Beyond 1.5°C What Lies Ahead?

2023 was Earth's hottest year ever recorded, beating the previous record set in 2016 by a huge margin. 2023 was also the first in which the world was close to 1.5°C (1.48°C) hotter than the pre-industrial average (1850-1900). We are brushing against the threshold scientists urged us to limit long-term warming to. Some scientists, including former NASA climatologist James Hansen, predict 2024 will be humanity's first year beyond 1.5°C. As once dire warnings from climate experts become our shared reality, what can you expect?

The 1.5°C temperature target, enshrined in the 2015 Paris agreement, is not shattered on first contact. Most of the climate tipping points scientists fear could send warming hurtling out of control are not expected until Earth is consistently warmer than 1.5°C. The global average temperature is likely to dip down again once the present El Niño (a warm phase in a natural cycle focused on the equatorial Pacific Ocean) dissipates.

Instead, 2024 could be our first glimpse of Earth at 1.5°C. Here’s what research suggests it will look like for people and nature.

Ecosystems on the Brink

Tropical coral reefs are in hot water. These habitats comprise a network of polyp-like animals (related to jellyfish) and colourful algae encased in calcium carbonate. The complex forms they build in shallow water around the Earth’s equator are thought to harbour more species than any other ecosystem. “Corals have adapted to live in a specific temperature range, so when ocean temperatures are too hot for a prolonged period, corals can bleach—losing the colourful algae that live within their tissue and nourish them via photosynthesis—and may eventually die,” say coral biologists Adele Dixon and Maria Beger (University of Leeds) and physicists Peter Kalmus (NASA) and Scott F Heron (James Cook University).