Pricing climate risk: Hurricane models and home insurance over the last two decades

Climate Change Climate Disasters & Environment Climate Policy

气候变化 气候灾害与环境 气候政策

Homeowners insurance premiums have risen sharply across the U.S., particularly in places exposed to hurricanes, wildfires, and other disasters caused by extreme weather.

美国各地的房主保险费大幅上涨，特别是在遭受飓风、野火和极端天气造成的其他灾害的地区。

How much of these higher premiums reflect worsening climate risk, and how much reflect other factors such as inflation, litigation costs, or changes in insurance markets?

这些较高的保费中有多少反映了日益恶化的气候风险，又有多少反映了通货膨胀、诉讼成本或保险市场变化等其他因素？

This paper provides new evidence by examining the relationship between hurricane risk and homeowners insurance premiums in Florida over nearly two decades.

本文通过研究佛罗里达州近二十年来飓风风险与房主保险费之间的关系，提供了新的证据。

The study draws on two sources of data.

该研究利用了两个数据来源。

The first consists of proprietary catastrophe (“CAT”) models used by insurers to estimate hurricane risk for individual properties.

第一个包括保险公司用来估计个别财产的飓风风险的专有巨灾（“CAT”）模型。

These models—developed by firms such as AIR (Verisk) and RMS (Moody’s)—are the foundation of modern insurance pricing and capital management.

这些模型由 AIR (Verisk) 和 RMS (Moody's) 等公司开发，是现代保险定价和资本管理的基础。

The second source is a hand-collected database of insurer rate filings submitted to Florida regulators by 16 large insurers who represent 70% of the current market share.

第二个来源是由占当前市场份额 70% 的 16 家大型保险公司向佛罗里达州监管机构提交的手工收集的保险公司费率备案数据库。

The filings separately report the hurricane and non-hurricane components of homeowners insurance premiums.

这些文件分别报告了房主保险费的飓风和非飓风部分。

Together, these data allow the authors to trace how changes in modeled hurricane risk translate into the premiums homeowners pay.

总之，这些数据使作者能够追踪模拟飓风风险的变化如何转化为房主支付的保费。

Hurricane risk has increased substantially, but not nearly enough to explain the sharp rise in insurance premiums.

飓风风险大幅增加，但还不足以解释保险费的大幅上涨。

According to the industry’s leading catastrophe models, expected hurricane losses for a representative Florida home increased by roughly 50% between 2006 and 2023.

根据行业领先的灾难模型，2006 年至 2023 年间，佛罗里达州代表性房屋的飓风损失预计增加了约 50%。

Over the same period, however, hurricane insurance premiums increased by more than 200%.

然而，同期飓风保险保费却增长了 200% 以上。

In short, growing climate risk explains only part of the increase in insurance costs.

简而言之，日益增长的气候风险只能解释保险成本增加的部分原因。

A central finding is that insurers charge far more than the expected annual hurricane losses on an insured property.

一个重要的发现是，保险公司对受保财产收取的费用远远高于预期的年度飓风损失。

Focusing on major model updates that follow the 2017 severe hurricane season, the study finds that a Florida homeowner with a typical pre-2001 masonry home paid roughly $4 dollars in hurricane premiums for every $1 of modeled expected hurricane loss.

该研究重点关注 2017 年严重飓风季节后的主要模型更新，发现拥有 2001 年之前典型砖石房屋的佛罗里达州房主为每 1 美元的模拟预期飓风损失支付约 4 美元的飓风保费。

Why?

为什么？

The answer lies in the economics of catastrophic risk rather than in climate change alone.

答案在于灾难性风险的经济学，而不仅仅是气候变化。

Hurricanes create highly correlated losses: A single storm can damage hundreds of thousands of properties simultaneously.

飓风会造成高度相关的损失：一场风暴可以同时损坏数十万处财产。

Because insurers must remain solvent even after rare but devastating events, they need access to enormous amounts of capital, either by holding reserves or purchasing reinsurance.

由于保险公司即使在罕见但毁灭性的事件发生后也必须保持偿付能力，因此他们需要通过持有准备金或购买再保险来获得大量资本。

The costs of financing this “tail risk” are substantial and are ultimately passed through to homeowners in the form of higher premiums.

为这种“尾部风险”融资的成本是巨大的，并最终以更高的保费形式转嫁到房主身上。

The study highlights reinsurance—insurance purchased by insurance companies themselves—as an important driver of premium growth.

该研究强调再保险（保险公司自己购买的保险）是保费增长的重要驱动力。

Florida insurers rely heavily on global reinsurers to absorb the financial risk of major hurricanes.

