The UN climate bus is traveling to Baku, Azerbaijan, for the COP29 UN climate conference, which begins on November 11. With global temperatures soaring almost 1.5°C warmer than pre-industrial levelsThe big question hanging over Baku is whether rising temperatures will prompt the international community to take more urgent action to mitigate global warming and combat its effects. This COP is called the “Finance COP” because a large increase in funding is a major agenda item.

Meaningful action on global warming requires much more money than is currently available. But country representatives will travel to Baku, finding themselves deadlocked over who should pay and how much. One of the biggest questions is: what exactly should climate finance include? One action in particular could make a big difference: climate diplomats could formally request that the Intergovernmental Panel on Climate Change (IPCC) release a special report on climate finance. They must do this before binding decisions are made.

Why the timing of climate assessments matters

Next year, countries will need to update their climate action plans (called Nationally determined contributionsor NDC), so that their ambition matches what is needed to prevent temperatures from reaching dangerous levels. Currently, some of the most common actions include installing more solar and wind power plants and protecting forests and other ecosystems.

But the speed and scale of these developments pale in comparison to what researchers say is needed to keep the average global temperature rise from exceeding the 1.5°C target set during the COP21 in Paris in 2015. Even if all current NDCs are met, the world is still looking at a rise in temperatures of 2.1 to 2.8°C above pre-industrial levels by 2100. In a scenario in which warming is kept below 1.5°C, greenhouse gas emissions are expected to be 43% lower than 2019 levels by 2030, according to the IPCC.

Achieving the above presupposes that extremely large sums of money can be found to cover the costs of the transition to sustainability. Low- and middle-income countries (LMICs) will need to increase their annual investments to around US$2.4 trillion by 2030, according to a widely cited report from an international group of climate finance researchers released for COP28. last year (see go.nature.com/4fgwt1i). This represents around 20 times the climate finance ($116 billion) allocated to LMICs in 2022, according to data from the Organization for Economic Co-operation and Development (OECD). published in May.

But there is no consensus on these figures, nor on other issues. Who will pay the additional amounts and when? How much should grants versus loans be? How much should be spent on climate change mitigation, for example by funding technologies that help prevent global warming? How much for adaptation measures such as flood defences? Climate negotiators have been meeting all year ahead of COP29, but there is little agreement on what is called a new collective quantified objective on climate financing.

Biases in “sustainable finance” indicators could hinder the provision of loans to those who need them most

High-income countries want LMICs to take more responsibility for climate finance, while LMICs want the opposite – to receive a greater share of grants rather than loans – to reflect the fact that some of the most vulnerable are those who are least responsible for climate finance. climate change.

Matters are made worse by the lack of an agreed definition of the building blocks of climate finance – something recognized in Chapter 15 of the IPCC Sixth Assessment Report on climate finance (see go.nature.com/4el1luq). Some argue that climate finance should not include funding for projects that, strictly speaking, are not solely about climate change. For example, if money is used to finance a housing estate powered by renewable energy, there is no consensus on how much of the total cost should be classified as climate finance. Too high a figure risks overestimating the amount of money classified as climate finance.

This is why Nature suggests that the IPCC be called upon to give its opinion. This is the organization that everyone should trust to build an evidence base to answer questions that struggle to find consensus. A group of countries is expected to make a specific request to the IPCC secretariat, based in Geneva, Switzerland, for a special report on climate finance. The IPCC would then launch a call for evidence. This would encourage funders and researchers to come together, commission and conduct research that would be included in the special report.

Return on investment

The IPCC has already played such a role at key moments in climate policy development. A special IPCC report was requested after the Paris climate agreement to assess the evidence on the impacts of 1.5°C versus 2°C warming, as well as the range of proposed trajectories to reach 1. 5°C (JE Livingston and M. Rummukainen Approximately. Sci. & Policy. 11210-16; 2020). This is a proven way to provide the international community with the knowledge and data needed to make sound decisions. It took approximately two years from commissioning the report to its publication, so countries should apply as soon as possible.

Climate finance is no small matter: even $2.4 trillion represents Italy’s gross domestic product. But ultimately, these sums must be seen as investments that will pay off, rather than as a cost. It is understandable that there is a diversity of views, and the IPCC is not the body responsible for deciding to what extent this is feasible and under what conditions: responsibility for these decisions lies with country representatives. But the IPCC can help negotiators by helping them answer their questions based on the most recent literature – while also updating that literature.

Amid all these arguments, no one can doubt that a radical change in climate finance will be necessary if rising temperatures are to be kept within safe limits. The IPCC cannot decide, but it can advise. Countries should waste no time asking him for this.