By Robert B. Catell and Joanna D. Underwood, The New York Times.

The administration of Mayor Bill de Blasio of New York has set clear, aggressive goals for reducing greenhouse gas emissions that would make the city a national leader in mitigating climate change. But other decisions now in the works could prevent the city from meeting them.

In the wake of last year’s Paris climate agreement, the mayor announced plans to cut emissions from activities controlled by the city government by 80 percent by 2050. Mr. de Blasio’s pledge included cutting emissions from the city’s vehicle fleets by 50 percent by 2025, and by 80 percent by 2035.

Halving emissions in less than a decade requires immediate, concerted action. But the Department of Sanitation — the city agency with the highest vehicle fuel consumption and greenhouse gas emissions — plans to buy 340 new refuse trucks this year, with at least 300 powered by diesel engines. That would lock in high diesel emissions for the seven-year service life of these trucks — and put the 2025 emissions goal out of reach.