Nature: liberated by lockdown?

Emission control

Fewer cars, trains and buses on the roads meant one obvious environmental effect: an instant alleviation of air pollution. The sky-high observatory on top of the iconic BT tower in central London found that carbon dioxide emissions dropped by 60% during lockdown.

'Lockdown measures in the UK and around the globe have demonstrated that air quality can improve rapidly,' says Dr Carole Helfter, environmental physicist at the UK Centre for Ecology & Hydrology.

'It's important to recognise that greenhouse gases are long-lived, but the lessons learnt from the COVID-19 pandemic can help shape future emission mitigation strategies.'

That was just one of the positive emission effects of the UK suddenly becoming a traffic-free zone. Exhaust fumes contain nitrogen oxides, which cause respiratory and cardiovascular disease. During lockdown, some UK cities produced 60% less nitrogen dioxide (one of the nitrogen oxide gases) compared to the same period last year.

Good vibrations

But staying at home produced another remarkable effect on the natural world. As human movement has calmed, so has the entire planet.

Seismologists measure the vibrations of the Earth. Most of these vibrations - simply another word for sound - are caused by vehicles, construction and other human activity. Yet this 'hum' of daily life quietened dramatically during lockdown, with sensors across the country detecting up to a 50% drop in vibrations.

'We see that some of the biggest noise reductions are at sites closest to sources of human-generated noise,' says Dr Brian Baptie, seismologist at the British Geological Survey. 

'If this were to become the new normal, we might be able to put sensors in places where we've never been able to put them before. Much of our understanding about the Earth comes from observations of earthquakes. So in theory, this could lead to new insights about our planet.' 

But what immediate effect did this quieting have on nature? People in cities across the world felt as though the birds were singing louder. In fact, with competing urban noise down by five decibels (60% quieter), the birds were probably actually singing quieter. And this is good news. 

Birdsong is a soundtrack for survival. It's how birds find a mate or defend their territory. With no traffic to compete with, birds can sing and be heard. Bats, who rely on echolocation, benefit even more from the sound of silence.

In fact, animals of all kinds are acutely sensitive to noise pollution. It has a huge impact on their behaviour, stress levels and even growth. Sound can travel further and faster in water than in air. Which is why whales, for example, pause their singing when cargo ships are near.

This became apparent when Turkey's Bosphorus, normally one of the world's busiest shipping routes, went quiet during lockdown. With the tankers and freighters gone, schools of dolphins were seen jumping in the waters.

Animal kingdom

Indeed, as the weeks rolled by, it appeared as though nature was returning to reclaim many of the spaces left by people, often in surreal ways.

Welsh villagers watched sheep pushing each other on a roundabout in a deserted children's playground. A coyote was photographed daytripping at the Golden Gate Bridge. And, spared from the intrusion of daily visitors, a pair of giant pandas in a Hong Kong park mated for the first time in a decade.

Certainly, animals noticed that people simply weren't around as much. But these animals were also noticed far more by us humans. Perhaps because we had more time to slow down and look around, people in the UK became significantly more interested in the natural world around them. 

In the first 100 days that we were told to stay indoors, there were nearly half a million wildlife sightings submitted to wildlife spotting website iRecord. That's up 54% compared to the same period last year.

So which animals were catching our eyes most? The most popular lockdown animals were butterflies (129,000 sightings) and moths (90,000 sightings). But in comparison to last year's records, it's bat sightings that have soared the most, with 2.4 times as many bats seen in lockdown as the same time last year.

Truthfully, all this probably tells us a lot more about human behaviour than the animals themselves. Perhaps unsurprisingly, the surge in lockdown wildlife sightings was dominated by another familiar visitor to gardens and parks: birds.

Lockdown, it seems, turned us all into birdwatchers. The British Trust for Ornithology had twenty times as many people sign up for their Garden BirdWatch scheme (free during lockdown) as the previous five years, with new participants jumping from a few hundred to nearly 9,000.

And while garden bird sightings shot up when lockdown hit, we weren't able to go to the favourite habitats of many wetland birds: nature reserves.

'We saw a clear increase in wildlife sightings during the lockdown period, as people enjoyed the sunny weather and had more time to notice wildlife and connect with nature,' says David Roy, Head of UKCEH's Biological Records Centre.

'This data is incredibly valuable for researchers to better understand how animal and plant species are faring across the UK.'

Without question, this remarkable global event has been an eye-opening reminder that we live in a deeply connected world. A world whose climate is startlingly sensitive to being harmed or healed. A world in which cities are every bit a part of nature as forests and oceans.

The sudden withdrawal from sight of the most dominant species on Earth has made visible some of the many ways in which human activity impacts our environment. And how fast things can change.

The full impact of lockdown on the natural world won't become clear for some time. For many of us, the greatest effect may have been a stronger awareness of the planet we share. And, perhaps, a stronger motivation to take care of it.