Ok but really...how important is the 1.5°C target?

Understanding the 1.5°C Target

In the battle against climate change, one critical benchmark stands out–the 1.5°C target. This threshold, established by the Paris Agreement in 2015, is a key goal aimed at mitigating the most catastrophic repercussions of global warming. However, it's important to understand that limiting global warming to this level does not mean we are entirely safe from its impacts. Rather, the 1.5°C target is about minimising the severity of these impacts–the table below summarises the difference in impacts between 1.5°C and 2°C warming.

Source: IPCC, 2018

For more info on 1.5°C vs 2 vs 2.5°C, Carbon Brief and NASA provide good overviews.

The Current State and Implications of Global Warming

Currently, our planet is experiencing an unprecedented rate of warming due to human activities, particularly the emission of greenhouse gases. Compared to pre-industrial levels, the global average temperature has already increased by 1.2°C. This increase in temperature, although seemingly small, has had significant effects on our climate system.

One of the most noticeable impacts of this global warming is the intensification of extreme weather events. As the planet warms, weather patterns are disrupted and extreme weather events such as heatwaves, storms, and heavy rainfall become more frequent and severe. For example, the year 2023 witnessed a series of such extreme weather events that have been directly linked to human-induced climate change.

In Asia, record-breaking heatwaves scorched many parts of the continent, causing widespread distress to both human and animal populations. In Chile, Europe, and the US, similarly extreme heat events were recorded, causing heat-related illnesses and deaths, wildfires, and other environmental damage.

In Australia, the extreme heat led to severe bushfires, causing extensive damage to property and wildlife habitats. These fires, exacerbated by the dry conditions brought on by the heat, were some of the most severe in the country's history.

Moreover, in Libya, an unusual and severe storm, named Storm Daniel, caused destructive floods that led to loss of life and property. Such storms are relatively rare in Libya, and the severity of Storm Daniel has been attributed to the changing climate.

These events serve as a stark reminder of the tangible and devastating impacts of global warming. They underline the urgent need for concerted global action to reduce greenhouse gas emissions and limit the extent of future warming. If the current trends continue, such extreme weather events will only become more common and more severe, posing significant challenges for societies and ecosystems worldwide. This reality is even more daunting as we approach tipping points in global climate change.

Tipping Points and Escalating Impacts Beyond 1.5°C

For every fraction of a degree of warming beyond 1.5°C above pre-industrial levels, the impacts become more severe, and the costs of adaptation rise. Crucially, the relationship between temperature rises and impacts is not linear. Increases beyond a certain temperature could lead to more serious impacts than those under that temperature, some of which may be irreversible and interconnected.

Many earth systems1 are at risk of crossing “tipping points” – critical thresholds that, if surpassed, could push us into an entirely new, irreversible state. Currently, the IPCC classifies 7 most probable tipping points resulting from human activity (for more information, read the following, or this article about coral reefs).

Crossing tipping points would have catastrophic impacts on societies, with the potential to escalate violent conflicts, mass displacement and financial instability.

1 An Earth system is like a big, interconnected puzzle that makes up our planet's environment and climate. It includes physical things like the air we breathe (atmosphere), the water in our oceans, rivers, and lakes, and the land that makes up our continents. It also includes all living things, from tiny microbes to large animals and plants, and the ecosystems they form. These pieces of the puzzle all connect and interact in complex ways that shape our environment and climate. If one piece is disturbed, like crossing a tipping point, it can cause big changes to the whole puzzle, affecting our global environment and climate.

Climate scientists warn that our current trajectory could push us past some of these tipping points if the global warming increase reaches 1.5°C. Five major tipping points are already at risk of being crossed due to warming right now and three more are threatened in the 2030s.

Some researchers believe that promoting positive social tipping points in socio-behavioural, technological, economic and political systems is the only realistic governance option to limit the risks. Like negative Earth system tipping points, one positive social tipping point can trigger another, leading to a cascade effect that generates widespread societal change. However, some ‘positive social tipping points’ have already been achieved, such as cheaper green energy, with insufficient impact. Also, whilst these may be powerful factors, much like other climate concerns, they require global coordination, which is a separate challenge given the current geopolitical landscape.

Why we need to act now

The window to achieve the Paris 1.5°C goal is rapidly closing. Recent assessments indicate that keeping below 1.5°C will be an immense challenge. Our current temperature trajectory implies we will reach the 1.5°C level of global warming in 2034.

The current failure to reduce emissions in line with 1.5°C has reinvigorated the discussion of a temperature ‘overshoot’, where a temperature safety limit is temporarily exceeded before warming is returned below it at a later stage.

While it might seem like a flexible option, it is problematic due to a number of reasons.

Firstly, uncertainties in our understanding of climate change mean that even if we follow an emission path designed to limit temperature rises to 1.5°C, there's still a risk of higher warming. For instance, there's about a 1-in-6 chance that maximum warming could reach 2°C instead.

An overshoot scenario significantly increases the probability of surpassing tipping points, which would be disastrous and trigger irreversible damage to our ecosystems and biodiversity.

Secondly, overshooting the 1.5°C target would intensify extreme weather events, causing greater harm to societies and economies across the world. Heatwaves, storms, floods, and droughts would become more frequent and severe, leading to devastating impacts on agriculture, health, and infrastructure.

Thirdly, overshooting would require a rapid and drastic reduction in temperatures after the threshold has been surpassed. This would require massive deployment of carbon dioxide removal technologies, many of which are currently at an experimental stage, come with considerable uncertainties, and could have substantial negative side effects.

If warming exceeds 1.5°C, we may need to remove up to 1100 billion tons of CO2 from the atmosphere to bring it back to 1.5°C, which is a daunting task. The effectiveness of CO2 removal technologies is also uncertain.

Furthermore, it's assumed that temperature will decline when CO2 is removed from the atmosphere, but this is also uncertain. In fact, there's a chance that warming might continue to increase even after net zero CO2 emissions are achieved. This means we might need even more CO2 removal just to stop further warming.

Lastly, there is a justice aspect to consider. The impacts of a temporary overshoot would disproportionately affect the most vulnerable societies who are least equipped to cope with climate change, thereby amplifying global inequality.

The bottom line

The climate fight has never been more urgent or more real. 

Aiming to limit global warming to 1.5°C is not just about meeting a target, it's about minimising irreversible damage to our planet. Even limiting to 1.5°C, we will suffer serious damage and impacts. 

The 1.5°C target is not foolproof, and every additional inch of warming increases the chances of crossing irreversible tipping points. This relationship is non-linear, and actual impacts are greatly uncertain. 

These risks highlight the urgent need for fast and coordinated global climate action. However, policies put into place must also consider how climate policies interact and connect across different countries, as well as socio-economic and equity issues.