Northern East Asia Research Articles

Phylogeographic analyses of a widely distributed Populus davidiana: Further evidence for the existence of glacial refugia of cool-temperate deciduous trees in northern East Asia.

Despite several phylogeographic studies had provided evidence to support the existence of glacial refugia of cool‐temperate deciduous trees in northeast China, the species used in these studies were limited by the species ranges, which could not exclude the possibility that northern populations were the colonists from southern refugial populations during the last glacial maximum (LGM). Here, we estimated the nucleotide variation in Populus davidiana, a widespread species distributed in Eurasia. Three groups in northeast, central, and southwest China were constructed according to the simulation results from SAMOVA, composition of chloroplast haplotypes and structure results. We revealed that the northeast China had endemic haplotypes, the haplotypes and nucleotide diversity in northern regions were not lower than that in southern China, and this species has not experienced population expansion base on the estimation of Bayesian skyline plots. Ecological niche modeling (ENM) indicated that the northeast China had a high suitability score during the last glacial maximum. The combined evidence clearly demonstrated that northeastern and southwestern refugia were maintained across the current distributional range of P. davidiana during the LGM. The genetic differentiation between these two refugia might be mainly caused by differences of climate among these areas. The phylogeographic analyses of a widely distributed P. davidiana provided robust evidence to clarify the issue of refugia in northeast China, and these results are of great importance for understanding the influence of Quaternary glaciations on the distribution and evolution of species in East Asia.

Revisiting the Northern Mode of East Asian Winter Monsoon Variation and Its Response to Global Warming

This study revisits the northern mode of East Asian winter monsoon (EAWM) variation and investigates its response to global warming based on the ERA dataset and outputs from phase 5 of the Coupled Model Intercomparison Project (CMIP5) models. Results show that the observed variation in East Asian surface air temperature (EAT) is tightly coupled with sea level pressure variation in the expanded Siberian high (SH) region during boreal winter. The first singular value decomposition (SVD) mode of the EAT and SH explains 95% of the squared covariance in observations from 1961 to 2005, which actually represents the northern mode of EAWM variation. Meanwhile, the first SVD mode of the EAT and SH is verified to be equivalent to the first empirical orthogonal function mode (EOF1) of the EAT and SH, respectively. Since the leading mode of the temperature variation is significantly influenced by radiative forcing in a rapidly warming climate, for reliable projection of long-term changes in the northern mode of the EAWM, we further employ the EOF1 mode of the SH to represent the northern mode of EAWM variation. The models can well reproduce this coupling between the EAT and SH in historical simulations. Meanwhile, a robust weakening of the northern mode of the EAWM is found in the RCP4.5 scenario, and with stronger warming in the RCP8.5 scenario, the weakening of the EAWM is more pronounced. It is found that the weakening of the northern mode of the EAWM can contribute 6.7% and 9.4% of the warming trend in northern East Asian temperature under the RCP4.5 and RCP8.5 scenarios, respectively.

The role of anthropogenic aerosols in future precipitation extremes over the Asian Monsoon Region

The role of anthropogenic aerosols in future projections (up to 2100) of summertime precipitation and precipitation extremes over the Asian monsoon region is investigated, by comparing two sets of the Community Earth System Model (CESM1) large ensemble simulations under the Representative Concentration Pathway 8.5 scenario (RCP8.5) and the corresponding scenario with aerosol fixed at 2005 levels (RCP8.5_FixA). The model is verified to be performing well in capturing present-day (1986–2005) climate and precipitation extremes. Our results suggest that the Asian monsoon region would become progressively warmer and wetter in the future under RCP8.5, while precipitation extremes will be significantly aggravated due to anthropogenic aerosol mitigation, particularly over East Asia. Specifically, aerosol reductions are found to shift the distribution of precipitation mean and extremes to larger values. For example, aerosol reductions would result in an increased likelihood of extreme precipitation (e.g. the maximum consecutive 5-day precipitation amount) and related disasters. Sensitivities of changes in precipitation mean and extremes to local warming from aerosol reductions are much larger than that from greenhouse gas increases. This is particularly important over East Asia in accordance with larger magnitudes of aerosol reductions compared to South Asia. Finally, by investigating the response of the climate system to aerosol changes, our findings demonstrate that aerosol induced precipitation changes would be dominated by aerosol–radiation–cloud forcing over northern East Asia and aerosol forcing induced large-scale circulation anomalies over southern East and South Asia.

