Westerly jet waviness modulates mid-latitude hydroclimate variability

Area of Science:

• Paleoclimatology
• Climate Dynamics
• Environmental Science

Background:

• Mid-latitude ecological environments face threats from hydroclimate variability.
• Understanding the drivers of this variability is limited by short observational records and climate model biases.

Purpose of the Study:

• To reconstruct a long-term precipitation record for mid-latitude East Asia.
• To investigate the mechanisms controlling past hydroclimate variability and its future implications.

Main Methods:

• Analysis of a 300.8-meter fluvio-lacustrine sediment core from northern China.
• Development of a sub-millennial resolution precipitation record spanning ~5.7 million years.
• Idealized sensitivity simulations to test hypotheses regarding climate drivers.

Main Results:

• A persistent influence of the westerly jet on mid-latitude precipitation since the Pliocene.
• Reduced mid-latitude precipitation variability after ~3 million years ago, coinciding with amplified low-latitude variability.
• Attribution of pre-3 Ma variability to enhanced westerly jet waviness driven by Arctic warming.

Conclusions:

• Arctic warming historically amplified mid-latitude hydroclimate variability through increased jet waviness.
• Projected future global warming may increase jet waviness, leading to more frequent hydroclimate extremes in mid-latitudes.
• These findings highlight the vulnerability of mid-latitude ecosystems to future climate change.