Inconsistency between process-based model and dose-response function in estimating biomass losses in Northern Hemisphere due to elevated O.

Tropospheric ozone (O) concentrations in the Northern Hemisphere have significantly increased since the pre-industrial era, with ongoing growth driven by emissions from industrial, agricultural, and transportation activities, further exacerbated by the warming temperatures and altered atmospheric circulation patterns associated with climate change. This study compared different methodologies for estimating biomass potential losses (BPL) in forests due to elevated O using both concentration-based (AOT40) and flux-based (POD1) metrics. Moreover, to further assess the impact of O on forest health and carbon uptake across the dominant forest types in the Northern Hemisphere, we also compared BPL estimates from dose-response functions with those derived from the process-based model ORCHIDEE.

Meteorological, chemical and biological evaluation of the coupled chemistry-climate WRF-Chem model from regional to urban scale. An impact-oriented application for human health.

Extreme climatic conditions, like heat waves or cold spells, associated to high concentrations of air pollutants are responsible for a broad range of effects on human health. Consequently, in the recent years, the question on how urban and peri-urban forests may improve both air quality and surface climate conditions at city-scale is receiving growing attention by scientists and policymakers, with previous studies demonstrating how nature-based solutions (NBS) may contribute to reduce the risk of population to be exposed to high pollutant levels and heat stress, preventing, thus, premature mortality. In this study we present a new modeling framework designed to simulate air quality and meteorological conditions from regional to urban scale, allowing thus to assess the impacts of both air pollution and heat stress on human health at urban level.

Stomatal responses of terrestrial plants to global change.

Quantifying the stomatal responses of plants to global change factors is crucial for modeling terrestrial carbon and water cycles. Here we synthesize worldwide experimental data to show that stomatal conductance (g) decreases with elevated carbon dioxide (CO), warming, decreased precipitation, and tropospheric ozone pollution, but increases with increased precipitation and nitrogen (N) deposition. These responses vary with treatment magnitude, plant attributes (ambient g, vegetation biomes, and plant functional types), and climate.

Ozone modelling and mapping for risk assessment: An overview of different approaches for human and ecosystems health.

Tropospheric ozone (O) is one of the most concernedair pollutants dueto its widespread impacts on land vegetated ecosystems and human health. Ozone is also the third greenhouse gas for radiative forcing. Consequently, it should be carefully and continuously monitored to estimate its potential adverse impacts especially inthose regions where concentrations are high.

Legislative and functional aspects of different metrics used for ozone risk assessment to forests.

Surface ozone (O) is a threat to forests by decreasing photosynthesis and, consequently, influencing the strength of land carbon sink. However, due to the lack of continuous surface O measurements, observational-based assessments of O impacts on forests are largely missing at hemispheric to global scales. Currently, some metrics are used for regulatory purposes by governments or national agencies to protect forests against the negative impacts of ozone: in particular, both Europe and United States (US) makes use of two different exposure-based metrics, i.

Impact of ground-level ozone on Mediterranean forest ecosystems health.

Given the high ozone concentrations observed in the Mediterranean region during summer, it is crucial to extend our knowledge on the potential ozone impacts on forest health with in situ studies, especially to protect typical endemic forests of the Mediterranean basin. This study is focused on ozone measurements and exposures over the Eastern Adriatic coast and on the calculation of different O metrics, i.e.

Economic impacts of ambient ozone pollution on wood production in Italy.

Worldwide, tropospheric ozone (O) is a potential threat to wood production, but our understanding of O economic impacts on forests is still limited. To overcome this issue, we developed an approach for integrating O risk modelling and economic estimates, by using the Italian forests as a case study. Results suggested a significant impact of O expressed in terms of stomatal flux with an hourly threshold of uptake (Y = 1 nmol O m leaf area s to represent the detoxification capacity of trees), i.

Short-term and long-term health impacts of air pollution reductions from COVID-19 lockdowns in China and Europe: a modelling study.

Background: Exposure to poor air quality leads to increased premature mortality from cardiovascular and respiratory diseases. Among the far-reaching implications of the ongoing COVID-19 pandemic, a substantial improvement in air quality was observed worldwide after the lockdowns imposed by many countries. We aimed to assess the implications of different lockdown measures on air pollution levels in Europe and China, as well as the short-term and long-term health impact.

Economic losses due to ozone impacts on human health, forest productivity and crop yield across China.

China's economic growth has significantly increased emissions of tropospheric ozone (O) precursors, resulting in increased regional O pollution. We analyzed data from >1400 monitoring stations and estimated the exposure of population and vegetation (crops and forests) to O pollution across China in 2015. Based on WHO metrics for human health protection, the current O level leads to +0.

Growing season extension affects ozone uptake by European forests.

Climate change significantly modifies terrestrial ecosystems and vegetation activity, yet little is known about how climate change and ozone pollution interact to affect forest health. Here we compared the trends of two metrics widely used to protect forests against negative impacts of ozone pollution, the AOT40 (Accumulated Ozone over Threshold of 40 ppb) which only depends on surface air ozone concentrations, and the POD (Phytotoxic Ozone Dose) which relies on the amount of ozone uptaken by plants through stomata. Using a chemistry transport model, driven by anthropogenic emission inventories, we found that European-averaged ground-level ozone concentrations significantly declined (-1.

