Former Colombian president Gustavo Petro gestures as he speaks during his conference, "Capital in the 21st Century: The Political Economy of the Climate Crisis," at the National Autonomous University of Mexico (UNAM) in Mexico City on September 2, 2026. (Photo by YURI CORTEZ / AFP via Getty Images)

Former Colombian president Gustavo Petro gestures during his conference, "Capital in the 21st Century: The Political Economy of the Climate Crisis," at the National Autonomous University of Mexico (UNAM) in Mexico City on September 2, 2026. (Photo by YURI CORTEZ / AFP via Getty Images)

Former Colombian president Gustavo Petro gestures during his conference, "Capital in the 21st Century: The Political Economy of the Climate Crisis," at the National Autonomous University of Mexico (UNAM) in Mexico City on September 2, 2026. (Photo by YURI CORTEZ / AFP via Getty Images)

Former Colombian president Gustavo Petro gestures during his conference, "Capital in the 21st Century: The Political Economy of the Climate Crisis," at the National Autonomous University of Mexico (UNAM) in Mexico City on September 2, 2026. (Photo by YURI CORTEZ / AFP via Getty Images)

Former Colombian president Gustavo Petro gestures during his conference, "Capital in the 21st Century: The Political Economy of the Climate Crisis," at the National Autonomous University of Mexico (UNAM) in Mexico City on September 2, 2026. (Photo by YURI CORTEZ / AFP via Getty Images)

Former Colombian president Gustavo Petro gestures during his conference, "Capital in the 21st Century: The Political Economy of the Climate Crisis," at the National Autonomous University of Mexico (UNAM) in Mexico City on September 2, 2026. (Photo by YURI CORTEZ / AFP via Getty Images)

Former Colombian president Gustavo Petro gestures during his conference, "Capital in the 21st Century: The Political Economy of the Climate Crisis," at the National Autonomous University of Mexico (UNAM) in Mexico City on September 2, 2026. (Photo by YURI CORTEZ / AFP via Getty Images)

Guatemalan Nobel Peace Prize laureate Rigoberta Menchu waves upon arriving to attend former Colombian president Gustavo Petro's conference, "Capital in the 21st Century: The Political Economy of the Climate Crisis," at the National Autonomous University of Mexico (UNAM) in Mexico City on September 2, 2026. (Photo by YURI CORTEZ / AFP via Getty Images)