanes around the world had slowed by about 10% between 1949 and 2016, hitting the brakes. More strongly above the ground. It was met with some criticism in the scientific community, but it was followed by another research paper with NASA’s Timothy Hall in 2019 that narrowed down the slowdown of storms near the North American coast since 1950. They found that a hurricane’s forward speed had decreased since 1900, which could lead to More precipitation and flooding as the storm stops above ground.
More study is needed to determine how much of a slowdown will occur as warming continues. However, it is quite plausible that local increases in precipitation could be dominated by this slowing rather than expected increases in precipitation due to global warming. Knutson, with NOAA, called it “the most compelling evidence of a trend I’ve seen so far.” But he cautioned that just because this trend is observed does not automatically mean that climate change is to blame. “This is an open research question.”
May have more landing sites in the future
In the past, many storms at sea were not detected unless ships unlucky enough to encounter them were notified. But the good records go back a century or more on the records making the beach. New research by Knutson, based on running past data into a computer model, shows what might happen to hurricane tracks in the future if global warming continues unchecked. He found that while the number of storms making landfall has not changed much in the past century, an increasing portion could occur in the future.
Combined with other research suggesting fewer but stronger storms may appear in the future, Knutson said his findings suggest cities are being hit less, but increasingly.
“It’s kind of a lot of the many influences that cut in different directions,” he said. Knutson was always a careful scientist, and he also cautioned that his work was only a speculation. “This is in form. We’ll see what happens in the real world,” he said.
Written by Alex Harris and Nicholas Rivero, The Miami Herald
• • •
Tampa Bay Times coverage of Hurricane Ian
how can I help: Where to donate or volunteer to help victims of Hurricane Ian.
FEMA: Florida residents affected by Ian can now apply for FEMA assistance. Here’s how.
The storm passed What now? Safety tips for going home.
Post-Storm Questions: After Hurricane Ian, how to get help with fallen trees, damaged food and shelter.
Atmosphere effects: Hurricane Ian was supposed to hit Tampa Bay. what happened?
What to do if a hurricane damages your home: Stay calm, then call your insurance company.
Schools: Will schools reopen quickly after Hurricane Ian passes? It depends.
More storm coverage: Prepare and stay tuned at tampabay.com/hurricane.
from San Jose News Bulletin https://sjnewsbulletin.com/how-does-climate-change-affect-hurricanes-like-ian/
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