SINGAPORE: Planet-warming emissions from Singapore’s land use sector are expected to grow between now and 2030 – a sign that more deforestation could be on the cards for the country.
Total emissions from this sector are low, contributing just 0.06 per cent to the nation’s total emissions inventory in 2022. The bulk of Singapore’s emissions come from the energy sector.
But figures on projected emissions from land use change – detailed in a climate report that Singapore submitted to the United Nations in November – show that planting new trees cannot replace carbon loss from forest clearance in the short term.
The report showed that in 2022, greenhouse gas emissions from Singapore’s land use, land use change and forestry sector were 0.04 million tonnes of carbon dioxide equivalent (MtCO2eq). CO2eq is a measure of greenhouse gas emissions.
Emissions are expected to more than double to 0.09 MtCO2eq in 2025, before rising to 0.14 MtCO2eq in 2030, stated the Republic’s first biennial transparency report.
This is despite reforestation and tree planting efforts, such as the ongoing initiative to plant a million more trees across the island by 2030. Since the launch of the OneMillionTrees movement in April 2020, more than 730,000 trees have been planted here.
The report also showed that from the year 2000 up until the early 2010s, Singapore’s land use, land use change and forestry sector was a net sink – meaning that land in the Republic absorbed more emissions than it released.
Forests help to reduce the amount of CO2 in the atmosphere through the process of photosynthesis, locking up the carbon in biomass such as their trunks. The bigger the tree, the more carbon it stores.
The land use, land-use change and forestry sector turned into a net source of emissions in 2014, contributing 0.02 MtCO2eq that year.
Data on greenhouse gases from that sector was derived from area figures based on past satellite images, Lim Liang Jim, senior director for international biodiversity conservation at the National Parks Board (NParks), told The Straits Times.
The area figures were then projected to 2030.
“Actual figures could change based on the rate of new planting, as well as the rate of conversion of higher to lower carbon stock areas, such as from forest land to settlement,” Lim said. Carbon stock refers to the carbon locked up in an ecosystem, like in trees and soil.
“For example, as natural regrowth or new planting is added and grows, this will be taken into account in subsequent reporting,” he added.
Given Singapore’s small land size and highly urbanised landscape, emissions from agriculture, forestry and land use are negligible in comparison with other economic sectors, said the report.
Experts told ST that the declining ability of Singapore’s land to absorb more carbon than is released is not unexpected, given developments that entail the felling of forests for other purposes, such as housing.
For example, ST reported in early December that two forested areas in Sembawang and Woodlands will be cleared for housing projects.
The 53ha Sembawang site is about one-third of the area of Bukit Timah Nature Reserve. And adjacent to the Sembawang site is a larger plot of forest that is also zoned for residential use. The Woodlands site is 7.27ha, roughly the size of 13 football fields.
Nature experts pointed out that the vegetation that is often cleared for development are secondary forests – vegetation that grew on land that was cleared before.
Assistant Professor Lim Jun Ying from the NUS Centre for Nature-based Climate Solutions noted that secondary forests are generally carbon sinks, as the trees are relatively young and still growing, and therefore accumulating biomass.
Former Nature Society Singapore president and botanist Shawn Lum said between the 1980s and 2000s, green cover across the island steadily increased. One reason for this was secondary forests sprouting over previously cleared land that was zoned for development.
Carbon is just one dimension of ecosystem function. We depend on our forests for much more than that, for urban cooling, for water management and drainage, for removal of pests like mosquitoes and rats, and more.
One reason for this was secondary forests sprouting over previously cleared land that was zoned for development, said Dr Lum.
These places include Tengah forest and Dover forest, which were recently partially cleared, as well as land slated for future projects such as the Paya Lebar Air Base area.
“Clearing these secondary forests leads to carbon emissions, both from the decomposition of the vegetation and from the release of organic carbon in the soil... This increase in emissions was inevitable, so long as the planned change in land cover from greenery to built areas took place,” added Dr Lum.
Prof Lim added: “Singapore has very little land-based capacity to store carbon in forests, given how little land overall we have, and the high opportunity costs of not using them, for housing for example.”
Singapore’s recent efforts to turn into a City in Nature and weave more greenery through the country may not necessarily equate to reducing emissions, the experts said, although they emphasised that planting trees offered many other benefits.
Muhammad Nasry Abdul Nasir, executive director of the Singapore Youth Voices for Biodiversity, said: “Native trees planted on streetscapes grow at much slower rates, as they’re adapted to rainforest conditions such as dense shade and humidity compared with dry, direct sunlight.”
He added: “In fact, in the short term, urban planting can be a (source of) emissions – resources spent germinating the sapling, transporting, digging up the soil and releasing trapped carbon at lower rates, and fertilising.”
Prof Lim said that despite this, Singapore’s greening efforts have significant benefits beyond carbon.
These benefits include furthering wildlife conservation and ecological functions, as well as improving people’s well-being.
Sprucing up green buffers around the nature reserves and having the streetscapes resemble the layers of a forest helps to connect wildlife from one habitat to another. These “nature corridors” help to improve the survival and genetic resilience of wildlife.
Lush parks nestled in neighbourhoods, such as the the Bishan-Ang Mo Kio Park and Bidadari Park can help to cool the urban environment.
Restoring mangroves along coastlines helps to fight future sea-level rise.
Nasry said: “Carbon is just one dimension of ecosystem function. We depend on our forests for much more than that – for urban cooling, for water management and drainage, for removal of pests like mosquitoes and rats.
“Focusing just on emissions neglects the other diverse values of an ecosystem.” - The Straits Times/ANN
[Shabana Begum is a correspondent, with a focus on environment and science, at The Straits Times.]