Assessing the internal variability in multi-decadal trends of summer surface air temperature over East Asia with a large ensemble of GCM simulations

This study investigates the impact of internal variability on East Asian summer (June–July–August) surface air temperature (SAT) trends on the multidecadal time scale based on a 30-member ensemble of simulations that share the same external forcing from 1970 to 2005. The ensemble-mean SAT in East Asia shows a positive trend, but the patterns and the magnitudes in the individual members are remarkably diverse, highlighting the strong effect of internal variability. The first two leading empirical orthogonal function (EOF) modes of the SAT trends among ensemble members are used to represent the leading patterns of internally generated SAT change in East Asia. The first EOF mode displays a south-north dipole structure, associated with a zonally banded circulation pattern over East Asia and the North Pacific. The second mode represents coherent trend in North China, Korea and Japan, accompanied by the Northern Hemisphere annular mode (NAM)-like circulation changes. A dynamical adjustment method is applied to reduce circulation-induced internal variability in SAT, and the adjusted SAT trends are much less variable among ensemble members and more in line with the ensemble mean than the raw trends. Observed evidences show that the summertime SAT in most of East Asia, especially in northern East Asia, has experienced rapid warming in recent decades. After dynamical adjustment, the residual trends of SAT in observations are weaker than the raw trends, especially at high and middle latitudes, suggesting the enhanced warming in northern East Asia over the recent decades was not entirely anthropogenic but partly caused by internal variability.

Water Vapor Transport Related to the Interdecadal Shift of Summer Precipitation over Northern East Asia in the Late 1990s

In this study, an interdecadal shift of summer precipitation over northern East Asia (NEA) was identified, demonstrating that summer precipitation decreased abruptly after 1998/99. The synchronous shift in summer moisture budget and water vapor transport over NEA was further investigated by using the NCEP/NCAR reanalysis data. The results indicate that water vapor transported northward into NEA from three low-latitude paths was limited because most water vapor was transported eastward. Water vapor transported from the westerly path in mid–high (WMH) latitudes exhibited significant correlations with summer precipitation in NEA and experienced a significant adjustment in the late 1990s. Regarding the spatial distributions of water vapor transport, less input was found through the western boundary while more output occurred through the eastern boundary of NEA, and zonal water vapor transport fluxes mainly concentrated at the low to middle levels, which led to the summer precipitation shift in NEA around the late 1990s. Furthermore, it is also confirmed that the wind anomalies (rather than the moisture disturbance) as the dominant internal dynamic factor and Pacific Decadal Oscillation/Atlantic Multidecadal Oscillation (PDO/AMO) as possible external force played important roles in influencing the water vapor transport and causing the summer precipitation shift over NEA in the late 1990s.

A Centennial Episode of Weak East Asian Summer Monsoon in the Midst of the Medieval Warming

AbstractRecent paleoproxy evidence has suggested that there is a centennial episode of weaker East Asian summer monsoon (EASM) within the Medieval Warm Period, in which the EASM is generally strong. This study aims to explore the causes of this phenomenon and determine what controls the centennial variability of the EASM. With the Community Earth System Model, a suite of control and forced experiments were conducted for the past 2,000 years. The model simulates a warm period over EA (East Asia) from CE 801–1250 with a generally increased summer mean precipitation over the northern EA; however, during CE 980–1100, the EASM is significantly weaker. On the multi‐decadal to centennial time scale, a strong EASM is associated with a La Niña‐like Indo‐Pacific warming, and a weak EASM with the El Niño‐like conditions. This sea surface temperature anomaly pattern represents the leading EOF (empirical orthogonal function) mode of centennial sea surface temperature variations, which are primarily forced by solar radiation and volcanic activity. In contrast, land use/land cover and greenhouse gases as well as internal dynamics play a negligible role. The weak EASM during CE 980–1100 is attributed to the relatively low solar radiation, which leads to a prevailing El Niño‐like Indo‐Pacific cooling with the strongest cooling occurring in the equatorial western Pacific. The suppressed convection over the equatorial western Pacific directly induces a Philippine Sea anticyclone anomaly, which increases the southern China precipitation, while suppressing Philippine Sea precipitation. The latter excites a meridional teleconnection that induces anomalous northerly winds and dry conditions over northern China.

Functional characterization of an oxidosqualene cyclase (PdFRS) encoding a monofunctional friedelin synthase in Populus davidiana.

