AGU membership reached 50,000 in September 2007. Membership has doubled since the early 1990s. Membership grew moderately through the late 1990s, reached 40,000 members in 2001, and grew at a rate of 5% or more for each of the past 3 years.

The size of AGU membership is not the only factor reinforcing the role of AGU as a leader in the increasingly interdisciplinary global endeavor that encompasses the Earth and space sciences. Diversity is another key factor. AGU members hail from 137 different countries. Members residing outside North America now represent more than 35% of the membership compared with 29% in 1995. There has also been a large increase in the number of women: 24% in 2007 compared with 13% in 1995. In addition, students now account for 20% of the membership.