David Changnon

An Introduction to Trends in Extreme Weather and Climate Events: Observations, Socioeconomic Impacts, Terrestrial Ecological Impacts, and Model Projections*

Weather and climatic extremes can have serious and damaging effects on human society and infrastructure as well as on ecosystems and wildlife. Thus, they are usually the main focus of attention of the news media in reports on climate. There are some indications from observations concerning how climatic extremes may have changed in the past. Climate models show how they could change in the future either due to natural climate fluctuations or under conditions of greenhouse gas-induced warming. These observed and modeled changes relate directly to the understanding of socioeconomic and ecological impacts related to extremes.

Human Factors Explain the Increased Losses from Weather and Climate Extremes

Abstract Societal impacts from weather and climate extremes, and trends in those impacts, are a function of both climate and society. United States losses resulting from weather extremes have grown steadily with time. Insured property losses have trebled since 1960, but deaths from extremes have not grown except for those due to floods and heat waves. Data on losses are difficult to find and must be carefully adjusted before meaningful assessments can be made. Adjustments to historical loss data assembled since the late 1940s shows that most of the upward trends found in financial losses are due to societal shifts leading to ever—growing vulnerability to weather and climate extremes. Geographical locations of the large loss trends establish that population growth and demographic shifts are the major factors behind the increasing losses from weather—climate extremes. Most weather and climate extremes in the United States do not exhibit steady, multidecadal increases found in their loss values. Without majo...

Effects of Recent Weather Extremes on the Insurance Industry: Major Implications for the Atmospheric Sciences

Abstract Frequent and extremely damaging severe weather conditions in the United States during 1991–94 caused

Annual Snowpack Patterns across the Rockies: Long-Term Trends and Associated 500-mb Synoptic Patterns

40 billion in insured losses, creating major impacts and eliciting diverse responses in the weather insurance industry. Population, one reason for the growing national sensitivity to storm damage, explained much of the increase in the number of catastrophes (property losses >

Evaluation of Weather Catastrophe Data for Use in Climate Change Investigations

10 million) as well as the increases in the amount of losses. The largest increases in storms occurred in areas experiencing the greatest population growth (west, southwest, south, and southeast). Shifts in atmospheric variables (particularly in the frequency of extratropical cyclones) explained most of the 1949–94 fluctuations found in the intensity of catastrophic storms (losses divided by storm frequency). The property-casualty sector raised rates, made major changes in insurance availability in high-risk areas, tightened underwriting restrictions in hurricane-prone areas, and is making extensive assessments of weather r...

Uses and applications of climate forecasts for power utilities

Abstract Winter snowpack was investigated to determine spatial and temporal climate variability in a five-state region (Colorado, Idaho, Montana, Utah, and Wyoming) in the northern Rocky Mountains, covering the period 1951–85. Annual 1 April snowpack (SN) measurements were selected for analyses. Three basic and persistent patterns of annual SN values surfaced: years with a consistent anomaly over the entire region (wet or dry); years with a distinct north-to-south gradient; and average years. Nearly 90% of the nonaverage annual SN patterns were explained by the frequency of seven 500-mb winter synoptic patterns. The wet-north-dry-south gradient SN patterns occurred only before 1974, and the dry-north-wet-south gradient SN patterns did not occur before 1973. The long-term wet and dry periods experienced in the northern and southern areas of the five-state region are due to periods when one of the two north-to-south gradient SN patterns occurred and are explained by the changes in the frequency of synoptic ...

Long-Term Fluctuations in Hail Incidences in the United States

A 1950–1994 data set of major weather losses developed by the property insurance industry was examined to assess its potential utility in climate change research and use in assessing the relevance of recent extreme losses in the United States. A process for adjusting these historical storm losses to ever-changing factors including dollar values, amount of insurance coverage per area, and the sensitivity of society to damaging storms was developed by the industry. Analysis of the temporal frequency and losses of these adjusted weather catastrophes revealed differences according to the amount of loss. Temporal changes since 1975 in the catastrophes causing

Temporal and Spatial Characteristics of Snowstorms in the Contiguous United States

35 to

A Pilot Study Examining U.S. Winter Cyclone Frequency Patterns Associated with Three ENSO Parameters

100 million in loss were strongly related to changes in U.S. population, whereas catastrophes that created insured losses greater than

Record-High Losses for Weather Disasters in the United States During the 1990s: How Excessive and Why?

100 million appear related to both shifting weather conditions and to regional population changes. This evaluation revealed that the industrys catastrophe adjustment technique did not adequately allow for changes in various demographic and social factors affecting damage; however, results suggest use of population values for normalizing the adjusted catastrophe database to allow meaningful studies of their temporal variability.