Why the world needs trees more than ever before

Earlier this month at COP-27, leaders of twenty-six countries launched the Forests and Climate Leaders’ Partnership to reverse the loss of forests by 2030. 

The initiative recognises that trees are one of the best defence mechanisms in the fight against climate crisis – a fight that is currently being lost.  

As most children learn in school, trees absorb carbon monoxide. Globally forests absorb 7.6 billion metric tons of carbon every year, helping to slow down rising temperatures. 

With hot seasons becoming longer and more intense, air conditioning and electric fans now account for almost 20 percent of all energy consumption globally. Air conditioner use is expected to triple by 2050 as households in emerging economies acquire cooling systems to cope with the extreme heat they will face if carbon emissions are not reduced. 

During the hot season, trees can lower temperatures in urban areas by several degrees and help to reduce energy use, and prevent power outages that can put lives at risk during a heat wave. 

Trees also help to protect areas from flooding during heavy rainfall by slowing down the rate at which rain hits the ground. Branches and leaves diffuse the effect of a rainstorm, and some water evaporates before it ever even hits the ground, reducing the amount of surface runoff. 

The water that does hit the ground during rainfall is then distributed deeper into the soil through tree roots rather than left to lie on the surface. When the dry season starts, this water can then travel back up through the roots and is released into the air through leaves. 

If trees were a new technology, there would be millions of dollars of investment pouring into it from investors and venture capitalists – and neighbourhoods and city councils wouldn’t spend so much time trying to knock down these sophisticated offspring of Mother Nature. 

Over the last 30 years, the world has lost 178 million hectares of forest – an area approximately the size of Libya. Today, forests continue to be cut down at a rate of about 10 million hectares per year. To end deforestation by 2030, there needs to be a 10 percent annual cut in deforestation.

A lack of forests and grassland areas makes warm coastal cities particularly vulnerable to global warming and rising sea levels. 

Almost 800 people died in flooding in the Sindh Province in southern Pakistan during the summer monsoon season. Roads became deadly rivers in the province’s capital Karachi, a metropolis of 20 million people that lies along the Arabian Sea. 

Winds driving the monsoon rains from the Bay of Bengal appear to be shifting towards Karachi and away from the agricultural lands of Punjab. This means that Karachi will likely face shorter and more intense rainfall over the coming years. This year, for example, 87 percent more rainfall fell in Pakistan during the monsoon season than the annual average.

Anyone who has visited Karachi will also note the acute lack of drainage systems and green spaces. The city is dominated by impermeable surfaces like concrete. 

Urban development specialist Farhan Anwar believes that the heavy concretisation of Karachi – the result of “contract-driven greed of officials in numerous government departments and six cantonments that ‘own’ two-thirds of the city” – has had disastrous consequences for the city’s ability to withstand flooding.

“Open spaces serve as infiltration beds, and water runs down the ground,” he says. Without this natural open ground, the city cannot absorb the intense monsoon rainfall that comes every summer.  

Some efforts have begun to regenerate Karachi’s greenspaces and make them more resilient in the face of flooding and extreme heat. 

Masood Lohar created the Clifton Urban Forest as a tiny green lung in the concrete of Karachi. The forest is more of a wild park in its size, but it’s full of the sound of singing birds, in sharp contrast to the busy traffic on most streets. Green spaces like this regenerate the biodiversity that has been lost from the city while absorbing the heat and heavy rain that are a regular fixture.

It’s much better to preserve the trees and grassland that are already there rather than planting new trees. Young trees absorb less carbon and, if planted in the wrong environment, can cause fires and damage local ecosystems. Regular water is also critical for trees for at least two years after they’ve been transplanted and is a problem in many of the countries that could benefit the most from more trees. 

Along Karachi’s coast, activists are trying to protect the mangrove swamps, which have long served as important flood defences for warm coastal cities. By sequestering carbon, mangroves help slow climate change and protect locals against rising sea levels and increasingly severe storms.

Tariq Qaiser is a local architect in Karachi. He describes mangrove swamps as the city’s “air-conditioning” and “oxygen supply”. “If you just increase the mangrove cover, Karachi’s next thirty years will be much better than if you build over them,” he said in an interview with Time.

Yet, despite Pakistan being one of the signatories to the Forests and Climate Leaders’ Partnership, activists are still concerned that the mangroves can extinct in Karachi.

Perhaps in a few years, someone in Silicon Valley will spend millions developing a device that can lie along the coast and sequester carbon and hold together the sea beds in the face of storms and high seas. They’ll probably be called after the mangroves that were destroyed.