What Is Already
Happening

Heat waves are becoming more frequent, more intense, and longer-lasting. The 2021 Pacific Northwest heat dome killed over 1,400 people in Canada and the US. Europe's 2022 summer heat killed more than 61,000. These events — once considered once-in-a-century — are now occurring every decade or less.

Extreme heat strains power grids, damages crops, makes outdoor work dangerous, and disproportionately kills the elderly, the poor, and those without air conditioning. By 2050, billions of people could face dangerous heat for 45+ days per year.

Global sea levels have risen about 20 cm since 1900 — and the rate is accelerating. The primary drivers are thermal expansion of warming oceans and melting ice sheets in Greenland and Antarctica. By 2100, seas could rise by 0.5–1 metre under moderate scenarios, and up to 2 metres under high-emission pathways.

Low-lying coastal cities — Miami, Jakarta, Mumbai, Shanghai, Amsterdam — face chronic flooding, saltwater intrusion into freshwater supplies, and eventual uninhabitability. Small island nations like Tuvalu and the Maldives face existential threats.

Climate change does not cause weather — but it loads the dice. A warmer atmosphere holds more moisture (about 7% more per degree of warming), fuelling more intense rainfall and flooding. Warmer oceans provide more energy to hurricanes. Prolonged droughts dry out vegetation, creating conditions for catastrophic wildfires.

Attribution science — a relatively new field — can now calculate how much more likely a specific extreme event was made by climate change. The 2021 British Columbia floods were made 60% more likely. The 2019–20 Australian bushfires were made at least 30% more likely.

Climate change is one of the primary drivers of what scientists call the sixth mass extinction — the fastest loss of biodiversity in 65 million years. Species are shifting their ranges poleward and to higher elevations, but many cannot move fast enough. Coral reefs — which support 25% of all marine life — are bleaching and dying as ocean temperatures rise.

Phenological mismatches are disrupting food webs: flowers bloom before pollinators arrive; birds migrate before insects hatch. These cascading disruptions threaten the ecosystem services — clean water, pollination, carbon storage — that human civilization depends on.

Climate change is already reducing crop yields in many regions. Heat stress, drought, and flooding damage harvests of staple crops — wheat, maize, rice — that feed billions. The IPCC projects that without adaptation, yields of major crops could decline 2–6% per decade while demand continues to grow.

Glaciers that supply freshwater to hundreds of millions of people in Asia and South America are retreating rapidly. Changing precipitation patterns are making some regions wetter and others far drier. Water scarcity is projected to be one of the defining humanitarian crises of the 21st century.