The 81-page report was released by the heads of last year's COP29 conference in Azerbaijan and the upcoming COP30 gathering in Belem, Brazil, as leaders prepare to meet in the Amazonian city this week.

"This Roadmap aims to contribute as catalyst and foundation for the next phase of climate action," COP29 president Mukhtar Babayev and COP30 head Andre Correa do Lago said in the paper's foreword.

"It reminds us that the resources exist, the tools are ready, and the time is now," they said.

The COP29 gathering in Baku ended with developed nations agreeing to provide $300 billion annually in climate finance to poorer countries by 2035, a figure criticised as way below what is needed to meet the challenge.

They also set a much less specific target of helping raise $1.3 trillion annually from public and private sources.

The "Baku to Belem Roadmap" aims to turn that vague target into concrete proposals, at a time when rich nations face their own budget constraints, rising debt, tariff battles and conflicts abroad.

"We are aware that this journey begins in turbulent times, with scarce financial resources and difficult budgetary trade-offs," Babayev and Correa do Lago said.

Developing nations will be demanding more details during COP30 in Belem, where leaders will meet on Thursday and Friday before the two-week conference formally begins on Monday.

"The task is ambitious, but achievable. The tools exist; what's been missing is coordination and shared commitment," said UN climate chief Simon Stiell.

But climate campaigner Harjeet Singh, founding director of Satat Sampada Climate Foundation, said the roadmap was "like offering a band-aid for a mortal wound and fundamentally fails to prescribe the cure".

Here are some of the report's proposals for the public and private sectors, inspired by nearly 230 recommendations from NGOs, researchers and the financial sector, some of which have already been debated for several years:

- Development banks -

Multilateral development banks (MDBs) -- such as the African Development Bank or the Asian Development Bank -- will have a "central role" to play in achieving the ambitious target, mainly by improving the financial systems that would allow them to lend more, the report said.

The report called for closer coordination among those banks, multilateral climate funds and the philanthropic sector to free up additional financing capacity.

- International Monetary Fund -

The report recalls that the IMF, whose mission includes reducing poverty, has at its disposal Special Drawing Rights (SDRs) -- a reserve asset it can issue and make available to vulnerable countries.

When the IMF issues SDRs, it normally distributes them in proportion to each member's shareholding -- meaning most go to wealthy countries.

But governments can pledge to redirect them to poorer nations and channel them toward fighting climate change, potentially freeing up between $100 billion and $500 billion a year, according to the report's estimates.

- Central banks -

Central banks and financial regulators do not usually come to mind when it comes to helping developing countries cope with climate change, but the roadmap said they "can also play their part".

It said they can, for instance, simplify rules to facilitate financing for the climate fight.

- Tax hikes -

The report lists some tax measures that could be undertaken.

Wealth taxes could bring in anywhere between $200 billion and $1.36 trillion, "depending on the rate applied at different income thresholds".

Convincing countries would be a tall task: G20 talks led by Brazil to create a global tax on billionaires already failed in 2024.

Aviation and maritime transport fees could generate between $4 billion and $223 billion, but the United States has rejected the latter.

A tax on financial transactions could rake in between $105 billion and $327 billion.

- Debt relief -

The roadmap stresses the need to ease the debt burden of countries facing the double blow of high capital costs and heavy spending caused by climate disasters.

Debt payments could be paused more often countries are hit by weather disasters.

The report also suggests debt-reduction programs tied to financing environmentally-friendly projects.