IPCC's Latest Findings Suggest Future Increases in Global Sea-Level Rise and More Extreme Rainfall in the Region

Climate science findings released in Stockholm on 27 September by the Inter-governmental Panel on Climate Change (IPCC) suggest significant changes in rainfall patterns and increased global sea-level rise by 2100.

The findings were released as part of IPCC’s 5th Assessment Report (AR5) ‘Summary for Policymakers’ (SPM) by Working Group I (WGI): The Physical Science Basis (refer to Annex A for details). The SPM contains updated interpretations of past climate as well as projections of the future.

The findings of AR5 are consistent with those of the 4th Assessment Report (AR4), and show that the climate is undergoing significant change. The Singapore Government will contextualise the global findings from AR5 and study their impact on Singapore and its people. As new knowledge and information on the effects of climate change become available, continual efforts are being made to review and adjust plans.

Rainfall

For future rainfall, the SPM shows that trends vary widely across different regions of the world. Nonetheless, the SPM notes that in a warmer world, extreme rainfall events over wet tropical regions will very likely become more intense and more frequent. The view from the scientific community is that detailed prediction of rainfall in the tropics is a major challenge due to the complexity of the physical processes involved, and remains an area of active research.

The SPM, in its analysis of past rainfall, shows that more regions of the world experienced an increase in the number of intense events. However, a number of regions experienced decreases, and there was no uniform pattern world-wide.

In Singapore, analysis by the Centre for Climate Research Singapore (CCRS) indicates that there has been more frequent and intense short duration heavy rainfall over the past few decades. Over this period, the number of days each year with heavy rainfall of more than 70 mm in an hour increased as a regular trend from five days in 1980 to ten days in 2012. The annual maximum rainfall intensity in an hour also increased from 80 mm in 1980 to 107 mm in 2012. There was no significant trend for prolonged dry spells over this period.

Scientifically, it is not possible with current models to pinpoint the cause of past rainfall changes in Singapore, as a combination of factors such as global warming, natural climate variability and other effects could have played a part. However, research is ongoing and advances could be made in the future.

Sea Level

Using global sea level over the period of 1986 - 2005 as the reference point, the SPM’s current analysis is that there could be a rise of 0.26m - 0.82m by the period of 2081 - 2100, depending on the level of greenhouse gas emissions. The most aggressive climate change scenario¹ could see a total rise of 0.52m - 0.98m by the year 2100. Location-specific coastal effects, which could be due to ice sheet/glacial processes, tectonic processes, coastal processes, and local human activities will add to this change in mean global sea level.

Looking further ahead, the SPM mentions that the Greenland Ice Sheet could take over a millennium or longer to melt completely. If this were to happen, mean global sea level would rise by up to 7m compared to present day. However the uncertainty is large in projecting the climate over such a long time-scale, and further research is required to refine the estimates.

Temperature

For the period of 2081 - 2100, the SPM projects that average surface temperatures across the world will increase by at least 0.3°C - 1.7°C under the least severe climate change scenario², and by 2.6°C - 4.8°C for the most aggressive climate change scenario.

The findings of the SPM imply that the temperatures that Singapore encounter occasionally could become the norm in the future. More aggressive climate change may affect how Singaporeans carry out their day-to-day activities and the way that future infrastructure is planned.

Staying Resilient In The Face Of Climate Change

he effects of climate change operate in the long term, but the Government is taking a proactive approach to address its potential impact. The Inter-Ministerial Committee on Climate Change (IMCCC) was established in 2007 to enhance Whole-of-Government coordination on climate change policies. The Resilience Working Group (RWG), an inter-agency platform under the IMCCC, studies Singapore’s vulnerability to the effects of climate change and recommends long-term plans that ensure the nation’s adaptation to future environmental changes.

Through Singapore’s 1st National Climate Change Study (2007 - 2013), which made use of data and scenarios from IPCC AR4, a preliminary understanding was gained of how climate change could affect Singapore. The Study was conducted by the National Environment Agency (NEA), under the auspices of RWG. Phase 1 of the Study was completed in 2009 and Phase 2 concluded this year. Phase 2 looked into the potential impacts of climate change on biodiversity, public health, the urban temperature profile, and energy consumption of buildings. The relevant agencies have taken these findings into account in their resilience plans, such as in enhancing the stability and connectivity of our existing green areas, reviewing our monitoring and maintenance regimes, as well as putting in place plans to better understand the effects of urbanisation together with climate change.

With the release of IPCC AR5, it is necessary to leverage the global and regional-level findings and investigate them at country/ city level, so that we can update our knowledge and resilience plans. This will be carried out in Singapore’s 2nd National Climate Change Study. Work is now ongoing at CCRS, in collaboration with the UK Met Office, to project climate parameters in greater detail to help the Government better understand the local impacts of climate change. The results will eventually strengthen Singapore’s climate resilience and adaptation plans.

¹ “Representative Concentration Pathway” (RCP) 8.5. In AR5, a selection of four greenhouse gas concentration pathways were used as the input to drive climate models: RCPs 2.6, 4.5, 6.0 and 8.5. The higher numbers represent greater projected imbalances in the climate by the year 2100.

² “Representative Concentration Pathway” (RCP) 2.6. See footnote 1.

Source: National Environment Agency