BRASÍLIA — The destruction of the Amazon rain forest in Brazil has increased rapidly since the nation’s new far-right president took over and his government scaled back efforts to fight illegal logging, ranching and mining.

Protecting the Amazon was at the heart of Brazil’s environmental policy for much of the past two decades. At one point, Brazil’s success in slowing the deforestation rate made it an international example of conservation and the effort to fight climate change.

But with the election of President Jair Bolsonaro, a populist who has been fined personally for violating environmental regulations, Brazil has changed course substantially, retreating from the efforts it once made to slow global warming by preserving the world’s largest rain forest.

While campaigning for president last year, Mr. Bolsonaro declared that Brazil’s vast protected lands were an obstacle to economic growth and promised to open them up to commercial exploitation.