6.1 Introduction

Most environmental risks have been recognized as top global risks in terms of their likelihood and impact (WEF 2015, 2016). In recent years, environmental risks facing society are apparently systematic in nature and greatly impaired ecosystem and resulted in huge losses to socioeconomic domain (Briggs 2008). Thus, integrated assessment of environmental risks is necessary for risk management. Several integrated risk indices have been developed to describe global risk patterns or trends (Dilley 2005; Shi 2009; Joern et al. 2014). For example, the United Nations Development Programme (UNDP 2004) has developed a disaster risk index (DRI) to assess the global integrated risk by combining the exposure of human to the hazards such as flood, drought, and cyclone. The United Nations University (Joern et al. 2014) has promulgated a world risk index (WRI) for the assessment and estimation of disaster risk for a country. WRI takes into consideration both external and internal factors, i.e., threats by natural hazards, climate change, and societal conditions. WRI was calculated for 171 countries by combining the exposure of individual countries to natural hazards, and the socioeconomic and ecological conditions of these countries. Shi and Kasperson (2014) used a total risk index (TRI) and a multi-hazard risk index (MRhI) to estimate the world risk with respect to annual mortality and affected population.

Many assessments have reported that China is being or will be under relatively high environmental risks (Dilley 2005). In this chapter, an integrated assessment of environmental risks focuses on the risks estimation for human, society, and natural system under changing climate was presented. To achieve this, the climate change risks in multiple sectors were assessed using multiple climate impact models (Warszawski et al. 2014; Tang and Oki 2016). The risk assessments of heat wave, agricultural production, and ecosystem shift were then combined into one integrated assessment. It is expected to present a more comprehensive and advanced assessment of China’s environmental risks based on the climate impact assessments across sectors under new climate and socioeconomic scenarios developed for the Intergovernmental Panel on Climate Change (IPCC).

6.2 Methodology

In this study, we adopted a variation of the integrated environmental risk index (IERI) similar to the TRI after Shi and Kasperson (2014). First, three disaster hazards, i.e., the heat wave hazard, agricultural hazard in terms of crop yield, and ecosystem shift hazard, were estimated under various climate scenarios in the future. The corresponding risks were then estimated and normalized to the consistent risk levels (from 1 to 10 as risks increase) and finally, the IERI was calculated as the weighted sum of the three disaster risks using the following equation:

$$ IERI = \sum\limits_{i = 1}^{n = 3} {r_{i} \times w_{i} } $$
(6.1)

where r i is the risk level of a disaster, w i is the weight of the disaster. In this study, equal weights were used for IERI calculation.

Climate data from five general circulation models (GCMs) under four representative concentration pathways (RCPs) were used to drive the impact models to estimate the risks in China in the twenty-first century. The uncertainties cross GCMs and impact models were also addressed in terms of standard deviations of risk levels for each single RCP scenario. The estimations of the risks were described in Chaps. 3–5 in this atlas. The integrated environmental risk zones (IERZ) were then delineated based on the IERI estimates.

6.3 Results

The integrated environmental risks were estimated for the four RCPs, i.e. RCP2.6, RCP4.5, RCP6.0, and RCP8.5, respectively. The IERI values were also generalized to ten levels denoted as 1–10 from low to high risk. In general, there were relatively low risks in China under RCP2.6, and relatively high risks under RCP8.5. Both the maps of IERI and the associated uncertainty will be shown in the Maps section.

Six level-I IERZs, i.e., the Northwest-Low-Risk region, Northeast-Relatively-Low-Risk region, Tibet-Moderate-Risk region, Jin-Shaan-Moderate-Risk region, South-China-High-Risk region, and Huang-Huai-Hai-High-Risk region, were delineated using the top-down approach for China under RCP8.5 and RCP6.0 scenarios. Level-II IERZs were delineated from bottom to top by combining local counties that have similar environmental risks. According to the characteristics of local environmental risks, total 42 and 54 level-II IERZs were further identified under RCP8.5 and RCP6.0 scenarios, respectively.

6.4 Maps