Posted on

Analysis | The great drought and the great deluge, all at the same time

Analysis | The great drought and the great deluge, all at the same time

Comment

You’re reading an excerpt from the Today’s WorldView newsletter. Sign up to get the rest free, including news from around the globe and interesting ideas and opinions to know, sent to your inbox every weekday.

In the age of climate change, our past intrudes upon the present. Last week, receding water levels in a Serbian stretch of the Danube, Europe’s second-largest river, surfaced a flotilla of Nazi-era German warships that were still packed with ammunition and unexploded ordnance. They were exposed at a time when Europe is experiencing what appears to be the worst dry spell in half a millennium, with two-thirds of the continent under some form of drought warning.

Other ruins and wrecks are popping up as waterways shrink. A submerged 1st century A.D. Roman bridge possibly constructed under the orders of Emperor Nero emerged from the Tiber River last month; further to the north, out of the depths of Italy’s tourist-clogged Lake Como, emerged a 100,000-year-old skull of a deer and the ancient remains of lions, hyenas and rhinos.

Scorching high temperatures left the Iberian Peninsula drier than any time in the last 1,200 years. In Spain, parched riverbeds and shrinking reservoirs have exposed a Neolithic monument known as the Spanish Stonehenge, a Roman fortress, a medieval church, and a number of more recent “ghost towns” that had been abandoned and flooded following 20th century dam projects.

In France, which is experiencing its worst drought on record, wine makers are harvesting their grapes earlier than ever. At a time where anxiety is already mounting over energy costs, surging temperatures and sparse rainfall have hit hydropower capacity in parts of Europe. They have also wreaked havoc on the continent’s agricultural output.

On this front, too, Europe’s rivers are turning up bleak omens — the receding waters in parts of central Europe have revealed old “hunger stones,” markers placed along riverbeds that locals centuries prior left as guides to earlier droughts. One stone that emerged out of the Elbe read: “When this goes under, life will become more colorful again.”

How ‘heat officers’ plan to help cities survive ever-hotter summers

These maps show how excessively hot it is in Europe and the U.S.

Yet what’s being experienced now in Europe — and all over the world — isn’t simply a rerun of the past. The northern hemispheric summer has been defined by a relentless series of unwelcome climate-related superlatives. Heat waves set record temperatures across cities in the Middle East and Europe. China is in the grips of its worst drought on record, which has dried up parts of the Yangtze River and impacted swaths of the country’s industrial sector. Meanwhile, in the space of only five weeks, U.S. cities experienced five instances of 1,000-year rain events — that is, episodes of severe flooding that have just 0.1 percent probability of happening in any given year.

The scale and ferocity of what’s taking place is supercharged by climate change. “Studies have found that heat waves are increasing in intensity and duration in China, as well as delivering warmer temperatures at night, because of human-induced climate change,” my colleagues reported. “The increase has been observed in urban and rural locations. Heat waves are also starting earlier and ending later.”

In China, the droughts in some parts of the countries have been met by a deluge in others. The western province of Qinghai experienced such heavy rains that some rivers changed course; landslides and floods killed more than a dozen people earlier this month.

In some cases, there is a direct link between drought and floods — soil actually absorbs water better when damp, while heavy rains slosh off parched landscapes into waterways. That explains why researchers in Central Texas are fearful of what may happen after a drought exposed 113-million-year-old dinosaur tracks in a dried-up riverbed.

“Given the wild fluctuations in weather and precipitation, we can have these long dry periods exposing things and then catastrophic flooding,” Vincent Santucci, senior paleontologist at the National Park Service, told my colleagues. “The high-energy nature of those floods can completely destroy a fossil site.”

Five 1,000-year rain events have struck the U.S. in five weeks. Why?

In South Asia, searing heat earlier in the summer gave way to an erratic and intense monsoon season. That, in turn, has stoked major flooding and landslides across Pakistan, India and Bangladesh. Pakistan has been ravaged in recent weeks, with heavy rains and rising rivers leading to the deaths of more than 1,000 people and the displacement of over 10 million. Pakistan declared a state of emergency over the weekend and requested international aid, with officials describing the devastation wrought by a summer of extreme weather as the worst in over a decade.

Pakistan is experiencing a “climate catastrophe,” the nation’s climate change minister told NPR this weekend.

“Extreme climate events have become a regular phenomenon in South Asia,” wrote Hamid Mir for The Washington Post’s opinion pages last month. “We are facing weather-related problems in almost all parts of Pakistan. Flooding has become almost routine in some areas; others are plagued by drought. Glaciers are melting fast, resulting in reduced water flow in rivers. Farming is suffering as a result, and the decline in agricultural productivity is creating food insecurity. All this is accelerating migration from rural areas to cities.”

