Greenpeace activists met in Copenhagen today to show the way forward for renewables. Courtesy of Greenpeace, 2014

In the most comprehensive, authoritative and scrutinised assessment of climate change ever produced, the Intergovernmental Panel on Climate Change (IPCC) has offered its starkest warning yet about the challenges facing humanity.
Not only does the IPCC show that climate change is real and that its impacts are happening faster than ever, but for the first time it lays out the true extent of human influence on the climate system.
While previous estimates say human activity – primarily the burning of fossil fuels – is responsible for more than half of all warming, the latest report shows we are actually responsible for all warming since 1951.
R. K. Pachauri, Chair of the IPCC said:

The scientific case for prioritizing action on climate change is clearer than ever. We have little time before the window of opportunity to stay within 2ºC of warming closes. To keep a good chance of staying below 2ºC, and at manageable costs, our emissions should drop by 40 to 70 percent globally between 2010 and 2050, falling to zero or below by 2100. We have that opportunity, and the choice is in our hands.

But the main takeaway for decision makers is this: governments can no longer just be talking about emissions reductions, they need to work towards a complete phase out out of fossil fuel emissions globally.
The IPCC makes it clear that emissions need to go to zero if the world is to keep global warming below the internationally agreed limit of 2DegC.
In the words of experts and observers tracking the IPCC process: “The science is in and it’s game over for fossil fuels”.
May Boeve, Executive Director of 350.org said:

The scientists have done their job, now it’s the politicians’ turn. World leaders have everything they need to act: clear scientific evidence, a strong economic case, and huge public support. The only thing they lack is the will. The report strengthens the case for fossil fuel divestment. It clearly states that the vast majority of coal, oil and gas must remain underground and that investments in the sector must fall by tens of billions of dollars a year. The fossil fuel industry’s business plan and a liveable planet are simply incompatible.

For the first time, the Fifth Assessment Report includes a strict carbon budget for governments, of which over two-thirds have already been used up. At current rates the world would burn through the rest in less than 30 years.
For the best chance of avoiding severe levels of warming, governments will need to peak emissions, rapidly phase fossil fuels down to zero and transition to 100 percent renewable energy.
Such a transition is not only possible, but is economically viable, according to the IPCC. Rapid development of renewables since the body’s last Assessment Report in 2007 means that clean energy is cheaper and stronger than ever before, and bringing multiple societal benefits – including increased energy access, jobs and improved public health.
Continuing down such a path and investing in renewable energy in the next few decades will also be cheaper than paying a rapidly growing bill for “severe, pervasive, and irreversible impacts.” Such cost savings would vastly outweigh the costs associated with the clean energy transition, says the IPCC.
Greenpeace Head of International Climate Politics, Martin Kaiser said:

For scientists, there is nothing vague about how to deal with climate change. Governments need to pay attention and phase out coal and oil now or end up doing it later at a much higher cost. However, those who seize the potential of renewable energy will leap ahead to a sustainable future.

Requested and endorsed by governments, the release of this report – which ends a five year process covering 30,000 pieces of evidence and involving over 2000 scientists – should act as a guide for governments working on a new global climate agreement which is due for sign off in Paris next December.
Speaking at the launch press conference, IPCC Chair Rajendra Pachauri said the scientists were now “passing the baton to policymakers and the decision making community” to act on the report’s findings.
Also addressing reporters in Copenhagen, UN Secretary-General Ban Ki-moon warned that “the science has spoken, there is no ambiguity in the message. Leaders must act now, time is not on our side.”
Frances Beinecke, president of the Natural Resources Defense Council said:

This report should galvanize the world to take urgent and collective action to curb climate change, and to deal with its here-and-now devastating impacts. We’re almost out of time to avoid the worst—but we’re not out of solutions. For the sake of our children and all future generations, we need to take significant action, and soon.

At the Secretary-General’s climate meeting in New York in September, government leaders put climate change back on the political agenda, while outside the UN hundreds of thousands of people took to the streets calling for more climate change as part of the Peoples’ Climate Marches.
The people have spoken, businesses demand action, investors want long-term certainty, and IPCC scientists have set government’s a clear choice: “either put policies in place to achieve this essential shift, or they can spend the rest of their careers dealing with climate disaster after climate disaster.