Impacts of air pollution on human and ecosystem health, and implications for the National Emission Ceilings Directive: Insights from Italy.

Across the 28 EU member states there were nearly half a million premature deaths in 2015 as a result of exposure to PM, O and NO. To set the target for air quality levels and avoid negative impacts for human and ecosystems health, the National Emission Ceilings Directive (NECD, 2016/2284/EU) sets objectives for emission reduction for SO, NOx, NMVOCs, NH and PM for each Member State as percentages of reduction to be reached in 2020 and 2030 compared to the emission levels into 2005. One of the innovations of NECD is Article 9, that mentions the issue of "monitoring air pollution impacts" on ecosystems.

Trends and inter-relationships of ground-level ozone metrics and forest health in Lithuania.

Lithuania is representative of maritime to continental climate, no water limitation, and moderate ground-level ozone (O) pollution. We investigated the trends of meteorological variables and O and how these environmental conditions associate with tree health from 2001 onward. Ozone metrics for forest protection, based on Accumulated O exposure Over a Threshold of X ppb (AOTX) or on Phytotoxic O Dose over a Y threshold (PODY), were modeled at nine ICP-Forests plots over the time period 2001-2014.

Commentary: EPA's proposed expansion of dose-response analysis is a positive step towards improving its ecological risk assessment.

The United States Environmental Protection Agency (US EPA) has recently proposed changes to strengthen the transparency of its pivotal regulatory science policy and procedures. In this context, the US EPA aims to enhance the transparency of dose-response data and models, proposing to consider for the first time non-linear biphasic dose-response models. While the proposed changes have the potential to lead to markedly improved ecological risk assessment compared to past and current approaches, we believe there remain open issues for improving the quality of ecological risk assessment, such as the consideration of adaptive, dynamic and interactive effects.

Nationwide ground-level ozone measurements in China suggest serious risks to forests.

We processed hourly ozone (O) concentrations collected in 2015 and in 2016 by a network of 1497 stations across China, with the main aim of assessing the risk that present ambient O exposure is posing to Chinese forests. Our results indicate that the values of the metrics AOT40 (the accumulated hourly O concentrations above 40 ppb during daylight hours) recommended as European Union standard, and W126 (the sum of weighted hourly concentrations from 8:00 to 20:00) recommended as USA standard for forest protection, exceeded the critical levels (5 ppm h across 6 months for AOT40 and 7-21 ppm h over 3 months for W126) on average by 5.1 and 1.

The role of plant phenology in stomatal ozone flux modeling.

Plant phenology plays a pivotal role in the climate system as it regulates the gas exchange between the biosphere and the atmosphere. The uptake of ozone by forest is estimated through several meteorological variables and a specific function describing the beginning and the termination of plant growing season; actually, in many risk assessment studies, this function is based on a simple latitude and topography model. In this study, using two satellite datasets, we apply and compare six methods to estimate the start and the end dates of the growing season across a large region covering all Europe for the year 2011.

Five-year volume growth of European beech does not respond to ozone pollution in Italy.

A unique database of stand volume growth, estimated as periodic annual volume increment (in m ha per year over the period 2001-2005) from 728 European beech (Fagus sylvatica L.) sites distributed across Italy, was used to assess the effects of ambient ozone (O), expressed as annual average (M24), accumulated exposure above a 40 ppb hourly threshold (AOT40), and total stomatal ozone flux (POD0). Growth data were from the National forest inventory of Italy, while climate data and ozone concentrations were computed by the WRF and CHIMERE models, respectively.

Ozone exposure affects tree defoliation in a continental climate.

Ground-level ozone (O) affects trees through visible leaf injury, accelerating leaf senescence, declining foliar chlorophyll content, photosynthetic activity, growth, carbon sequestration, predisposing to pests attack and a variety of other physiological effects. Tree crown defoliation is one of the most important parameters that is representative of forest health and vitality. Effects of air pollution on forests have been investigated through manipulative experiments that are not representative of the real environmental conditions observed in the field.

Comparing concentration-based (AOT40) and stomatal uptake (PODY) metrics for ozone risk assessment to European forests.

Tropospheric ozone (O3) produces harmful effects to forests and crops, leading to a reduction of land carbon assimilation that, consequently, influences the land sink and the crop yield production. To assess the potential negative O3 impacts to vegetation, the European Union uses the Accumulated Ozone over Threshold of 40 ppb (AOT40). This index has been chosen for its simplicity and flexibility in handling different ecosystems as well as for its linear relationships with yield or biomass loss.

Evaluation of terrestrial carbon cycle models for their response to climate variability and to CO2 trends.

The purpose of this study was to evaluate 10 process-based terrestrial biosphere models that were used for the IPCC fifth Assessment Report. The simulated gross primary productivity (GPP) is compared with flux-tower-based estimates by Jung et al. [Journal of Geophysical Research 116 (2011) G00J07] (JU11).