Effects of Climate Change Around the World: Weighing Harms and Benefits

Let's start with a ship

For centuries, European explorers searched for a sea route through the Arctic, the Northwest Passage. Most expeditions were stopped by ice, and some ended in disaster. Today, in late summer, ships regularly sail through Canada's Arctic waters, including cargo ships and cruise ships.

Is that good news or bad news? It depends on who you ask and what you look at: shorter shipping routes and new jobs, or oil-spill risks, noisy waters for whales, and less sea ice for the people and animals that depend on it. Most effects of climate change are like this. In this lesson you'll learn to analyse effects carefully: positive and negative, on people and on natural systems, around the world.

How to analyse an effect

For any effect, ask:

1. What climate change drives it? (warming, less ice, sea-level rise, heavier rain, drought)
2. What is affected? A natural system (an ecosystem or species) or a human activity (farming, fishing, travel, health, housing, culture)?
3. Positive or negative, and for whom? The same change can help one group and harm another.
4. Current or potential? Is it already happening (with evidence), or projected?
5. How serious, and who is most vulnerable?

The Arctic: sea ice, wildlife and Inuit communities

The Arctic is warming much faster than the global average. Effects include:

• Natural systems: polar bears hunt seals from sea ice; ringed seals raise pups in snow dens on the ice; walrus rest on ice between dives. Shorter ice seasons reduce hunting time and habitat. Some Arctic fish and seabirds are shifting their ranges, while species from the south move north.
• Inuit communities: for Inuit, sea ice is a highway and a hunting ground. Thinner, less predictable ice makes travel more dangerous and harvesting harder, which affects food security, culture and the passing on of knowledge to young people. Permafrost thaw damages buildings, roads and airstrips. Inuit organizations and communities are leading responses, combining Inuit knowledge with new technology (such as the SmartICE ice-monitoring program you met in Grade 9) and advocating for their rights in national and international climate discussions.
• Economy: a longer open-water season allows more shipping, tourism and resource development, which may bring jobs and lower costs for northern resupply, but also risks of oil spills, accidents in remote waters, underwater noise that disturbs whales, and questions of Arctic sovereignty and who decides how northern waters are used.

Drylands: drought, desertification and famine

About 40% of Earth's land is drylands, home to billions of people. In many dry regions, a warmer climate increases evaporation and makes droughts more severe. Combined with overgrazing, clearing vegetation and poor soil management, land can lose its productivity: desertification.

• In the Sahel, the semi-arid belt south of the Sahara, severe droughts in the 1970s and 1980s caused famine. African countries are now working on the Great Green Wall initiative, launched by the African Union in 2007, to restore degraded land across the region.
• In the Horn of Africa, five rainy seasons in a row failed between 2020 and 2023, leaving millions of people facing severe hunger and killing large numbers of livestock. Scientists who studied the drought found that human-caused climate change had made such a severe drought much more likely, mainly by increasing evaporation.

Losing arable land (land that can grow crops) threatens food security, especially where people depend on rain-fed farming and have few resources to adapt. Food shortages can push up prices worldwide and contribute to migration and conflict.

Low-lying coasts: flooding, disease and resettlement

Rising seas make storm surges reach farther inland. Low-lying coasts and river deltas are especially exposed.

• Bangladesh sits on a huge, low river delta where millions of people live close to sea level. Cyclone storm surges, river floods and saltwater intrusion into wells and rice fields threaten homes, farms and drinking water.
• Water-borne diseases such as cholera and other diarrheal diseases can spread after floods contaminate drinking water, and warmer water helps some harmful bacteria grow.
• Resettlement: some communities are planning to move. The low-lying Pacific island nation of Tuvalu signed a treaty with Australia in 2023 (the Falepili Union) that includes a pathway for Tuvaluans to move to Australia, while Tuvalu also works to protect and adapt its islands.

Canada has coastal risks too: Atlantic communities face erosion and storm flooding made worse by sinking land (Lesson 13), and northern coastal communities face erosion as sea ice that once protected the shore disappears.

Farming regions: longer growing seasons, with catches

In cool regions, including much of Canada, warming lengthens the growing season and increases growing degree days (Lesson 6). Frost-free seasons in parts of Canada are already longer than in the mid-1900s.

Possible benefits: crops that need longer seasons (corn, soybeans, some fruits) can be grown farther north, and farmers are exploring new farmland, including in northern Ontario's Clay Belt. Livestock may need less winter shelter.

Catches: more heat waves and droughts during the growing season; heavier rains that erode soil and delay planting; new pests and diseases that survive milder winters; northern soils that are often thinner, rockier or wetter than prairie or southern Ontario soils; and the loss of forests and peatlands if land is cleared (releasing carbon). In hot regions such as South Asia and parts of Africa, crops are already near their heat limits, so further warming tends to reduce yields.

Putting it together

Across these examples, several patterns appear:

• Benefits are real but limited, usually local, and often come with new risks.
• Harms grow faster as warming increases, and some (species extinction, loss of glaciers, loss of land to the sea) can't be reversed on human time scales.
• The most affected are often the least responsible: communities that have produced few emissions, such as Arctic communities and low-income countries, often face the biggest impacts and have fewer resources to adapt. This raises questions of fairness, which you'll consider when assessing initiatives in Lesson 16.