Yangyang Xu

Texas A&M University | TAMU · Department of Atmospheric Sciences

Global climate models project a large increase in the frequency and intensity of heat extremes (HEs) during the 21st century under the Representative Pathway Concentration (RCP8.5) scenario. To assess the relative sensitivity of future HEs to the level of greenhouse gas (GHG) increases and aerosol emission decreases, we contrast Community Earth Sys...

Radiative forcing by reflecting (e.g., sulfate, SO4) and absorbing (e.g., black carbon, BC) aerosols is distinct: the former cools the planet by reducing solar radiation at the top of the atmosphere and the surface, without largely affecting the atmospheric column, while the latter heats the atmosphere directly. Despite the fundamental difference i...

There is growing international interest in mitigating climate change during the early part of this century by reducing emissions of short-lived climate pollutants (SLCPs), in addition to reducing emissions of CO2. The SLCPs include methane (CH4), black carbon aerosols (BC), tropospheric ozone (O3) and hydrofluorocarbons (HFCs). Recent studies have...

[1] Carbonaceous aerosols have the potential to impact climate directly through absorption of incoming solar radiation and indirectly by affecting cloud and precipitation. Recent modeling studies have made great efforts to simulate both the spatial and temporal distributions of carbonaceous aerosol's optical properties and radiative forcing. This s...

The Earth's climate system was subject to two multi-decadal warming trends in the beginning (1910-1940) and end (1975-2005) of the 20th century, having been interrupted only by a cooling trend in mid-century (1940-1975). The spatio-temporal distribution of surface temperature during this time, especially the land-ocean warming contrast in recent de...

The day-to-day diversity of thermal conditions determines the range of human thermal sensation within a year, and its long-term shift affects thermal comfort demand with profound economic and public health implications. While previous studies have documented historical trends in specific thermal stress events regionally, such as heat waves and cold...

We collected surface snow samples from three different glaciers – Yala, Thana, and Sachin – in the central and western Himalayas to understand the spatial variability and radiative impacts of light-absorbing particles. The Yala and Thana glaciers in Nepal and Bhutan, respectively, were selected to represent the central Himalayas. The Sachin glacier...

Significance This study clarifies the need for comprehensive CO 2 and non-CO 2 mitigation approaches to address both near-term and long-term warming. Non-CO 2 greenhouse gases (GHGs) are responsible for nearly half of all climate forcing from GHG. However, the importance of non-CO 2 pollutants, in particular short-lived climate pollutants, in clima...

Climate change and air pollution are two intimately interlinked global concerns. The frequency, intensity, and duration of heat waves are projected to increase globally under future climate change. A growing body of evidence indicates that health risks associated with the joint exposure to heat waves and air pollution can be greater than that due t...

Stratospheric aerosol geoengineering has been proposed as a potential solution to reduce climate change and its impacts. Here, we explore the responses of the Hadley circulation (HC) intensity and the intertropical convergence zone (ITCZ) using the strategic stratospheric aerosol geoengineering, in which sulfur dioxide was injected into the stratos...

The global mean surface temperature cooled slightly in the mid-twentieth century despite a continuous increase in greenhouse gas concentrations. The cooling was strongest in the Northern Hemisphere mid-latitudes, while the Southern Hemisphere mid-latitudes experienced moderate warming. This apparent contradiction is often attributed to internal mul...

The redesign of energy and economic systems to stabilize climate change is hindered by the lack of quantitative treatment of the role that human–natural systems interactions play in what society can do to tackle climate change. Here we present an integrated socio–energy–ecologic–climate model framework for understanding the role of human–natural sy...

Surface level ozone pollution imposes significant crop yield damages. However, the quantification has mainly involved chamber experiments, which may not be representative of results in farm fields. Additionally, the relative impacts of ozone under future climate change and their possible interactions remain poorly understood. Here we attempt to emp...

