Obama mentioned climate change during his evening speech organized by a club for leaders from the internet and communications industries was on the theme, "Fear Less, Innovate More".
President Trump gave Obama all the incentive he may have needed when Bloomberg reported Monday that the Trump administration is disbanding an interagency panel created by Obama to help cities deal with the effects of climate change.
All of which makes the former president's address on Monday at the two-day North American Climate Summit in Chicago especially newsworthy.
Chicago Mayor Rahm Emanuel and several other mayors have signed onto the Chicago Climate Charter, committing to reduce emissions.
Google pulling YouTube from Echo Show and Fire TV
YouTube is also cutting access again today for a second time to Amazon's Echo Show video device. Whether or not things get resolved by the end of the year remains to be seen, though.
Former President Barack Obama is in Chicago on Tuesday and among his stops: delivering remarks at the North American Climate Summit hosted by Mayor Rahm Emanuel.
He explained mayors are stepping up because there's no consensus from national governments. Leaders elsewhere have taken similar action, despite Trump's announcement earlier this year that the USA would pull out of the 2015 Paris agreement, which involves nations setting benchmarks to reduce emissions of heat-trapping gases.
Earlier, Obama also discussed climate issues with Paris Mayor Anne Hidalgo. Some mayors have specifically agreed to commitments to expand public transportation and invest in natural climate solutions such as tree canopy and vegetation.
Mayors from 51 cities around the world attended the event.