How one extreme weather event can make the next one more dangerous

Last year was The hottest year on recordThis enthusiasm has triggered many events – Heat waves, heavy rains, fires — reached an unprecedented scale. Its impact is still reverberating today.

Canada had record fires last year Smoldering all winter And start to regain strength. Atlantic Very likely Much higher than normal This is partly because the oceans absorbed a huge amount of heat last year. Heat waves and mild winters in many parts of the world set the stage for even more severe heat this year, increasing the risk of Maybe hotter Worse than last time. Finland, Mexicoand India We are experiencing a heat wave before the arrival of summer.

Different types of disasters may also intensify. Wildfires can burn trees, burn vegetation, and damage the landscape, causing Vulnerable to landslidesYears of drought can dry out the soil, causing it to compress and become impermeable, so when heavy rains come, they cause Flooding is more widespread.

Weather is naturally variable, including extremes, but human emissions of greenhouse gases are raising average global temperatures, increasing the likelihood and intensity of many extreme weather events.

The increasing frequency and intensity of extreme weather events is creating a new pattern: many disasters are not isolated, stand-alone events, but build on previous heat waves, droughts, wildfires and heavy rains.

It’s not just that disasters happen one after another, extreme events make subsequent disasters more destructive. There is a cumulative effect that doesn’t necessarily repeat itself every year. More and more people are facing these combined impacts. It is estimated that more than 90% of the world’s population China is facing greater risks of heat waves and droughts due to changes in the climate system and changes in water and land use. In addition, the population in vulnerable areas is increasing.

The result is that disasters are more frequent, more dangerous, and more costly.

Understanding how extreme weather triggers extreme weather can help people predict and respond to future threats. But right now, scientists are still struggling to gather the basic information they need to figure out how extreme weather events affect each other.

There are many ways in which disasters can affect each other. One example is that extreme droughts can lead to more severe flooding. The western United States remains affected by Decades of droughtWorst drought in at least one year 1200The lack of rainfall combined with rising average temperatures has led to drying of soil and vegetation because warmer air absorbs more moisture.

Less ground moisture causes soil to compact, making it less able to hold water, and withered grass, shrubs and trees are less able to absorb rainwater with their root systems.

Therefore, when heavy rains come, such as California’s Atmospheric Rivers Earlier this year, storms dumped more water onto land with less capacity to absorb it, leading to more flooding. The back-and-forth cycle between drought and flooding has created what some scientists describe as a phenomenon Weather Whip.

Wildfires can exacerbate this situation. They burn trees and other plants that hold the soil in place with their roots, thus triggering dangerous landslides when heavy rains fall. 2018 Montecito, CaliforniaThe previous year, a wet winter had caused vegetation to bloom early and profusely, but the hot, dry spring and summer that followed quickly withered them. These grasses and shrubs ignited and fueled Thomas Felldriven by the monsoon, the fires burned 280,000 acres of land. California’s largest fire on recordOn January 9, 2018, after a heavy rainstorm, Montecito residents woke up to a muddy 15 feet and above The mudslide slid towards them, killing 23 people and destroying more than 400 houses.

Another example we’ve seen this year is that ocean temperatures are rising over time and becoming a factor in hurricane formation.

In 2023, Atlantic Ocean Temperature Hurricanes require surface water temperatures of at least 80 degrees Fahrenheit, but they also require minimal wind shear at sea level. boyA warm phase in the Pacific temperature cycle peaked last year. It tends to raise global temperatures, but it also increases wind shear over the Atlantic, which limits hurricane formation. This fills the Atlantic with more heat, causing water temperatures to rise. This year remains high. As El Nino gives way to That girl This year, the air over the Atlantic will stabilize, providing a An above-normal hurricane season. Buckle up, the National Oceanic and Atmospheric Administration (NOAA) predicts 25 named storms and seven major hurricanes.

These extreme events are intertwined and have an impact on the real world. In addition to directly affecting people’s lives and property, one of the most serious consequences is the impact on food security.

Extreme heat, drought and excess moisture are all factors that can affect harvests, but when these factors combine, crop yields are even more affected. Of particular concern is “heat drought,” where high temperatures are combined with below-normal precipitation, a particularly stressful combination for plants. In places like India, Ethiopia and the United States, these extreme weather combinations could cause Production reduction up to 30%.

“As average temperatures get warmer, droughts tend to be warmer on average,” Corey Leskea researcher at Dartmouth College who studies climate impacts. Heavy rainfall events precipitation is not evenly distributed during the growing season; Fewer, more intense eventsNot only does this cause flooding, it also means that plants don’t get the moisture they need between heavy rains.

But Leske points out that other factors are driving higher yields, too. Climate change could mean longer growing seasons in some parts of the world, leading to better harvests. Increased carbon dioxide in the atmosphere is helping, in part, to boost plant growth. And agricultural technology is improving with the spread of tools like hardery crop varieties, precision fertilization and early disease detection. “Overall, the strongest trend driving higher yields is the technology trend,” Leske says.

Increasingly extreme weather isn’t just hurting our stomachs, it’s also eating into our wallets. Insurance provides a vivid example. In the United States, insurers are dropping customers or leaving some states altogether because their risk profiles are beyond what they can bear under the coverage and price regulations they face in some states. Losing insurance can affect more fundamental decisions, such as where people should live and where they may need to give up.

One challenge for insurers is that it is increasingly difficult to predict how different types of extreme situations will intersect and develop. Intergovernmental Panel on Climate Change Special Report on the Ocean and Cryosphere (frozen parts of the Earth), compound hazards “are examples of deep uncertainty, as data paucity often prevents assessment of the probability and consequences of compound event risks.”

Although epochal storms and raging wildfires are major events, they are relatively uncommon compared with normal natural phenomena, so there aren’t a lot of reliable measurements of how they vary. Most of the best data on hurricanes, for example, date back only to the 1970s, when new High-resolution satellite instrument enters orbitInsurers use historical records to gauge risk, but without accurate data, it’s hard for them to build a basic understanding of how last year’s drought will affect this year’s landslides. As average temperatures rise, it’s even more uncertain how these variables will align in the future.

To complicate matters further, climate change could lead to unexpected and fundamental shifts in the underlying mechanisms of extreme weather patterns. For example, further warming could lead to West Antarctic Ice Sheet Entering a self-propagating collapse loop. “Climate drivers leading to compound events are likely to cross tipping points in the future,” the report said.

In the face of these unknowns, the wise approach is to invest in measures that can save lives. This includes upgrading infrastructure to make it more resilient, developing more powerful predictive models, and deploying Early warning system Keep people away from danger. But to stop the continued warming of the earth, humans must reduce greenhouse gas emissions to zero. Otherwise, there will be more disasters in the future.