Impacts on Extreme Events

Causes of Extreme Events

• Multiple causes for all extreme events.
• Direct attribution to climate change is challenging.
• Aim to understand the extent of impact by climate change.
• Analysis is retrospective, not predictive.

Statistical Analysis in Extreme Events

• Helps communities prepare by understanding potential increases in event severity.
• Techniques Used:
  • Percentiles: to evaluate frequency distribution and categorize events.
  • Standard Deviations (Sigmas): measure how far an event is from the mean.
  • Recurrence Interval/Return Period: statistical frequency of event occurrence (e.g., 100-year flood is a 1% annual probability).
  • Probabilities: calculated as event frequency over time.

Historical Context and Climate Change

• 2016 National Academy of Science report made connections between extreme weather and climate change.
• Warming Effects:
  • Warmer atmospheres increase evaporation, affecting floods and droughts.
  • Heat waves appear to be increasing in magnitude and duration.
• Unclear Impacts:
  • No direct links between climate change and tornadoes, hurricanes, wildfires.
  • Wildfires influenced more by land management.
  • Global decrease in hurricane numbers, though individual hurricanes may be more extreme.

Recent Trends in Extreme Events

• Examples include hurricanes Harvey, Maria, and Florence showing increased extremity.
• Tornadoes in the US have significantly decreased, with no current explanation.

Conclusion

• Research continues to understand nuances in climate change's impact on extreme events.
• Importance of statistical methods in evaluating and preparing for future challenges.