1.5°C Climate Threshold: What Happens If We Reach It?

Here’s what’s at stake if we exceed the 1.5°C climate threshold.

There is no denying it: significant shifts are happening in our climate faster than anticipated. From intensified storms to unprecedented heat waves, the impact of human activities on global warming is increasingly evident.

As the climate change narrative unfolds, one number has taken center stage: 1.5°C. It’s the globally agreed climate threshold, a line in the sand drawn by climate scientists and policymakers alike. It marks the territory between adaptation and potentially catastrophic events.

But what happens to our planet if we cross this line and let global warming surge past 1.5°C? Let’s delve into the reality of a world at and beyond the climate threshold.

In this article:

Sign that reads "If not now, when? There is no planet B" during a climate change protest

What is the climate threshold?

The term “climate threshold” defines the tipping point that our planet is rapidly approaching, driven by human-induced global warming. The tangible evidence is becoming harder to ignore as extreme weather events, such as powerful storms and record-breaking heat waves, grow in frequency and intensity.

The current goal is to alter our trajectory and steer away from the most severe impacts of climate change by limiting global temperature increases to 1.5°C (2.7°F) by 2100. This could avert drastic climate upheavals that would intensify global crises such as food scarcity, widespread conflicts, and debilitating droughts.

Achieving a 1.5°C warming limit is no small task. Its successful implementation calls for the full deployment of every available technological asset and solution. Moreover, we cannot ignore the importance of incremental changes, as every tenth of a degree counts. As of 2023, our world is already 1.1°C (1.9°F) warmer than the average temperatures recorded during the pre-industrial era (1850-1900). 

In 2015, the Paris Agreement, a treaty made up of 196 nations, agreed to strive to limit global warming to under 2°C (3.6°F), closer to 1.5°C if possible. The Paris Agreement’s roadmap aims to phase out heat-trapping carbon emissions by 2050. Achieving this goal requires reinforcing commitments to slashing greenhouse gases progressively over time.

Learn More: Climate Change vs Global Warming: What’s the Difference?

What happens if we don’t limit warming?

Sea Level Rise
Rising sea levels is a consequence of melting ice caps and thermal expansion as ocean waters warm. At 1.5°C, scientists expect sea-levels to rise approximately 1.5 feet by 2100. This would result in adverse impacts on low-lying coastal regions and small islands, threatening biodiversity, human settlements, and economic infrastructure.

At 2°C, sea-levels would rise roughly 1.8ft by the end of this century. This would escalate the threat to coastal communities through increased flooding and coastal erosion. 

Coral Reefs Will Die Off
At 1.5°C, climate scientists expect approximately 70-90% of existing coral reefs to disappear. This is due to coral bleaching, a stress response to warmer oceans, making them vulnerable to disease and death.

If our planet warms by 2°C, 99% of coral reefs worldwide could be eradicated due to prolonged and frequent episodes of coral bleaching. The loss of these biodiversity hotspots could trigger a domino effect, disrupting marine ecosystems and resulting in the decline of species that rely on the reefs for survival.

Melting icebergs as we reach the climate threshold

An Arctic with No Ice
By keeping the rise in global temperature to 1.5°C, we may buy more time for the Arctic’s dwindling ice caps. At this warming level, the Arctic could experience at least one ice-free summer per century.

In contrast, the rate of ice-free summers in the Arctic jumps to at least once per decade if we reach 2°C. The repercussions would extend beyond the Arctic region, affecting global climate patterns, sea-level rise, biodiversity, and the livelihoods of indigenous communities.

Severe Heat Waves
In a future where warming is capped at the 1.5°C climate threshold, heat extremes are still predicted to rise in frequency and duration. Over 1 billion people will be exposed to extreme heat waves every 5 years.

But if we cross the 2°C threshold, extreme heat waves would impact over 2.7 billion people every 5 years. This translates to heightened health risks and a potential spike in heat-related deaths. This would also exacerbate droughts and affect food production, fuelling inflation, food insecurity, and potential social unrest.

Learn More: Global Heat Waves Shatter Records in 2023

Increased Flooding and Storms
Limiting global warming to 1.5°C leads to observable changes in our weather systems. Intense and more frequent rainfall, snowfall, and hail would increase the risk of flooding by 100%.

At the higher climate threshold of 2°C, the intensity and frequency of precipitation would increase by 170%. Furthermore, storms, especially hurricanes and typhoons, could become more powerful, leading to more substantial and widespread devastation.

Dead trees in the middle of a desert, no longer able to support wildlife due to climate threshold

Loss of Wildlife Habitats
At 1.5°C, plants and animals risk losing their habitats. This would pose risks such as heightening competition for resources and an increase in localized extinctions. We would lose roughly 6% of insects, 8% of plants, and 4% of vertebrates. But at this threshold, it’s still possible for organisms to evolve and adapt to their new climate.

If the climate threshold reaches 2°C, we would lose 18% of insects, 16% of plants, and 8% of vertebrates. These changes would involve dramatic losses with less potential for adaptability.

Learn More: Is Climate Changing Igniting Canada’s Wildfires?

When are we expected to hit the climate threshold?

While numerous nations commit to ambitious goals for emission reduction, these commitments are falling short. The Earth is still on track to breach the 2.5°C climate threshold by the century’s end. Present day, we sit 1.1°C hotter compared to 150 years ago.

For eleven days in June 2023, the global surface air temperatures temporarily rose to 1.5°C for the first time. 
Between 2017 and 2021, there was only a 10% chance of exceeding the 1.5°C climate threshold. Currently, we have a 50% chance of temporarily doing so again in the next five years.

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