佛罗里达州的保险公司严重依赖全球再保险公司来吸收重大飓风的财务风险。

As reinsurance prices rose sharply after the severe hurricane seasons beginning in 2017, primary insurance premiums rose as well.

2017 年开始的严重飓风季节过后，随着再保险价格大幅上涨，主险保费也随之上涨。

Premium increases closely tracked the global reinsurance pricing cycle, suggesting that homeowners are paying not only for higher expected hurricane losses but also for the rising cost of transferring catastrophic risk to global capital markets.

保费上涨密切跟踪全球再保险定价周期，这表明房主不仅要为预期更高的飓风损失买单，还要为将灾难性风险转移到全球资本市场的成本上升买单。

Florida’s insurance market structure amplifies these effects.

佛罗里达州的保险市场结构放大了这些影响。

Large national insurers, such as Allstate and State Farm, have limited their exposure in Florida’s highest-risk areas, leaving many coastal markets to smaller Florida-based insurers and the state-backed Citizens Property Insurance Corporation.

Allstate 和 State Farm 等大型全国性保险公司限制了其在佛罗里达州风险最高地区的风险敞口，将许多沿海市场留给了佛罗里达州规模较小的保险公司和国家支持的公民财产保险公司。

Because these smaller insurers have less geographic diversification, they depend more heavily on costly reinsurance, and therefore charge larger premium increases for a given increase in hurricane risk than do diversified national companies.

由于这些规模较小的保险公司的地域多元化程度较低，因此它们更加依赖昂贵的再保险，因此与多元化的全国性公司相比，在飓风风险增加的情况下，他们收取的保费涨幅更大。

The authors investigate several alternative explanations for rising premiums.

作者调查了保费上涨的几种替代解释。

They find little evidence that catastrophe models have become substantially more pessimistic about the probability of extremely rare losses beyond the increase in expected annual losses.

他们发现几乎没有证据表明灾难模型对超出预期年度损失增加的极其罕见损失的可能性变得更加悲观。

Likewise, litigation costs and other non-hurricane expenses do not appear to explain the rapid growth in hurricane premiums.

同样，诉讼费用和其他非飓风费用似乎并不能解释飓风保费的快速增长。

Instead, the data point to the interaction of increasing climate risk with the financial costs of managing catastrophic risk.

相反，数据表明气候风险的增加与管理灾难性风险的财务成本之间存在相互作用。

The paper also provides a statewide index of homeowners insurance prices that separates hurricane-related premiums from premiums covering other perils.

该文件还提供了全州范围内的房主保险价格指数，将飓风相关保费与其他灾害的保费区分开来。

The index shows that most of the acceleration in Florida homeowners insurance costs since 2020 has been driven by hurricane coverage rather than by other components of homeowners insurance.

该指数显示，自 2020 年以来佛罗里达州房主保险成本的加速增长大部分是由飓风承保推动的，而不是房主保险的其他组成部分。

The index also closely matches observed premiums from mortgage escrow data, providing confidence that the standardized rate filings accurately capture market-wide pricing trends.

该指数还与抵押贷款托管数据中观察到的溢价密切匹配，为标准化利率备案准确捕捉整个市场的定价趋势提供了信心。

The findings have important implications for public policy.

研究结果对公共政策具有重要影响。

Measures that simply suppress insurance premiums may improve affordability in the short run but risk weakening the price signals that encourage households and communities to adapt to increasing climate risk.

简单地抑制保险费的措施可能会在短期内提高负担能力，但可能会削弱鼓励家庭和社区适应日益增加的气候风险的价格信号。

At the same time, the research suggests there may be opportunities to reduce insurance costs without undermining risk-based pricing.

与此同时，研究表明，在不损害基于风险的定价的情况下，可能有机会降低保险成本。

Potential approaches include reforms that encourage greater participation by well-diversified national insurers in Florida.

潜在的方法包括鼓励佛罗里达州多元化的国家保险公司更多参与的改革。

For example, the financing structure of the state insurance guaranty fund can penalize well-capitalized insurers who are more likely to survive severe disasters.

例如，国家保险担保基金的融资结构可能会惩罚资本充足、更有可能在严重灾难中幸存下来的保险公司。

Other options include policies that expand the supply of reinsurance—including revising the tax treatment of reinsurance or government-backed reinsurance programs that lower the cost of financing catastrophic risks.

其他选择包括扩大再保险供应的政策，包括修改再保险的税收待遇或政府支持的再保险计划，以降低灾难性风险的融资成本。

Such policies could reduce the frictional costs of insuring against hurricanes while preserving incentives for households to account for the risks posed by a changing climate.

此类政策可以减少飓风保险的摩擦成本，同时保留家庭应对气候变化带来的风险的动力。