An oxidosqualene cyclase (PdFRS) from Populus davidiana was characterized as a monofunctional friedelin synthase by its heterologous expression in yeast and overexpression in plants. Triterpenesare one of the largest classes of plant chemical compounds composed of threeterpeneunits, which form the basic skeleton of all sterols and saponins. Friedelin (friedelan-3-one), a pentacyclic triterpene, occurs in many plant families and is particularly present in rich amounts in cork tissues from trees. The biosynthesis of friedelin occurs through the oxidosqualene cyclase (OSC) enzyme that generates friedelin from 2,3-oxidosqualene after the maximum rearrangement of a triterpene skeleton. Populus davidiana is called Korean aspen and grows in northern East Asia. From 57,322 unique sequences generated from the P. davidiana transcriptome database, one complete coding sequence (PdFRS) was obtained from a contig, which showed 74% identity to Betula platyphylla β-amyrin synthase and 73% identity with friedelin synthase from Maytenus ilicifolia. The open reading frame (ORF) region of the PdFRS sequence was 2280bp long and composed a 759 amino acid protein with a predicted molecular mass of 87.81kDa. qPCR analysis revealed that methyl jasmonate treatments strongly upregulated PdFRS gene expression and resulted in enhanced friedelin accumulation in leaves. Heterologous expression of the PdFRS gene in yeast resulted in the production of friedelin triterpene as a single product, which was confirmed by comparison with the mass fragmentation pattern from an authentic friedelin standard by GC/MS analysis. Transgenic P. davidiana overexpressing the PdFRS gene was constructed via Agrobacterium-mediated transformation. Overexpression of PdFRS in transgenic P. davidiana lines resulted in enhanced friedelin production.

Dissimilar effects of two El Niño types on PM2.5 concentrations in East Asia

We investigate the effects of natural variability of meteorological fields on surface PM2.5 concentration changes in East Asia during El Niño periods for the past three decades (1980–2014) through GEOS-Chem 3D global chemical transport model simulations. First, our evaluation of the model with anthropogenic emissions for 2006 and a comparison against observations show that the simulated results accurately reproduced the observed spatial distribution of annual mean aerosol concentrations for 2006–2007 including inorganic (sulfate, ammonium, and nitrate) and carbonaceous (organic and black carbon) aerosols in the surface air. Based on the Oceanic Niño Index, the assimilated meteorological data used in the model simulations indicate that 10 El Niño events occurred for the past three decades (1980–2014). We further classified the 10 El Niño events into 6 central Pacific El Niño (C-type) and 4 eastern Pacific El Niño (E-type) to examine the different roles of two El Niño types in determining seasonal surface PM2.5 concentrations in East Asia. We find opposite impacts on the seasonal surface PM2.5 concentrations depending on two El Niño types, such that the surface PM2.5 concentrations during the E-type period are higher than the climatological mean value, especially in northern East Asia. The peak increase of as much as 20% occurs in winter and is sustained until the following spring. However, the C-type period shows a decrease in seasonal PM2.5 concentrations in northern East Asia compare to the climatological mean, and the peak decrease of as much as 10% occurs in the following spring. The different of two El Niño types also have dissimilar impacts on surface PM2.5 concentrations in southeastern China. Natural variation of aerosol concentrations driven by the different of two El Niño types appears to be significant and would be an important factor in determining the inter-annual variation of aerosol concentrations in East Asia.

Ancient migrations in Southeast Asia

Human Genomics The past movements and peopling of Southeast Asia have been poorly represented in ancient DNA studies (see the Perspective by Bellwood). Lipson et al. generated sequences from people inhabiting Southeast Asia from about 1700 to 4100 years ago. Screening of more than a hundred individuals from five sites yielded ancient DNA from 18 individuals. Comparisons with present-day populations suggest two waves of mixing between resident populations. The first mix was between local hunter-gatherers and incoming farmers associated with the Neolithic spreading from South China. A second event resulted in an additional pulse of genetic material from China to Southeast Asia associated with a Bronze Age migration. McColl et al. sequenced 26 ancient genomes from Southeast Asia and Japan spanning from the late Neolithic to the Iron Age. They found that present-day populations are the result of mixing among four ancient populations, including multiple waves of genetic material from more northern East Asian populations. Science , this issue p. [92][1], p. [88][2]; see also p. [31][3] [1]: /lookup/doi/10.1126/science.aat3188 [2]: /lookup/doi/10.1126/science.aat3628 [3]: /lookup/doi/10.1126/science.aat8662

Understanding the Interdecadal Variability of East Asian Summer Monsoon Precipitation: Joint Influence of Three Oceanic Signals

