Abstract:

IPCC special report on the ocean and cryosphere in a changing climate (SROCC) was formally approved at the second joint session of working groups I and II of the IPCC and accepted by the 51st session of the IPCC on 24 September 2019. Assessment content related to extreme event, abrupt change and its impact and risk of ocean and cryosphere in SROCC is synthesized in this paper. Based on new assessment results in SROCC, it is indicated that extreme events of ocean and cryosphere have become more frequently, and their intensity has increased. The frequency of landslides, snow avalanches and floods events caused by changes in cryosphere has increased. Marine heat wave happens more frequently. Extreme El Niño events become more intense. Atlantic Meridional Overturning Circulation (AMOC) has weakened. In coastal areas, extreme sea level and extreme wave height have increased, and the impact of extreme tropical cyclones has amplified. Those changes, such as marine heat wave, can be attributed to anthropogenic temperature increase. Furthermore, changes in ocean and cryosphere related extreme events are projected to be exacerbated. Those changes can have severe impacts on lives and livelihoods in high mountain, polar and coastal community, and on ocean and cryosphere ecosystem service function. Better prediction and early warning systems, including seasonal prediction system, annual to decadal prediction system of extreme events and abrupt change, are needed to be well-prepared to reduce extreme events risk. What’s more, improved scientific understanding and technical capacities of extreme events and suitable post-recovery and reconstruction are also key points in risk management.

Key words: Ocean, Cryosphere, Extreme event, Risks management