Climate change strategies must factor in the need to augment the shade amenity, ideally through the planting of indigenous trees.
With stifling, protracted summer heat becoming the norm, translating into an uncanny dependence on costly (both financially and environmentally speaking) air conditioning, the ability to cool homes in a cost-effective manner has never been as fundamental an issue as it is nowadays.
Within such a context, low-tech cooling measures are of the essence and the paragon of such measures is definitely shade.
Shade might not always be viewed favourably, especially with the contemporary surge in high-rise buildings which, in turn, are shielding the sun from adjoining streets (and amenities such as PV panels, which are inherently dependant on the same sunlight) for extended periods of the day.
But in terms of its cooling potential, shade is definitely viewed as a panacea.
And Los Angeles is perhaps the epitome in this shift in mindset with respect to shade: while modern LA was built to maximise access to sunshine, enticing migrants from eastern US with visions of endless sunlight, scorching summer temperatures have motivated some, including LA’s chief design officer, Christopher Hawthorne, to state that it’s time to “turn off the sunlight”.
Trees and their canopies are inextricably associated with shade
Trees and their canopies are inextricably associated with shade, which is just one of the plethora of ecosystem services that these provide.
For instance, shading objects on a sweltering summer afternoon from solar rays can lower their temperature by up to seven degrees centigrade.
The cooling effect imparted by a tree canopy, however, is not only restricted to the shading aspect. According to the senior manager for Urban Forestry Policy in California, Yujuan Chen, rain or groundwater evaporating from trees can further significantly lower air temperatures.
So far, we are mostly stating the obvious and the known. What is perhaps a tad more elusive is the social inequality surrounding the distribution of trees and, consequently, of the cooling respite these offer.
For instance, a recent study conducted in Los Angeles has revealed a stunning disparity between the density of trees within affluent and poorer regions of the metropolis. Nearly 20 per cent of the city’s mature trees can, in fact, be found in just five blocks, home to just one per cent of the city’s population.
Consequently, in the absence of mature tree cover and unaffordable air conditioning units, resourceful residents in the struggling neighbourhoods have mastered the art of impromptu shading solutions, cobbling together discarded items as umbrellas, gazebos, tents and whatnot in a pastiche canopy.
A stunning disparity between the density of trees within affluent and poorer regions
Residents of less well-off parts of the city cannot afford to invest in the upkeep of vegetation along the curtilage of their property while, in the drive to make space for more vehicles, the city felled trees lining the streets and narrowed walkways.
Sounds eerily familiar, no? Mature trees in urban areas on these islands frequently get frowned upon and are even demonised by accentuating the damage these can wreak to properties and other ‘unpalatable’ aspects, such as the volume of dead foliage these shed or the obstruction these pose to traffic and to parking bays.
In order to bridge somewhat the inequity in tree cover between neighbourhoods of different financial clout, Los Angeles aims to plant 90,000 more trees by the end of 2021, with the ambitious objective of bolstering canopy cover by 50 per cent by 2028 in neglected neighbourhoods.
And LA is not a flash in the pan when it comes to a US city promoting a wider distribution of shade.
Boston, for instance, has drawn up sophisticated shade maps to drive future planning efforts in the city while Phoenix is targeting the hottest neighbourhoods (which, unsurprisingly, concurrently happen to be low-income and mostly Hispanic) for tree-planting, shade structures and redesigned streets. The city of Baltimore is even hiring residents to plant trees in underserved communities.
The direct risk of mortality from prolonged exposure to anomalously high temperatures is very real, especially for the elderly and the very early ages and is probably downplayed and not fully acknowledged on these islands.
Southern Europe will bear the brunt of consistently higher temperatures, with the rate of mortality expected to rise
But the risk is very real. For instance, a study published in 2017 within the Lancet Planetary Health journal predicts that southern Europe will bear the brunt of consistently higher temperatures during the summer season, with the rate of mortality from heat stress expected to rise from the current 11 per million inhabitants to a whopping 700 per million inhabitants in 2070, translating into 350 annual deaths for the Maltese islands.
This figure is on a similar par to figures for COVID-mediated mortalities on these islands.
Hence, climate change adaptation strategies currently being formulated need to factor in the need to augment the shade amenity, ideally through the planting and upkeep of indigenous trees (which, needless to say, also release oxygen, trap particulates on their foliage, serve as a habitat and roosting ground for an array of faunal species and afford a pleasant landscape) and not through the greenlighting of more high-rise development or obtrusive structures in rural areas.
With respect to the latter, the proposed gargantuan 43,000 square metre solar farm at Mġarr (Malta) is a case in point, given its deleterious shading impact on underlying agricultural land and swathes of garrigue.
The planting of more trees, however, should be accompanied by provisions for watering, as this summer has aptly taught us, with the shrivelling up of considerable numbers of mature olive trees in areas like Mellieħa and Mġarr.
Without such pro-shade measures in place, some of our buildings, especially those perpetually exposed to solar radiation, will become uninhabitable, along with their asphalt-dominated environs (asphalt, along with concrete, releases captured heat into the atmosphere for hours, being responsible for the ‘urban heat island effect’).
This column was inspired by ‘The Shady Divide’, an article featured in the July 2021 edition of The National Geographic magazine.