Zen master Thich Nhat Hanh, one of the world's leading spiritual teachers, is a man at great peace even as he predicts the possible collapse of civilisation within 100 years as a result of runaway climate change.

The 86-year-old Vietnamese monk, who has hundreds of thousands of followers around the world, believes the reason most people are not responding to the threat of global warming, despite overwhelming scientific evidence, is that they are unable to save themselves from their own personal suffering, never mind worry about the plight of Mother Earth.

Thay, as he is known, says it is possible to be at peace if you pierce through our false reality, which is based on the idea of life and death, to touch the ultimate dimension in Buddhist thinking, in which energy cannot be created or destroyed.

By recognising the inter-connectedness of all life, we can move beyond the idea that we are separate selves and expand our compassion and love in such a way that we take action to protect the Earth.

Look beyond fear

In Thay's new book, Fear, he writes about how people spend much of their lives worrying about getting ill, ageing and losing the things they treasure most, despite the obvious fact that one day they will have to let them all go.

When we understand that we are more than our physical bodies, that we didn't come from nothingness and will not disappear into nothingness, we are liberated from fear, he says; fearlessness is not only possible but the ultimate joy.

"Our perception of time may help," Thay told me in his modest home in Plum Village monastery near Bordeaux. "For us it is very alarming and urgent, but for Mother Earth, if she suffers she knows she has the power to heal herself even if it takes 100m years. We think our time on earth is only 100 years, which is why we are impatient. The collective karma and ignorance of our race, the collective anger and violence will lead to our destruction and we have to learn to accept that.

"And maybe Mother Earth will produce a great being sometime in the next decade ... We don't know and we cannot predict. Mother Earth is very talented. She has produced Buddhas, bodhisattvas, great beings.

"So take refuge in Mother Earth and surrender to her and ask her to heal us, to help us. And we have to accept that the worst can happen; that most of us will die as a species and many other species will die also and Mother Earth will be capable after maybe a few million years to bring us out again and this time wiser."

Confront the truth

Thay suggests that our search for fame, wealth, power and sexual gratification provides the perfect refuge for people to hide from the truth about the many challenges facing the world. Worse still, our addiction to material goods and a hectic lifestyle provides only a temporary plaster for gaping emotional and spiritual wounds, which only drives greater loneliness and unhappiness.

Thay, who has just celebrated the 70th anniversary of his ordination, reflects on the lack of action over the destruction of ecosystems and the rapid rate of biodiversity loss: "When they see the truth it is too late to act ... but they don't want to wake up because it may make them suffer. They cannot confront the truth. It is not that they don't know what is going to happen. They just don't want to think about it.

"They want to get busy in order to forget. We should not talk in terms of what they should do, what they should not do, for the sake of the future. We should talk to them in such a way that touches their hearts, that helps them to engage on the path that will bring them true happiness; the path of love and understanding, the courage to let go. When they have tasted a little bit of peace and love, they may wake up."

Thay created the Engaged Buddhism movement, which promotes the individual's active role in creating change, and his mindfulness training – an ethical roadmap – calls on practitioners to boycott products that damage the environment and to confront social injustice.

Given the difficulty of convincing those with vested interests to change their behaviour, Thay says a grassroots movement is necessary, citing the tactics used by Gandhi, but insists that this can be effective only if activists first deal with their own anger and fears, rather than projecting them onto those they see at fault.

Awakened consumers can influence how companies act

On companies that produce harmful products, he says: "They should not continue to produce these things. We don't need them. We need other kinds of products that help us to be healthier. If there is awakening in the ranks of consumers, then the producer will have to change. We can force him to change by not buying.

"Gandhi was capable of urging his people to boycott a number of things. He knew how to take care of himself during non-violent operations. He knew how to preserve energy because the struggle is long, so spiritual practice is very much needed in an attempt to help change society."

Thay, the author of more than 100 books, including the best-selling Miracle of Mindfulness, says that while it is difficult for those holding the strings of power to speak out against the destructive nature of the current economic system, for fear of being ostracised and ridiculed, we do need more leaders to have the courage to challenge the status quo.

For business and political leaders to do that, they need to cultivate compassion in order to embrace and diminish the ego, Thay says.

"You have the courage to do it [speak out] because you have compassion, because compassion is a powerful energy," he says. "With compassion you can die for other people, like the mother who can die for her child. You have the courage to say it because you are not afraid of losing anything, because you know that understanding and love is the foundation of happiness. But if you have fear of losing your status, your position, you will not have the courage to do it."

A moment of contemplation

While many people are becoming disorientated by the complexity of their lives and by the overwhelming array of choices offered by our consumer society, Thay's retreats offer a profoundly simple alternative.

Over Plum Village's three-month winter retreat, Thay repeatedly instructs the hundreds of monks, nuns and lay practitioners about switching off the non-stop noise in their heads and focusing on the core of mindfulness; the joy of breathing, of walking, of contemplation in the present moment.

Rather than searching for answers to life in the study of philosophy, or seeking adrenaline charged peak experiences, Thay suggests that true happiness can be found by touching the sacred in the very ordinary experiences of life, which we largely overlook.

How often do we fully appreciate, for example, how hard our hearts work day and night to keep us alive? He suggests it is possible to discover profound truths through concentrating on something as basic as eating a carrot, as you get the insight that the vegetable cannot exist without the support of the entire universe.

