Dynamical evidence for causality between galactic cosmic rays and interannual variation in global temperature.

Area of Science:

• Climate Science
• Astrophysics
• Atmospheric Physics

Background:

• A 1959 hypothesis suggested solar activity influences climate via galactic cosmic rays (CR).
• Laboratory experiments demonstrate a theoretical mechanism linking CR flux to climate processes.
• The causal relationship between CR and climate remains a subject of scientific debate.

Purpose of the Study:

• To directly investigate the causal link between galactic cosmic rays (CR) and year-to-year global temperature changes.
• To assess the contribution of CR to the 20th-century global warming trend.
• To examine the influence of CR on short-term climate variability.

Main Methods:

• Analysis of observational time series data using convergent cross mapping.
• Direct examination of causal relationships between CR flux and global temperature.
• Statistical assessment of correlations and causal effects on different timescales.

Main Results:

• No measurable causal effect of CR on the overall 20th-century global warming trend was found.
• A significant, though modest, causal effect of CR on short interannual timescales (year-to-year variability) was identified.
• The findings suggest nonlinearities within the climate system influencing the CR-temperature relationship.

Conclusions:

• Galactic cosmic rays do not measurably contribute to the 20th-century global warming trend.
• CR act as a nontraditional forcing on short interannual timescales, influencing global temperature variability.
• The study highlights the complex, nonlinear interactions within the climate system and the potential role of CR in short-term climate dynamics.