Rising synchrony controls western North American ecosystems

Area of Science:

• Climatology and Ecology
• Atmospheric Science
• Ecosystem Dynamics

Background:

• The North Pacific High (NPH) significantly impacts Western North America's climate, influencing coastal upwelling, storms, precipitation, and river discharge.
• Coherence in these climate factors leads to synchronized physical and biological processes in adjacent marine and terrestrial ecosystems.

Purpose of the Study:

• To investigate the historical trends in ecosystem synchrony along western North America.
• To determine the relationship between North Pacific High (NPH) variability and ecosystem synchrony.
• To assess the long-term context of current synchrony levels using paleoclimate data.

Main Methods:

• Analysis of historical climate data and ecological records over the past century.
• Utilizing blue oak (Quercus douglasii) growth chronologies spanning 250 years to reconstruct past climate- NPH relationships.
• Statistical analysis to quantify the degree and spatial extent of ecosystem synchrony and its correlation with NPH variance.

Main Results:

• A substantial increase in the degree and spatial extent of ecosystem synchrony over the last century.
• This rise in synchrony is directly correlated with increased variance in the winter North Pacific High (NPH).
• Modern synchrony levels are among the highest observed in the last 250 years, as indicated by blue oak growth data.

Conclusions:

• Increased NPH variability is driving unprecedented ecosystem synchrony in western North America.
• This heightened synchrony may destabilize ecosystems and increase extinction risks.
• Potential links to changing El Niño Southern Oscillation impacts on midlatitude ecosystems warrant further investigation.