Biomass and fossil fuel burning impact air quality by injecting fine particulate matter (PM2.5) and its precursors into the atmosphere, which poses serious threats to human health. However, the surface concentration of PM2.5 depends not only on the magnitude of emissions, but also secondary production, transport, and removal. For example, in respon...

The response of precipitation extremes (PEs) to global warming is found to be nonlinear in Community Earth System Model version 1 (CESM1) and other global climate models (Pendergrass et al., 2019), which led to the concern that it is not accurate to approximate the response of PE to a single forcing as the difference between simulations with all fo...

This paper compiles indices for the El Niño—Southern Oscillation (ENSO) and seven unforced decadal-to-multidecadal climate modes (Interdecadal Pacific Oscillation (IPO), Tripole Pacific Index (TPI), Pacific Decadal Oscillation focused over North Pacific (PDO) and South Pacific (SPDO), North Atlantic Multidecadal Oscillation (AMO), South Atlantic Mu...

Anthropogenic aerosols (AAs) induce global and regional tropospheric circulation adjustments due to the radiative energy perturbations. The overall cooling effects of AA, which mask a portion of global warming, have been the subject of many studies but still have large uncertainty. The interhemispheric contrast in AA forcing has also been demonstra...

We collected surface snow samples from three different glaciers: Yala, Thana, and Sachin in the central and western Himalayas to understand the spatial variability and radiative impacts of light-absorbing particles. The Yala and Thana glaciers in Nepal and Bhutan, respectively, were selected to represent the central Himalayas. The Sachin glacier in...

Global climate change has increased the risks of extreme weather-related disasters, leading to severe public health burdens. In February 2021, Winter Storm Uri brought severe cold to southern United States and caused unprecedented health and safety concerns. Residents in subsidized rental housing were among the most vulnerable to cold stress during...

Frequent and severe PM2.5 pollution over China seriously harms natural environment and human health. Changes in meteorological conditions in the recent decades has been recognized to contribute to the long-term increase in PM2.5 pollution in North China (NC). However, the dominant climatic factors driving the interdecadal changes of the weather con...

Thermal stress poses a major public health threat in a warming world, especially to disadvantaged communities. At the population group level, human thermal stress is heavily affected by landscape heterogeneities such as terrain, surface water, and vegetation. High-spatial-resolution thermal-stress indices, containing more detailed spatial informati...

As the largest emitter in the world, China recently pledged to reach a carbon peak before 2030 and carbon neutrality before 2060, which could accelerate the progress of mitigating negative climate change effects. In this study, we used the Minimum Complexity Earth Simulator and a semi-empirical statistical model to quantify the global mean temperat...

Anthropogenic Aerosols (AA) induce global and regional tropospheric circulation adjustments due to the radiative energy perturbations. The overall cooling effects of AA since the pre-industrial (PI) era, to mask a portion of global warming, have been the subject of many studies with large uncertainty remaining. The interhemispheric contrast in AA f...

Methane mitigation is essential for addressing climate change, but the value of rapidly implementing available mitigation measures is not well understood. In this paper, we analyze the climate benefits of fast action to reduce methane emissions as compared to slower and delayed mitigation timelines. We find that the scale up and deployment of great...

This study discusses year-long (October 2016–September 2017) observations of atmospheric black carbon (BC) mass concentration, its source and sector contributions using a chemical transport model at a high-altitude (28°12'49.21"N, 85°36'33.77"E, 4900 masl) site located near the Yala Glacier in the central Himalayas, Nepal. During a field campaign,...

Anthropogenic aerosol (AA) forcing has been shown as a critical driver of climate change over Asia since the mid-20th century. Here we show that almost all Coupled Model Intercomparison Project Phase 6 (CMIP6) models fail to capture the observed dipole pattern of aerosol optical depth (AOD) trends over Asia during 2006–2014, last decade of CMIP6 hi...

Though highly motivated to slow the climate crisis, governments may struggle to impose costly polices on entrenched interest groups, resulting in a greater need for negative emissions. Here, we model wartime-like crash deployment of direct air capture (DAC) as a policy response to the climate crisis, calculating funding, net CO2 removal, and climat...