Abstract East Asian summer monsoon precipitation (EASMP) features complicated interdecadal variability with multiple time periods and spatial patterns. Using century-long datasets of HadISST, CRU precipitation, and the ECMWF twentieth-century reanalysis (ERA-20C), this study examines the joint influence of three oceanic interdecadal signals [i.e., Pacific decadal oscillation (PDO), Atlantic multidecadal oscillation (AMO), and Indian Ocean Basin mode (IOBM)] on the EASMP, which, however, is found not to be simply a linear combination of their individual effects. When PDO and AMO are out of phase, the same-sign SST anomalies occur in the North Pacific and North Atlantic, and a zonally orientated teleconnection wave train appears across the Eurasian mid-to-high latitudes, propagating from the North Atlantic to northern East Asia along the Asian westerly jet waveguide. Correspondingly, the interdecadal precipitation anomalies are characterized by a meridional tripole mode over eastern China. When PDO and AMO are in phase, with opposite sign SST anomalies in the North Pacific and North Atlantic, the sandwich pattern of anomalous stationary Rossby wavenumber tends to reduce the effect of the waveguide in the eastern Mediterranean region, and the teleconnection wave train from the North Atlantic travels only to western central Asia along a great circle route, causing Indian summer monsoon precipitation (ISMP) anomalies. The ISMP anomalies, in turn, interact with the teleconnection wave train induced by the PDO and AMO, leading to a meridional dipole mode of interdecadal precipitation anomalies over eastern China. Through the impact on the ISMP, the IOBM exerts significantly linear modulation on the combined impacts of PDO and AMO, especially over northern East Asia.

Vegetation change and evolutionary response of large mammal fauna during the Mid-Pleistocene Transition in temperate northern East Asia

We present new pollen data from a drilling core from the North China Plain which illustrate the nature of vegetation evolution in the temperate zone of Asia during an interval containing the Mid-Pleistocene Transition (MPT), ~1.2–0.7 Ma. Results show that, from 1.7–1.2 Ma, closed needle-leaved and broadleaved mixed forest predominated. The most important vegetation change event occurred at 1.2 Ma when there was a decline in coniferous forest and a significant increase in Artemisia, Chenopodiaceae and Poaceae grassland. There was a continued degradation of the regional forest vegetation and its replacement by woody grassland about 0.7 Ma. Patterns of vegetation change correlate closely with the key climate fluctuations of the MPT and coincide with major turnover events of large mammalian fauna (>10 kg) in China. In particular, >50% of large mammalian species became extinct in the course of the forest decline; however, they were replaced by new mammalian species after 0.7 Ma. Comparison of the vegetation and faunal records indicates that the process of forest replacement by grassland in the northern temperate zone during the MPT was associated with an acceleration of the rate of turnover of the large mammalian fauna, in terms of extinction and speciation.

Social and biological intergroup hierarchy beliefs: A cross-cultural comparison between the US and South Korea

The present research investigated social and biological intergroup hierarchy beliefs in the US and South Korea, representative Northern European-heritage and East Asian cultures, respectively. We h...

Social and biological intergroup hierarchy beliefs: A cross-cultural comparison between the US and South Korea

The present research investigated social and biological intergroup hierarchy beliefs in the US and South Korea, representative Northern European-heritage and East Asian cultures, respectively. We hypothesized that individual-orientation (the emphasis on individuals and individual achievements) and group-orientation (the emphasis on groups and efficient functioning of groups) would predict social and biological hierarchy beliefs differently within and between these cultures. As expected, intergroup hierarchy beliefs were stronger in South Korea than in the US, particularly for biological hierarchy beliefs. Multigroup structural equation modeling analyses revealed that group-orientation predicted intergroup hierarchy beliefs across cultures, but more strongly in South Korea than in the US. Also, an emphasis on individual achievements predicted social hierarchy beliefs only in the US, whereas an emphasis on roles/positions within groups predicted social and biological hierarchy beliefs only in South Korea. Results implied that intergroup hierarchy beliefs may be generally associated with group-orientation and the value of competence or efficiency in each culture.

Ancient genomes document multiple waves of migration in Southeast Asian prehistory.

Southeast Asia is home to rich human genetic and linguistic diversity, but the details of past population movements in the region are not well known. Here, we report genome-wide ancient DNA data from 18 Southeast Asian individuals spanning from the Neolithic period through the Iron Age (4100 to 1700 years ago). Early farmers from Man Bac in Vietnam exhibit a mixture of East Asian (southern Chinese agriculturalist) and deeply diverged eastern Eurasian (hunter-gatherer) ancestry characteristic of Austroasiatic speakers, with similar ancestry as far south as Indonesia providing evidence for an expansive initial spread of Austroasiatic languages. By the Bronze Age, in a parallel pattern to Europe, sites in Vietnam and Myanmar show close connections to present-day majority groups, reflecting substantial additional influxes of migrants.

