The last two years have been a roller coaster ride in respect to securing a new global treaty to combat climate change. Some even despair that the window for action is closing fast.

But giving up is not an option. The latest round of climate negotiations, held last month in Cancún, Mexico, put the world's efforts on climate change back on track - albeit at a pace and on a scale that will undoubtedly leave many onlookers frustrated.

President Felipe Calderón's government in Mexico and the Executive Secretary of the United Nations Framework Convention deserve credit for gains in a range of important areas, including forestry, a new Green Fund to assist developing nations, and the anchoring of the emission-reduction pledges made at the December 2009 climate change conference in Copenhagen.

But, as the UN Environment Program and climate modelers made clear in the run-up to the Cancún meeting, a significant emissions gap exists between what is being promised by countries and what is needed to keep the rise in global temperature below two degrees Celsius, let alone move towards the 1.5-degree threshold needed to protect low-lying island states.

Despite some gains, that gap - which, under the most optimistic scenario, amounts to the combined emissions of all the world's cars, buses, and trucks - remains firmly in place post-Cancún. Indeed, no one should underestimate the magnitude of the challenge now facing South Africa, the host of next year's talks, in terms of midwifing a new legally binding agreement to bridge this gap and securing the finance needed to bring the Green Fund into operation.

Yet, while the official summit in Cancn struggled to a conclusion, an unofficial one being held a few minutes away also concluded. This parallel summit brought together progressive heads of state, regional and local government, business, and civil society, and underscored just how far and how fast some sectors of society will make the transition to a low-carbon future and build the green and clean-tech economies of the twenty-first century.