In 1998 there were no elephants on the 75,000 acres of Rukinga Sanctuary where Wildlife Works is based, said Rob Dodson, vice president of African operations. Now wildlife has returned. One recent evening, a herd of elephants, including babies, gathered at a water hole during a tranquil sunset. As many as 2,000 elephants live in the corridor, depending on the season; so do zebra, giraffe, buffalo, warthogs and several kinds of antelope, from slender dik-diks to impala. Lions had vanished from the area; now there are about 40, including two males seen lounging by a water hole on a hot Friday afternoon.

Illegal activities haven’t been wiped out. In January, seven elephants were poached for ivory. Every week rangers catch people burning trees to produce charcoal. But forest and wildlife in the Kasigau Corridor have been visibly revitalized by conservation efforts. And poaching has dropped. In the last few years, Wildlife Works hired more unarmed local rangers to supplement the Kenyan Wildlife Service, and in 2014 Kenya toughened its poaching laws. Seventy-six elephants were killed for ivory in the area in 2012, in contrast to 21 last year.

The key to preserving wildlife here is human relationships. Impoverished locals need alternatives to poaching and burning. So Wildlife Works has created hundreds of new jobs, including increasing the number of its rangers sevenfold to 85 in the past few years. (Many are former charcoal burners and poachers themselves.) Critically, this expansion won support for conservation from local elders and villagers, and the organization is now their county’s third-largest employer.

This community development work got a much-needed financial lifeline when Wildlife Works started the world’s first REDD+ project in 2011. REDD+, which stands for “reducing emissions from deforestation and forest degradation,” is an international system to combat climate change by preserving forests. It essentially pays communities in poor countries not to cut down trees.

Three United Nations agencies laid the groundwork for REDD+ in 2008. Gas-guzzling cars are commonly associated with global warming. But deforestation — cutting down trees and releasing the carbon stored in them — contributes 17 percent of the world’s greenhouse gases, more than the global transportation industry.