Plain Language Summary Anthropogenic increase in aerosol concentrations in the Northern Hemisphere caused not only severe local air pollution but also atmospheric circulation changes as far away as in the Southern Hemisphere. Climatologically, the Southern Hemisphere westerlies show significant seasonal variation; the subtropical jet dominates the...

To mitigate the projected global warming in the 21st century, it is well-recognized that society needs to cut CO2 emissions and other short-lived warming agents aggressively. However, to stabilize the climate at a warming level closer to the present day, such as the “well below 2 ∘C” aspiration in the Paris Agreement, a net-zero carbon emission by...

Extreme heat occurrence worldwide has increased in the past decades. Greenhouse gas emissions, if not abated aggressively, will lead to large increases in frequency and intensity of heat extremes. At the same time, many cities are facing severe air pollution problems featuring high‐PM episodes that last from days to weeks. Based on a high‐resolutio...

Analysis of past recoveries shows a low-carbon reboot matters more for climate than does the brief emissions crash. Analysis of past recoveries shows a low-carbon reboot matters more for climate than does the brief emissions crash.

Future projection of diffusion conditions associated with extreme haze events over eastern China is of great importance to government emission regulations and public human health. Here, the diffusion conditions and their changes under future warming scenarios are examined. The relative strength of haze events in the Northern China Plain region incr...

The Asian monsoon (AM) played an important role in the dynastic history of China, yet it remains unknown whether AM-mediated shifts in Chinese societies affect earth surface processes to the point of exceeding natural variability. Here, we present a dust storm intensity record dating back to the first unified dynasty of China (the Qin Dynasty, 221–...

Abstract. To mitigate the projected global warming in the 21st century, it is well recognized that society needs to cut CO₂ emission and other short-lived warming agents aggressively. However, to stabilize the climate at a warming level closer to the present day, such as the well below 2 °C aspiration in the Paris agreement, a net-zero c...

Climate change, induced by human greenhouse gas emission, has already influenced the environment and society. To quantify the impact of human activity on climate change, scientists have developed numerical climate models to simulate the evolution of the climate system, which often contains many parameters. The choice of parameters is of great impor...

Many Indian metropolitan areas currently suffer from severe air pollution such as PM2.5, which might continue into future decades, dependent on the trends in emission growth and regional climate. Based on a multiyear Nested Regional Climate Model coupled with Chemistry simulation, we developed a daily index (Hazy Weather Index for India, HWII) to c...

Forcings and feedbacks controlling the seasonally sea ice-free Arctic Ocean during the mid-Piacenzian Warm period (3.264–3.025 Ma, MPWP), a period when CO2 level, geography, and topography were similar to present day, remain unclear given that many complex Earth System Models with comparatively higher skills at simulating twentieth century Arctic s...

The Community Atmosphere Model version 6 (CAM6), released in 2018 as part of the Community Earth System Model version 2 (CESM2), is a major upgrade over the previous CAM5 that has been used in numerous global and regional climate studies. Since CESM2–CAM6 will participate in the upcoming Coupled Model Intercomparison Project phase 6 (CMIP6) and is...

The Community Atmosphere Model version 6 (CAM6) released in 2018, as part of the Community Earth System Model version 2 (CESM2) modeling framework, is a major upgrade over the previous CAM5 that has been used in numerous global and regional climate studies in the past six years. Since CESM2/CAM6 will participate in the upcoming Coupled Model Interc...

China has experienced a substantial increase in severe haze events over the past several decades, which is primarily attributed to the increased pollutant emissions caused by its rapid economic development. The climate changes observed under the warming scenarios, especially those induced by increases in greenhouse gases (GHGs), are also conducive...

Three trends will combine to hasten it, warn Yangyang Xu, Veerabhadran Ramanathan and David G. Victor. Three trends will combine to hasten it, warn Yangyang Xu, Veerabhadran Ramanathan and David G. Victor.

