Diplomats, activists, scientists and many other environmentalists descended on Lima this week to continue the long, tortuous process of working out how to deal with one of the biggest problems faced by humanity: climate change.
Part of the annual United Nations Framework Convention on Climate Change (UNFCC) meetings known as the Conference of the Parties (COP), the meeting in Lima is the 20th year when officials from almost 200 countries will come together.
In an important sense, this meeting is a pre-show for the COP21 in Paris in December 2015, which many observers see as the final opportunity for world leaders to agree on a global treaty for climate action that could replace the Kyoto Protocol, which expired in 2012.
In order for the COP21 in Paris to fulfill its potential and get the world to agree to sufficient greenhouse gas cuts, the negotiators and heads of state there will need a draft text from which to start their discussions. Producing this draft will be one of the main targets for the Lima meeting.
There have already been significant sets of meetings and announcements on climate change this year - Ban Ki-moon convened a day-long conference of heads of state (and a few Hollywood celebrities) in New York in September to begin the momentum to Paris next year.
And the thousands of climate researchers on the Intergovernmental Panel on Climate Change released their carefully-considered scientific review of the latest evidence showing how climate change was not only real, but also that humans were causing it.
But these moves were all outside the official UNFCC climate-negotiation process, which is the main forum for countries to agree to action. While other meetings are important to signal moves and test ideas, the COPs form the basis of international treaties.
According to many observers, there is a “rising optimism” that the years of standoffs and prevarication is starting to give way to real action on climate change. “I have never felt as optimistic as I have now,” Tony de Brum, the foreign minister of the Marshall Islands, which are sinking as the waters of the Pacific rise around it, told The Guardian:
Some of the optimism is down to the bilateral deal announced by the US and China in November, in which China proposed to cap its output of carbon by 2030 and to increase its use of clean, carbon-free energy to 20 per cent by 2030.
In turn, the US agreed to cut emissions by around 26 per cent from 2005 levels by 2025.
Before that, the European Union had already agreed to cut its emissions by 40 per cent, compared to 1990 levels, by 2030.
Not everyone thinks these moves are enough on their own to curb dangerous climate change, which is defined as an average global temperature rise by more than 2C by the end of the century. Anything more than this is expected to lead to increased storms, droughts, rising sea levels and melting of ice at the polar ice cap, all catastrophic effects for the lives of humans as well as plants and animals.
On the table in Lima is how the hundreds of countries might be able to agree a framework for their overall cuts in greenhouse gas emissions - some want them to be legally binding, others would prefer more voluntary targets.
Also under examination will be who should shoulder most of the burden - less-developed countries will lobby hard for exemptions in order to grow their economies or they will (rightfully) want cash from the richer countries (who have historically caused most of the climate change problem) in order to pay for their own low-carbon development.
Part of that latter agenda will be felt in negotiators trying increase pledges to the Green Climate Fund, the UN’s attempt to fairly re-distribute money from richer to poorer countries, which are already at the sharp end of the problems associated with a changing climate and least capable of paying their way out of it. So far, the fun has a budget of £6bn, well short of its $10bn annual target.
Between now and COP21 in Paris, there will be many further key meetings and announcements. March 2015 is particularly important, as it is the deadline for countries to announce their Intended Nationally-Determined Contributions, in which all members of the COP have to reveal their proposed greenhouse gas cuts for the future.
Tasneem Essop, WWF’s head of delegation to the UNFCC, has called the meeting in Lima a “litmus test for political will for urgent action on climate, and specifically for an ambitious and equitable global agreement on climate change.”
All eyes will be on what comes out of the huddle of negotiators at the end of next week. If they produce a viable draft text that has the potential to be shaped into an agreement over the next year, it will no doubt bolster the growing mood of cautious optimism on climate action.
If the parties fall out in public, as they did so spectacularly in the much-hyped Copenhagen COP15 in 2009, it might spell disaster for Paris 2015 and, more importantly, the health of our planet.