Chain reaction, the ripple or butterfly effect – these can all be used to describe the intertwined nature of the world’s ecosystems. Jessica Black investigates how even a small change in temperatures and seasons can affect an entire system and cause profound change to natural landscapes.

Scottish Soay sheep are shrinking due to changing climate. Image: Jonesor

According to studies of spring phenology, over 80% of the 1500 species exhibiting signs of change are a result of climate change and rising temperatures.

Director of the Research Earth Policy Institute, Janet Larsen, says change in the ecology of a single species can wreak havoc with an ecosystem, sending shock waves to the very top of the food chain.

“You can think about ecosystems like airplanes. You probably can tweak a few knobs here or there…and still keep flying fine. But if you keep tinkering with the system…[you’ll] bring the plane down. In nature, even small changes can cause unexpected cascades through the ecosystem.”

While it’s still too early to say which of the animal and plant kingdom will come out on top, early bets would favour animals, plants and insects with a shorter life cycle, an evolutionary advantage when adapting to rapid environmental changes.

In Scotland, the wild Soay Sheep are trying to adapt to temperature changes.

As a result of milder winters and the earlier onset of spring, the sheep have gradually decreased their size, as smaller sheep stand an increasingly better chance of reaching maturity and passing on their genetic make-up to a new generation.

“The Soay sheep show us that climate change can turn ‘survival of the fittest’ on its head,” says Larsen.

“It’s still hard to tell, though, whether the species that don’t seem to be changing their ranges or life cycle timing along with warmer temperatures and early springs will ultimately start to adapt or what ecosystems of the future will look like.”

The Soay are an example of an evolution success story, as plant and animal species race to beat the clock under increasing pressure from climate change wrought by human activity.

Spring phenology studies have shown that species experiencing a change in their life cycles did so by advancing an average of 5 days in their blooming or birthing stage.

Should one species adjust to an earlier spring by blossoming sooner, those species depending upon its flowering become out of sync, causing a prey-predator mismatch.

This is known as a “trophic cascade” whereby the numbers of one species become out of proportion with other species in the food chain.

This distorts the balance that is central to a properly functioning ecosystem.

“The number of prey influence the number of predators and vice versa – we say the species are ‘couple’d however, both species might be influenced by the weather too,” says Professor Tim Coulson, Professor of Population Biology at the Imperial College London.

“If the weather reduces the number of prey, then the number of predators will also be affected just because there are fewer animals for them to eat.”

The endangerment of these species means an ecosystem loses those the links between predator and prey that make up an ecosystem.

According to Geoff Lawton, Managing Director of the Permaculture Research Institute, ecosystems play a vital role in the moderation and translation of the sun’s energy and therefore have a stabilising effect on the weather.

“In a natural situation we have a wonderfully abundant living system that receives that [sun’s] energy and stores that energy better than any other system we know in the universe.”

However, when the ecosystem loses the power to store and moderate that energy, Lawton says the affects of climate change will be visible and felt everywhere.

He says in order to maintain the ability of ecosystems to mitigate the sun’s energy, we need to negotiate a new hierarchy with those species who have come out on top – in this case, the weeds.

Those annoying weeds may be the answer to saving our ecosystem. Image: Peripitus

With an increase in temperatures, exotic plants and weeds which are responsive to CO2 and receptive to warmer temperatures thrive, while native plants lose ground.

“If we want to get anything, like the diversity and quality of ecosystems that were represented in recent history, then we’re going to have to work with the weeds. There’s nothing wrong in taking part…we shouldn’t get sentimental of nature, nature isn’t sentimental about nature,” Lawton says.

How successful a natural world such as this might be, is yet be be answered.

Rising temperatures also create a knock on effect by altering weather patterns.

Species might miss a crucial feeding time, having become accustomed to birthing at a specific time to coincide with that time when their prey is most abundant.

The skewing of species populations also means less biodiversity as those species unable to keep up with the changes will inevitably begin decreasing in numbers.

Wet, tropical forests, known as “biodiversity hotspots” are especially vulnerable to the effects of warming as are birds with longer migration routes such as the swallow.

For these birds, their passageway may become drier, creating fewer chances to feed. They are also faced with the double burden of having to adapt to several climates undergoing change.

On the other hand, species that are able to inhabit a range of terrains can be an advantage.

Deers for example, are familiar with several territories and therefore more mobile, says Professor Coulson.

Species with short ranges such as amphibians, are unable to move on if one area no longer provides the resources necessary for their survival.

Although climate is seen to have greater sway over an ecosystem, a greater interdependence of weather and ecosystems may be on the horizon, says Head of Climate Monitoring and Prediction at the Bureau of Meteorology, Dr David Jones.

“Certainly in the context of climate change, it is largely changing climate [that is] affecting changes in ecosystems. This may change in future as we put in training very large shifts in ecosystems which could then affect climate,” says Dr Jones.

The evidence at hand would indicate that we are likely to experience a radical overhauling of natural landscapes as changes to seasonal indicators continue to cause ructions up and down the food chain.

While no one can say for sure what will happen next, the interdependence of climate change and ecosystems, and the interrelated nature of ecosystems in themselves will ensure that any change will resonate around the world.