scholarly journals Understanding the Climate Effects of Anthropogenic Aerosols

2021 ◽  
Author(s):  
◽  
Kalle Nordling
Keyword(s):  
Greenhouse Gases ◽  
Future Climate ◽  
Cooling Effect ◽  
The Arctic ◽  
Future Climate Change ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Climate Effects ◽  
Key Drivers ◽  
The Difference

Anthropogenic aerosols alter the climate by scattering and absorbing the incoming solar radiation and by modifying clouds’ optical properties, causing a global cooling or warming effect. Anthropogenic aerosols are partly co-emitted with anthropogenic greenhouse gases, and future climate mitigation actions lead to the decline of anthropogenic aerosols’ cooling effect. However, the exact cooling effect is still uncertain. Part of this uncertainty is related to the structural differences of current climate models. This work evaluates the present-day anthropogenic aerosol temperature and precipitation effect and factors affecting the model difference. The key objectives of this thesis were: 1) What are the climate effects of present-day anthropogenic aerosols?, 2) What mechanisms drive the model-to-model differences?, and 3) How do future reductions affect local and global climates? The global models ECHAM6 and NorESM1 were used to evaluate the present-day climate effects with theidentical anthropogenic aerosol scheme MACv2-SP. Results reveal that an identical anthropogenic aerosol description does not reduce the uncertainty related to anthropogenic aerosol climate effects, and the difference in the estimated difference is due to model dynamics and oceans. The key mechanism driving the difference in the models was evaluated using data from the Precipitation Driven Model Intercomparison Project (PRMIP). Similar mechanisms drive the model-to-model difference for greenhouse gases and aerosols, where the key drivers are the differences in water vapor, the vertical temperature structure of the atmosphere, and sea ice and snow cover changes. However, on a regional scale, the key drivers differ. Future anthropogenic aerosol effects were evaluated using new CMIP6 data. This work shows the importance of anthropogenic aerosols for current and future climate change. For amore accurate assessment of climate impacts of anthropogenic aerosols, one needs to also consider remote effects of the local aerosols. The Arctic regions are particularly sensitive to midlatitude aerosols, such as Asian aerosols, which are expected to decline in the next decades. To gain a more accurate estimation of anthropogenic aerosols, it is not sufficient to only focus on composition and geographical distribution of aerosols, as the dynamic response of climate is also important. On global temperature results did not indicate clear aerosols signal, however future temperature development over the Asian regions is modulated by the future Asian aerosol emissions.

Are there pre-Quaternary geological analogues for a future greenhouse warming?

2011 ◽  
Vol 369 (1938) ◽  
pp. 933-956 ◽  
Author(s):  
Alan M. Haywood ◽  
Andy Ridgwell ◽  
Daniel J. Lunt ◽  
Daniel J. Hill ◽  
Matthew J. Pound ◽  
...  
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Future Climate ◽  
Future Climate Change ◽  
Anthropogenic Emissions ◽  
Earth System ◽  
System Sensitivity ◽  
Earth History ◽  
Scientific Papers

Given the inherent uncertainties in predicting how climate and environments will respond to anthropogenic emissions of greenhouse gases, it would be beneficial to society if science could identify geological analogues to the human race’s current grand climate experiment . This has been a focus of the geological and palaeoclimate communities over the last 30 years, with many scientific papers claiming that intervals in Earth history can be used as an analogue for future climate change. Using a coupled ocean–atmosphere modelling approach, we test this assertion for the most probable pre-Quaternary candidates of the last 100 million years: the Mid- and Late Cretaceous, the Palaeocene–Eocene Thermal Maximum (PETM), the Early Eocene, as well as warm intervals within the Miocene and Pliocene epochs. These intervals fail as true direct analogues since they either represent equilibrium climate states to a long-term CO 2 forcing—whereas anthropogenic emissions of greenhouse gases provide a progressive (transient) forcing on climate—or the sensitivity of the climate system itself to CO 2 was different. While no close geological analogue exists, past warm intervals in Earth history provide a unique opportunity to investigate processes that operated during warm (high CO 2 ) climate states. Palaeoclimate and environmental reconstruction/modelling are facilitating the assessment and calculation of the response of global temperatures to increasing CO 2 concentrations in the longer term (multiple centuries); this is now referred to as the Earth System Sensitivity, which is critical in identifying CO 2 thresholds in the atmosphere that must not be crossed to avoid dangerous levels of climate change in the long term. Palaeoclimatology also provides a unique and independent way to evaluate the qualities of climate and Earth system models used to predict future climate.