An inter-decadal increase in summer sea level pressure over the Mongolian region around the early 1990s

The East Asian summer monsoon is affected by processes in the mid-high latitudes in addition to various tropical and subtropical systems. The present study investigates the summer sea level pressure (SLP) variability over northern East Asia (NEA) and emphasizes the closed active center over the Mongolian region. It is found that the seasonal mean Mongolian SLP (MSLP) anomaly is closely connected with the variability of summertime regional synoptic extra-tropical cyclones on longer time scales. A significant inter-decadal increase in the MSLP around the early 1990s has been detected, which is accompanied by a weakening in the activity of regional extra-tropical cyclones. Recent warming over NEA may have a contribution to the inter-decadal change, which features evidently meridional inhomogeneity around 45°N. The inhomogeneous air temperature anomaly distribution results in decreased vertical wind shear, reduced atmospheric baroclinicity over the Mongolian region, and thus inactive regional cyclones and increased MSLP in the latter decade. The associated temperature anomaly distribution may be partly attributed to regional inhomogeneity in cloud and radiation anomalies, and it is further maintained by two positive feedback mechanisms associated with atmospheric internal processes: one via adiabatic heating and the other via horizontal temperature advection.

Seasonal variation and chemical characterization of PM<sub>2.5</sub> in northwestern Philippines

Abstract. The seasonal and chemical characteristics of fine particulate matter (PM2.5) were investigated in Burgos, Ilocos Norte, located at the northwestern edge of the Philippines. Each 24 h sample of fine aerosol was collected for four seasons. Fine particulate in the region shows strong seasonal variation in both concentration and composition. Highest mass concentration was seen during the boreal spring season with a mean mass concentration of 21.6 ± 6.6 µg m−3, and lowest was in fall with a mean concentration of 8.4 ± 2.3 µg m−3. Three-day wind back trajectory analysis of air mass reveals the influence of the northwestern Pacific monsoon regimes on PM2.5 concentration. During southwest monsoon, sea salt was the dominant component of fine aerosols carried by moist air from the South China Sea. During northeast monsoon, on the other hand, both wind and receptor model analysis showed that higher particulate concentration was due to the long-range transport (LRT) of anthropogenic emissions from northern East Asia. Overall, sea salt and soil comprise 33 % of total PM2.5 concentration, while local biomass burning makes up 33 %. LRT of industrial emission, solid waste burning and secondary sulfate from East Asia have a mean contribution of 34 % to the total fine particulate for the whole sampling period.

The chill of a warming world

Climate Extremes Why have some winters been so cold in some of the northern midlatitudes, even though global climate is getting hotter? Paradoxically, the answer may be that the Arctic itself is warming so quickly. Cohen et al. show that there is a clear relationship between Arctic temperatures and severe winter weather for the United States over the past two decades and that severe winter weather in the eastern United States has become more frequent as Arctic temperatures have risen. Although they were not included in the analysis, this relationship is likely valid for northern Europe and East Asia as well. Nat. Commun. 10.1038/s41467-018-02992-9 (2018).

Toward Predicting Changes in the Land Monsoon Rainfall a Decade in Advance

Predictions of changes of the land monsoon rainfall (LMR) in the coming decades are of vital importance for successful sustainable economic development. Current dynamic models, though, have shown little skill in the decadal prediction of the Northern Hemisphere (NH) LMR (NHLMR). The physical basis and predictability for such predictions remain largely unexplored. Decadal change of the NHLMR reflects changes in the total NH continental precipitation, tropical general circulation, and regional land monsoon rainfall over northern Africa, India, East Asia, and North America. Using observations from 1901 to 2014 and numerical experiments, it is shown that the decadal variability of the NHLMR is rooted primarily in (i) the north–south hemispheric thermal contrast in the Atlantic–Indian Ocean sector measured by the North Atlantic–south Indian Ocean dipole (NAID) sea surface temperature (SST) index and (ii) an east–west thermal contrast in the Pacific measured by an extended El Niño–Southern Oscillation (XEN) index. Results from a 500-yr preindustrial control experiment demonstrate that the leading mode of decadal NHLMR and the associated NAID and XEN SST anomalies may be largely an internal mode of Earth’s climate system, although possibly modified by natural and anthropogenic external forcing. A 51-yr, independent forward-rolling decadal hindcast was made with a hybrid dynamic conceptual model and using the NAID index predicted by a multiclimate model ensemble. The results demonstrate that the decadal changes in the NHLMR can be predicted approximately a decade in advance with significant skills, opening a promising way forward for decadal predictions of regional land monsoon rainfall worldwide.

