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Why 1.5°C? The crucial climate target explained

Why every fraction of a degree matters in the fight to limit global warming and keep 1.5°C alive

Written by Alex Avard | 13 Oct 2021

Women wait for water at Sabawanag village. Image credit: Colin Cosier/Tearfund

You’ve probably heard the number 1.5 bandied about in conversations around the climate emergency. These two digits have become a rallying cry for climate scientists and activists across the globe in the lead-up to COP26 in Glasgow later this month, where the number will loom large over world leaders’ discussions.

But what is 1.5°C actually referring to, and why is it considered such a crucial metric in addressing the ongoing climate emergency?

What is 1.5°C?

When people talk about degrees of warming, they’re referring to the increase in the earth’s average temperature compared to pre-industrial times, before 1850. This baseline reflects a time before the use of fossil fuels skyrocketed during the Industrial Revolution. 

It’s important to note that, because it’s a global average, even small fractions of an increase in warming can have massive impacts. To reduce the devastation of a warming planet, we don't want to see any further rise in global average temperatures.

Our world is already 1.1°C hotter than pre-industrial times, and 1.5°C is the maximum level of warming we need to stay within if we are to avoid the worst impacts of the climate emergency. 

In the 2015 Paris Agreement, world leaders made a ground-breaking commitment to stop the global average temperature from increasing by more than 2°C and do all they could to limit it to 1.5°C. Since then, the need to focus on the target limit of 1.5°C has become strikingly clear, gaining wide consensus and a strong backing from science.

According to the Intergovernmental Panel on Climate Change (IPCC), the reality we now face is that even the biggest cuts in global emissions are unlikely to stop us reaching 1.5°C by 2040. But if we act urgently with deep and sustained emissions cuts, this 1.5°C overshoot could be temporary. This is why we all need to see strong outcomes from the climate talks in Glasgow. 

What happens at 1.5°C of warming?

A 1.5°C increase in temperature might sound fairly moderate, but it would still have a huge impact. This is particularly true for those living in poverty in the countries most vulnerable to the climate crisis.

1.5°C of warming will expose millions of people to more extreme climates, rising sea levels and more frequent weather-related disasters including heatwaves, drought, flooding and wildfires. We are already seeing these types of climate disasters make headlines every year, and any further rise in average temperature will only make their severity and frequency greater. 

What’s more, these consequences of a warming world are hitting the world’s poorest and most vulnerable communities hardest (ie those who have contributed the least to climate change). These temperature rises aren’t just an environmental crisis, but a humanitarian one as well. 

In short, a world that’s 1.5°C warmer is one that will need to adapt to all kinds of new struggles and injustices. We have a narrow window of opportunity to keep this as an achievable future and avoid the far worse scenarios which lie beyond that threshold. 

What happens beyond 1.5°C of warming?

The IPCC has also presented predictions of what our world might look like at each consecutive half degree of warming beyond 1.5°C. As you can imagine, the gravity of the situation only escalates. 

With an average temperature rise of more than 1.5°C, all climate impacts become more severe, including extreme temperature, droughts, water and food scarcity, and biodiversity loss. This is partly due to ‘tipping points’ – where climate change causes damage to the natural systems that help to stabilise temperatures, resulting in accelerated warming. 

If the average global temperature were to rise by 2°C, for example, the IPCC has predicted that 37 per cent of the world’s population would be exposed to at least one deadly extreme-heat event every five years, compared to 14 per cent in a 1.5°C scenario. That’s an extra 1.7 billion people affected with just half a degree of further warming. This is just one illustration of why every decimal point matters in the fight to stay within 1.5°C.

It’s difficult to portray accurately what our world will look like with 2.5°C or more of warming, but large areas could become uninhabitable for humans. As we’ve already seen, it’s the world’s poorest who are most vulnerable and will be hit first and worst. Out of love for our global neighbours and for God’s creation, we must take action and pray for an urgent breakthrough in this crisis.

What can we do about it? 

We all have a part to play in praying and speaking up for change. As the UK hosts COP26 in just a few weeks, we have a once-in-a-lifetime opportunity to influence world leaders to take decisive climate action. They must commit to deep emissions reductions with policies, investments and international agreements which reflect the urgency of the situation.  

We’d love for you to join us in prayer and action for COP26, calling on world leaders to ‘keep 1.5 alive’ and secure a better future for those already suffering the worst impacts of the climate crisis. You can find the latest ways to get involved on our COP26 page, including details on how to join a local march for the global Day of Action on Saturday 6 November.



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Written by  Alex Avard

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