What Drought Science Says about Drought Predictions and Projections

Christopher J. Anderson, PhD

Assistant Director, Climate Science Program

Iowa State University

Midwest Climate Collaboration Meeting21-22 August 2012

2012 Drought Resembles Past Droughts

The 2012 Heat Wave Resembles Past Heat Waves

2012 Drought: A large departure from recent trends• Recent June-August maximum

temperature has been below the 20th Century average.

• Recent June-August rainfall has been above the 20th Century average.

2012 Drought: Natural variability in a warming world creates larger year-to-year variability

Drought Risk Varies with Sea Surface Temperature

Expect Sea Surface Temperature to Change

• If we project decadal changes using historical performance, then… AMO becomes negative 2025-2030.

Expect Sea Surface Temperature to Change

• If we project decadal changes using historical performance, then… PDO becomes positive 2020-2025.

Expected Drought Risk Based on Historical Performance2020-2030

Caveat: 2020 and Beyond has Larger Uncertainty

• While historical performance is the best available guidance for 2020-2030, a systematic approach for blending recent trends and past performance is lacking.• How closely will 2020-2030 resemble the past given the recent

trends?

Climate projections indicate Warm-Dry AND Warm-Wet Summers are possible

Caveat: 2020 and Beyond has Larger Uncertainty

• While historical performance is the best available guidance for 2020-2030, a systematic approach for blending recent trends and past performance is lacking.• How closely will 2020-2030 resemble the past?

• Beyond 2030, the warming climate will have an increasingly greater impact on variability and the range of possible conditions is broader.

Good News: Seasonal Predictions of Summer Drought are more skillful

• Skill of June-August forecast made with NOAA CFSv2 is 0.7-0.8.

Wei et al. (J. Appl. Meteor. Clim. 2012)

Good News: 2012 CFS forecast of near record July warmth for Iowa

Improvements in Seasonal Forecasts may enable tests of adaptive strategies

Adaption: Adjustment in natural or human systems in response to actual or expected climate stimuli or their effects, which moderates harm or exploits beneficial opportunities.

Resistance-Resilience-Transformation Adaptation Framework

U. S. Forest Service, 2010

Resistance Strategies

Maintain the status quo over the near term through management that builds resistance to climate change

Resilience Strategies

Longer-term actions that build adaptive capacity by improving the system’s ability to moderate effects of climate

Transformation Strategies

Increase adaptive capacity by facilitating the transition to a new system with different structure and function better adapted

Development of Adaptive Actions for Agriculture

• La Niña means risk of yield loss is higher.

• La Niña forecasts provide 3 to 6 months advanced guidance for crop insurance and crop variety selections.• Resistance Adaptation

The 2012 Drought with Heat Wave is evidence that the combination of natural and forced climate changes will amplify year-to-year variability in the Midwest.

• Resistance adaptation strategies may be tested with existing seasonal forecasts due to new predictive capabilities for seasonal drought forecasts.

• Resilience and transformative strategies require development of novel projection techniques to infer potential changes in year-to-year variability.