South Asia is at the sharp end of a planetary crisis. “Unrelenting heat waves have led scientists to wonder whether areas in the region may soon become uninhabitable or too dangerous for human life. “Across India and around the world, summer has become a season of peril, when society’s poorest and most vulnerable members must live and work in conditions that push the limits of human endurance,” my colleagues detailed in a grim but important piece that charted life for Indian day laborers with no choice but to work outside.

No part of the world is shielded from the reality of climate change. “The signature of a warming world is now perceptible every day in the conditions we regularly face,” wrote my colleague Matthew Cappucci, when exploring the scientific causes of increased rainfall in the United States.

“For many people, the concept of a changing climate might seem distant and removed — a two-millimeter rise in sea levels a year or a subtle uptick in global temperatures may appear inconsequential,” he added. “But human influence is affecting the dynamics of weather systems, the periodicity of the jet stream and the moisture-holding capacity of the atmosphere.”

The experience of these weather extremes is not forcing major climate policy reforms. The global panic over energy has led to the short-term pursuit of more fossil-fuel extraction. China had to scramble for more coal after the summer heat and drought delivered a blow to its hydropower capacity.

“After this crisis, the coal lobby will be saying, ‘This is why you need to have more coal mines and more coal-fired power plants,’” Philip Andrews-Speed, a senior fellow at the National University of Singapore’s Energy Studies Institute, told my colleagues. “As in Europe, the key is keeping the lights on and keeping the heating and the air conditioning going. That is the short-term priority.”

Posted on

Analysis | Five 1,000-year rain events have struck the U.S. in five weeks. Why?

Analysis | Five 1,000-year rain events have struck the U.S. in five weeks. Why?

Comment

Five weeks. Five instances of 1,000-year rain events. If it seems like the weather across the Lower 48 as of late has been bonkers, you’re not imagining things. It’s been a maelstrom of weather extremes, a seesaw fluctuating wildly from significantly dry to record wet conditions.

Parts of the United States, especially in the West, are gripped by an inveterate and devastating drought — yet many drought-stricken areas have experienced rare and extreme flooding over the summer, bringing fiercely different precipitation extremes to the region in a matter of hours.

At least one dead after Dallas area hit by 1-in-1,000-year flood

On Monday, parts of the Dallas-Fort Worth metroplex awoke to torrential downpours that dropped totals of 10 to 16 inches, bringing calamitous impacts and prompting widespread water rescues. Entire neighborhoods near the suburb of Mesquite were left beneath water, and at least one person died.

What happened in the Dallas area came after the city and 29 percent of the state were gripped in a top-tier “exceptional” drought that impacted crops and drove water shortages. Some farmers were forced to thin their herds in a process called “culling,” according to the U.S. Drought Monitor. DFW International Airport was 11.11 inches behind for rainfall since Jan. 1.

Then Monday became the airport’s wettest calendar day on record.

The extreme rainfall in Dallas was a “1,000-year rain event,” an episode of flooding that has just a 0.1 percent probability of happening in any given year. It joins the company of 1,000-year rain events that struck Kentucky, St. Louis, eastern Illinois and Death Valley, Calif., since the end of July — all of which were experiencing abnormally dry conditions or in a severe drought beforehand.

Droughts can often make flooding worse. Droughts kill plants and leaves the ground bare, reducing soil absorption. They also harden top soils, which makes it easier for water to run off. The extremely dry ground, combined with the rapid rainfall, can trigger widespread flooding.

While no single weather event is caused by mankind’s influence on the atmosphere, the weather facing the nation bears the fingerprint of a warming world. While it seems contradictory, both drought and flooding are closely tied to human-driven warming and are altering our environment and how we interact with it.

We are witnessing firsthand the effects of ordinary weather events — a product of chaotic randomness and natural variability — supercharged by climate change.

What is a 1,000-year rain event?

We haven’t been taking measurements for 1,000 years, so how can we know what constitutes a 1,000-year rain event? It comes from constructing what’s called a probability distribution, and requires some basic grade-school statistics.

Using an available data set of, say, 100 years or so, we can plot the frequency of rain events of varying magnitudes for a given time window. Once that’s done, we can note the shape of whatever distribution results. Think back to the bell curve in math class — most of the data is clumped around the middle, with more extreme events on the edges as frequency trails off. Finding the likelihood of an extreme weather event is similar.

