CHICAGO (WLS) -- City officials are expected to announce Wednesday, a 15% reduction in total carbon emission in 2019.The results were published in a new report from Greenhouse Gas Inventory and represent the equivalent of taking 1.2 million passenger vehicles off the road for one year or eliminating the energy used to power over 653,500 homes for a year.Along with the findings, city officials are expected to announce the purchase of nearly 100,000 renewable energy credits.The credits will replace reliance on electricity and natural gas and expand renewable energy for some of Chicago's more iconic buildings including City Hall, the Chicago Cultural Center and Harold Washington Library, the mayor's office said.Chicago is one of 25 cities selected to participate in the American Cities Climate Challenge, an effort to enable cities to take strong action to reduce pollution that contributes to climate change and impacts public health.Mayor Lightfoot said her administration wants to implement a Climate Action plan that will guide measurable climate improvements over the next decade.