Climate change threatens ‘severe, pervasive and irreversible impacts’ – IPCC

Options are available to adapt, and stringent mitigation activities could keep impacts within a manageable range

Marking the end of a year that saw the international climate science community thrash out and compile six years’ worth of research into three major reports covering climate change science, impacts and mitigation; the Intergovernmental Panel on Climate Change (IPCC) Synthesis Report was released early in November.

The report summarises the organisation’s comprehensive work on the various facets of climate change into one 100-page document. And its headline findings? That climate change threatens irreversible and dangerous impacts for people and ecosystems, but options exist to limit its effects.

The Fifth Assessment continues the trend of successive IPCC reports where the headline language becomes increasingly stark, direct, and certain. This time is no exception, with the impacts of inaction on climate change being described as ‘severe, pervasive and irreversible’.

However, the Synthesis Report also says that options are available to adapt to climate change, and that implementing ‘stringent mitigations activities’ can ensure that climate change impacts ‘remain within a manageable range’.

The report reaffirms the message from the IPCC’s last assessment in 2007 – that climate change is being registered around the world and warming of the climate system is unequivocal. Since the 1950s, many of the observed changes are unprecedented over decades to millennia.

The report expresses with greater certainty than previous assessments that emissions of greenhouse gases and other anthropogenic drivers have been the dominant cause of observed warming since the mid-20th century. And it states that the more that human activity disrupts the climate, the greater the risks.

The report indicates that a certain amount of adaptation to climate change will be necessary. But, substantial and sustained reductions of greenhouse gas emissions are at the core of limiting the risks of climate change, it says, both in terms of the magnitude and rate of warming.

The IPCC states that there are multiple mitigation pathways to achieve the substantial emissions reductions over the next few decades necessary to limit, with a greater than 66% chance, warming to 2ºC. It states that delaying mitigation will substantially increase the technological, economic, social and institutional challenges associated with keeping below 2ºC.

Mitigation cost estimates vary but the report states that implementing efforts to curb climate change would reduce economic growth by around 0.06 percentage points.

‘Addressing climate change will not be possible if individual agents advance their own interests independently; it can only be achieved through cooperative responses, including international cooperation,’ said IPCC Chair RK Pachauri.

‘The scientific case for prioritising 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% globally between 2010 and 2050, falling to zero or below by 2100. We have that opportunity, and the choice is in our hands.’