What Is Climate Change and Why Does It Matter?
Climate change refers to long-term shifts in global temperatures and weather patterns. While climate has changed naturally throughout Earth’s history due to volcanic eruptions, solar variations, and orbital cycles, the current warming trend is overwhelmingly driven by human activities — primarily the burning of fossil fuels, deforestation, and industrial agriculture. Since the Industrial Revolution, the global average temperature has risen by approximately 1.2 degrees Celsius, with the rate of warming accelerating dramatically in recent decades.
The scientific evidence is unequivocal. The Intergovernmental Panel on Climate Change, representing the consensus of thousands of scientists worldwide, has concluded with greater than 95 percent certainty that human activities are the dominant cause of observed warming since the mid-20th century. This warming is not a distant future threat — it is happening now, driving more frequent and intense heatwaves, droughts, floods, and storms that affect communities on every continent.
How Does the Greenhouse Effect Work?
The greenhouse effect is a natural process essential to life on Earth. Without it, our planet’s average temperature would be approximately minus 18 degrees Celsius — far too cold for most life to survive. The process works because certain gases in the atmosphere, including carbon dioxide, methane, water vapor, and nitrous oxide, allow incoming solar radiation to pass through but trap some of the infrared radiation that Earth emits back toward space.
The problem is not the greenhouse effect itself but its intensification. Human activities have increased atmospheric carbon dioxide concentrations from approximately 280 parts per million before the Industrial Revolution to over 425 parts per million today — a level not seen in at least 800,000 years. Methane concentrations have more than doubled. These additional greenhouse gases trap more heat, causing the planet to warm beyond its natural equilibrium.
The carbon cycle — the natural process by which carbon moves between the atmosphere, oceans, soil, and living organisms — has been fundamentally disrupted. Burning fossil fuels releases carbon that was stored underground over millions of years, flooding the atmosphere with CO2 faster than natural systems can absorb it. The oceans have absorbed roughly 30 percent of human-emitted CO2, causing ocean acidification that threatens marine ecosystems.
What Evidence Supports Human-Caused Climate Change?
Multiple independent lines of evidence converge to demonstrate that current warming is driven by human activities. Ice cores drilled from Antarctica and Greenland contain tiny air bubbles that preserve a record of atmospheric composition stretching back hundreds of thousands of years, showing that current CO2 levels are unprecedented. Satellite measurements since the 1970s show decreasing heat radiation escaping to space at exactly the wavelengths absorbed by greenhouse gases.
The pattern of warming itself is a fingerprint of greenhouse gas forcing rather than natural variability. The lower atmosphere is warming while the stratosphere is cooling — exactly what greenhouse gas physics predicts, and opposite to what solar variability would cause. Nights are warming faster than days. Winters are warming faster than summers in many regions. These patterns all match the signature of enhanced greenhouse warming.
Attribution science, which uses climate models to determine the causes of specific weather events, has advanced dramatically. Scientists can now quantify how much more likely or intense a particular heatwave, flood, or hurricane was because of human-caused climate change. Study after study confirms that many recent extreme weather events would have been virtually impossible without the warming influence of human greenhouse gas emissions.
What Are the Impacts of Climate Change?
The impacts of climate change are already being felt across every ecosystem and human society on Earth. Arctic sea ice has declined by roughly 13 percent per decade since satellite records began. Glaciers worldwide are retreating at accelerating rates. The Greenland and Antarctic ice sheets are losing mass, contributing to sea level rise that threatens coastal communities housing hundreds of millions of people.
Extreme weather events are becoming more frequent and severe. Heatwaves that were once expected to occur every 50 years are now occurring roughly every decade. Heavy precipitation events have increased in intensity and frequency in many regions. Wildfires are burning larger areas for longer seasons, as warmer temperatures and drier conditions create more combustible landscapes.
Canada is warming at roughly twice the global average rate, with the Arctic warming at three times the average. Permafrost thaw is destabilizing northern infrastructure and releasing additional greenhouse gases. Prairie droughts threaten agriculture. British Columbia and Alberta face increasingly severe wildfire seasons. Coastal communities confront rising sea levels and storm surge.
Biodiversity is under severe pressure as species struggle to adapt to rapidly changing conditions. Coral reefs, which support roughly 25 percent of all marine species, are experiencing mass bleaching events with increasing frequency. Forests are stressed by drought, heat, and bark beetle outbreaks. Timing mismatches between species — such as when flowers bloom versus when pollinators emerge — disrupt ecological relationships that evolved over millennia.
What Solutions Exist for Climate Change?
Addressing climate change requires both mitigation — reducing greenhouse gas emissions — and adaptation — preparing for impacts that are already unavoidable. The Paris Agreement, adopted in 2015 by virtually every nation, set a goal of limiting warming to well below 2 degrees Celsius above pre-industrial levels, with efforts to limit it to 1.5 degrees.
The energy transition is accelerating. Solar and wind power are now the cheapest sources of new electricity in most of the world. Electric vehicle sales are growing exponentially. Battery storage technology is making renewable energy increasingly reliable. Nuclear power is being reconsidered as a low-carbon baseload source. Green hydrogen produced from renewable electricity could decarbonize hard-to-electrify sectors like shipping and steel production.
Carbon capture, utilization, and storage technologies aim to remove CO2 from industrial emissions or directly from the atmosphere. While still expensive and limited in scale, these technologies are advancing rapidly. Nature-based solutions — reforestation, soil carbon sequestration, wetland restoration — offer additional pathways for carbon removal while providing biodiversity benefits.
Canada has committed to reaching net-zero emissions by 2050 and has implemented a national carbon pricing system. Canadian cleantech companies are leaders in carbon capture, small modular nuclear reactors, and sustainable mining practices. The country’s vast forests, while threatened by climate change, also represent an enormous carbon sink that must be protected and managed sustainably.
What Can Individuals Do?
While systemic change driven by policy and industry is essential, individual actions collectively make a difference. The highest-impact personal choices include reducing air travel, shifting toward plant-based diets, using public transit or electric vehicles, improving home energy efficiency, and supporting climate-forward policies and companies.
Perhaps most importantly, individuals can drive change by engaging in their communities and democratic processes, supporting organizations working on climate solutions, and having conversations about climate change with family, friends, and colleagues. The transition to a sustainable economy creates opportunities for new jobs, healthier communities, and improved quality of life.
For more on these topics, read about the renewable energy revolution, ocean acidification and marine life, wildfire science in Canada, and carbon capture technology.
