The 2015 Paris Agreement saw nearly 200 countries commit to limiting human-induced global temperature increases to well below 2 degrees Celsius (°C), while pursuing the goal of keeping the rise to 1.5°C. Three years later, the Intergovernmental Panel on Climate Change (IPCC) laid out the stark differences between a 1.5°C and a 2°C world.

The IPCC was established in 1988 by the United Nations to provide expert scientific guidance on human-induced climate change. The IPCC’s approaches are unprecedented in their collaborative nature, often including contributions from hundreds of authors across all regions of the globe, and are subject to intense levels of scientific scrutiny.

In recent years, the panel has played a critical role in filling in the scientific understanding behind the goals of the Paris Agreement.

The Special Report on Global Warming of 1.5°C in 2018 laid out the confronting differences between a 2°C and a 1.5°C world. For example, compared to a rise of 1.5°C, a 2°C increase sees an additional 10 centimetres of sea level rise, near-disappearance of many coral reefs and an additional 420 million people exposed to frequent heatwaves.

The IPCC’s clear statement of what’s at stake kickstarted a wave of momentum. Last year’s Glasgow Pact reaffirmed the goal of 1.5°C.

Also last year, the IPCC’s physical science working group released an updated report based on the latest science. This update presents a stark picture: if global emissions were to stay at current levels, it would take only 11.5 years (from 2021) for the world to effectively lock in 1.5°C of warming.

The IPCC’s findings have a clear message: there are still global pathways that take us to the 1.5°C goal, but we have a limited window of time in which to get on track.

This year, for the first time, the IPCC highlighted three Illustrative Mitigation Pathways (from its database of more than 3,000 scenarios) that have a greater than 50 per cent chance of limiting the global temperature rise to less than 1.5°C. While these three pathways have their differences, the main thing they have in common is deep emission reductions over the next decade.

An important, yet often overlooked, feature of these 1.5°C pathways is they allow for up to 0.1°C of temperature overshoot to occur. This means that a 1.5°C scenario could see global temperatures peak at 1.6°C above the pre-industrial average, before being drawn back down.

Overshooting the global 1.5°C goal is far from an ideal outcome. Exceeding 1.5°C by too much could lead to increased climate impacts that are non-reversible, including ecosystem loss. Drawing temperatures back down also relies on a considerable effort to remove carbon from the atmosphere. However, the additional headroom provided by this allowance for overshoot may prove a key factor that keeps the long-term 1.5°C goal on the table.

Regardless of any temperature overshoot, a common feature of all 1.5°C pathways is the need for transformational action and deep emission reductions this decade. Last year, the IEA published their first ever 1.5°C roadmap for the global energy sector.

Climateworks’ own Decarbonisation Futures research laid out the solutions that can set Australia on track towards this goal, and key players in the economy are increasingly incorporating 1.5°C scenarios into their decision making, including Australia’s energy market operator.

With the transformational decade for climate action well and truly underway, the global goal of 1.5°C is still very much on the table. Today, better than any point in history, we understand the actions that can be taken this decade to set us on the path there.

Stay tuned for more on 1.5 degree Celsius pathways.

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