Here is a 1958 picture of DC-8 jet airliner taking off. It is a bit of an extreme case, because it (like many other jets at the time) used to inject water to its engines at take-off to increase thrust. And soot formation. But jets did carve dark smoke trails in the sky.

Us 40+ year youngs may also recall the 80s talk about acid rain. SO2 pollution was so severe that in places, sulphuric acid literally rained from the sky. Killing plants and forests. Even stripping paint from cars. But scientists sounded alarm, activists acted, and politicians regulated. Behold:

Or consider lead. Or nitrous oxides. Or smog. Or the stench that used to waft from numerous polluted waterways. There has been real, measurable, genuine progress in many, many areas. Not enough. Not quickly enough. Not even nearly enough to let us ignore current issues. But progress regardless.

I do not write this to coddle anyone into inaction. Quite the reverse. All the victories and successes for progress have been achieved by people working and often struggling for a better world. Without hope, there is no point in struggling. And it is *so* easy to lose hope these days.

Unlike even activists of the past, we are constantly bombarded by numerous warning signals from many sources. Many of them warn of very real dangers and risks. But warnings keep beeping, loudly, until the situation is fixed. Whereas the "bing" of a problem solved sounds once, and often faintly.