She has one of the toughest jobs in the world - and to add to the challenge, not everyone agrees that someone needs to do it.
Christiana Figueres, in charge of steering debate at the Durban climate summit which began on Monday, is remarkable for her ability to keep the faith without appearing over-optimistic.
Since taking over from flamboyant Dutch diplomat Yvo de Boer, who stepped down after talks in Copenhagen in 2009 collapsed in chaos, Figueres has quietly shifted the focus to the practical and achievable.
De Boer was outspoken and charismatic, charming the press with regular media updates and jokes about his big ears.
Elegant, yet steely, Figueres' difference in style has been reflected in her choice of imagery.
She opened her first summit as executive secretary of the United Nations Framework Convention on Climate Change last year in Cancun, Mexico, by invoking the ancient Jaguar goddess Ixchel - goddess of the moon, of reason, creativity and weaving.
May she inspire you, because today, you are gathered in Cancun to weave together the elements of a solid response to climate change, using both reason and creativity as your tools, she told the assembled delegates.
I am convinced that 20 years from now, we will admire the policy tapestry that you have woven together and think back fondly to Cancun and the inspiration of Ixchel.
Figueres' patient weaving is a complement to the work of the rest of her family.
Her father Jose Figueres Ferrer was president of Costa Rica three times and is considered the founder of modern democracy in the country.
Her brother Jose Maria Figueres was also president of Costa Rica and has been credited with getting the nation on the path to sustainable development. But he had to resign as head of the Geneva-based World Economic Forum after confirming he took consulting service fees from telecommunications firm Alcatel, although he said they had been legal.
POLITICS IN THE BLOOD
Having politics in the blood has helped to make Figueres a leader, say analysts in her native Costa Rica.
Christiana has that capacity for leadership inherited from her father, said Jorge Mora, director of the Costa Rica chapter of Latin American social science institute FLACSO.
She also has wisdom. In the face of climate change deniers and the international focus on short-term economic strife, Figueres has refrained from rash claims about how quickly progress can be made.
Shortly after her appointment, Figueres, who is in her mid-50s, told reporters she did not believe the problem of climate change would be solved in her life-time.
After the devastating blow of failing to agree a new deal in Copenhagen, virtually all involved in the process shifted the rhetoric to incremental progress pending an elusive global, legally binding treaty.
Cancun talks did not deliver a new accord to enforce action once the first Kyoto Protocol commitment period expires at the end of 2012 and almost no-one thinks that Durban can.
But Cancun achieved agreement on targets that were not adopted by consensus in Copenhagen.
Figueres worked effectively with Mexican Foreign Minister Patricia Espinosa to win a deal to set up a Green Climate Fund to channel aid to developing nations. Cancun also fixed a target of limiting global warming to below 2 degrees Celsius above pre-industrial times.
Some see Figueres as marking a return to bureaucracy. Others welcome her aptitude for the smaller steps as appropriate to our times.
Christiana Figueres is a strong character, a canny operator and an unusual combination of expertise gained from all sides of climate policy and the carbon market as well, said a prominent representative of the carbon trading market, one of the instruments created to combat climate change. He asked not to be named.
Figueres is also well-placed to heal the rift between developed and developing nations on the climate issue in contrast to De Boer, who was accused of deepening divisions by denouncing developed countries for doing too little.
As representative of Costa Rica, a developing nation that has set the ambitious goal of becoming carbon-neutral by 2021, Figueres quietly wins hearts and minds as she works the back-rooms and corridors of international debates.
Christiana has a warmth and an ability to understand where different delegations are coming from and that has made her beloved, said Annie Petsonk, who has been attending the climate treaty talks since the start.
She is warm and open and invites that in other people, said Petsonk, who is international counsel for U.S. environmental advocacy group the Environmental Defense Fund.
(Additional reporting by Alex Leff in San Jose, Alister Doyle in Boston and Jeff Coelho in London; Editing by Janet Lawrence)