Climate / Operator / CEO
Hana Kajimura
She put a carbon number on the side of a sneaker, then handed the formula to her competitors. The whole point was for them to copy it.
She put a carbon number on the side of a sneaker, then handed the formula to her competitors. The whole point was for them to copy it.
On the side of an Allbirds shoe there is a number, printed like a calorie count on a cereal box. It tells you, in kilograms, what that shoe cost the atmosphere. Hana Kajimura is the reason it is there - and she did not keep the method to herself. She published the entire carbon-accounting toolkit, free, label templates included, so any fashion brand on earth could do the same arithmetic and print the same uncomfortable truth on its own products.
Today she runs Trellis Group, the media-and-events company behind GreenBiz, Circularity and Trellis Impact - the largest gathering of sustainability professionals in North America. It is a strange promotion for someone who spent five and a half years counting carbon shoe by shoe. She used to be the practitioner sweating the soil-science footnotes. Now she runs the room those practitioners fill.
The throughline is a bet she made young: that companies, not committees, move fast. She picked the private sector on purpose. While her peers headed to nonprofits and ministries, she went to a footwear startup and a corporate-partnerships internship, convinced that a balance sheet could turn an idea into a shipped product faster than a policy paper ever could.
What she names as her own best quality is not technical. It is social. "The ability to bring many different types of stakeholders along," she says - which is a polite way of describing the unglamorous craft of getting a CFO, a supply-chain lead, a designer and a wool farmer to agree on the same number. Sustainability work fails less often on the science than on the people, and she built a career on the second problem.
Businesses can move much more swiftly than nonprofits or government.
Hana Kajimura, on why she chose corporate sustainabilityShe arrived at college expecting to be a liberal-arts major. Then she went to Cape Town.
Studying abroad, she worked in a township urban garden alongside six women in their eighties. Watching how directly their livelihood was tied to the land - how a bad season was not an abstraction but a meal - rearranged her plans. She came home and switched to environmental science. The lecture hall did not make her an environmentalist. A vegetable plot did.
That instinct - that climate is a thing happening to specific people in specific places, not a chart - never left. Years later it would show up as a fixation on regenerative agriculture, on indigenous knowledge, and on making sure people of color had real representation in a field that too often forgets to invite them.
It also gave her a particular message for the women who follow her into the field. She thinks they compromise too readily, settling for the commitment a company finds comfortable rather than the one the planet needs. Her advice is blunt: demand more. Ambition, in her telling, is not impolite. It is the job.
In 2021 she authored the Allbirds "Flight Plan" - a public, dated commitment to halve the per-product carbon footprint by 2025 and push it toward near-zero by 2030. The bars below sketch the trajectory she set, from a neutral baseline to a sub-kilogram target.
Every Allbirds product carries its exact carbon footprint, modeled on a nutrition label. Her argument: you cannot fight what you refuse to measure in public.
She published Allbirds' footprint methodology, calculation tools and pre-formatted labels for free download - so competitors could replicate it. Standardization beats secrecy.
A push for 100% regenerative-source wool, less raw material per shoe, and renewable energy at owned facilities - soil science turned into procurement policy.
GreenBiz, Circularity, Trellis Impact - the conferences where the sustainability field actually meets. She moved from doing the work to gathering the people who do it.
Trellis offset thousands of tonnes through high-integrity projects and committed to mitigating half the emissions of its three largest 2025 conferences.
She has written about sustainability leaders being exhausted by AI and intensely curious about it at once - unwilling to dismiss a tool this loud.
Most corporate climate strategy is built to be admired from a safe distance - a glossy report, a pledge with a date far enough away that nobody present will be held to it. Kajimura's instinct ran the opposite direction. She wanted the number on the product, where a customer could see it before buying, and she wanted the formula behind that number to be auditable by strangers.
That is the through-logic of the open-source toolkit. If only Allbirds printed its footprint, the label was marketing. If every brand could print one using the same method, the label became a standard - and a standard is the thing greenwashing cannot survive. Giving the math away was not generosity. It was a strategy to make transparency unavoidable for everyone, including the people she competed with.
The materials work followed the same discipline: a set of dated, quantitative commitments rather than vibes. Wool from regenerative sources. Less raw material per shoe. Renewable energy at owned facilities. Even consumer education on lower-impact ways to clean footwear - because the footprint does not end at the cash register. Each is a number someone can check.
Running a conference company is a curious place to land for someone obsessed with measurable footprints - events fly people in from everywhere. So Trellis made its own commitments. It partnered to mitigate half the emissions of its three largest 2025 gatherings, GreenBiz, Circularity and Trellis Impact, and offset thousands of tonnes through high-integrity projects spanning landfill-gas capture, peatland conservation and improved forest management.
It is the same move she made at Allbirds, scaled to a different stage: do not just tell the field to act, show your own ledger first. The room she now runs is the one where sustainability professionals compare notes, argue, and occasionally admit they are exhausted - by burnout, by the slow grind of corporate buy-in, and lately by the noise of AI. She has written about that last one honestly: tired of it, curious about it, unwilling to pretend it is not in the room.
She guards her own stamina deliberately, too. There is a weekly support group of people doing the same hard job, and there is the ocean, which she returns to when the work threatens to flatten into spreadsheets. It is a small, telling habit for someone whose entire career has been about keeping the human stakes of climate in view - the woman in the garden, the customer reading a label, the colleague one bad quarter from quitting. The number on the shoe was never really about the shoe.
The lists found her before the title did. GreenBiz - now Trellis itself - named her to its 30 Under 30 in 2020, a roll call of the people the sustainability field expected to matter. A year later the Glossy 50 put her among the most consequential figures in fashion, an industry that spent a long time treating sustainability as a press release and slowly learned otherwise. The recognition tracked a simple fact: she kept shipping things other companies could only announce. There is a tidy symmetry in the arc, too. She started as an intern in the Environmental Defense Fund's corporate-partnerships program, learning how a company and a cause talk to each other. She is now the person convening the entire conversation.
Named to the field's marquee early-career list - by the organization she would one day run.
Recognized among the most influential people reshaping fashion, sustainability column.
An internship in corporate partnerships planted the thesis: business and cause, in the same room.
This year, I was proud to introduce our Flight Plan to cut our per-unit carbon footprint in half by the end of 2025.
My greatest strength is the ability to bring many different types of stakeholders along.
Women often compromise too readily - we need to demand more from companies.
Businesses can move much more swiftly than nonprofits or government.