The primary goal of the Intergovernmental Panel on Climate Change's (IPCC) Climate Change 2014 Synthesis Report (AR5 SYR) is to provide a single, comprehensive report that embodies the findings of the group’s fifth assessment cycle. This includes the contributions of individual working groups, which publish separate reports on relevant subjects during each IPCC assessment cycle, as well as Special Reports, commissioned by the IPCC to address pressing issues. Contributions to the fifth assessment cycle include studies on the physical basis of climate change, its impacts, and how to mitigate it, along with special reports addressing renewable energy and natural disasters. Released in November of 2014, the AR5 SYR provides an overview of the state of the climate as known up to that point. In it, four key areas are addressed: observed changes in climate and their causes; future climate change, risks and impacts; future pathways for adaptation, mitigation and sustainable development; and adaptation and mitigation.

Firstly, the IPCC details the ways in which our climate has changed. At the time of publication, the global mean temperature had risen 0.85 oC since 1880, global sea level had risen by about 0.19 m since 1901, and carbon dioxide absorption into the ocean had caused its pH to drop by 0.1 pH units, corresponding to a 26% increase in acidity, since pre-industrial levels. The number of warm days had increased globally, while cold days had decreased, and extreme weather events increased in frequency. Through all of these events, anthropogenic greenhouse gas (GHG) emissions have climbed to levels unprecedented in the last 800,000 years. Based on increasingly clear evidence, the AR5 SYR is 95% certain that humans are causing climate change. The impacts of climate change are diverse, and affect each region differently – but in general, climate change will negatively impact biodiversity, fish stocks, sea ice mass, water supply, precipitation, local economies, and livelihoods.

Secondly, the report’s authors acknowledge that CO2 emissions will be a key driver of climate change, and especially warming, moving forward. Reducing emissions will be a key element in keeping warming below 2oC. The impacts of global warming and further climate change, they assert, will include more frequent and more intense versions of what we have already seen – higher occurrence of heatwaves, lower rates of precipitation, increased ocean acidification, and further sea level rise. This, of course, presents dangers to human beings, threatening our homes, cities, livelihoods, food sources, and ultimately lives. This risk is much greater for people living in poverty or with disabilities, and those residing in coastal communities. It is recognized that the accumulated GHGs in the atmosphere will cause warming will persist long after emissions have been reduced.

The third section of the AR5 SYR deals with strategies for mitigating and adapting to climate change. Mitigation involves taking steps to reduce or reverse the effects of climate change, while adaptation means making it easier to live in a warming planet.These are necessary because further warming without mitigation will begin to produce disastrous and irreversible effects by the 2100s. Moreover, those most vulnerable to the effects of climate change often contribute little to its progression. Therefore, mitigation is absolutely crucial for a sustainable, equitable future. This, of course, comes with its own risks (mostly economic), but these pale in comparison with the cost of climate change and its effects. Strategies for adaptation can be implemented at any level of government, but are most effective when carried out in a coordinated effort; for example, these can involve reducing vulnerability to climate change, promoting economic diversification (as in avoiding economic reliance on a single certain product or service), and limiting the impacts of increased environmental variability. While adaptation is effective for lowering the risks of climate change, mitigation is favourable, as it aims to prevent these risks. Climate scientists widely agree that keeping global warming below 2 C over pre-industrial levels will prevent the irreversible effects. Multiple strategies exist for this, but the authors of this report stress the importance of reducing GHG emissions, particularly CO2. High emission scenarios make it unlikely to remain even below 3 C of warming.

Finally, AR5 SYR acknowledges that adaptation and mitigation are often enabled by similar underlying mechanisms. For these to be possible options, significant structural change will need to occur. By far, the best option for implementing these strategies is a policy approach, and thus the political space necessary to put these policies in place needs to first be created. International cooperation plays a key role in ensuring climate goals are met, in part because it helps to reduce the cost of mitigation strategies and maintains stability in markets. National governments may also play a role, and potential policy suggestions include cap and trade strategies, regulatory approaches that place emissions limits (on automobile manufacturers, for example), and informational approaches that inform the consumer of a product’s carbon footprint. The report concludes with remarks about the economic benefits of mitigation – how efforts for sustainable development are now linked to the job creation, improved livelihoods, and socioeconomic well-being.

Released almost six years ago, the AR5 SYR is an important historical document, detailing the state of our knowledge about the climate and our impact on it at that time. When it was released, the report was highly influential – its contents were used to inform and direct subsequent talks at the famous 2015 Climate Change Conference in Paris. The synthesis report for AR6 is expected in 2021.

Find the full report here.

References

1. IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp. Available from https://www.ipcc.ch/site/assets/uploads/2018/05/SYR_AR5_FINAL_full_wcover.pdf