Where some are planning walls, others are planning windows. Or rather, pipelines.

Across the dusty 1,954-mile border between Mexico and the United States, international companies are gearing up to spend more than $10 billion on thousands of miles of steel tubes carrying cheap natural gas from Texas to hungry markets on the other side of the Rio Grande.

The recent surge in natural gas investment is just one element of the colossal changes underway in Mexico’s energy portrait. Fracturing monopolies, surging demand, falling oil prices and ambitious climate change mitigation goals are intersecting in Mexico, creating unprecedented challenges and opportunities for curbing greenhouse gases.

Mexico doesn’t fit well into any existing power bloc in U.N. climate negotiations. Instead, it borrows elements from all of them, hurdling over the old rich-poor divide.

The United States’ southern neighbor is the world’s 10th-largest oil producer, and by 2050 is expected to become the world’s fifth-largest economy. Though it contributes less than 2 percent of the planet’s carbon emissions, the country made an aggressive climate pledge toward a new global accord: to peak national emissions by 2026 and drive them down 22 percent by 2030. That makes Mexico one of the largest developing countries to issue such a proposal.

The world is watching. Emerging economies have often argued that they should be compensated before they take action against climate change. Mitigation opponents in wealthy nations, on the other hand, justify inaction because cutting carbon pollution from developing countries is sine qua non for curbing global warming.

Mexico pokes a hole in both arguments. As a large developing resource economy in the Western Hemisphere—and a major oil producer, as well—it has embraced unconditional emissions targets. Moreover, Mexico doesn’t fit well into any existing power bloc in U.N. climate negotiations. Instead, it borrows elements from all of them, hurdling over the old rich-poor divide.