Time of emergence in regional precipitation changes: an updated assessment using the CMIP5 multi-model ensemble

This study conducted an updated time of emergence (ToE) analysis of regional precipitation changes over land regions across the globe using multiple climate models from the Coupled Model Intercomparison Project phase 5 (CMIP5). ToEs were estimated for 14 selected hotspots over two seasons of April to September (AS) and October to March (OM) from three RCP scenarios representing low (RCP2.6), medium (RCP4.5), and high (RCP8.5) emissions. Results from the RCP8.5 scenario indicate that ToEs would occur before 2040 over seven hotspots including three northern high-latitude regions (OM wettening), East Africa (OM wettening), South Asia (AS wettening), East Asia (AS wettening) and South Africa (AS drying). The Mediterranean (both OM and AS drying) is expected to experience ToEs in the mid-twenty-first century (2040-2080). In order to measure possible benefits from taking low-emission scenarios, ToE differences were examined between the RCP2.6 scenario and the RCP4.5 and RCP8.5 scenarios. Significant ToE delays from 26 years to longer than 67 years were identified over East Africa (OM wettening), the Mediterranean (both AS and OM drying), South Asia (AS wettening), and South Africa (AS drying). Further, we investigated ToE differences between CMIP3-based and CMIP5-based models using the same number of models for the comparable scenario pairs (SRESA2 vs. RCP8.5, and SRESB1 vs. RCP4.5). Results were largely consistent between two model groups, indicating the robustness of ToE results. Considerable differences in ToEs (larger than 20 years) between two model groups appeared over East Asia and South Asia (AS wettening) and South Africa (AS drying), which were found due to stronger signals in CMIP5 models. Our results provide useful information on the timing of emerging signals in regional and seasonal hydrological changes, having important implications for associated adaptation and mitigation plans.

Projections of temperature-related excess mortality under climate change scenarios

SummaryBackgroundClimate change can directly affect human health by varying exposure to non-optimal outdoor temperature. However, evidence on this direct impact at a global scale is limited, mainly due to issues in modelling and projecting complex and highly heterogeneous epidemiological relationships across different populations and climates.MethodsWe collected observed daily time series of mean temperature and mortality counts for all causes or non-external causes only, in periods ranging from Jan 1, 1984, to Dec 31, 2015, from various locations across the globe through the Multi-Country Multi-City Collaborative Research Network. We estimated temperature–mortality relationships through a two-stage time series design. We generated current and future daily mean temperature series under four scenarios of climate change, determined by varying trajectories of greenhouse gas emissions, using five general circulation models. We projected excess mortality for cold and heat and their net change in 1990–2099 under each scenario of climate change, assuming no adaptation or population changes.FindingsOur dataset comprised 451 locations in 23 countries across nine regions of the world, including 85 879 895 deaths. Results indicate, on average, a net increase in temperature-related excess mortality under high-emission scenarios, although with important geographical differences. In temperate areas such as northern Europe, east Asia, and Australia, the less intense warming and large decrease in cold-related excess would induce a null or marginally negative net effect, with the net change in 2090–99 compared with 2010–19 ranging from −1·2% (empirical 95% CI −3·6 to 1·4) in Australia to −0·1% (−2·1 to 1·6) in east Asia under the highest emission scenario, although the decreasing trends would reverse during the course of the century. Conversely, warmer regions, such as the central and southern parts of America or Europe, and especially southeast Asia, would experience a sharp surge in heat-related impacts and extremely large net increases, with the net change at the end of the century ranging from 3·0% (−3·0 to 9·3) in Central America to 12·7% (−4·7 to 28·1) in southeast Asia under the highest emission scenario. Most of the health effects directly due to temperature increase could be avoided under scenarios involving mitigation strategies to limit emissions and further warming of the planet.InterpretationThis study shows the negative health impacts of climate change that, under high-emission scenarios, would disproportionately affect warmer and poorer regions of the world. Comparison with lower emission scenarios emphasises the importance of mitigation policies for limiting global warming and reducing the associated health risks.FundingUK Medical Research Council.