Connecting the dots between natural disasters and climate change in the US

The last year has brought record-breaking natural disasters of all shapes and sizes to the U.S., from massive hurricanes in the Gulf to wildfires and flash-flooding in the Pacific. Though isolated in time and space, it would be an oversight to consider these events entirely unrelated.

For years, climate scientists have been predicting more extreme weather as carbon emissions increase and global temperatures rise. And what we’re seeing is exactly that, producing wreckage well beyond your every-few-years event. Let’s have a look at the last 12 months.

{mosads}In August, Houston all but disappeared under Hurricane Harvey’s torrential downpour. Over 30,000 people were displaced, 200,000 homes and business damaged, and nearly 100 lives lost. Harvey dropped over a foot more rain than any prior storm on record in the lower 48 states. Over $125 billion dollars in damage was incurred, costing more than any prior natural disaster in U.S. history, except for Hurricane Katrina.

Weeks later, the country braced again. While most remember Hurricane Irma as “that Category 5 hurricane that calmed before hitting Florida,” — it did not weaken before first depopulating the Caribbean island of Barbuda, where at least 95 percent of property was destroyed or damaged, according to the LA Times. Irma’s 185 mph winds lasted for 37 hours, setting a new world record. Weather.com stated after the storm that “Hurricanes of this intensity often undergo fluctuations in intensity, but Irma did not.”

Then came Hurricane Maria, which left much of the island of Puerto Rico in ruins. While initial reports showed a death toll of 64, a recent Harvard study put the number at closer to 5,000 — as many households went weeks and even months without electricity and water. Maria’s $90 billion tab made the storm the third costliest in U.S. history, just behind Harvey.

As hurricane season wound down, an unprecedented summer of wildfires across the Pacific coast only intensified. In October came the most destructive wildfire in California history, claiming over 5,600 structures and 22 lives. Not two months later, the Thomas Fire became the largest fire on record in the state, scorching over 280,000 acres.

In just the last three months of 2017 the state experienced five of its 20 most destructive wildfires. But California hasn’t been the only record-breaker. Four of the 10 largest wildfires on record in Oregon have occurred in just the last five years.

As fires died out West, a new guise of climate disaster emerged with winter as snowstorm after snowstorm battered the Northeast. In one case, a “bomb cyclone” packed enough energy to topple power lines that led to blackouts from Virginia to Maine.

Only months prior, the region experienced record cold. In Boston, the maximum daily temperature in December reached a new low of 12 degrees.

According to the U.S. Global Change Research Program, the Northeast has experienced a more than 70 percemt rise in the amount of precipitation falling during “very heavy” weather events over the 1958 to 2010 period. Of the 10 heaviest snowstorms in Boston, half occurred since 2000 — with two taking place in the same two weeks of 2015, making it the all-time snowiest season for the city.

Strangely, the Northeast has also seen anomalous mid-winter warming. For two years in a row, February soared above 70 degrees in some areas. Temperatures in February are usually in the teens, and sometimes lower.  This past winter, 19 areas across the Northeast experienced their warmest February on record, including Washington D.C., Philadelphia, and Baltimore. Around the same time, temperatures in the North Pole were above freezing despite the region still being enshrouded in total winter darkness — setting a new February heat record according to the Danish Meteorological Institute.

As for our island neighbors, Hawaii just made headlines in April by incurring more rainfall in a single day than any prior storm on record in the country. According to the Washington Post, flash flooding and mudslides destroyed roads, bridges, and homes, cutting off locals and leaving thousands of tourists stranded.

Despite temperature and weather anomalies in all directions, the trends we’ve been observing are not a total surprise. In the case of hurricanes, the Intergovernmental Panel on Climate Change has warned of increased storm severity due to climate change. According to its latest report, “intense tropical cyclone activity has increased in the North Atlantic since 1970” and “extreme precipitation events will become more intense and frequent in many regions” as global temperatures continue to rise. In another piece, I explain why hurricanes will intensify under a warmer climate.

Similarly, increased wildfires are arriving on schedule and may be here to stay. A recent study by the Forest Service suggests that wildfires can be expected to increase throughout the region as warming trends continue. In a 2006 study of wildfires in the western U.S., recent decades were reported to have seen a four-fold increase in major wildfires. The area burned by these fires has risen six-fold.

What about the confused weather in the Northeast? Scientists attribute this to the instability of the so-called polar vortex — caused by warming of the planet. Under normal conditions, frigid temperatures remain relatively isolated to the polar regions. As temperatures rise, however, these circular polar winds weaken and begin to meander, allowing frigid Arctic air to descend to the south, and warmer equatorial air to penetrate further north.

Despite temperature ups and downs, a comparison of daily record high temperatures with record low temperatures averaged across the U.S. demonstrates a trend toward increased heat, consistent with the notion of global warming. A recent study by the National Center for Atmospheric Research showed the current ratio of record high to record low temperatures at about 2-to-1; with models suggesting this ratio could increase to 20-to-1 by mid-century.

The frequency and severity of major natural disasters has risen sharply over the years. The National Centers for Environmental Information maintains a record of U.S. natural disasters that cost $1 billion or more in damage. In 2016, $46 billion was spent on such disasters, due to 15 major events. This was three times the average since 1980. In 2017, the number rose to 16, with costs exceeding $300 billion. This shattered the prior U.S. annual record cost of $219 billion that occurred in the wake of Hurricane Katrina and other storms in 2005. In total, 230 natural disasters occurring since 1980 have cost the U.S. over $1.5 trillion. These numbers are critical to take into account when we consider the cost of reducing carbon emissions.

While it’s important to pick ourselves up after tragedy, we must connect the dots of extreme weather and take notice of an underlying pattern that is consistent with predictions by climate scientists. Only by recognizing the link between carbon emissions, climate change, and extreme weather can we begin to appropriately address the climate crisis and prevent future tragedy in the long run. Furthermore, the business-as-usual approach to carbon emissions is not free. It comes at a cost — a cost that is growing with every passing year.

The science is there, and solutions are on the table. Citizens, policymakers, and industry must take notice and help move the U.S. in a direction that curbs carbon pollution and secures a safer and less costly future for our nation. 

Shahir Masri, Sc.D., is an assistant specialist in air pollution exposure assessment and epidemiology at the University of California at Irvine, and also teaches at the Schmid College of Science and Technology at Chapman University. Masri is launching “On the Road for Climate Action,” a public outreach project to communicate the crucial message of climate science and solutions in over 35 different states.