Have we already gone past 1.5 degrees of warming?

24.06.24 By

2023 was the hottest year ever recorded. In the months of July and August, temperatures reached 1.6°C above pre-industrial levels of warming. This news creates a lot of confusion about whether or not this means we’ve collectively failed to honour the international treaty on climate signed by almost 200 countries in 2015 known as the Paris Agreement. 

Let’s break down what it all means and set the record straight.

Why is 1.5°C of global warming so dangerous?

There is no safe level of global warming. 

By digging up and burning coal, oil and gas we have profoundly altered the Earth’s carbon cycle by drawing huge quantities of carbon out of long-term underground storage and pumping it into our atmosphere. This has tipped our Earth System out of balance and blanketed the planet in pollution that traps heat inside our atmosphere. 

Our global temperature is now rising faster than anything we have seen over the Earth’s entire history. Around the planet, we are dealing with more dangerous, unpredictable and more frequent extreme weather events like bushfires, flooding rains, heatwaves and droughts.

Climate scientists have long warned that, to avoid the worst impacts of climate change, we need to drastically cut climate pollution and limit global warming as close as possible to 1.5°C above pre-industrial levels. Every fraction of global warming beyond this level exponentially increases climate harm, as well as the risk of crossing tipping points in the climate system – which would trigger abrupt and irreversible changes and accelerate warming. In other words, tipping points are points of no return.

How is the Paris Agreement linked to 1.5°C of global warming?

In 2015, 196 countries came together and signed an agreement to substantially reduce climate pollution to hold the increase in long-term global average temperature to well below 2°C and pursue efforts to limit it to 1.5°C. It was signed in Paris; hence the name ‘The Paris Agreement’. 

It might sound like a small number, but every fraction of a degree of global warming carries huge, real-world consequences for us all. 

How do we know if we’ve exceeded the Paris Agreement 1.5°C target?

average temperature over a period of at least 20 to 30 years. For the pre-industrial period, the average temperature between 1850-1900 is commonly used, as it’s the earliest period when near-global reliable measurements were available. The global average temperature for the most recent 10-year period, from 2014 to 2023, is estimated to be the warmest 10-year period on record, at around 1.2°C above the 1850-1900 average.

Image Source: European Space Agency

Similarly, the 1.5°C threshold also needs to be assessed on decadal timescales. This means that if the world breaches 1.5°C on an individual day, month or year, it does not mean the 1.5°C threshold has been breached because it must be assessed over a longer period of time. These breaches, however, act as signs that we are getting very close to breaching the long-term limit. 

The Paris Agreement itself does not specify how many years should make up the long-term trend for measuring temperature changes. This means different experts may come to different conclusions about when this threshold is crossed in the future. Adding to this complexity, the Paris Agreement aims to limit temperatures as close as possible to 1.5°C above pre-industrial levels by the end of the century. This means that temperatures might exceed 1.5°C for a time (referred to as “overshoot”) and then come back to 1.5°C by the end of the century (for example, by removing greenhouse gases from the atmosphere). 

Despite the complications of assessing and measuring the 1.5°C threshold, we know that it has not yet been crossed. Scientists have found that the world has warmed by 1.2°C based on averaging temperatures over the most recent 10 year period. This means that, although a lot of work needs to be done to maintain a safe and healthy climate, we have not yet gone past 1.5°C of warming.

At what temperature do the impacts start?

We are already experiencing climate harms through worsening and more frequent extreme weather events.

Globally, millions are already experiencing the impacts of climate change in the form of extreme temperatures, heavy rains, flooding and more. Closer to home, Australians are experiencing ‘climate whiplash’ from being hurled from flooding rains to heatwaves to fierce fires, and back again. The only solution that addresses the root cause of this is to reduce climate pollution as quickly as possible, with the lion’s share of action taking place this decade.

In other words, the impacts are already well underway, but limiting warming to 1.5°C with limited or no “overshoot” would prevent some of the most deadly impacts of climate change. 

Are we too late?

It’s ‘game on’ for slashing climate pollution, not game over.

Everything we do now matters. After years of climate denial and delay, Australia is finally on the right path by scaling up clean energy and industries so we can phase out polluting coal, oil and gas. Governments at all levels have the opportunity to build on this progress and momentum to seize this decade and ensure millions more Australians enjoy the benefits of a cleaner, safer future.

The further and faster we can cut climate pollution in the 2020s, the better the prospects for all of us.