From there, meteorologists and statisticians extract “recurrence intervals,” or the average frequency with which a given extreme event should occur. That means a 1,000-year rain event has an 0.1 percent chance of happening in any given year. A 100-year event would have a 1 percent chance, and so on.

Nowadays, however, our climate is evolving rapidly enough that previously-defined recurrence intervals based on historic data may no longer apply. Michael Mann, a climate scientist at Pennsylvania State University, explained that today’s climate is making some of these reference points relics of the past.

“Recurrence intervals start to lose their meaning for ‘nonstationary’ systems,” he wrote, “in this case because there is a trend toward greater extremes in a warming climate.”

Extreme weather tormenting the planet will worsen because of global warming, U.N. panel finds

In a 2017 paper, he found the return period of a 7.4-foot storm surge flood in New York City had decreased from once every 500 years in preindustrial times to once every 25 years since. It could become a once-per-five-year event toward the middle of the century. Precipitation extremes follow a similar trend.

Five 1,000-year rain events in five weeks

It’s normal that somewhere will see a 1,000-year rain each year. It’d be abnormal if that wasn’t the case. But five in five weeks is extreme, and hints at an overarching trend.

  • On the morning of July 26, St. Louis awoke to historic flooding in the city. A staggering 7.87 inches of rain fell in six hours during the morning commute, inundating vehicles and prompting hundreds of water rescues. It came from training thunderstorms, or storms moving along a stalled frontal boundary. A total of 8.64 inches was logged for the day, becoming St. Louis’s wettest day on record. It crushed the previous record of 5.59 inches on May 16, 1995, by a wide margin; records date back to 1931. Some places west of the city received close to 13 inches.
  • On July 27, rains began in eastern Kentucky north of Hazard and quickly turned fatal. Rainfall rates topping 2 inches per hour contributed to rapid rises on area rivers, including the North Fork of the Kentucky River at Whitesburg, which rose 11 feet in five hours. That was six feet above the previous record. The water probably kept rising, but the sensor was washed away. It was another 1,000-year rain event that tragically killed 38 people.
  • On the night of Aug. 1, training thunderstorms in eastern Illinois dumped 8 to 13 inches of rain in about 12 hours near the town of Effingham. Fortunately the landscape was able to handle the rainfall, but there were some reports of flash flooding.
  • On Aug. 5, heavy storms dumped 1.46 inches of rain on Death Valley, Calif. That doesn’t sound like much, but it’s just 0.01 inches shy of the all-time daily record. Given the rapidity with which it fell, it was classified as a 1,000-year rain event. Death Valley averages just 0.11 inches of rain in August; 1.46 inches is equivalent to nine months’ worth of rainfall. According to the Park Service, the flooding destroyed a water system that serves numerous park residences and facilities. A number of vehicles were also damaged.
  • On Aug. 22, moisture pooling on a stalled frontal boundary over Dallas translated to training thunderstorms. DFW International Airport saw both its wettest day and wettest hour on record. Flash flood warnings were issued across the city.

All five events stemmed from stationary fronts and anomalously-humid air masses.

The fingerprint of climate change

It’s well-established that a warmer world is a wetter world. That’s due to something called the Clausius-Clapeyron relation. For every degree Fahrenheit the air temperature warms, the air can hold about 4 percent more water. That’s leading to higher humidity and heat indexes — which can be taxing on the human body — but is also manifesting in precipitation extremes.

It’s not noticeable in the day-to-day, but let’s consider that we take a storm in preindustrial times and copy it into today’s environment. With about 1.8 degrees of warming since preindustrial times, the air would have a 7 to 8 percent greater capacity to store and transport moisture.

In a water-loaded environment like a thunderstorm complex or tropical system, you might think that would mean 7 or 8 percent more rainfall. But that’s where things get murky. Because an air mass is being constantly replenished and fed into these storms, that can quickly lead to a 10 or 20 percent increase in precipitation totals.

We’re seeing this quite prominently in rainfall rates, meaning the wetter atmosphere is leading to heavier instantaneous downpours. Dallas, for example, saw its highest one-hour total on record between 1 and 2 a.m. on Monday, with 3.01 inches coming down. Records at DFW International extend back to 1953, but seven of the top 10 wettest one-hour totals have occurred in the 2000s.

There’s already been a 24 percent spike in the frequency of top 1 percent rainfall events in Texas since the dawn of the 20th century. That trend is echoed across the country and world.

No weather is caused by climate change. Weather will always be weather. But the signature of a warming world is now perceptible every day in the conditions we regularly face.

