CARE2022 Hong Kong Conference

79 7 Workshop: Scholars’ Day Using flexible modelling tools for producing regional climate predictions with a cloud-resolving resolution, scientists found that the strengthening of tropical cyclone precipitation due to warming may be several times higher than previous estimations at spatial and temporal scales relevant to cities. More research are needed to understand this accelerated intensification at urban scales and its implications for urban infrastructures. 4. Sea level rise and storm surge risks Prof. Zhenning Li (Division of Environment and Sustainability, HKUST) With a long and meandering shoreline and well-developed economy, Hong Kong is highly vulnerable to tropical cyclone (TC)-caused storm surges. The current global warming is expected to continue or even worsen in the rest of the 21st century. Therefore, the warmer sea surface temperature (SST) and lifted mean sea level tend to fuel much more ferocious storm surges. We use regional air-wave-ocean coupled simulations to reproduce three severe landfalling TCs affecting Hong Kong. The present-day and global warming context mimicking the 2090s has been simulated to investigate the effect of climate change. The 2090s status will effectively increase the intensity of the severe TCs and related Shaoming Shi, HKUST storm surges. On average, the maximum storm surges are lifted by 0.3-0.8 meters over the open sea while aggravating much higher along the coastline, especially for narrowing estuaries where the maximum surge level can be elevated up to 2 meters. Changes in maximum significant wave height show more complicated patterns due to their sensitivity to TC tracks. For Typhoon Vicente (2012), a more than 2-meter wave height increase is observed both in the open sea and along the coastline. In the 2090s context, a combination of mean sea level rise, storm surge, and wave height can reach more than 4 meters increase in total water level at certain coastal hot spots. This will cause much more severe damage and losses at the end of the 21st century. SESSION 2 Forestry, Heat Stress, Infrastructure and Health 1. Forests in climate mitigation, adaptation and resilience Dr. Billy Hau (School of Biological Sciences, HKU) Zhenning Li, HKUST Hong Kong’s Climate Action Plan 2050 does not include nature-based solutions among its decarbonisation strategies. In fact, a growing forest absorbs carbon. In years past, Hong Kong was wholly covered by tropical forests, which over time have become degraded through human settlement and urbanisation. Today, only ~29% of the total land area is forested. It is estimated that this is equivalent to about 48.2 million tonnes of carbon. The secondary vegetation is made up of grassland (15%) and shrubland (21%). It is possible to reforest these areas. Estimates show that if these areas were reforested, in 15 years i.e., by 2038, there could be a gain of 6.97 million tonnes of carbon. It is not yet possible to estimate accurately the annual carbon capture by Hong Kong’s forest because of lack of information on wood density and diameterheight relationship of the diverse tree species in Hong Kong. Billy Hau, HKU