An Introduction to Climate Change
Changes in the climate have been happening for hundreds of thousands of years, and until recent centuries, most of these changes were naturally occurring – for instance, because of ice-ages and then post-glacial periods. The present-day is not the first time carbon dioxide (CO2) and other greenhouse gas levels in the atmosphere have been high. So what’s the difference now?
Starting with the Industrial Revolution of the 19th century until today, changes in the climate have been mainly the result of human activity. (This is a 95% certainty according to the Intergovernmental Panel on Climate Change or IPCC.) The Industrial Revolution meant a shift from human labour to machinery, and kickstarted the era of combustion engines – including the automobile – and, as a result, the excessive burning of fossil fuels.
The burning of fossil fuels releases pollutants including greenhouse gases. Over the past century, human activities have released large amounts of heat-retaining greenhouse gases into the atmosphere, which in turn causes the global surface temperature to rise.
And the rate of warming in Canada is double that of the global average. Between 1950 and 2010, average temperature over land in Canada has increased by 1.5ºC. Over the next 100 years temperature is projected to rise another ~1 to 5ºC.
Whether it’s reading the daily newspaper, listening to the radio or catching up on news on your phone, many climate change stories share common terms:
- Fossil fuels (FF) – there are three main types: coal, oil and natural gas. All were formed hundreds of millions of years ago by dead trees and plants that have died, broken down, have become compacted and covered by additional materials over time. Since plants produce and store CO2 during photosynthesis, this gas is released when fossil fuels (which are formed through organic material) are burned. This is the main concern regarding human-caused climate change.
- Greenhouse gas (GHG) – simply put, these are gases that absorb and trap heat in the atmosphere. The main GHGs are carbon dioxide, methane, nitrous oxide and water vapour.
- Carbon Dioxide (CO2) –a naturally occurring gas used by trees and other plants during photosynthesis to synthesize organic matter . This gas is also released when fossil fuels and biomass are burned.
- Anthropogenic – relating to or resulting from the influence of human beings on nature.
- Adaptation – adjustment in natural or human systems in response to actual or expected changes in order to moderate/reduce harm (for example, building a seawall to protect against storm surge and erosion).
- Mitigation – an intervention used to reduce negative effects and lessen their impact, such as the impact of greenhouse gas emissions on the climate system (for example, geoengineering removal of CO2 from the atmosphere, carbon taxes and reducing our individual carbon footprints).
- Resilience – the ability of a system and its component parts to anticipate, absorb, accommodate, or recover from the effects of a hazardous event in a timely and efficient manner.
- Adaptive capacity – the combination of the strengths, attributes, and resources available to an individual, community, society, or organization that can be used to prepare for and undertake actions to reduce adverse impacts, moderate harm, or exploit beneficial opportunities. Developed (or First World) countries have a larger adaptive capacity than developing (or Third World) countries do.
The Greenhouse Effect
The Greenhouse Effect is a naturally occurring and essential process that is regulated by nature. It enables the Earth to be a livable planet by moderating the Earth’s temperature. However, due to the burning of fossil fuels and other activities, humans are adding more GHGs into the atmosphere than are needed, throwing off the natural balance, resulting in an enhanced Greenhouse Effect.
The Earth is warmed directly by energy from the sun and re-radiates that energy into the atmosphere. Greenhouse gases act like a blanket around Earth, trapping some of the sun’s energy in the atmosphere, causing the atmosphere to warm. Some GHGs have a lifespan in the atmosphere for centuries; this is important because the warming will continue for decades even if we curb our behaviour tomorrow.
What Causes Anthropogenic Climate Change?
Anthropogenic climate change is caused by the burning of fossil fuels, deforestation (since trees and plants naturally store CO2), agricultural practices (farm animals release methane gas, and nitrous oxide is found in synthetic fertilizers), land-use changes, pollution, etc.
All of these activities release GHGs into the atmosphere at unsustainable rates and are forcing natural cycles to overload and surpass a threshold which then results in changes to our climate. Our lives are directly connected to the climate and the environment. The Earth is a closed system, full of intertwining cycles that require balance – we are dependent on it, though it is not dependent on us.
What are the Impacts of Climate Change?
- Rising global temperatures both on land and sea
- Sea level rise = sinking land and melting ice
- Changes in precipitation = more droughts/floods
- Glacier and sea ice melt
- Ocean acidification
- Loss of biodiversity/habitat reorganization
- Increased frequency/severity of extreme weather events
- Coral bleaching (due to warmer waters, they expel the algae in their tissue which causes them to lose all colour and die)
What are the Consequences of Climate Change?
- Human health (mental and physical) – spread of disease, increase rate of anxiety after a storm event
- Transportation – damage to roads, bridges, waterways
- Food security – changes in growing seasons and local growing capabilities
- Water security – saltwater intrusion due to floods, storm surge
- Energy security
- Infrastructure – need for changes to buildings, wharfs, bridges
- Natural environment
Future Projections for Nova Scotia
- Sea levels could rise by almost 1 metre by 2100 if things continue on same trajectory. It is also important to note that sea levels would be rising around our province even without climate change because of natural erosion of coastal land.
- Annual precipitation could increase by 100mm from the 1980s.
- We could have seven-fold more hot days (over 30) than in the 1980s.
- By 2080, there will be fewer days with snow than in the 1980s.
- Average annual temperature could increase almost 4 degrees by 2080 from 1980 levels.
- Longer growing seasons for agriculture with high potential for growings new species – this could mean higher yields but this is short-term.
- Introduction of new species due to species migration in search of more suitable habitats.
- Loss of local species northward as temperatures become too warm and habitats become unlivable or competition for habitat is too high.
Weather vs. Climate
It is important to recognize that many people do not know or see the difference between weather and climate – they are not interchangeable.
The difference between weather and climate is the measure of time. Weather is what conditions of the atmosphere are like over a short period of time (hour-to-hour, day-to-day, season-to-season), and climate is how the atmosphere “behaves” over relatively long periods of time (typically 30 years or more). It’s the average of weather over time and space. Therefore, when we talk about climate change, we talk about changes in the long-term averages of daily weather.
Climate Change vs. Global Warming
Although related, these two terms are not interchangeable and should not be substituted for one another.
Global warming refers to the recent and ongoing rise in global average temperature near the Earth’s surface. It is caused mostly by increasing concentrations of GHGs in the atmosphere. Global warming is causing climate patterns to change. However, it represents only one aspect of climate change.
Climate change refers to any significant change in the measures of climate lasting for an extended period. In other words, changes in temperature, precipitation, or wind patterns, among other effects, that occur over several decades or longer.
Facts and information contained within this document were obtained from the following sources:
Dire Predictions: Understanding Climate Change (2012) by Michael E Mann and Lee R Kump