6 . The Amazon rainforest is as undisturbed a place as most people can imagine, but even there, the effects of a changing climate are playing out. Now, research suggests that many of the region’s most sensitive bird species are starting to evolve in response to warming.

Birds are often considered sentinel (哨兵) species — meaning that they indicate the overall health of an ecosystem — so scientists are particularly interested in how they’re responding to climate change. In general, the news has not been good. For instance, a 2019 report by the National Audubon Society found that more than two-thirds of North America’s bird species will be in danger of extinction by 2100 if warming trends continue on their current course.

For the new study, researchers collected the biggest database so far on the Amazon’s resident birds, representing 77 non-migratory species and lasting the 40 years from 1979 to 2019. During the study period, the average temperature in the region rose, while the amount of rainfall declined, making for a hotter, dryer climate overall. According to the report on November 12 in the journal Science Advances, 36 species have lost substantial weight, as much as 2 percent of their body weight per decade since 1980. Meanwhile, all the species showed some decrease in average body mass, while a third grew longer wings.

Because of the study’s long time series and large sample sizes, the authors were able to show the morphological (形态学的) effects of climate change on resident birds. However, the researchers themselves are unsure and wonder what advantage the wing length changes give the birds, but suppose smaller birds may have an easier time keeping cool. In general, smaller animals have a larger rate of surface area to body size, so they dissipate more heat faster than a bigger animal. Less available food, such as fruit or insects, in dryer weather might lead to smaller body size.

9 . The woods are turning orange. Drifts of dry leaves are growing on forest floors and flying into street corners. From a distance, it is beautiful. But the air is still warm and summery. This turning and leaf fall is not the usual gradual preparation for winter in temperate zones (温带) but a stress response by trees trying to preserve water. We are now in a false autumn, caused by heat and drought. And it feels wrong.

There is, therefore, something deeply disturbing about such a graphic alteration of familiar rhythms. Droughts are not unknown to the UK, of course, and too many parts of the world are certainly familiar with far more severe versions. But increasingly they are occurring in the context of a climate emergency, and record-breaking heat. And the beauty of a false autumn, specifically, has an emotional effect, a deep weirdness, something mysteriously suggestive of evil or danger.

Cultures across the world contain ceremonies for the propitiation (宽恕) of the weather; a sense of responsibility for the natural world- and the belief that it will punish us if we fail it—is as old as humanity. One of the reasons why the Romantic poet Samuel Taylor Coleridge’s 1798 poem The Rime of the Ancient Mariner is so effective is the directness with which it links the shooting of an albatross (信天翁)—the destruction of innocent wildlife—to a terrible change in the weather: no rain, just burning, death-dealing sun. We may not understand the mechanism, but at an instinctual (本能的) level it feels right.

And in a similar way it has not really been a surprise to hear that birds are struggling. In London, young swifts (雨燕) were seen falling out of the sky. Fewer—and too early—nuts and berries mean some animals will not live through this winter. Older trees, with their longer roots, will hopefully survive, but young trees may not—all that promises further warming. There will always be a degree of uncertainty about the causes of specific weather events, but we cannot deny that we have not taken care of the albatross. Now we must hope we are doing enough to make sure that these fearful golden days can be an autumn of autumns.