The importance of limiting warming to 1.5°c

The scientific community has stressed the urgency of limiting warming to 1.5°C because the health of oceans, ecosystems, and humans depends on it.

Human activities have caused approximately 1.1°C of global warming compared to pre-industrial levels (IPCC, 2023). If business as usual continues, warming will likely reach 3°C above pre-industrial levels by the end of the century (Hausfather and Peters, 2020).

Recently, global initiatives, such as the Science Based Targets Initiative, revised their standards to align with the 1.5°C pathway rather than the previous limit of well below 2°C.

Protecting our People

Scientists estimate climate-related risks to human health, food security, water supply, and livelihoods are far lower at 1.5°C of warming vs 2°C or higher.

Limiting warming to 1.5°C could spare several hundred million people from climate-related risks and poverty, and could halve the proportion of the global population exposed to increased water stress.

Scientists project 10 cm less sea level rise at 1.5°C vs. 2°C, translating to 10 million fewer people from small islands, low-lying coastal areas, and deltas being exposed to damage from rising seawater.

If we can slow the warming rate, communities will have a better chance to adapt, manage, and restore vulnerable infrastructure and coastal ecosystems.

Protecting our Oceans

We depend on our water bodies to provide invaluable ecosystem services such as food, jobs, transportation, fuel, energy, and recreation. Restricting warming to 1.5°C is expected to limit ocean temperature increases, acidity, and decreased oxygen levels and reduce risks to marine biodiversity, fisheries, and ecosystems.

Warmer oceans will cause marine species to relocate to higher latitudes, which will exacerbate the unequal distribution of global fish stocks, drive the loss of coastal resources, and reduce the productivity of fisheries and aquaculture.

With 1.5°C of warming, the global marine fisheries catch is expected to decline 1.5 million tonnes. However, this is half the losses projected in the 2°C scenario, estimated at 3 million tonnes annually.

Warmer oceans impact sea life physiology, survival, habitat, reproductive health, and disease occurrence while increasing the risk of invasive species. These impacts will be more intense at 2°C of warming. Coral reefs, for example, already face very high risks of bleaching and mortality at 1.5°C of warming. With warming below 2°C, almost all coral reefs will degrade from their current state, greatly depreciating the services they provide such as food, coastal protection, and tourism.

Protecting our Land

On land, limiting warming to 1.5°C will decrease impacts on biodiversity and ecosystems. With 1.5°C of warming, scientists predict that 3 to 14% of the species assessed will likely face a very high risk of extinction, increasing to 3 to 18% at 2°C (IPCC, 2023).

In addition, of the 105,000 species studied, 6% of insects, 4% of vertebrates, and 8% of plants will lose their geographical range at 1.5°C of warming compared to 18% of insects, 8% invertebrates and 16% of plants at 2°C.

The Bottom Line

Damage caused by climate change escalates with every increment of global warming. Our adherence to a net-zero carbon emissions strategy will determine whether warming can be limited to 1.5°C or 2°C (IPCC, 2023). That is why we must take responsibility and do whatever it takes to achieve our climate goals.