Earth's Future

Li, Kai; Zhang, Jingyong; Wu, Lingyun; Yang, Kai; Li, Suosuo

doi: 10.1029/2021ef002377pmid: N/A

The ongoing climate change has posed severe threat to the natural system and human society. However, how soil temperature feedbacks matter for climate change projections is not yet well explored. In this study, we assess the role of soil temperature feedbacks for summer air temperature variability over East Asia under global warming. Regional climate model simulations with and without soil temperature‐atmosphere interactions were performed to isolate the role of soil temperature feedbacks under historical (1976–2005) and future (2071–2100) warming conditions. Results indicate that soil temperature feedbacks can largely enhance interannual variability of summer daily mean and minimum surface air temperatures over East Asia, with strongest impacts over Mongolia and many areas of northern Tibetan Plateau and northern China, in the historical period. The soil temperature feedback strength below 925‐hPa mainly depends on changes in longwave radiation, surface heat flux partitioning, and temperature advections, while it is largely determined by the diabatic heating processes in the lower troposphere. The spatial distribution of soil temperature feedbacks is projected to change notably over East Asia under future warming condition. In particular, the impacts of soil temperature feedbacks on summer temperature are shown to be stronger in the lower troposphere under future condition. These results imply the important role of soil temperature feedbacks on air temperature variability for regional climate modeling especially in the context of climate change.

Ding, Yakui; Li, Yongping; Zheng, Heran; Ma, Yuan; Huang, Guohe; Li, Yanfeng; Shen, Zhenyao

doi: 10.1029/2021ef002225pmid: N/A

China's urban population will increase by 268 million from 2010 to 2030, with the consumption of a large number of resource‐intensive products. Quantitative analysis of the environmental impacts (water, energy and carbon) of urban agglomerations can make trade‐offs among water conservation, energy use, climate change mitigation, and urban development. In this study, a multi‐layer water‐energy‐carbon production path analysis (MWPPA) model is developed for identifying the key final demands, sectors and supply chain paths of the Pearl River Delta urban agglomeration (PUA). Results show that, water, energy and carbon‐emission intensities respectively reduced by 27.3%, 35.6% and 27.6% in 2015, compared to the levels in 2012. More than half of the water‐energy‐carbon (WEC) footprints are export‐driven, where Guangzhou, Shenzhen and Foshan dominate the WEC footprints of PUA. Results also disclose that Shenzhen is the main recipient of water‐energy, while Jiangmen and Huizhou are the main providers of water and energy, respectively. Policy makers are suggested that each industry actively integrate into global value chains in order to leverage its comparative advantage, and Huizhou should take full advantage of its fossil base to form a complete industry chain from the R&D end to the production end around the energy industry.

Walker, David W.; Cavalcante, Louise; Kchouk, Sarra; Ribeiro Neto, Germano G.; Dewulf, Art; Gondim, Rubens S.; Martins, Eduardo S. Passos Rodrigues; Melsen, Lieke A.; Souza Filho, Francisco de Assis; Vergopolan, Noemi; Van Oel, Pieter R.

doi: 10.1029/2021ef002456pmid: N/A

Drought management is currently informed by a variety of approaches, mostly responding to drought crisis when it happens. Toward more effective and integrated drought management, we introduce a conceptual drought diagnosis framework inspired by diagnostic concepts from the field of medicine. This framework comprises five steps: 1. Initial diagnostic assessment; 2. Diagnostic testing; 3. Consultation; 4. Communication of the diagnosis; and 5. Treatment and prognosis. To illustrate the need for the proposed approach, four case studies of recently drought‐affected regions were selected: the city of Cape Town, the state of California, the Northeast region of Brazil, and the Horn of Africa. Contrasting elements for these cases include the geographic extent and political boundaries, climate, socio‐economics, and the relevance of different water resources (e.g., rainfall, reservoirs, and aquifers). For each case, we identified documented practices and policies and reflected on them in terms of drought misdiagnosis or incomplete diagnosis that have aggravated socio‐economic and environmental drought impacts. A common example is the preference for technical solutions (e.g., installing infrastructure to augment water supply), rather than measures that reduce vulnerability. Analysis of these four drought case studies confirmed the anticipated need for a comprehensive approach to drought diagnosis for more successful treatment and prevention of drought. Using an analogy with medical science can be helpful toward comprehensively diagnosing droughts for a variety of contexts and assessing the effectiveness of proposed interventions. This framework can help drought managers to be more proactive in enabling drought‐affected regions to become more drought resilient in the future.