For many people, the concept of a changing climate might seem distant and removed — a two-millimeter rise in sea levels a year or a subtle uptick in global temperatures may appear inconsequential. But human influence is affecting the dynamics of weather systems, the periodicity of the jet stream and the moisture-holding capacity of the atmosphere.

As is becoming evident in the Lower 48 and across the world, 1,000-year floods may happen a lot more than once every 1,000 years. “Unprecedented” may, in fact, become precedented. And the uptick in extremes and changing conditions means our environment is evolving faster than our infrastructure. That’s the crux of the problem.

Posted on

Contributions of event rates, pre-hospital deaths, and deaths following hospitalisation to variations in myocardial infarction mortality in 326 districts in England: a spatial analysis of linked hospitalisation and mortality data

Contributions of event rates, pre-hospital deaths, and deaths following hospitalisation to variations in myocardial infarction mortality in 326 districts in England: a spatial analysis of linked hospitalisation and mortality data

Summary

Background

Myocardial infarction mortality varies substantially within high-income countries. There is limited guidance on what interventions—including primary and secondary prevention, or improvement of care pathways and quality—can reduce myocardial infarction mortality. Our aim was to understand the contributions of incidence (event rate), pre-hospital deaths, and hospital case fatality to the variations in myocardial infarction mortality within England.

Methods

We used linked data from national databases on hospitalisations and deaths with acute myocardial infarction (ICD-10 codes I21 and I22) as a primary hospital diagnosis or underlying cause of death, from Jan 1, 2015, to Dec 31, 2018. We used geographical identifiers to estimate myocardial infarction event rate (number of events per 100 000 population), death rate (number of deaths per 100 000 population), total case fatality (proportion of events that resulted in death), pre-hospital fatality (proportion of events that resulted in pre-hospital death), and hospital case fatality (proportion of admissions due to myocardial infarction that resulted in death within 28 days of admission) for men and women aged 45 years and older across 326 districts in England. Data were analysed in a Bayesian spatial model that accounted for similarities and differences in spatial patterns of fatal and non-fatal myocardial infarction. Age-standardised rates were calculated by weighting age-specific rates by the corresponding national share of the appropriate denominator for each measure.

Findings

From 2015 to 2018, national age-standardised death rates were 63 per 100 000 population in women and 126 per 100 000 in men, and event rates were 233 per 100 000 in women and 512 per 100 000 in men. After age-standardisation, 15·0% of events in women and 16·9% in men resulted in death before hospitalisation, and hospital case fatality was 10·8% in women and 10·6% in men. Across districts, the 99th-to-1st percentile ratio of age-standardised myocardial infarction death rates was 2·63 (95% credible interval 2·45–2·83) in women and 2·56 (2·37–2·76) in men, with death rates highest in parts of northern England. The main contributor to this variation was myocardial infarction event rate, with a 99th-to-1st percentile ratio of 2·55 (2·39–2·72) in women and 2·17 (2·08–2·27) in men across districts. Pre-hospital fatality was greater than hospital case fatality in every district. Pre-hospital fatality had a 99th-to-1st percentile ratio of 1·60 (1·50–1·70) in women and 1·75 (1·66–1·86) in men across districts, and made a greater contribution to variation in total case fatality than did hospital case fatality (99th-to-1st percentile ratio 1·39 [1·29–1·49] and 1·49 [1·39–1·60]). The contribution of case fatality to variation in deaths across districts was largest in women aged 55–64 and 65–74 years and in men aged 55–64, 65–74, and 75–84 years. Pre-hospital fatality was slightly higher in men than in women in most districts and age groups, whereas hospital case fatality was higher in women in virtually all districts at ages up to and including 65–74 years.

Interpretation

Most of the variation in myocardial infarction mortality in England is due to variation in myocardial infarction event rate, with a smaller role for case fatality. Most variation in case fatality occurs before rather than after hospital admission. Reducing subnational variations in myocardial infarction mortality requires interventions that reduce event rate and pre-hospital deaths.

Funding

Wellcome Trust, British Heart Foundation, Medical Research Council (UK Research and Innovation), and National Institute for Health Research (UK).

Introduction

Mortality from ischaemic heart disease has declined substantially in high-income countries, driven by both a decline in incidence and improved survival of myocardial infarction—the acute presentation of ischaemic heart disease which has the potential to be rapidly fatal in the absence of appropriate interventions.

  • Grey C
  • Jackson R
  • Schmidt M
  • et al.
One in four major ischaemic heart disease events are fatal and 60% are pre-hospital deaths: a national data-linkage study (ANZACS-QI 8).