The heat arrives earlier and goes later, it rains less in some places, in others more and torrentially … there are many meteorological anomalies that have been registered in recent years due to global warming, and we are only beginning to know its consequences on the functioning of ecosystems.
A latest research published in the specialized journal Scientific Reports has found that, for every 10 degrees of latitude that we move north with respect to the equator, spring comes four days earlier. Furthermore, this season is currently advancing globally at a rate three times faster than in recent years. For example, in Los Angeles, in the southern United States, spring now arrives a day earlier than it did a decade ago. If we move north to Chicago, Seattle or Washington DC, spring is already four days early. And, in the Arctic, we are talking about an advance, not inconsiderable, of 16 days.
“Our work confirms an idea that has been heard for some time in both the scientific community and the media,” explains Eric Post, from the Department of Wildlife, Fisheries and Conservation at Davis University in California. “Spring comes earlier, and in the Arctic this advance is much greater than in other latitudes.”
Some of the variables that give us clues about this seasonal advance are those related to phenology, a science that studies precisely the effect that the climate has on some biological phenomena such as flowering, the emergence of leaves or the start of migrations of birds and other animals. To analyze the differences between latitudes, the researchers reviewed more than 700 scientific articles published in the last 86 years and that document seasonal advances in different latitudes of the northern hemisphere, concluding that, indeed, these changes are stronger in the regions more northern.
Effects on migratory birds
The consequences of this phenomenon are only beginning to be quantified, but it is likely that it will generate a mismatch that affects the functioning of ecosystems. A very clear case is that of migratory birds , which move from wintering areas to breeding areas. In these cases, the biological cycles of the plants and animals that serve the birds as food are highly synchronized with migration, and lags can occur that affect the availability of food and, therefore, reproduction. “The signals that tell the birds when to start the migration could become unreliable if the early spring in northern latitudes is amplified in the future due to global warming,” explains Post.
Some research and follow-ups related to this issue already suggest that changes are taking place in the migratory patterns of many species, that they advance their movements or even make shorter trips.
Reference: Post et al. 2018. Acceleration of phenological advance and warming with latitude over the past century. Scientific Reports volume 8, Article number: 3927
