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We thank the authors (hereafter referred to as CCC) for providing us an opportunity to clarify some points of our original paper. CCC list in their abstract three “key points”that we respond to in this Reply. The first comment is the central one and the most developed. It deals mainly with discussion of features of methods of spectral analysis, mainly SSA. We have quoted the sub‐parts of that comment as items 1a to 1k. The replies to comments/key points 2 and 3 are shorter. We disagree with most of the comments by CCC and explain why. We conclude that we have successfully countered CCC's criticism and shown many of their points to be unsubstantiated. The main problem seems to reside in differences concerning the literature on Singular Spectral Analysis and our use of it. Much of our response to the comments can be found in textbooks and review papers on SSA and time series analysis; we quote extensively, both in our original paper and in this response to CCC, Golyandina and Zhigljavsky (2013).

Academics fly a lot: to research sites and archives, to conferences and workshops. Yet flying has many negative repercussions. Air travel has disproportionate climate impacts, and for reasons of time, money, and border security, produces many barriers for marginalized scholars, shaping who is able shows up at conferences and thus, who participates in the conversations that define a community of study. Forms of knowledge exchange that do not depend on aviation are thus urgently needed. E-conferences offer on such possibility. As scholars of media and energy, and as e-conference organizers and participants ourselves, we wrote this white paper to highlight what’s worked in the past, what hazards lie ahead for the future, and what potential gains could be won in the present. We hope our words will be useful to small conference organizers and professional associations alike. Our aim is not to end in-person meetings but rather to foster effective low-carbon alternatives that can help reduce the amount of travel necessary to participate in global knowledge communities. Meeting together in person is invaluable, but we can augment it with effective alternatives through critical reflection and smart design choices. We aim to spark further reflections and innovations in collaborative experiments in digital research exchange - or even other forms of scholarly community. We hope such experimentation continues long after the pandemic is over, and that its effects will shape the university for the better.

The Madden–Julian oscillation (MJO) identified by Madden and Julian in the early 1970s has been well recognized as the most prominent intraseasonal signal in the tropics. Its discovery and its relationship with other weather phenomena such as tropical cyclones (TCs) are among the most significant advancements in modern meteorology with broad and far-reaching impacts. The original study by Madden and Julian used radiosonde data on Canton Island, and their spectral analysis revealed the signal of a 40–50-day oscillation.It has come to our attention that an earlier study by Xie et al. published in a Chinese journal documented an oscillatory signal of a 45-day period using radiosonde data from several stations between 70° and 125°E in the tropics. The 40–50-day signal found by Xie et al. is strikingly evident without any filtering. Xie et al. identified that occurrences of TCs are correlated with the 40–50-day variation of low-level westerlies at these stations. The original figures in Xie et al.’s article were hand drawn. Their results are verified using data from a longer period of 1958–70. The 40–50-day oscillation in the monsoon westerlies and its relationship with the occurrence of TCs are confirmed and further expanded upon.This study serves the purpose of bringing recognition to the community of the identification of a 40–50-day signal published in Chinese in 1963 and the discovery of the correlation between MJO phases and TC genesis three decades earlier than studies on this subject published outside China.

S. Trivikrama Rao, Ph.D.There is scientific consensus that climate change has been contributing to rising surface temperatures, changing weather pattens, and extreme weather events leading to extre...

The STatistical Analogue Resampling Scheme (STARS) statistical approach was recently used to project changes of climate variables in Germany corresponding to a supposed degree of warming. We show by theoretical and empirical analysis that STARS simply transforms interannual gradients between warmer and cooler seasons into climate trends. According to STARS projections, summers in Germany will inevitably become dryer and winters wetter under global warming. Due to the dominance of negative interannual correlations between precipitation and temperature during the year, STARS has a tendency to generate a net annual decrease in precipitation under mean German conditions. Furthermore, according to STARS, the annual level of global radiation would increase in Germany. STARS can be still used, e.g., for generating scenarios in vulnerability and uncertainty studies. However, it is not suitable as a climate downscaling tool to access risks following from changing climate for a finer than general circulation model (GCM) spatial scale.

In his article Willems (Clim Chang 120(4):931–944, 2013) proposed a methodology to analyse extremes in rainfall series. When applying it to artificially generated, non-cyclic random variables we were able to detect cyclic behavior. Therefor we had a closer look on the methodology. Here we discuss our considerations, why this method generates cycles, depending on chosen subperiods and their coherence between detected cycle lengths. To verify these relationships some examples based on random data samples are given.

The paper describes the hydrodynamic part of the coupled ice-ocean model that also includes the ecosystem predictive model. The Baltic Sea model is based on the Community Earth System Model (CESM from NCAR – National Centre for Atmospheric Research). CESM was adopted for the Baltic Sea as a coupled sea-ice model. It consists of the Community Ice CodE (CICE, model version 4.0) and the Parallel Ocean Program (POP, version 2.1). The models are linked through a coupler (CPL7), which is based on the Model Coupling Toolkit (MCT) library. The current horizontal resolution is about 2 km (1/48 degrees). The ocean model has 21 vertical levels and is forced by atmospheric fields from the European Centre for Medium Weather Forecast (ECMWF). A preliminary validation of the hydrodynamic module with in situ measurements and reanalysis from My Ocean ( http://www.myocean.eu ) has also been done. In the operational mode, 48-hour atmospheric forecasts provided by the UM model from the Interdisciplinary Centre for Mathematical and Computational Modelling of Warsaw University (ICM) are used. The variables presented on the website in real time for a 48-hour forecast are temperature, salinity, currents, sea surface height, ice thickness and ice coverage ( http://deep.iopan.gda.pl/CEMBaltic/newlay/index.php ). The embedded model of the marine ecosystem, like ice, is not taken into account in this paper.

