We are struck by and deeply worried about two recent wake-up calls for this planet.

The first is the disappearance of nearly 3 billion birds in the last 50 years.

The second is an emotional warning from a 16-year-old, who rightly accuses adults of destroying the planet.

There you go, in stark language, what climate change has wrought. Bird populations disappearing on our watch and a Swedish girl calling us out, in front of the United Nations Climate Action Summit no less, for wrecking her world.

Against this backdrop are the head-scratching tactics of the Trump administration; stripping California of its ability to set more rigorous vehicle emission standards and telling Detroit it no longer needs to manufacture such efficient cars. Thankfully, both entities appear willing to ignore or fight such directives in favor of common sense. In the case of the automakers, they’ve already made huge investments in less-polluting or electric vehicles. Can you imagine the cost of reversing that engineering?

But about those birds.

The journal Science published a study completed by U.S. and Canadian scientists who looked at ornithologic records and data going back to 1970 and studied current bird populations by species using today’s technology. The researchers went into the work understanding that song birds and shore birds were in decline, but they were shocked that 300 species have experienced devastating losses during that time frame.

Want some examples? Nearly half of Baltimore orioles have disappeared; 25 percent of all blue jays; red-wing blackbirds are down by 92 million. These are species we can see out our windows in this region, but dramatically less often now.

And these numbers are in comparison to a time — the early 1970s — when DDT, known for its deleterious impact on birds’ eggs, was still having an impact. The only good news that emerged from the study is that waterfowl seem to be on the rise — maybe a lesson can learned there.

Rachel Carson wrote “Silent Spring” in 1962, first serializing in the New Yorker her theories on the impact of pesticides on animal life. Were she alive today, she could write its unfortunate sequel. Here’s how the website rachelcarson.org describes Carson’s enduring work:

“She identified human hubris and financial self-interest as the crux of the problem and asked if we could master ourselves and our appetites to live as though humans are an equal part of the earth’s ecosystem and not the master of them.”

Sound familiar? Of course. Which brings us to our second warning.

Swedish climate activist Greta Thunberg dressed down the U.N. Assembly in a breathtaking way that did not mince words or subvert any intensity.

“People are suffering, people are dying, entire ecosystems are collapsing,” the teen exclaimed. “We are in the beginning of a mass extinction, and all you can talk about is money and fairy tales of eternal economic growth. How dare you continue to look away and come here saying that you’re doing enough when the politics and solutions needed are still nowhere in sight.”

Thunberg’s anger triggered the inevitable tweet from President Trump, who mocked her.

“She seems like a very happy young girl looking forward to a bright and wonderful future,” he said. “So nice to see!”

Happy? Are you kidding? She’s petrified about what adults, businesses and governments are leaving her. She only has her words, as powerful as they are, to push for change.

Of course, this is a president who thinks climate change is a hoax, and has populated his Cabinet and key environmental agencies with similar deniers. It’s been his goal to deregulate and defang environmental safeguards, even when the industries that might financially profit from looser rules say they don’t need relaxed standards.

Trump will be the last person to get it — that the losses of bird life and the warnings of a teenager are inescapable indicators that all is not well with the world.

But perhaps he can take solace that there seem to be more turkeys today.