Potočki, K.; Hartmann, T.; Slavíková, L.; Collentine, D.; Veidemane, K.; Raška, P.; Barstad, J.; Evans, R.

doi: 10.1029/2021ef002491pmid: N/A

Flood risk management (FRM) aims to integrate necessary technical measures with environmental and societal approaches. Focusing on the process and governance of how to plan, implement, and maintain solutions therefore becomes essential. Among the different stakeholders, landowners are a key group to be considered. This contribution elaborates on the interconnections between land policy, FRM and private land ownership. It is based on the European COST Action network LAND4FLOOD, which brings together academics and stakeholders from various disciplines and more than 35 countries. We argue for a less project oriented and more process oriented approach, a focus on land management and more emphasis on small‐scale measures. This represents a break with some of the recent working paradigms of FRM.

Di Virgilio, Giovanni; Ji, Fei; Tam, Eugene; Nishant, Nidhi; Evans, Jason P.; Thomas, Chris; Riley, Matthew L.; Beyer, Kathleen; Grose, Michael R.; Narsey, Sugata; Delage, Francois

doi: 10.1029/2021ef002625pmid: N/A

Global climate models (GCMs) are essential for investigating climate change, but their coarse scale limits their efficacy for climate adaptation planning at the regional scales where climate impacts manifest. Dynamical downscaling of GCM outputs better resolves regional climate and thus provides improved guidance for climate policy at regional scales. Being expensive to run, downscaling uses a subset of GCMs, necessitating careful GCM selection. This evaluation identifies a suitable subset of CMIP6 GCMs for downscaling over Australia by assessing individual GCMs against three criteria: (a) performance simulating daily climate variable distributions, climate means, extremes, and modes; (b) model independence; and (c) climate change signal diversity. Over Australia, GCMs are generally biased cold (warm) for maximum (minimum) temperature, with larger biases for minimum temperature. GCMs are generally wet biased, especially over the monsoonal north, but dry biased over eastern regions. Most GCMs show larger biases for temperature and precipitation over geographically complex, heavily populated eastern regions, relative to other regions. Evaluations identify a distinct group of 11 GCMs that perform consistently poorly across climate variables, statistics, and timescales with widespread, statistically significant biases, versus 13 GCMs that show consistent adequate‐to‐good performance with substantially reduced errors. Assessment of model independence highlights the lack of independence between several high‐performing GCMs, particularly from allied modeling groups, demonstrating the importance of careful ensemble selection when making selective samples of climate space. Once GCM climate signal diversity is considered, 6–8 mid‐to‐high‐performing, independent GCMs occupy the full range of the future climate space and, thus, are suitable for dynamical downscaling over CORDEX‐Australasia.

Yin, Lichang; Tao, Fulu; Zhai, Ran; Chen, Yi; Hu, Jian; Wang, Zhenghui; Fu, Bojie

doi: 10.1029/2021ef002138pmid: N/A

Terrestrial ecosystem water retention (TEWR) service is subject to climate change and elevated atmospheric carbon dioxide concentration (eCO2), however, the relevant processes by which future climate change and eCO2 affect TEWR are poorly understood. Here, we use the factorial simulation experiments from the Inter‐Sectoral Impact Model Intercomparison Project to address this research question. The experiments are based on three dynamic global vegetation models forced with the same climate change scenarios. Results suggest that compared to the preindustrial level, during 2070–2099, (a) TEWR change is highly uncertain, especially in the Southern Hemisphere. (b) Climate change will dominate the pattern of future TEWR change compared with eCO2. (c) Precipitation and runoff change will dominate the future TEWR change in various regions, and the direct role of evapotranspiration (ET) on TEWR will be relatively small. (d) eCO2 will mainly affect vegetation dynamics in energy‐limited regions to affect the runoff, and consequently affecting TEWR change. (e) eCO2 will decrease ET and increase the runoff, resulting in a slight TWER change. These findings improve the understanding of the responses of TEWR to future climate change and eCO2.

Dezfuli, Amin; Razavi, Saman; Zaitchik, Benjamin F.

doi: 10.1029/2022ef002683pmid: N/A

The Middle East is one of the world's most vulnerable areas to climate change, which has exacerbated environmental, agricultural, water conflict, and public health issues in the region. Here we analyze the latest climate model projections of precipitation and temperature for the very high emissions scenario, SSP5‐8.5, to detect potential future changes in this region. A baseline period (1981–2010) is compared with the middle (2040–2069) and end (2070–2099) of the 21st century. The results, representing the worst‐case scenario, identify the Tigris‐Euphrates headwaters as the hotspot of future compounding effects of climate change in the Middle East. Those effects result from the coincidence of elevated temperature, reduced precipitation, and enhanced interannual variability of precipitation. The hotspot overlays the location of the Southeastern Anatolia Project (in Turkish, Güneydoğu Anadolu Projesi [GAP]) irrigation initiative. In this climate context, risks to GAP viability and downstream water security, and associated potential for water‐related conflicts and migration are considerable and demand a reconsideration of the risk‐benefit assessment of GAP. This need has become more urgent after the recent widespread and deadly climate‐related conflicts and wildfires in summer 2021 across the Middle East that further underlined vulnerability of the region to climate extremes.

