Observed humidity trends in dry regions contradict climate models
Isla R Simpson1, Karen A McKinnon2,3,4, Daniel Kennedy1,5
1Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO 80305.
Summary
Greenhouse gas-driven hydroclimate change poses risks to arid regions. Observed atmospheric water vapor trends contradict climate models, indicating potential issues with future projections.
Area of Science:
- Climatology
- Environmental Science
Background:
- Arid and semi-arid regions face significant risks from greenhouse gas-induced hydroclimate shifts.
- Climate models are crucial for projecting future hydroclimate scenarios for adaptation planning.
Purpose of the Study:
- To identify and analyze discrepancies between observed and model-based historical hydroclimate trends in arid and semi-arid regions.
- To assess the implications of these discrepancies for future hydroclimate projections.
Main Methods:
- Analysis of historical hydroclimate data from observational records.
- Comparison of observed trends with simulations from multiple climate models over the past four decades.
- Identification of regions exhibiting the most significant discrepancies, including arid/semi-arid areas and humid regions during dry periods.
Main Results:
- Climate models consistently project an increase in atmospheric water vapor in arid/semi-arid regions, driven by a warmer atmosphere's increased water-holding capacity.
- Observational data do not support this projected increase in atmospheric water vapor for these regions.
- The discrepancy suggests that models overestimate moisture availability relative to atmospheric demand in reality.
Conclusions:
- A significant gap exists in understanding and modeling hydroclimate in arid and semi-arid regions.
- This discrepancy may lead to inaccurate projections of future hydroclimate, potentially impacting assessments of risks like fire hazard.
- Further research is needed to improve climate model accuracy for these vulnerable areas.
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