Wiley Interdisciplinary Reviews: Computational Statistics

The performance of 21 Coupled Model Intercomparison Project Phase 5 (CMIP5) models in the simulation of the Indian Ocean Dipole (IOD) mode is evaluated. Compared to CMIP3, CMIP5 models exhibit a similar spread in IOD intensity. A detailed diagnosis was carried out to understand whether CMIP5 models have shown improvement in their representation of the important dynamical and thermodynamical feedbacks in the tropical Indian Ocean. These include the Bjerknes dynamic air-sea feedback, which includes the equatorial zonal wind response to sea surface temperature (SST) anomaly, the thermocline response to equatorial zonal wind forcing, the ocean subsurface temperature response to the thermocline variations, and the thermodynamic air-sea coupling that includes the wind-evaporation-SST and cloud-radiation-SST feedback. Compared to CMIP3, the CMIP5 ensemble produces a more realistic positive wind-evaporation-SST feedback during the IOD developing phase, while the simulation of Bjerknes dynamic feedback is more unrealistic especially with regard to the wind response to SST forcing and the thermocline response to surface wind forcing. The overall CMIP5 performance in the IOD simulation does not show remarkable improvements compared to CMIP3. It is further noted that the El Nio-Southern Oscillation (ENSO) and IOD amplitudes are closely related, if a model generates a strong ENSO, it is likely that this model also simulates a strong IOD.

Indian Ocean variability in the CMIP5 multi-model ensemble:The Zonal Dipole mode

Carbon emissions and driving forces of an island economy: A case study of Chongming Island, China

In developing countries like Pakistan, agriculture constitutes the primary source of support for the majority of rural and the adjacent urban population. Despite the large part it plays in the economy, it faces significant challenges caused by climate change, such as rising temperatures, floods, droughts, and yield losses. In Pakistan, rice, which is the second most essential food crop and livelihood source for the millions of farm households, is facing significant yield reduction due to climate change. It is pertinent to consider the vulnerabilities of farm households and related factors to create a climatic-resilient farming system. The current study is aimed at mapping the vulnerability of rice-growing communities of Punjab province while considering climatic challenges beyond temperatures and rainfall changes. The Climate Change Vulnerability Index (CCVI) was calculated for four rice-growing districts of Punjab province using the Intergovernmental Panel on Climate Change’s three-indicator approach (sensitivity, exposition, and adaptive capacity). According to the results, farmers in the study area are highly vulnerable to climate change (CCVI 0.81). Specifically, the indices of vulnerability components showed that farmers have a high level of exposure (EVI 0.72) and susceptibility (SVI 0.59) to the climatic uncertainties with the least adaptive capacity (AVI 0.50). Further, the vulnerability analysis across different rice-growing regions showed that farmers, particularly in the low-yield region, are more vulnerable (EVI 0.73, SVI 0.61, AVI 0.49, CCVI 0.85) than the farmers in the high-yield region (EVI 0.71, SVI 0.58, AVI 0.51, CCVI 0.78). These findings imply that regional priority must be given despite the difference in farm performance to reduce production losses. Besides, climate-smart adaptation initiatives should be facilitated at the farm and regional levels through the implementation of appropriate policies and investment plans.

Mapping farmers’ vulnerability to climate change and its induced hazards: evidence from the rice-growing zones of Punjab, Pakistan

Mean surface temperature is projected to rise by about 4.4 °C by the end of the century compared to the period between 1976 and 2005 when following the most extreme scenario of the greenhouse gas emissions pathway (Krishnan et al., 2020). With this rise in mean temperature, there is a lot of uncertainty on how weather and climate extremes would unfold, especially for various climate zones of India. It is therefore essential that the potential changes in both magnitude and direction of weather and climate extremes at the regional level when the global temperature reaches the different warming levels from 1 °C to 3 °C be established to allow for informed policy formulation. The present study explores the potential changes in the Expert Team on Climate Change Detection and Indices of rainfall and temperature estimated from the coupled model inter-comparison project CMIP5 multi-model ensemble over different climatic zones of India at 1 °C, 1.5 °C, 2 °C, 2.5 °C and 3 °C global temperature rise relative to pre-industrial levels under two Representative Concentration Pathways, RCP4.5 and RCP8.5. Projected changes in temperature extremes indicate significant changes at all warming levels across the nine climate zones of India. Hot temperature extremes are expected to increase while cold temperature extremes decrease. For India, country average at 3 °C under the RCP8.5 and 2 °C under the RCP4.5 scenarios, ensemble median shows that Warm Spell Duration Index will increase by 131 days and 66 days; hot days increase by 44% and 52%, warm nights increase by 23% and 13%; cold days decrease by 10% and 9%, and cold nights decrease by 13% and 12% relative to pre-industrial levels. The greatest changes in temperature based indices are projected in the colder northern parts of the country followed by the arid zone. Ensemble median for rainfall indices shows an increase in high precipitation indices, though with large model spread indicating the large uncertainties in the projections. Annual total precipitation and heavy rainfall related extreme indices show statistically significant increases in the tropical, temperate and semi-arid regions of India, moving from 1 °C to 3 °C warming level under RCP8.5 scenario whereas there is generally no significant change in the maximum number of consecutive dry and wet days. Moreover, the potential changes in climate extremes at the regional level are expected to have far-reaching impacts on the social and economic statuses of the respective climate zones. This information at a regional scale also calls attention to the national and state action plan on climate change and adaptation to be more responsive in order to take coherent and integrated policy decisions.

Temperature and rainfall extremes change under current and future global warming levels across Indian climate zones

The present study assessed climate change vulnerability in agricultural sector of low-lying Sagar Island of Bay of Bengal. Vulnerability indices were estimated using spatially aggregated biophysical and socio-economic parameters by applying principal component analysis and equal weight method. The similarities and differences of outputs of these two methods were analysed across the island. From the integration of outputs and based on the severity of vulnerability, explicit vulnerable zones were demarcated spatially. Results revealed that life subsistence agriculture in 11.8% geographical area (2829 ha) of the island along the western coast falls under very high vulnerable zone (VHVZ VI of 84–99%) to climate change. Comparatively higher values of exposure (0.53 ± 0.26) and sensitivity (0.78 ± 0.14) subindices affirmed that the VHV zone is highly exposed to climate stressor with very low adaptive capacity (ADI= 0.24 ± 0.16) to combat vulnerability to climate change. Hence, food security for a population of >22 thousands comprising >3.7 thousand agrarian households are highly exposed to climate change. Another 17% area comprising 17.5% population covering 20% villages in north-western and eastern parts of the island also falls under high vulnerable (VI= 61%–77%) zone. Findings revealed large spatial heterogeneity in the degree of vulnerability across the island and thus, demands devising area specific planning (adaptation and mitigation strategies) to address the climate change impact implications both at macro and micro levels.

S. Sadhu

Papers

Climate change vulnerability to agrarian ecosystem of small Island: evidence from Sagar Island, India