On September 23 at the U.N. Climate Summit 2026, Secretary-General Antonio Guterres renewed calls for climate finance to reach $1.3 trillion annually by 2035, arguing that leadership must come from G20 members, which account for roughly 80% of global emissions.
A day later, four climate-finance leaders took up a practical question at the Climate Week panel "Who Writes the Trillion-Dollar Check?"
"If we wrote it, it would bounce," said Colin le Duc, founding partner of Generation Investment Management.
"We don't have a trillion dollars ourselves," he continued. "But we can certainly help influence that capital reallocation, which is the fundamental challenge of sustainability."
Le Duc joined Mindy Lubber, president and CEO of Ceres; Nigel Topping, co-founder, Ambition Loop; and Kyung-Ah Park, head of ESG investment management and managing director of sustainability at Temasek, for a discussion that touched on both risks and opportunities that climate change presents for investors, looking at where capital might come from and where it should go.
For financial advisors, the conversation shed light on how climate now belongs in a client's portfolio as it becomes less of a thematic bet and more of a systemic risk that touches all of their holdings.
Here are four themes that emerged from the talk:
From climate risk to climate opportunity
In recent years, sustainable investing has focused heavily on measuring and managing climate risk. Over time, however, investors have made meaningful progress in understanding that risk.
The resulting shift, according to Lubber, is that "it really is now about the opportunity side."
In analyzing recent conversations with 25 of the world's largest asset owners, Lubber said, "They're all doing it in different ways … but some of the common denominators are: We've got to take this investment straight from some special unique pitch to investing."
Ceres is a nonprofit that works with investors and companies on climate and other sustainability issues. Lubber, who serves as a bridge between greenery and the greenback, said investors need to make money, while asset allocators and owners have an obligation to their pensioners.
That means moving sustainable investing "out of some little niche within an investment house into how to work at everything," she said. "Because as our markets change, as we see the climatic changes, impact real estate, and in fact, everything in our lives, it's not going to be isolated to one little environmental fund. Integration is key."
Rethinking capital allocation
According to le Duc, in 2025, roughly $2.2 trillion flowed into clean energy, compared with about $1 trillion invested in fossil-fuel related "dirty energy."
"We're actually doing pretty well in terms of finance flows," he said. "The problem is that finance flows need to both go up and scale, but also they need to go to the right things."
Much of today's climate and sustainable finance is directed toward de-risked technologies in safe geographies, he said. While those investments remain important, le Duc argued they do not always address the sectors and regions where emissions reductions and climate adaptation are most needed.
To solve that mismatch, le Duc said financial mandates should better reflect where decarbonization opportunity actually lies — namely, in hard-to-abate sectors and geographies.
"We can design a beautiful investment strategy to do both of those things. But if none of our clients basically want to follow us, then that's a bit of a waste of time," he said, adding that greenwashing still prevails and that "a lot of the smartest asset owners in the world really understand the need."
Much of the conversation has also shifted away from sustainable alpha — how money can be made from sustainable investing — toward how sustainable investing strengthens beta, or the stability of the market, according to le Duc.
"There's this double return," he said.
Trillions start with millions
Topping, a former U.N. high-level climate champion and current chair of the UK Climate Change Committee, co-founded the Santiago, Chile-based nonprofit Ambition Loop, which is centered around action for nature and climate issues.
He emphasized the need for a trees-rather-than-forest mindset when it comes to "this obsession with the trillion dollars." Trillions typically arrive only after a sector or technology has matured, he said, pointing to solar and electric vehicles as examples.
"There are others, like the industrial decarbonization technologies, cement or steel, which are not at that mature stage yet," he said.
While interest is there, the money hasn't caught up because perceived risk remains too high for less mature technologies, according to Topping. Early-stage deals need financiers working alongside developers and governments to solve those issues, but "you never get to the trillion unless you go to the 10s and then 100s."
A two-speed transition and the cost of capital
Earlier in this decade, Singapore-headquartered Temasek, a global investment company, made a net-zero pledge with a 2050 target. Its interim goal included cutting portfolio emissions in half. So far, the first 30% of that cut has been successfully executed, but the coming 20% will be harder to complete, according to Park.
The "heavier lift," said Park, is decarbonizing portfolios.
"We are in a bit of a two-speed transition," she said. "On the one hand renewable energy [and] storage are actually scaling. We're being very clear where we need to head, but how we're doing it has become defined. In light of the fact that there is more geopolitical fragmentation, policy volatility, there's a lot more mind-share going towards, obviously, AI and energy security and affordability."
One of the most fundamental changes, according to Park, is the cost of capital, which has become much more expensive.
"Many other solutions that we need to be able to invest at scale, have significant upfront capex and long-term payback," Park said. "So that makes it actually quite challenging in terms of deploying capital."
