IPCC’s Latest Findings Suggest Increased Warming, More Changes In Extreme Weather Events With Higher Temperatures And Global Sea Level Rise
Singapore will continue to study, plan and implement adaptation measures
1 The Centre for Climate Research Singapore (CCRS), under the National Environment Agency (NEA)’s Meteorological Service Singapore (MSS), is studying the Intergovernmental Panel on Climate Change (IPCC)’s latest report – the first of three major reports that make up its Sixth Assessment Report (AR6) (refer to Annex for details). This report, which brings together the latest scientific assessments of climate change, was produced by the IPCC’s Working Group I (WGI) and was released together with a ‘Summary for Policymakers’ (SPM). The key findings of this report are:
• Human influence has warmed the atmosphere, ocean and land, and widespread and rapid changes in climate have occurred globally.
• Global warming of 1.5°C and 2°C will be exceeded during the 21st century, unless there are deep reductions in carbon dioxide and other greenhouse gas emissions in the coming decades.
• The rate of global mean sea level rise has accelerated and will continue throughout the 21st century, ranging from 0.32m to 1.01m by 2100.
• Every region in the world is projected to experience concurrent and multiple changes in climatic impact-drivers resulting in more extreme droughts, more intense and frequent extreme rainfall events, and flooding. Changes will be more widespread at 2°C as compared to 1.5°C global warming, and even more so for higher warming levels.
2 These findings underscore the urgency for the global community to reduce greenhouse gas emissions, while building resilience against the impact of climate change. Singapore is committed to play our part. The Government will rally and partner Singaporeans and businesses to advance our national agenda on sustainable development, as set out in the Singapore Green Plan 2030. We will also leverage climate science to understand the effects of climate change on Singapore and press on with efforts to mitigate and adapt to them.
Key Findings and Implications for Singapore
3 The key findings outlined in the SPM, and implications for Singapore are elaborated below:
• The SPM shows that global surface temperature around 2050 will be higher than today under all the climate change emission scenarios considered. Under all the scenarios except for the most aggressive emission scenario SSP5-8.5, the SPM states that the central estimate – of when the average surface temperature rise will cross the 1.5°C mark – lies in the early 2030s. In the highest emission scenario SSP5-8.5, average surface temperature rise will cross the 1.5°C mark by the end of this decade.
• For the period of 2081 – 2100, the SPM projects that average surface temperatures across the world will increase by at least 1.3°C – 2.4°C under the low emission scenario SSP1-2.6, and by 3.3°C – 5.7°C for the highest emission scenario SSP5-8.5 (numbers represent the “very likely” range of increase above pre-industrial period 1850-1900).
• Globally, we have experienced an increase in surface temperature of 1.09°C since pre-industrial times. Singapore has experienced a stronger than global warming trend over the past several decades due to the additional impact from urbanisation. The projected findings in the SPM suggest that the elevated temperatures will also be felt in Singapore in the coming decades.
• In general, on a global scale, the SPM reports that heavy precipitation events will intensify and become more frequent with each additional degree of warming. By year 2100, global annual precipitation over land is projected to be higher than today under all the emission scenarios.
• On a regional scale, the SPM also states that South East Asia will experience an increase in mean (monsoon) precipitation and pluvial flooding (which occurs when the ground cannot absorb rainwater effectively or drainage systems are overwhelmed during an extreme rainfall event).
• Singapore’s year-to-year rainfall is highly variable. However, the average annual rainfall for Singapore since 1980 has increased at an average rate of around 70mm per decade. The intensity and frequency of heavy rainfall events have also increased over the past few decades up until 2012, but these trends were modulated by strong El Niño conditions in 2015-2016.
• It is challenging to pinpoint the cause of past rainfall changes in Singapore with current models, as a combination of factors such as global warming, natural climate variability and other effects could have played a part. The science around climate change attribution is still evolving, and MSS will continue to study this, along with the impact of climate change on Singapore’s weather.
• The SPM projects a global mean sea level rise of 0.32m – 0.62m under the low emission scenario SSP1-2.6 considered in AR6, and a global mean sea level rise of 0.63m – 1.01m under the highest emission scenario SSP5-8.5 by year 2100. Sea level rise is virtually certain to continue throughout the 21st century in most regions of the world.
• AR6 also pulls together the latest scientific findings of ice sheet processes, including high impact-low probability events. Such processes (including marine ice cliff instabilities) could contribute more than one additional metre of sea level rise by the end of the 21st century .
• The changes in mean sea level do not differ significantly from earlier IPCC AR5 reports as sea level rise is a long-drawn process. Sea level change is also not globally uniform, and regional and local rates of sea level rise may differ from the global mean. The CCRS will be studying this in greater detail under the National Sea Level Programme (NSLP), which aims to strengthen local sea level research and provide more robust projections of sea level change for Singapore and the surrounding region.
4 CCRS will contextualise the findings from the NSLP and study their impact on Singapore. The Centre has started work on the Third National Climate Change Study for Singapore (V3), which provides localised and high-resolution climate projections derived from the latest climate models used by the IPCC. The study is expected to be completed by end 2022, and the findings will guide the ongoing planning and implementation of adaptation measures to safeguard Singapore against the impact of climate change. These measures will be continually reviewed and adjusted, as new knowledge and information on the effects of climate change become available.
Upcoming Virtual Symposium on Climate Change
5 A virtual symposium on climate change will be held in late August to discuss the scientific findings of the report. More details will be released on the Facebook pages of NEA and the Ministry of Sustainability and the Environment.