scholarly journals Reviews and syntheses: Arctic fire regimes and emissions in the 21st century

2021 ◽  
Vol 18 (18) ◽  
pp. 5053-5083
Author(s):  
Jessica L. McCarty ◽  
Juha Aalto ◽  
Ville-Veikko Paunu ◽  
Steve R. Arnold ◽  
Sabine Eckhardt ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Black Carbon ◽  
Biomass Burning ◽  
Fire Regimes ◽  
Future Climate ◽  
The Arctic ◽  
Future Climate Change ◽  
Fire Emissions ◽  
Extreme Fire

Abstract. In recent years, the pan-Arctic region has experienced increasingly extreme fire seasons. Fires in the northern high latitudes are driven by current and future climate change, lightning, fuel conditions, and human activity. In this context, conceptualizing and parameterizing current and future Arctic fire regimes will be important for fire and land management as well as understanding current and predicting future fire emissions. The objectives of this review were driven by policy questions identified by the Arctic Monitoring and Assessment Programme (AMAP) Working Group and posed to its Expert Group on Short-Lived Climate Forcers. This review synthesizes current understanding of the changing Arctic and boreal fire regimes, particularly as fire activity and its response to future climate change in the pan-Arctic have consequences for Arctic Council states aiming to mitigate and adapt to climate change in the north. The conclusions from our synthesis are the following. (1) Current and future Arctic fires, and the adjacent boreal region, are driven by natural (i.e. lightning) and human-caused ignition sources, including fires caused by timber and energy extraction, prescribed burning for landscape management, and tourism activities. Little is published in the scientific literature about cultural burning by Indigenous populations across the pan-Arctic, and questions remain on the source of ignitions above 70∘ N in Arctic Russia. (2) Climate change is expected to make Arctic fires more likely by increasing the likelihood of extreme fire weather, increased lightning activity, and drier vegetative and ground fuel conditions. (3) To some extent, shifting agricultural land use and forest transitions from forest–steppe to steppe, tundra to taiga, and coniferous to deciduous in a warmer climate may increase and decrease open biomass burning, depending on land use in addition to climate-driven biome shifts. However, at the country and landscape scales, these relationships are not well established. (4) Current black carbon and PM2.5 emissions from wildfires above 50 and 65∘ N are larger than emissions from the anthropogenic sectors of residential combustion, transportation, and flaring. Wildfire emissions have increased from 2010 to 2020, particularly above 60∘ N, with 56 % of black carbon emissions above 65∘ N in 2020 attributed to open biomass burning – indicating how extreme the 2020 wildfire season was and how severe future Arctic wildfire seasons can potentially be. (5) What works in the boreal zones to prevent and fight wildfires may not work in the Arctic. Fire management will need to adapt to a changing climate, economic development, the Indigenous and local communities, and fragile northern ecosystems, including permafrost and peatlands. (6) Factors contributing to the uncertainty of predicting and quantifying future Arctic fire regimes include underestimation of Arctic fires by satellite systems, lack of agreement between Earth observations and official statistics, and still needed refinements of location, conditions, and previous fire return intervals on peat and permafrost landscapes. This review highlights that much research is needed in order to understand the local and regional impacts of the changing Arctic fire regime on emissions and the global climate, ecosystems, and pan-Arctic communities.

scholarly journals Amplified Arctic warming by phytoplankton under greenhouse warming

2015 ◽  
Vol 112 (19) ◽  
pp. 5921-5926 ◽  
Author(s):  
Jong-Yeon Park ◽  
Jong-Seong Kug ◽  
Jürgen Bader ◽  
Rebecca Rolph ◽  
Minho Kwon
Keyword(s):  
Ecosystem Model ◽  
Future Climate ◽  
Marine Phytoplankton ◽  
The Arctic ◽  
Future Climate Change ◽  
Greenhouse Warming ◽  
Climate Projections ◽  
Arctic Warming ◽  
Marine Ecosystem Model ◽  
The Future

