Extreme Weather Events

How “Extreme” Is Extreme?

Logging, population density, and flood-control projects Image Source: Microsoft Clip Art and SFWMD

All weather events that cause loss of life, disrupt normal human activities, and result in property damage appear extreme. It is a question of perspective: How do today's severe weather events stack up against severe weather events in the recent and distant past?

Several variables (land-use practices, population density, and flood-control projects) can complicate making direct comparisons between past and present events. For example, since 1986 the global human population has grown by approximately 2 billion. Simply said, there are more people than ever living in formerly unpopulated or sparsely populated areas. So comparing death tolls between recent and past events may not be the most meaningful indicator of a particular weather event's intensity.

Nonetheless, the growing body of meteorological data indicates an increase in the number of extreme weather events occurring here in the United States since 1980, and the number of extreme events also appears to be rising worldwide.


Examples of Extreme Events

Read some examples of a few extreme events that have occurred around the world!

What Is the Significance of Weather Extremes?

Image Source: Microsoft Clip Art

The variability of these events — for example, excessive precipitation (rain and snow) or heat waves, drought, and wildfires — is so great, that scientists need a long record of observations and data to establish definitive links between severe events and climate change. By definition, extreme weather events are rare, which means that oftentimes there are very limited data available to use for comparison.

Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation Image Source: IPCC

However, the IPCC’s 2012 report, Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation, indicates that scientists have enough confidence in the data collected since 1950 to definitively link extreme temperatures to global climate change.

“It is very likely that there has been an overall decrease in the number of cold days and nights 3, and an overall increase in the number of warm days and nights 3, on the global scale, i.e., for most land areas with sufficient data. … It is virtually certain that increases in the frequency and magnitude of warm daily temperature extremes and decreases in cold extremes will occur in the 21st century on the global scale.” (Source: IPCC, 2011, SREX Summary for Policymakers, pp. 5, 10)

Image Source: Microsoft Clip Art

IPCC scientists also note “statistically significant trends in the number of heavy precipitation events in some regions,” but there is less confidence in whether the data confirm there is an overall global increase in these events (SREX, 2011). Scientific evidence of a link between climate change and specific, extremely large, violent hurricanes and tornadoes is also much less certain.

Wheat crop Image Source: Microsoft Clip Art

The increasing number of extreme weather events is consistent with what climate scientists have long predicted. They result in significant loss of life, destruction of public infrastructure and private property, economic hardship, and social disruption. Additionally, unusually high nighttime temperatures (in the absence of wildfires or other extreme events) can reduce crop yields, and prolonged drought can trigger crop failures — both of which increase the problem of worldwide food shortages and hunger.



Extreme Weather Map Image Source: NRDC

Multiple natural disasters occurring within a short timeframe (as we have recently experienced here in the U. S.) place added strain on fragile electrical grids and other aging systems and increase the cost for national, state, and local governments. And the huge economic damages that result from extreme weather threaten the stability of our insurance system.