China has experienced a substantial increase in severe haze events over the past several decades, which is primarily attributed to the increased pollutant emissions caused by its rapid economic development. The climate changes observed under the warming scenarios, especially those induced by increases in greenhouse gases (GHG), are also conducive t...

The sensitivity of precipitation extremes (PEs; i.e., the change in PE per degree of change in global mean surface temperature) to aerosol and greenhouse gas (GHG) forcings is examined using the twentieth century historical multimodel ensemble simulations from the Coupled Model Intercomparison Program phase 5 (CMIP5). We find a robustly larger sens...

Both mean and extreme rainfall decreased over India and Northern China during 1979–2005 at a rate of 0.2%/decade. The aerosol dampening effects on rainfall has also been suggested as a main driver of mean rainfall shift in India and China. Conflicting views, however, exist on whether aerosols enhance or suppress hazardous extreme heavy rainfall. Us...

The Paris Agreement commits to stabilizing global mean surface warming to below 2°C (above pre-industrial levels) and strives to limit it to 1.5°C to mitigate the risks of anthropogenic climate change. This study explores the impacts of stabilized 1.5°C and 2°C warming in the late 21st century on seasonal climate extremes over China by using a set...

Particulate matter with the diameter smaller than 2.5 micrometers (PM2.5) poses health threats to human population. Regardless of efforts to regulate the pollution sources, it is unclear how climate change caused by greenhouse gases (GHGs) would affect PM2.5 levels. Using century-long ensemble simulations with Community Earth System Model 1 (CESM1)...

Aridity, defined as the ratio of precipitation (P) to potential evapotranspiration (PET) over land, is critical to natural ecosystems and agricultural production. Global climate models project global decreases of P/PET (drying) in the 21st century. We examine the uncertainty of aridity projections due to scenarios of greenhouse gases (GHGs) and aer...

Understanding how impacts may differ across alternative levels of future climate change is necessary to inform mitigation and adaptation measures. The Benefits of Reduced Anthropogenic Climate changE (BRACE) project assesses the differences in impacts between two specific climate futures: a higher emissions future with global average temperature in...

Decadal climate variability of sea surface temperature (SST) over the Pacific Ocean can be characterized by interdecadal Pacific oscillation (IPO) or Pacific decadal oscillation (PDO) based on empirical orthogonal function (EOF) analysis. Although the procedures to derive the IPO and PDO indices differ in their regional focuses and filtering method...

The Paris Agreement of December 2015 stated a goal to pursue efforts to keep global temperatures below 1.5 °C above preindustrial levels and well below 2 °C. The IPCC was charged with assessing climate impacts at these temperature levels, but fully coupled equilibrium climate simulations do not currently exist to inform such assessments. In this st...

We examine the roles of fast and slow responses in shaping the total equilibrium response of the East Asian summer monsoon (EASM) to reflecting (sulfate, SO4) and absorbing (black carbon, BC) aerosol forcings over the industrial era using the Community Earth System Model version 1 (CESM1). Our results show that there is a clear distinction between...

The historic Paris Agreement calls for limiting global temperature rise to "well below 2 °C." Because of uncertainties in emission scenarios, climate, and carbon cycle feedback, we interpret the Paris Agreement in terms of three climate risk categories and bring in considerations of low-probability (5%) high-impact (LPHI) warming in addition to the...

We examine the roles of fast and slow responses in shaping the total equilibrium response of the East Asian summer monsoon (EASM) to reflecting (sulfate, SO4) and absorbing (black carbon, BC) aerosol forcings over the industrial era using the Community Earth System Model version 1. Our results show that there is a clear distinction between fast and...

The 2015 Paris Agreement aims to limit global warming below 2 °C and pursue efforts to even limit it to 1.5 °C relative to pre-industrial levels. Decision makers need reliable information on the impacts caused by these warming levels for climate mitigation and adaptation measures. We explore the changes in climate extremes, which are closely tied t...