Lockwood, Joseph W.; Oppenheimer, Michael; Lin, Ning; Kopp, Robert E.; Vecchi, Gabriel A.; Gori, Avantika

doi: 10.1029/2021ef002462pmid: 35860749

Future coastal flood hazard at many locations will be impacted by both tropical cyclone (TC) change and relative sea‐level rise (SLR). Despite sea level and TC activity being influenced by common thermodynamic and dynamic climate variables, their future changes are generally considered independently. Here, we investigate correlations between SLR and TC change derived from simulations of 26 Coupled Model Intercomparison Project Phase 6 models. We first explore correlations between SLR and TC activity by inference from two large‐scale factors known to modulate TC activity: potential intensity (PI) and vertical wind shear. Under the high emissions SSP5‐8.5, SLR is strongly correlated with PI change (positively) and vertical wind shear change (negatively) over much of the western North Atlantic and North West Pacific, with global mean surface air temperature (GSAT) modulating the co‐variability. To explore the impact of the joint changes on flood hazard, we conduct climatological–hydrodynamic modeling at five sites along the US East and Gulf Coasts. Positive correlations between SLR and TC change alter flood hazard projections, particularly at Wilmington, Charleston and New Orleans. For example, if positive correlations between SLR and TC changes are ignored in estimating flood hazard at Wilmington, the average projected change to the historical 100 years storm tide event is under‐estimated by 12%. Our results suggest that flood hazard assessments that neglect the joint influence of these factors and that do not reflect the full distribution of GSAT change may not accurately represent future flood hazard.

Zheng, Haiyan; Miao, Chiyuan; Li, Xiaoyan; Kong, Dongxian; Gou, Jiaojiao; Wu, Jingwen; Zhang, Shuping

doi: 10.1029/2021ef002564pmid: N/A

Documenting the spatiotemporal changes in vegetation cover and hydrological cycle of the Earth system and understanding how they interact are important especially under climate warming. In this research, we quantified the changes in vegetation and evapotranspiration (E) across China during 1982–2015 and then revealed the complex relationships in climate–vegetation–evapotranspiration system. Results show that the upward trend in vegetation leaf area index (LAI) during 2000–2015 (an increase of 0.95% per year) was almost 8 times the trend during 1982–1999. The zones of the Loess Plateau and the Three‐North Shelter Forest Program are the most notable areas for LAI increases between these two periods, with increases of 11.65% and 2.87%, respectively. Increased LAI, along with the warming climate, has accelerated E across China in the past several decades, and the annual increase in the E rate was 0.34% (1.34 mm year−1) during 1982–1999 and 0.40% (1.62 mm year−1) during 2000–2015. The zones of the Loess Plateau and the karst landform are the most notable areas for transpiration increases, with individual increases of 10% and 5%, respectively. In general, the dominant causes for evaporation changes across all of China are temperature and precipitation, while the main reasons for transpiration changes include temperature, LAI, and sunshine duration. This study improves our understanding of the relationships within the climate–vegetation–evapotranspiration system and provides important support for future ecological policies across China.

Murakmai, H.; Delworth, T. L.; Cooke, W. F.; Kapnick, S. B.; Hsu, P.‐C.

doi: 10.1029/2021ef002481pmid: N/A

The frequency of large‐scale anomalous precipitation events associated with heavy precipitation has been increasing in Japan. However, it is unclear if the increase is due to anthropogenic warming or internal variability. Also, it is challenging to develop an objective methodology to identify anomalous events because of the large variety of anomalous precipitation cases. In this study, we applied a deep learning technique to objectively detect anomalous precipitation events in Japan for both observations and simulations using high‐resolution climate models. The results show that the observed increases in anomalous heavy precipitation events in Western Japan during 1977–2015 were not made only by internal variability but the increases in anthropogenic forcing played an important role. Such events will continue to increase in frequency this century. The increases are attributable to the increasing frequency of tropical cyclones and enhanced frontal rainbands near Japan. These results highlight the mitigation challenge posed by the increasing occurrence of unprecedented precipitation events in the future.