Phytoplankton have attracted increasing attention in climate science due to their impacts on climate systems. A new generation of climate models can now provide estimates of future climate change, considering the biological feedbacks through the development of the coupled physical–ecosystem model. Here we present the geophysical impact of phytoplankton, which is often overlooked in future climate projections. A suite of future warming experiments using a fully coupled ocean−atmosphere model that interacts with a marine ecosystem model reveals that the future phytoplankton change influenced by greenhouse warming can amplify Arctic surface warming considerably. The warming-induced sea ice melting and the corresponding increase in shortwave radiation penetrating into the ocean both result in a longer phytoplankton growing season in the Arctic. In turn, the increase in Arctic phytoplankton warms the ocean surface layer through direct biological heating, triggering additional positive feedbacks in the Arctic, and consequently intensifying the Arctic warming further. Our results establish the presence of marine phytoplankton as an important potential driver of the future Arctic climate changes.

scholarly journals Evaluation of Arctic warming in mid-Pliocene climate simulations

2020 ◽  
Author(s):  
Wesley de Nooijer ◽  
Qiong Zhang ◽  
Qiang Li ◽  
Qiang Zhang ◽  
Xiangyu Li ◽  
...  
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Future Climate ◽  
The Arctic ◽  
Future Climate Change ◽  
Sea Ice Extent ◽  
Current Form ◽  
Arctic Warming ◽  
Amplification Ratio ◽  
Climate Simulations

Abstract. Palaeoclimate simulations improve our understanding of the climate, inform us about the performance of climate models in a different climate scenario, and help to identify robust features of the climate system. Here, we analyse Arctic warming in an ensemble of 16 simulations of the mid-Pliocene Warm Period (mPWP), derived from the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2). The PlioMIP2 ensemble simulates Arctic (60–90° N) annual mean surface air temperature (SAT) increases of 3.7 to 11.6 °C compared to the pre-industrial, with a multi-model mean (MMM) increase of 7.2 °C. The Arctic warming amplification ratio relative to global SAT anomalies in the ensemble ranges from 1.8 to 3.1 (MMM is 2.3). Sea ice extent anomalies range from −3.0 to −10.4 × 06 km2 with a MMM anomaly of −5.6 × 106 km2, which constitutes a decrease of 53 % compared to the pre-industrial. The majority (11 out of 16) models simulate summer sea ice-free conditions (≤ 1 × 06 km2) in their mPWP simulation. The ensemble tends to underestimate SAT in the Arctic when compared to available reconstructions. The simulations with the highest Arctic SAT anomalies tend to match the proxy dataset in its current form better. The ensemble shows some agreement with reconstructions of sea ice, particularly with regards to seasonal sea ice. Large uncertainties limit the confidence that can be placed in the findings and the compatibility of the different proxy datasets. We show that, while reducing uncertainties in the reconstructions could decrease the SAT data-model discord substantially, further improvements are likely to be found in enhanced boundary conditions or model physics. Lastly, we compare the Arctic warming in the mPWP to projections of future Arctic warming and find that the PlioMIP2 ensemble simulates greater Arctic amplification, an increase instead of a decrease in AMOC strength compared to pre-industrial, and a lesser strengthening of northern modes of variability than CMIP5 future climate simulations. The results highlight the importance of slow feedbacks in equilibrium climate simulations, and that caution must be taken when using simulations of the mPWP as an analogue for future climate change.

scholarly journals The response of Atlantic cod (Gadus morhua) to future climate change

2005 ◽  
Vol 62 (7) ◽  
pp. 1327-1337 ◽  
Author(s):  
Kenneth F. Drinkwater
Keyword(s):  
Climate Change ◽  
North Atlantic ◽  
Atlantic Cod ◽  
Future Climate ◽  
The Arctic ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Total Production ◽  
The North ◽  
The North Atlantic

Abstract Future CO2-induced climate change scenarios from Global Circulation Models (GCMs) indicate increasing air temperatures, with the greatest warming in the Arctic and Subarctic. Changes to the wind fields and precipitation patterns are also suggested. These will lead to changes in the hydrographic properties of the ocean, as well as the vertical stratification and circulation patterns. Of particular note is the expected increase in ocean temperature. Based upon the observed responses of cod to temperature variability, the expected responses of cod stocks throughout the North Atlantic to the future temperature scenarios are reviewed and discussed here. Stocks in the Celtic and Irish Seas are expected to disappear under predicted temperature changes by the year 2100, while those in the southern North Sea and Georges Bank will decline. Cod will likely spread northwards along the coasts of Greenland and Labrador, occupy larger areas of the Barents Sea, and may even extend onto some of the continental shelves of the Arctic Ocean. In addition, spawning sites will be established further north than currently. It is likely that spring migrations will occur earlier, and fall returns will be later. There is the distinct possibility that, where seasonal sea ice disappears altogether, cod will cease their migration. Individual growth rates for many of the cod stocks will increase, leading to an overall increase in the total production of Atlantic cod in the North Atlantic. These responses of cod to future climate changes are highly uncertain, however, as they will also depend on the changes to climate and oceanographic variables besides temperature, such as plankton production, the prey and predator fields, and industrial fishing.

