Alexander von Humboldt

Humboldt spent five years measuring the Americas with forty instruments, climbing Chimborazo and mapping vegetation against altitude. From that he derived the concept of interconnected climate zones, the first drawing of an ecosystem, and the earliest clear warning that human deforestation changes climate.

• Produced the Naturgemälde, the first infographic of an ecosystem, mapping plant life to altitude and climate
• Identified human-caused climate change from deforestation and irrigation at Lake Valencia in 1800
• Discovered the magnetic equator and the cold Peruvian current that bears his name
• Wrote Kosmos, a five-volume attempt to describe the entire physical universe as one system

Ecology, biogeography and climate science all start with his web-of-life framing; Darwin carried his Personal Narrative on the Beagle and said it determined his career. More places and species are named after him than any other person. Contemporary IPCC-style reasoning — that local human activity has planetary consequences — is his insight, made two centuries before it was politically audible.

Humboldt never married and had no children; he spent his entire inherited fortune funding his expeditions and publications and died in debt.