Pick your poison. Diesel emissions are bad for people, but mainly just in congested and/or stagnant areas like the LA Basin or the central valley around Bakersfield. But, they aren't especially bad for "climate change", which is the currently recognized threat to the earth. That comes from any CO2 emissions, i.e. burning any fossil fuels. The very best way to reduce that is to burn renewable fuels, as I do by using the new Diesel HPR which comes from bio sources. It does emit CO2, but not "net CO2" since it didn't come out of the ground. That carbon originated from CO2 in the air and thus just cycled back.

People running electric cars think they are smug not emitting CO2, but it was emitted to produce their electricity, especially in CA since they shuttered the massive San Onofre nuclear plant and the last one (Diablo Canyon) is next up. Most electricity comes from burning fossil fuels, and while some claim "at least not coal", that doesn't count when CA buys electricity from out of state. You can even pay a little extra to imagine the electricity you draw from the lines came only from renewable power and thus ignore the mostly fossil electricity on the grid.

But, "global warming" gases are still being studied. R-134A is being outlawed since it is now bad as a greenhouse gas. Recall it replaced Freon to close the "ozone hole" (maybe, read up). One supposedly major source is cow farts, and no joke since methane is worse than CO2. In nature, there were never as many herbivores farting as we have now to satisfy our cravings. In old England, only a chosen few were able to eat meat, like the "beef-eaters" who protected the queen. We might save the earth by returning to a diet of gruel, with a treat of oatmeal at Christmas.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans