Spring is no longer what it used to be... and it comes earlier

The changing climate is causing disruptions in the timing of spring, affecting ecosystems globally. Early springs pose challenges for plants and animals, leading to ecological imbalances and impacting pollination, hibernation, and species behavior.

By Wahid Bhat 26 Mar 2024

New Update

Uneven warming trends threaten spring season in India; study

Just like showing up too early or too late for a party can be a problem, changes in the spring climate can be tricky for many species. If you’re late to a party, you might miss out on the food and find people leaving. If you’re too early, you might end up waiting for the event to start, wasting time that could be used better.

This is similar to what’s happening with many plants and animals due to recent climate changes. These changes are messing up the usual timing of seasons and the balance between the behaviours of different species. We’re seeing this happen now, in this late winter and early spring.

Practical examples: Rising temperatures cause plants to flower earlier, but their usual pollinator still maintains its usual wake-up date. Consequently, the vegetables flourish in vain because no insect fertilizes them. Thus, they fail to produce fruit and seeds.

Another example: migratory birds reach a territory on their usual date, but they do not find the food sources they seek after a long journey, whether these are caterpillars or plant products. The bugs are still dormant and the plants have awoken prematurely and their peak time has passed.

A scientific discipline called Phenology dedicates itself to studying these issues. It observes the life cycle of living beings and relates their behaviour to the climate and the annual course of time in a given place.

Phenologists continue noticing anomalies as the climate changes and alters the usual rhythm of the seasons. Rising winter temperatures cause imbalances in animal and plant life around the world.

Some notorious examples

So far we have seen it in some parts of India, particularly in Kashmir, when the high temperatures of autumn and winter, added to days without clouds and greater exposure to the sun, have advanced the flowering of many plants.

publive-image — Spring’s Early Arrival, Rising temperatures cause plants to flower earlier. Photo Credit: Wahid Bhat/Ground Report

In the early 2000s, the scientific community published some pioneering large-scale assessments of the phenological changes that were being detected. These works were the basis of a work that is still going on all over the world and where the annotations contributed by thousands of participants in citizen science programs, annotating data on the first flowering or the arrival of a certain species of bird to a locality, service support to researchers.

A synthesis of these databases indicates that the life cycles of 203 species of plants and animals have advanced about 2.8 days per decade, according to the recently published Borders 2022 report, prepared by the UNEP program for the United Nations environment.

Humans may welcome the opportunity to put away our coats early. However, off-schedule springs can devastate ecology, as pollinators might miss the flowers they usually visit, and conflicts between humans and animals might increase due to shortened hibernation periods.

“An early spring can lead to all sorts of unexpected problems,” says Morgan Tingley, an ornithologist at the University of California, Los Angeles. The situation will only worsen as climate change makes warmer winters and earlier spring conditions ever more likely.

Tingley says, "The issue arises when early springs no longer remain the exception; instead, they rule. That is what we're witnessing with climate change in general. The extreme now typifies the standard. That's when stronger, really negative impacts start to emerge."

Timing nature’s cycles is called phenology

People call the study of how species time their behaviour with Earth's cycles, phenology. For example, as the days shorten or lengthen, birds migrate; temperatures dropping cause the leaves to turn gold or red. When species, that are ecologically intertwined, fall out of alignment with their seasonal cues, people refer to it as a phenological mismatch.

The risk of mismatching with their primary pollinators—such as hummingbirds or bees—follows flowers that bloom in early balmy weather, which can adhere to non-climate-dependent cues such as day length. This means that pollinators will not get the nectar they need for energy, and the flowers will not receive fertilization at their regular rate. These conditions will cause plants to produce fewer seeds and, in the case of crops, fewer fruits.

Susan Pell, the Botanic Garden executive director in Washington, D.C., expresses serious concern over this year's fruit tree harvests. “Pretty much everything is blooming much earlier than it should,” she observes. She also points out that fruit trees that bloom early face a risk of sudden frost if the weather changes. Such weather shifts can kill the delicate buds that yield fruit.

The lack of rain

Temperature has always been considered the fundamental element. However, the lack of rain is also important. In this sense, recent research has shown that the lack of rainfall also brings spring forward.

A study published in the journal Nature Climate Change led by Jian Wang, from the Ohio State University in the USA, and Josep Peñuelas, a research professor at the CSIC at CREAF in Barcelona, reveals that the absence of climate forecasts for rainfall for this century can advance spring between 1.2 and 2.2 days per decade.

The explanation has complex causes. According to the researchers, the lack of rain advances spring in the northern hemisphere because with less cloudiness, daytime and nighttime temperatures have more contrast, there is more solar radiation and more frosts, factors that confuse plants and take spring for granted.

“Less precipitation means less cloudiness, which gives more hours of sunshine, higher midday temperatures and cooler nights that advance the cold build-up needed for leaves to sprout. The cocktail of conditions confuses the plants and makes them sprout earlier," explains Peñuelas.

Early spring alters bear behaviors

A recent study discovered that climate change escalates conflicts between humans and wildlife by changing animals' locations and behaviors. An example of this is the hibernation of bears. Bears experience an extended active season due to mild winters and early springs, which leads to them coming into closer contact with humans as they search for food more frequently.

Ultimately, scientists still don't fully understand how earlier springs and warmer winters will affect ecosystems (and our daily lives). We need more long-term research to determine how these changes will impact the relationships among species. Perkins says that citizen science projects, which track events in nature, can assist researchers in understanding the effects of these seasonal shifts.

“It brings into focus, for people that don’t necessarily think about climate change on a day-to-day basis, that, indeed, conditions really are changing,” Peñuelas says. “We are poised to potentially see some pretty significant impacts.”

“The results are alarming due to the ecological risks associated with earlier flowering times,” says Ulf Büntgen, a climate scientist at the University of Cambridge and leader of the research.

“A certain plant blooms, attracts a particular type of insect, which attracts a particular type of bird, and so on. But, if one component responds faster than the others, there is a risk that they are not synchronized, which can cause the species to collapse if they cannot adapt quickly enough,” clarifies Büntgen.

How to adapt to the new spring?

In the opinion of the experts, measures can be taken to alleviate the effects that climate change is having on the cycle of the seasons, including spring, and the complex functioning of ecosystems.

Any measure of habitat restoration and biodiversity conservation is convenient, but corridors must also be designed to improve ecological connectivity and genetic diversity. Maintaining the genetic diversity of populations is key. The more genetic diversity a species has, the greater the chance that it can successfully adapt to climate change.

In the opinion of the experts, measures can be taken to alleviate the effects that climate change is having on the cycle of the seasons, including spring, and the complex functioning of ecosystems.

Any measure of habitat restoration and biodiversity conservation is desirable, but corridors must also be designed to enhance ecological connectivity and genetic diversity. Maintaining the genetic diversity of populations is key. The more genetic diversity a species has, the greater the chance that it can successfully adapt to climate change.

Keep diversity and improving habitat connectivity is vital for species survival, but the only way to effectively reduce the damage caused by uneven phenological changes around the world remains to rapidly reduce CO2 emissions, they say UNEP experts.

And in other parts of the world?

The global average temperatures have surged by 1.1°C compared to pre-industrial levels, signaling a significant shift in climate patterns. As temperatures continue to climb, experts anticipate further alterations in natural phenomena, such as early flowering seasons. This trend may begin as early as March or even sooner. Notably, regions worldwide, including the UK, have observed advancements in flowering seasons. Last year, Japan marked its earliest cherry blossom season in 1,200 years, while in 2019, a heatwave in the United States prompted sunflowers to bloom ahead of schedule.

In terms of animal behavior, there have been observable changes, particularly among species less genetically adaptable to warmer environments. Instances of delayed reproduction among bird and deer species have been noted, along with shifts in migration patterns among Arctic animals. However, despite these adaptations, numerous species remain vulnerable. The pace of adaptation may not align with the projected temperature increases, raising concerns about the adequacy of these adjustments for future climates.

Experts emphasize the need for comprehensive environmental datasets to grasp the full extent of climate change's impact on biodiversity. They assert, "We need much larger data sets that look at entire ecosystems over a long period of time" to truly comprehend the repercussions of climate change on the global ecosystem.