Creative Commons: Hiroyuki Takeda, 2010

The final instalment of the Fifth Assessment Report (AR5) by the Intergovernmental Panel on Climate Change (IPCC) is due for launch on 2 November in Copenhagen, Denmark – after  a week of government negotiations to agree a Summary for Policymakers (SPM).
Following the reports of three Working Groups over the past year – covering the physical science of climate change (Working Group 1), vulnerability to climate impacts and adaptation (Working Group 2), and mitigation strategies to tackle climate change (Working Group 3) – the final element of the AR5 series will be a “Synthesis Report”, combining and contrasting the work of the three Working Groups into one report.
It marks the culmination of a 5-year-effort by 830 authors, 1200 other contributors and 3700 expert reviewers drawing on more than 30,000 pieces of research and 143,000 expert comments to produce an unprecedented body of evidence.
Together the reports represent the most comprehensive global overview to date of the science behind climate change.
They show with extreme certainty that change is real, caused by human activity and already having profound impacts across all continent’s and the world’s oceans.

What is the IPCC’s Fifth Assessment Report?

The IPCC’s Fifth Assessment Report consists of three Working Groups. Working Group I, released 27 September, examined how and why the climate is changing, and what changes could be expected in the future.
Working Groups II will tackle the impacts of climate change – environmental, social and economic.
This will be quickly be followed in April by Working Group III – to be released in April which will examine the options to reduce greenhouse gas emissions and limit the consequences of climate change.
Together the reports will update the analysis of the IPCC’s Fourth Assessment, released in 2007, refining its conclusions, and highlighting the expansion of understanding about the climate system.
While there are many other climate reports that synthesise the science, the IPCC is the largest, and the latest round of reports are expected to be the most comprehensive review of climate science undertaken to date.
IPCC reports are one of the main guides used by governments to take the necessary action to prevent catastrophic global warming and adapt to the impacts of climate change.
The report assesses thousands of scientific peer-reviewed papers and other authoritative reports, providing a balanced summary of what is known and where the uncertainties lie.
In total, 831 scientists, from across 85 countries, were directly involved in writing the new report, and thousands more experts acted as reviewers, scrutinising the report and ensuring its reflects the full range of views in the scientific community.
Authors also include experts from business, industry and environmental organisations with a scientific or academic background.

What did Working Group I say?

The IPCC’s first report, released back in September 2013, examined the scientific basis on climate change. It showed that it is now clearer than ever that the warming of the entire climate system is “unequivocal” and that humans emitting greenhouse gases is the “dominant” cause.
The release prompted civil society groups to pronounce the debate around climate science over.
Global sea levels are rising, precipitation patterns are changing, sea ice is declining and oceans are acidifying – all with grave consequences for our communities, environments and economies.
According to the IPCC the three most recent decades have all been warmer than all preceding decades since the industrial revolution. The period covering 1983 – 2012 was very likely the warmest 30-year period in 800 years, and likely the warmest of the past 1400 years.
The Working Group II report will further build on this picture of a world of worsening climate change by emphasising the impacts our changing climate is having on the natural world and on communities and populations around the globe.

And Working Group II?

In the second of its three-part Fifth Assessment Report, the Intergovernmental Panel on Climate Change examined the potential impacts of a warming world.
It painted a disturbing picture of climate change and warned climate impacts are already having sweeping effects on every continent and through the world’s oceans and that big risks and impacts are far more immediate and local than scientists once thought.
It concluded that climate change was already having impacts – melting sea ice, thawing Arctic permafrost, killing off coral reefs and leading to heatwaves, heavy rain and weather disasters.
The IPCC warns that some risks of climate change could be considerable at just 1-2°C of warming and that any further warming could mean “severe, pervasive and irreversible impacts.
Not only does it warn of crop failure, food and water shortages, rising sea levels, and serious impacts on human health, but also that countries around the world are ill-prepared for these impacts.
For the first time WGII looks extensively at the world’s oceans and shows that marine species and biodiversity are highly sensitive to warming waters and ocean acidification.
Climate change will also threaten global security, causing civil wars and conflict between nations. The failure to act on climate change is the world’s “gravest threat to human and national security”.

And Working Group III?

The final report examined climate mitigation options and potential.

The report made it clear that we can still keep global warming below 2°C compared to pre-industrial levels. Even keeping warming below 1.5°C hasn’t been ruled out.

Achieving this and securing a safe climate future will also not cost the earth, according to the IPCC. In business-as-usual scenarios, consumption grows by 1.6 to 3% per year. Ambitious mitigation would reduce this growth by only around 0.06 percentage points a year, i.e. 2.94% growth instead of 3% growth. And that’s before considering the co-benefits of taking action – such as better public health and increased energy efficiency – or the cost savings which result from avoiding future impacts.

The IPCC said that large scale changes in the global energy mix are required, combined with deep and fast emissions cuts – with a quadrupling of zero and low carbon energy by 2050. Renewable energies must be a significant part of this change, and are an increasingly attractive option, according to the report – particularly if governments put in place stronger enabling policies.

The major expansion and price reduction associated with renewables such as solar PV and onshore wind makes them the energy sources of choice.

Why does the IPCC matter?

The IPCC serves as an interface between science and policymaking, and is one of the main guides used by governments to take the necessary action to prevent catastrophic global warming and adapt to the impacts of climate change.
The previous reports, released in 1990, 1995, 2001 and 2007, have become the evidence base for virtually all climate change related strategies developed by governments and businesses.
Governments have internationally agreed that global temperature rise must not surpass 2°C above pre-industrial levels. The latest report comes as nations work towards a new international deal to rein in rising emissions – set to be agreed in 2015.
The latest report is expected to make clearer than ever the links between climate change and humans and is expected to show that time is running out for governments to prevent catastrophic levels of warming.
The average global warming of 0.8ºC from pre-industrial levels so far has already seen climate impacts emerge around the world, affecting the lives of billions of people. Extreme weather events, such as droughts and floods, are already causing huge losses – both social and economic.
Research from Carbon Tracker and the World Bank warn that the current level of government action means the world is on track to warm by around 3ºC this century; the IPCC concur.
The damages of climate change and the high carbon economy may already be costing $1.2 trillion every year, now it appears that the IPCC’s comprehensive review of the science will tell us we are heading into deeper and darker territory where the costs will mount even higher.
Infographic to share: 
Irreversible (1)