I have just returned from spending an exhilarating and exhausting week in New York where I was one of the thirty-eight representatives from global civil society invited to attend the UN Climate Summit at the invitation of the Secretary General Ban Ki Moon. On Saturday I was invited to spend the afternoon in South Bronx with the South Bronx Unite community of people affected by Hurricane Sandy who are still struggling for environmental justice for the vulnerable communities. Their spirit of community was truly humbling and their music and street theatre was amazing. I was struck by how similar the struggles of the community of the South Bronx were to communities in Bangladesh. The same evening I was invited to speak to the Bangladeshi community in the Jackson Heights part of Queens at an event organised by the Bangladesh Environmental Network who are very active in the New York area.

The next day, Sunday, I joined the Peoples Climate March with the Bangladeshis under the BEN banner who were in turn part of the South Asian groups who were given the privilege by the March organisers of being up at the front of the march among the “Front Line Communities.” It was also nice to be joined by a number of alumni of the International Centre for Climate Change and Development who live in the New York area and who brought an ICCCAD banner to join the march.

It was by far the most exhilarating experience I have had as I marched with the South Asians from Bangladesh, India, Sri Lanka, Nepal, Pakistan and Bhutan who had come not just from New York but from across the USA, including California. We marched together to the fantastic rhythm of the contingent of Sikh drummers (indeed the drums are still ringing in my ears).

On Monday, as the heads of government and their official delegations started to arrive, I donned my suit and tie and went to brief some of the ministers and heads of delegation from the Least Developed Countries (LDC) including the ministers of Bangladesh, the Gambia, Nepal (who chair the LDC Group in the UNFCCC) and Benin (who chair the LDC Group in the SDG negotiations).

Finally, on Tuesday the official Climate Summit started in the United Nations General Assembly hall with an opening ceremony with speeches from the UN Secretary General Ban Ki Moon, the chair of the Intergovernmental Panel on Climate Change Dr. R.K. Pachauri, and the actor and newly appointed UN Special Envoy on climate change Leonardo Di Caprio. However, the entire assembly came to a standing ovation (something that rarely happens in that location) in response to a moving poem delivered by the poet Ms. Kathy Jetnil-Kijiner from the Marshall Islands to her newly born daughter (who also joined her on the podium at the end).

Then the heads of governments from over a hundred countries, including President Obama from the United States of America, Francois Hollande from France and many others, made their individual four-minute speeches each where they described what they were doing to combat climate change and what more they were prepared to do. Many of the heads of government echoed the demands for action from the Peoples Climate March from two days ago and some of them made some significant promises. Amongst the most important was the commitment from both the USA and China as the two biggest emitters of Greenhouse Gases to take ambitious actions, as well as a pledge from France to provide $1 billion towards tackling climate change in developing countries.

From my perspective, I was very pleased to see the heads of government from the LDCs, including Bangladesh, Nepal, Ethiopia, the Gambia, Benin and many others, stress the fact that the LDCs, while the most vulnerable and poorest countries are actually leading the world on tackling climate change impacts at home in every country. Thus changing the narrative of the LDCs from passive victims to proactive leaders for actions to tackle climate change.

After the heads of government had given their speeches a number of civil society groups and business leaders also made pledges for actions to tackle climate change. Then there were a number of parallel sessions on different themes, including science, energy, forestry, agriculture, transport, finance and voices from front line vulnerable communities. I attended the sessions on science and voices from the frontline communities.

As I took a taxi to the airport to catch my flight out of JFK airport, I started talking to the taxi driver, Shafiq, who turned out to be from Dhaka, Bangladesh and had been in been living in Jackson Heights neighbourhood of New York for eight years. He told me about his experiences during hurricane Sandy and how the experiences were so similar between Bangladesh and New York in dealing with natural disasters like hurricanes and cyclones.

On reflection, I have three main impressions from the past week in New York.

Firstly, that the citizens from all over the world, with demonstrations in over two hundred cities around the would and with over 300,000 in New York, it was a truly global coming together on the need to take climate change seriously. I was also struck by the similarities between people from both rich and poor countries.

Secondly, the heads of government who gave speeches at the official Climate Summit all recognised this demand for positive actions and responded, at least rhetorically. They will need to channel their rhetoric into the climate change negotiations under the UNFCCC where countries will meet in Lima, Peru in December this year and prepare a new global treaty in Pairs, France, in December 2015.

Thirdly the momentum for the global investment community to start the ball rolling on divestment from fossil fuel based companies and invest in clean energy companies has started to roll and will gain momentum in time.

So I think that we may have achieved a turning point this week in New York an around the world in accepting the magnitude of the climate change problem and also how to link bottom up efforts from all citizens with top down decisions by heads of government. The proof of the pudding will be seen in Paris in December 2015.

The writer is Senior Fellow at the London based International Institute for Environment and development (www.iied.org) and Director of the International Centre for Climate Change and Development (www.icccad.net) in Bangladesh.