Human Worlds, Wednesday’s final hour in Mike Gunton and David Attenborough’s bravura natural history series about plant life on Earth, doesn’t have the last word — at least, not exactly — but it arrives at an opportune time. The natural world is ablaze with wildfires, and it doesn’t take an advanced degree in climate science to know that human activity in our increasingly technological age is not helping.

In South Korea, just weeks ago, a fire started in the coastal county of Uljin that posed a threat to the Hanul Nuclear Power Plant. In Morocco, wildfires have burned through the provinces of Ouezzane, Tetouane and Taza, In France, wildfires burned through 50,000 acres in the southwestern region of Gironde, only a month ago. In Greece, this month, multiple fires have raged near the cities of Athens and Megara, as well as in the western Peloponnese and on the islands of Salamina and Lesbos — Lesbos ironically being a sanctuary and the first point of land for countless refugees fleeing war, drought and famine in even more parched parts of the world. Elsewhere, wildfires have broken out recently in Tuscany, in Italy, in Slovenia and Turkey, as well as Portugal and Spain. Across the Atlantic, Canada has not been spared. The Oak Fire in the US, just west of California’s Yosemite National Park, has forced the evacuation of 4,000 people, in a part of the continental US not known for its population density. A fire in New Mexico’s Santa Fe County had burned through 350,000 acres as of July 15. The list goes on.

Climate deniers insist human activity has little to do with climate breakdown, but no one can argue that cities keep growing as the human population grows. More people are moving to the big city from rural regions worldwide, and not just in the industrialized north or the developing south. It’s only natural, if in an unnatural way, that vegetation is adapting to urban areas — plants taking root in glass, steel and concrete, if you will. That is why Human Worlds is a fitting way to end a nature series about our green planet.

Climate deniers insist human activity has next to nothing to do with climate breakdown, but no one can argue that cities keep growing as the human population grows. More people are moving to the big cities from rural areas — worldwide, and not just in the industrialized north or developing south — and so it’s only natural, if in an unnatural way, that vegetation is adapting to urban areas … plants taking root in concrete, as it were. That is why Human Worlds is a fitting way to end a natural history series about our relationship with — and dependence on — plant life.

“The relationship between plants and humans is extraordinary,” Attenborough reminds us in Human Worlds’ opening moments. “We’ve been adapting to each other for as long as we’ve been on the planet.

“We rely upon plants for almost everything, the air we breathe, the water we drink, the food we eat, much of the clothes we wear, and in some parts of the world, the very buildings in which we live.”

Human Worlds has moments of exquisite beauty — and ominous foreboding — propelled by some of the most astonishing time-lapse photography you’re ever likely to see.

“But that relationship is now changing,” Attenborough continues. “How it changes next will shape the future of our green planet.”

We ignore that at our peril. Human Worlds is a fitting coda to a remarkable series that is both eye-filling and thought-provoking.

The Green Planet: Human Worlds premieres Wednesday, Aug. 3 on PBS at 8E/7C, and on the PBS app.