scholarly journals Comparison of Anthropogenic Aerosol Climate Effects among Three Climate Models with Reduced Complexity

Atmosphere ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 456 ◽  
Author(s):  
Xiangjun Shi ◽  
Wentao Zhang ◽  
Jiaojiao Liu
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Reliable Estimate ◽  
Anthropogenic Aerosol ◽  
Climate Effects ◽  
Cloud Forcing ◽  
Radiative Forcings ◽  
Ensemble Simulations ◽  
Aerosol Forcing ◽  
The Difference

The same prescribed anthropogenic aerosol forcing was implemented into three climate models. The atmosphere components of these participating climate models were the GAMIL, ECHAM, and CAM models. Ensemble simulations were carried out to obtain a reliable estimate of anthropogenic aerosol effective radiative forcing (ERF). The ensemble mean ERFs from these three participating models with this aerosol forcing were −0.27, −0.63, and −0.54 W∙m−2. The model diversity in ERF is clearly reduced as compared with those based on the models’ own default approaches (−1.98, −0.21, and −2.22 W∙m−2). This is consistent with the design of this aerosol forcing. The modeled ERF can be decomposed into two basic components, i.e., the instantaneous radiative forcing (RF) from aerosol–radiation interactions (RFari) and the aerosol-induced changes in cloud forcing (△Fcloud*). For the three participating models, the model diversity in RFari (−0.21, −0.33, and −0.29 W∙m−2) could be constrained by reducing the differences in natural aerosol radiative forcings. However, it was difficult to figure out the reason for the model diversity in △Fcloud* (−0.05, −0.28, and −0.24 W∙m−2), which was the dominant source of the model diversity in ERF. The variability of modeled ERF was also studied. Ensemble simulations showed that the modeled RFs were very stable. The rapid adjustments (ERF − RF) had an important role to play in the quantification of the perturbation of ERF. Fortunately, the contribution from the rapid adjustments to the mean ERF was very small. This study also showed that we should pay attention to the difference between the aerosol climate effects we want and the aerosol climate effects we calculate.

Predicting climate change effects on subarctic–Arctic populations of Atlantic salmon (Salmo salar)

2013 ◽  
Vol 70 (2) ◽  
pp. 159-168 ◽  
Author(s):  
Richard D. Hedger ◽  
Line E. Sundt-Hansen ◽  
Torbjørn Forseth ◽  
Ola Ugedal ◽  
Ola H. Diserud ◽  
...  
Keyword(s):  
Climate Change ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Climate Models ◽  
Global Climate Models ◽  
Future Climate ◽  
The Arctic ◽  
Future Climate Change ◽  
Northern Norway ◽  
Atlantic Salmon Salmo Salar

We predict an increase in parr recruitment and smolt production of Atlantic salmon (Salmo salar) populations along a climate gradient from the subarctic to the Arctic in western and northern Norway in response to future climate change. Firstly, we predicted local stream temperature and discharge from downscaled data obtained from Global Climate Models. Then, we developed a spatially explicit individual-based model (IBM) parameterized for the freshwater stage, with combinations of three different postsmolt survival probabilities reflecting different marine survival regimes. The IBM was run for three locations: southern Norway (∼59°N), western Norway (∼62°N), and northern Norway (∼70°N). Increased temperatures under the future climate regimes resulted in faster parr growth, earlier smolting, and elevated smolt production in the western and northern locations, in turn leading to increased egg deposition and elevated recruitment into parr. In the southern location, density-dependent mortality of parr resulting from low summer wetted-areas reduced predicted future smolt production in comparison to the other locations. It can be inferred, therefore, that climate change may have both positive and negative effects on anadromous fish abundance within the subarctic–Arctic according to geographical region.

Sign in / Sign up

Export Citation Format

Share Document