Judith Lean

Judith L. Lean is an Australian-American solar and climate scientist. She is a senior scientist at the United States Naval Research Laboratory. Lean is a three time recipient of the NASA Group Achievement Award and an elected member and fellow of several academic societies.

Education Lean completed a bachelor's degree in physics, with honors, at the Australian National University in 1974 and her doctorate in atmospheric physics at the University of Adelaide in 1980.

Career Lean worked at the Cooperative Institute for Research in Environmental Sciences and the Applied Research Research Corporation in Maryland. In 1988, she joined the United States Naval Research Laboratory (NRL) as a research physicist in the Space Science Division. She is a senior scientist for Sun-Earth System Research at the NRL.

The 1995 paper was published, Lean explains, at a time when there was a lot of speculation about how much solar variability may have influenced climate change in recent centuries. The research by Lean, Beer, and Bradley provided a new way to numerically estimate past changes in total and ultraviolet solar irradiance based on contemporary records observed from satellites, combined with estimates of long-term solar variability reported (at the time) in Sun-like-stars. With this new reconstruction of historical solar irradiance since 1610, scientists could quantitatively estimate the Sun's contribution to global surface temperature changes. Lean and her colleagues found that the Sun may have contributed half of the changes since 1610 and less than a third of the changes since 1970, contrary to earlier research suggesting that the Sun may be entirely responsible. This meant that solar variability was not the primary cause of global warming in the past decades. Since the 1995 paper, many climate change studies have used the irradiance reconstruction for a variety of analyses and as input to climate model simulations. Although subsequent work with NRL co-authors Yi-Ming Wang and Neil Sheeley has since revised the magnitude of the total irradiance change during the past four centuries, the overall approach and methodology were first established in this 1995 GRL paper, which has been cited more than 600 times.

She was the 2024 recipient of the George Ellery Hale Prize of the American Astronomical Society, given "for her foundational studies in solar irradiance variability and its impact on the Earth’s atmosphere and climate, on time scales from days to centuries".