"If you truly get in touch with a piece of carrot, you get in touch with the soil, the rain, the sunshine," he says. "You get in touch with Mother Earth and eating in such a way, you feel in touch with true life, your roots, and that is meditation. If we chew every morsel of our food in that way we become grateful and when you are grateful, you are happy."

Despite meditating every day for the past seven decades, Thay believes there is still much to learn. "In Buddhism we speak of love as something limitless," he says. "The four elements of love which are loving kindness, compassion, joy and equanimity, have no frontiers.

"Buddha is thinking like that. His followers call him the perfect one but that is out of love, for the truth is you can never be perfect. But we don't need to be perfect. That is a good thing to know. If you make a little bit of progress every day, a little bit more joy and peace, that is good enough so Thay continues to practice and his insight grows deeper every day.

"There is no limit of the practice. And I think that is true of the human race. We can continue to learn generation after generation and now is time to begin to learn how to love in a non-discriminatory way because we are intelligent enough, but we are not loving enough as a species."

Thich Nhat Hanh: a life lived away from the public eye

Thay is often compared to the Dalai Lama but has largely escaped the public's gaze, deciding to live the life of a simple monk. He has avoided the trap of being surrounded by celebrities and will give interviews only to journalists who have spent time beforehand meditating with him on the basis that mindfulness needs to be experienced, rather than described.

But Thay is no wallflower and has led an extraordinary life, including a nomination for the Nobel peace prize from Martin Luther King in 1967 for his work in seeking an end to the Vietnam war. In his nomination King said: "I do not personally know of anyone more worthy of [this prize] than this gentle monk from Vietnam. His ideas for peace, if applied, would build a monument to ecumenism, to world brotherhood, to humanity".

Thay set up Plum Village 30 years ago after being exiled from his home country and has since added monasteries in Thailand, Hong Kong and the US, as well as an applied Buddhist institute in Germany. He has continued to work for peaceful solutions to conflicts around the world, including holding several retreats for Israelis and Palestinians.

In 2009 he faced conflict in his own life, when the Vietnamese authorities closed down his recently opened monastery at Bhat Nha after a campaign of harassment and violence. Thay believes the action, which sparked an outcry from the EU and other countries, was orchestrated by the Chinese following his public support for Tibet. The 400 monks and nuns were dispersed but still operate quietly within the country.

The Guardian's release of US embassy cables highlighted concern about the crackdown. One confidential cable said: "Vietnam's poor handling of the situations at the Plum Village community at the Bat Nha Pagoda and the Dong Chiem Catholic parish last week – particularly the excessive use of violence – is troublesome and indicative of a larger GVN crackdown on human rights in the run-up to the January 2011 Party Congress"

Despite all his achievements, including a recent stint as guest editor at the Times of India, Thay is modest when he looks back at his life.

"There is not much we have achieved except some peace, some contentment inside. It is already a lot," he says. "The happiest moments are when we sit down and we feel the presence of our brothers and sisters, lay and monastic, who are practicising walking and sitting mediation. That is the main achievement and other things like publishing books and setting up institutions like in Germany, they are not important.

"It is important we have a sangha [community] and the insight came that the Buddha of our time may not be an individual but it might be a sangha. If every day you practice walking and sitting meditation and generate the energy of mindfulness and concentration and peace, you are a cell in the body of the new Buddha. This is not a dream but is possible today and tomorrow. The Buddha is not something far away but in the here and in the now."

While Thay is still in good health and sharp as a pin, he is not getting any younger and may soon begin to start pulling back from the strenuous schedule that has seen him repeatedly criss-crossing the world, leading retreats and passing on his teachings. This year he travels across the US and Asia – perhaps his last major foreign trip.

Given his belief in no birth and no death, how does he feel about his own passing?

"It is very clear that Thay will not die but will continue in other people," he says. "So there is nothing lost and we are happy because we are able to help the Buddha to renew his teaching. He is deeply misunderstood by many people so we try to make the teaching available and simple enough so that all people can make good use of that teaching and practice."

As he lifts a glass of tea to drink, he adds: "I have died already many times and you die every moment and you are reborn in every moment so that is the way we train ourselves. It is like the tea. When you pour the hot water in the tea, you drink it for the first time, and then you pour again some hot water and you drink, and after that the tea leaves are there in the pot but the flavour has gone into the tea and if you say they die it is not correct because they continue to live on in the tea, so this body is just a residue.

"It still can provide some tea flavour but one day there will be no tea flavour left and that is not death. And even the tea leaves, you can put them in the flower pot and they continue to serve so we have to look at birth and death like that. So when I see young monastics and lay people practicing, I see that is the continuation of the Buddha, my continuation."

Prompted by a letter that informed him that someone has built a temple in Hanoi to commemorate his life, Thay recently sent a letter to the Tu Hieu temple in central Vietnam, where he trained as a novice monk, making it clear he does not want a shrine built in his honour when he dies: "I said don't waste the land of the temple in order to build me a stupha. Do not put me in a small pot and put me in there. I don't want to continue like that. It is better to put the ash outside to help the trees to grow. That is a meditation."

He adds: "I recommend that they make the inscription outside on the front 'I am not in here'. And then if people do not understand, you add a second sentence 'I am not out there either' and if still they don't understand on the third and the last; 'I may be found maybe in your way of breathing or walking.'"

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