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n 2020, the pandemic slowed our usual hustle and bustle in incredible ways. What followed, as the pandemic raged and social justice issues arose, was the awareness of significant reductions in carbon dioxide and other greenhouse gases emitted from human activities. Forced reductions in land, sea, and air transportations, unoccupied commercial buildings, etc., lowered the amounts of fossil fuel we burned and the associated gases emitted to the atmosphere. Then, last August, the Intergovernmental Panel on Climate Change (IPCC), released its Assessment Report #6 or AR6, which showed unequivocally that human activities resulting in greenhouse gas emissions are causing the planet to warm up at accelerated rates. AR6 also reinforced the need to limit the rising global average temperature relative to preindustrial times to within 1.5°C. The 1.5°C target was initially given back in Paris in 2015 and, since then, the global average temperature has already risen from 1.1°C in 2015 to 1.2°C. The UN Secretary General called the report, “a code red for humanity”, and with only eight years to halve global emissions and curtail the temperature rise, we need changes on a massive scale. Effectively, the world is on a Race to Zero, to decarbonize human activities. But, what do these all mean? In this inaugural piece on Decarbonization, we’ll examine the meanings and fundamentals of the climate issues, why they are important to everyone, and our role as Canada’s construction professionals. Let’s start with Carbon dioxide, or CO2. THE FUSS ABOUT CARBON DIOXIDE We know from basic biology that humans and animals breathe out carbon dioxide, and plants absorb it as part of an ecobalance. It is less known that CO2 is a heat-trapping gas. Its ability to stretch and bend the bond between its carbon and oxygen molecules, allows it to absorb photons of light. CO2 in the atmosphere absorbs the sun’s energy reflected outward from the earth’s surface; then its molecules vibrate and it reemits the infrared energy in all directions, including sending some back to earth, rather than letting them all escape out to space. This keeps inward the heat that would otherwise exit earth and is one of the reasons that earth can maintain a warm temperature to sustain life – otherwise the planet would freeze up as a giant ice rock. If carbon dioxide is such a good thing, then why all the fuss? It turns out that “you can have too much of a good thing” as
22 | CONSTRUCTION ECONOMIST | www.ciqs.org | Winter 2021
Katharine Hayhoe, Chief Scientist at The Nature Conservancy puts it. She explains that it’s like when you have an extra blanket over your body at night, and you wake up sweating. We are putting extra carbon dioxide into the atmosphere, causing earth to heat up faster. Carbon dioxide is just one of known heattrapping gases, collectively known as greenhouse gases, but it is the most abundant one increasing rapidly under human influence. THE GOAL FOR DECARBONIZATION Since the industrial era dawned in the 1700s, humans have been extracting and transforming energy on a scale never seen in known history. We create technologies to build bigger and taller, heat and operate our buildings, manufacture, drive our vehicles, etc. These activities release tons of carbon dioxide equivalent (CO2e) of GHGs into the atmosphere, mostly through the burning of fossil fuels. We are currently headed to a total of 50 billion tons CO2e in annual global emissions, and current atmospheric CO2 concentration is over 400ppm – a record in human history. A reconstruction of the historical CO2 levels from ice cores shows rapid jump since 1950, as human energy use intensified in the current technological era (Figure 1). Previous CO2 levels, about 800 years prior, never went past 300ppm. The extra CO2 is upsetting the eco-balance that the planet has known for thousands of years. A similar reconstruction of 11,000 history of the planet’s average temperature indicates the accelerating rise in global average temperatures in modern times (Figure 2). These and much other scientific evidence are why the latest AR6 report earlier mentioned stated that “It is unequivocal that human influence has warmed the atmosphere, ocean and land.” The goal for Decarbonization is therefore, to reduce the current carbon dioxide equivalent greenhouse gas levels to net zero by mid-century (2050). Direct removal of emissions from the atmosphere is unfortunately an endeavor that is yet unproven to be feasible, at the scale required, within the time available. WHAT IF THE PLANET CONTINUES TO HEAT UP? What if the levels of CO2 and other GHGs continue to rise, and the planet continues to heat up? The impact of climate change is already affecting every region on the planet with increasing heat waves, longer warm seasons, shorter cold seasons, droughts, etc. Wind patterns too will continue to change, as extreme wind events become more frequent. There is also risk of biodiversity loss as regions and local habitats can no longer support the life they To return to Table of Contents CLICK HERE
