What is the IPCC WG III?
On 14th April 2014 the IPCC Working Group III (WG III) published their latest report (link) on climate change mitigation. This is the third of three reports from the IPCC, and follows on from their previous publications: WG I ‘The Physical Science Basis’, published in September 2013; and WG II ‘Impacts, Adaptation and Vulnerability’, published in March 2014. Their latest report draws together over four years of work by over 230 scientists, and presents our options for reducing greenhouse gas (GHG) emissions and developing a more sustainable future.
The report analyses the outcomes of 1200 published scientific studies. These studies, produced by 31 groups of climate modellers from around the world, indicate the possible future impacts of different climate change mitigation strategies. Through synthesising the findings of these studies, the IPCC have developed a series of suggested policy pathways for controlling (or ‘mitigating’) greenhouse gas emissions.
Scientists are the map makers. Policy makers are the navigators, they have to make decisions.
Dr Youba Sokono, co-chair of the IPCC WGIII
What is the current status of GHG emissions?
The last few decades have seen a major increase in the awareness of anthropogenic (human) GHG emissions, and the widespread adoption of sustainable energy policies. However, in their latest report, the IPCC have indicated that despite these efforts, emissions continued to increase from 1970 to 2010. In fact, emissions increased more quickly in the last decade (2000 to 2010), than in each of the previous three decades. By 2010, greenhouse gas emissions reached 49.5 billion tonnes (gigatonnes or Gt) of carbon dioxide equivalents (CO2eq) – the highest level in human history.
If we look at the longer-term trend, around 50% of the carbon emitted by human activity since 1750 has been released in the last 40 years. From 1979 to 2010 fossil fuel burning and industrial activity contributed around 78% of total greenhouse gas emissions.
What does this mean in reality?
Scientists indicate that we need to keep atmospheric CO2 concentrations under 450 parts per million (ppm) if we are to ensure that temperature change does not exceed 2°C (3.6°F) above pre-industrial levels by 2100. The 2°C limit has been agreed by the UN as a target figure to avoid major changes in the Earth’s climate system, and to limit dangerous implications for human populations. The latest IPCC report indicates that the current trend of global emissions of GHGs does not fit in with the goal of limiting global warming at 2°C. If major changes are not made to our emissions, global surface temperature increases will be between 3.7°C and 4.8°C by 2100.
Keeping to our 2°C goal, and keeping greenhouse emissions under 450 ppm by 2100, will require major shifts towards renewable energy sources (such as wind and solar energy) and large changes in the way that we use our land. The IPCC indicate that, to have a likely chance of limiting global temperature rise to 2°C, we will need to lower our greenhouse gas emissions by 40-70% (compared to 2010 emissions) by 2050; and by nearly 100% by 2100. This has major impacts on the way that we will need to source our energy. We may even need to remove CO2 from the atmosphere to help us meet our targets.
What does the report tell us about our options for reducing GHG emissions?
The IPCC’s analysis demonstrates that we need to make large scale changes to the way that we use energy sources, and we need to make these changes quickly. However, the authors are keen to emphasise that despite the major challenges that lie ahead, we have a wide range of options available to us that will allow us to stick to our ‘2°C goal’.
“Many pathways to substantial emissions reductions are available”
IPCC AR5 Press Release, 13th April 2014
We need to make a major shift from fossil fuel (and the emission of greenhouse gases) towards more sustainable, clean energy sources. Since the previous IPCC report (AR4, published in 2007) there have been major developments in renewable energy sources (such as solar and wind power). In many cases these now have very high levels of performance, they are cost effective, and they show very good potential for being used within large-scale projects. It is now in the hands of policy makers to take the scientific understanding of renewable energy sources, and convert this into an implementation strategy.
Land use is another key focus of the recent IPCC report. As well as major reductions in our use of fossil fuels, the analysis indicates that we need to also consider the role of afforestation in mitigating atmospheric greenhouse gas concentrations. The evidence shows that by slowing the rate of deforestation, and by planting more trees, the rate of greenhouse gas emissions from land use has slowed or even reversed. This is because trees act as a very effective sink of CO2 from the atmosphere – simply, the more trees, the more CO2 is stored.
What are the costs and benefits of such a large scale change in energy source?
Renewable energy sources offer a range of benefits, beyond those related to atmospheric composition and reducing global warming. In particular, renewable energy sources may provide a more secure international future by preventing the use of fossil fuel supplies (such as oil and gas) as a political tool.
Changes in land use may prove difficult to implement. While afforestation is a key step in curbing greenhouse gas emissions, this may lead to tensions over land ownership, and impacts on economic activities. Of the modelled scenarios analysed by the IPCC, which maintain atmospheric greenhouse gas levels below 450 ppm, in some instances global economic activity show a reduction of 1 to 4%. Policy makers will now need to work together with scientists to develop appropriate and sustainable plans for the future.
If our best efforts to reduce emissions to below 450 ppm remain insufficient, there are technologies to remove greenhouse gases from the atmosphere. These are based on carbon capture and storage. However, the IPCC suggest that we approach these techniques with caution as the technologies, methods, and impacts are uncertain, and may introduce significant challenges and risks.