Search

The influences of human activity on regional climate over China have been widely reported and drawn great attention from both the scientific community and governments. This paper reviews the evidence of the anthropogenic influence on regional climate over China from the perspectives of surface air temperature (SAT), precipitation, droughts, and surface wind speed, based on studies published since 2018. The reviewed evidence indicates that human activities, including greenhouse gas and anthropogenic aerosol emissions, land use and cover change, urbanization, and anthropogenic heat release, have contributed to changes in the SAT trend and the likelihood of regional record-breaking extreme high/low temperature events over China. The anthropogenically forced SAT signal can be detected back to the 1870s in the southeastern Tibetan Plateau region. Although the anthropogenic signal of summer precipitation over China is detectable and anthropogenic forcing has contributed to an increased likelihood of regional record-breaking heavy/low precipitation events, the anthropogenic precipitation signal over China is relatively obscure. Moreover, human activities have also contributed to a decline in surface wind speed, weakening of monsoon precipitation, and an increase in the frequency of droughts and compound extreme climate/weather events over China in recent decades. This review can serve as a reference both for further understanding the causes of regional climate changes over China and for sound decision-making on regional climate mitigation and adaptation. Additionally, a few key or challenging scientific issues associated with the human influence on regional climate changes are discussed in the context of future research. [ABSTRACT FROM AUTHOR]

Forests and the dynamic changes play decisive roles in soil erosion prevention, biodiversity conservation and climate warming mitigation, and are crucial for China to achieve carbon neutrality because of the ability for carbon uptake. China's forests experienced a substantial change over the past century, primarily since the forest conservation and restoration programs were implemented. In this paper, the progress of China's forest change and the similarities and differences of the spatio-temporal patterns from multi-dimension coupling with ground surveys and satellite observations were reviewed comprehensively, and the drivers of forest change were discussed. Our review reported that: 1) China's forests experienced an extensive forest gain/restoration in vegetation greenness, forest cover, and aboveground biomass since the 1970s. 2) Changes in various forest parameters suggested distinctive spatiotemporal patterns in China. Consistent hotspots of forest gain clustered in the Loess Plateau and the southwestern China from most studies, while controversial conclusions about forest loss/degradation were found in the spatial distribution. 3) The geographic discrepancy of forest changes may be related to climate change, human activities, and forest disturbances. Variations in forest dynamics are prerequisites to exploring the effects of natural conditions and forestry policies on forest cover, and strengthening understanding of the carbon cycle. These findings can provide valuable insights for various ecological services in further studies and a scientific basis for forest management and policy-making in China. [ABSTRACT FROM AUTHOR]

The current nationally determined contributions, pledged by the countries under the Paris Agreement, are far from limiting climate change to below 2 ∘C temperature increase by the end of the century. The necessary ratcheting up of climate policy is projected to come with a wide array of additional benefits, in particular a reduction of today's 4.5 million annual premature deaths due to poor air quality. This paper therefore addresses the question how climate policy and air pollution–related health impacts interplay until 2050 by developing a comprehensive global modeling framework along the cause and effect chain of air pollution–induced social costs. We find that ratcheting up climate policy to a 2 ∘ compliant pathway results in welfare benefits through reduced air pollution that are larger than mitigation costs, even with avoided climate change damages neglected. The regional analysis demonstrates that the 2 ∘C pathway is therefore, from a social cost perspective, a "no-regret option" in the global aggregate, but in particular for China and India due to high air quality benefits, and also for developed regions due to net negative mitigation costs. Energy and resource exporting regions, on the other hand, face higher mitigation cost than benefits. Our analysis further shows that the result of higher health benefits than mitigation costs is robust across various air pollution control scenarios. However, although climate mitigation results in substantial air pollution emission reductions overall, we find significant remaining emissions in the transport and industry sectors even in a 2 ∘C world. We therefore call for further research in how to optimally exploit climate policy and air pollution control, deriving climate change mitigation pathways that maximize co-benefits. [ABSTRACT FROM AUTHOR]