General Electric Co. CEO Jeffrey Immelt defended efforts to reduce emissions and fight climate change, after President Donald Trumpreversed rules that pushed U.S. utilities to use cleaner-burning fuels.

In a blog post to employees Wednesday, Mr. Immelt highlighted the administration’s move and said climate change “should be addressed on a global basis through multinational agreements” such as the 2015 Paris Agreement. The U.S. hasn’t withdrawn from that agreement, but the executive order on Tuesday fed concerns that the pact’s...