In the landmark Paris Agreement, adopted at the 2015 United Nations climate change conference (COP21), 196 countries agreed to limit global temperature increase to well below 2°C above pre-industrial levels, setting 1.5°C as the highest ambition. Individual nations thus began setting national emissions targets with this temperature goal in mind; although, at the time, these were considered insufficient to realise a Paris-aligned future. Countries have since kept ramping up their emissions ambitions.

The COP26 talks in Glasgow in November 2021 saw considerable breakthroughs. More than 120 countries upgraded their 2030 targets (NDCs), while major emitters representing over 70% of global CO₂ emissions announced commitments to transitioning to climate neutrality—indicatively, with the EU and US aiming for 2050, while others for later net-zero targets (e.g., China by 2060 and India by 2070).

In our new flagship study published in Nature Climate Change we show that, if fully implemented, these net-zero commitments could be enough to stabilise global warming to around 1.7-1.8°C within this century—which is in the vicinity of the “well below 2°C” Paris Agreement goal, even if 1.5°C would still remain out of reach. Although this does sound like relatively good news, our study also cautions that achieving net-zero pledges in decades from now would involve immediate decarbonisation efforts at unprecedented speed and scale.

In particular, we find that current ambition levels signalled through implemented policies are on track to increasing global temperatures to 2.1-2.4°C above pre-industrial levels by 2100, while ambition levels stated in present NDCs slightly limit this increase to 2.0-2.2°C, with warming in both cases projected to continue post-2100. Should countries additionally comply with their stated long-term goals, temperature increase could instead stabilise around 1.7-1.8°C. Considering the uncertainty in how emissions affect global temperatures, this translates to a 75% chance that global temperature increase stays below 2°C.

By performing deep dives into the largest economies, we furthermore assess individual countries’ ambitions. For example, the NDCs submitted by the USA and Japan are found ambitious in contrast to their policies in place that are found to lag behind. China, India, and Russia on the other hand display limited ambition in their 2030 goals. As a frontrunner in climate efforts, the EU is instead found to have ambitious policies already in place.

Although we explore different “optimal” pathways toward stated ambitions, each pathway would confront different hurdles and at different points of time. For instance, one route to net-zero could feature a significant challenge in ramping up diffusion of renewables to the required extent, while others would confront more barriers in terms of socioeconomic burdens or ramping up sustainable bioenergy supply and carbon capturing technologies. India and Japan are up against long-term bioenergy and carbon storage limitations in the long run, the US would find it hard to achieve the necessary energy consumption cuts in the next decades, while the EU should find ways to quickly power-boost the deployment of clean tech.

Despite the positive message that climate action seems to bear fruit, with climate policies having dramatically strengthened in the past few years, an alarming note is that—while we need to be less concerned about governments’ low long-term ambitions—we should nonetheless start worrying about empty promises.

The full journal article is publicly available here.

You may also read our commentary on the Conversation, a News & Views piece by Silvia Pianta and Elina Brutschin on Nature Climate Change, as well as a conversation between lead author Dirk-Jan van de Ven (Basque Centre for Climate Change) and climate reporter Zahra Hirji for Bloomberg.

All IAM COMPACT scientific publications are available on our website.

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