The frequency and intensity of extreme events especially heat waves (HW) are growing all around the world which ultimately poses a serious threat to the health of individuals. To quantify the effects of extreme temperature, appropriate information, and the importance of HW and heat index (HI) are carefully discussed for different parts of the world. Varied definitions of the HW and HI formula proposed and used by different countries are carried out systematically continent-wise. Different studies highlighted the number of definitions of HW; however, mostly used Steadman’s formulae, which was developed in the late 1970s, for the calculation of HI that uses surface air temperature and relative humidity as climatic fields. Since then, dramatic changes in climatic conditions have been observed as evident from the ERA5 datasets which need to be addressed; likewise, the definition of HW, which is modified by the researchers as per the geographic conditions. It is evident from the ERA5 data that the temperature has increased by 1–2 °C as compared to the 1980s. There is a threefold increase in the number of heatwave days over most of the continents in the last 40 years. This study will help the researcher community to understand the importance of HW and HI. Furthermore, it opens the scope to develop an equation based on the present scenario keeping in mind the basics of an index as considered by Steadman.

The coronavirus pandemic is one of the most fast-spreading diseases in the history, and the transmission of this virus has crossed rapidly over the whole world. In this study, we intend to detect the effect of temperature, precipitation, and wind speed on the Coronavirus infected cases throughout climate seasons for the whole year of epidemic starting from February 20, 2020 to February 19, 2021 with considering data patterns of each season separately; winter, spring, summer, autumn, in Mediterranean European regions, whereas those are located at the similar temperature zone in southern Europe. We apply the panel data approach by considering the developed robust estimation of clustered standard error which leads to achieving high forecasting accuracy. The main finding supports that temperature and wind speed have significant influence in reducing the Coronavirus cases at the beginning of this epidemic particularly in the first-winter, spring, and early summer, but they have very weak effects in the autumn and second-winter. Therefore, it is important to take into account the changes throughout seasons, and to consider other indirect factors which influence the virus transmission. This finding could lead to significant contributions to policymakers in European Union and European Commission Environment to limit the Coronavirus transmissions. As the Mediterranean region becomes more crowded for tourism purposes particularly in the summer season.

We discuss a recently proposed model for the sawtooth oscillations of atmospheric carbon observed in ice age cores. The model at its simplest arises from a single reaction involving just two species, oceanic biomass and nutrient, and bears similarity to models which have been proposed to explain oscillations in glycolysis. We show that the sawtooth behaviour, and associated spiking of one of the constituents, is associated with the existence of a conservative nonlinear oscillator with an asymmetric potential at high values of the energy, and we give asymptotic descriptions of the solutions. We extend the analysis to a more complicated model which includes competition between planktonic species.

In 2001–2007 aerosols were measured in the coastal zone (11 campaigns) and over the open waters of the Gdansk Basin (southern Baltic) (5 campaigns). The marine aerosols contained nitrogen and sulphur compounds, which increased their acidity. This situation intensified during the cool months of the year, when fossil fuel emissions were higher, proportionate to energy and heat requirements. Irrespective of the season, these acidic aerosols were neutralized in the reaction with sea salt. The likelihood of sodium nitrate being formed increased at air humidities > 80% and nitrate concentrations > 30 nmol m− 3. Sodium sulphate was present in aerosols mostly in autumn and winter, with northerly advection, and at the highest wind speeds. The excess of free ammonia resulted in the formation of ammonium sulphate and ammonium nitrate in aerosols over the southern Baltic.

The impacts of climate change on the seasonality of low flows were analysed for 134 sub-catchments covering the River Rhine basin upstream of the Dutch-German border. Three seasonality indices for low flows were estimated, namely the seasonality ratio (SR), weighted mean occurrence day (WMOD) and weighted persistence (WP). These indices are related to the discharge regime, timing and variability in timing of low flow events respectively. The three indices were estimated from: (1) observed low flows; (2) simulated low flows by the semi-distributed HBV model using observed climate as input; (3) simulated low flows using simulated inputs from seven combinations of General Circulation Models (GCMs) and Regional Climate Models (RCMs) for the current climate (1964–2007); (4) simulated low flows using simulated inputs from seven combinations of GCMs and RCMs for the future climate (2063–2098) including three different greenhouse gas emission scenarios. These four cases were compared to assess the effects of the hydrological model, forcing by different climate models and different emission scenarios on the three indices. Significant differences were found between cases 1 and 2. For instance, the HBV model is prone to overestimate SR and to underestimate WP and simulates very late WMODs compared to the estimated WMODs using observed discharges. Comparing the results of cases 2 and 3, the smallest difference was found for the SR index, whereas large differences were found for the WMOD and WP indices for the current climate. Finally, comparing the results of cases 3 and 4, we found that SR decreases substantially by 2063–2098 in all seven sub-basins of the River Rhine. The lower values of SR for the future climate indicate a shift from winter low flows (SR > 1) to summer low flows (SR < 1) in the two Alpine sub-basins. The WMODs of low flows tend to be earlier than for the current climate in all sub-basins except for the Middle Rhine and Lower Rhine sub-basins. The WP values are slightly larger, showing that the predictability of low flow events increases as the variability in timing decreases for the future climate. From comparison of the error sources evaluated in this study, it is obvious that different RCMs/GCMs have a larger influence on the timing of low flows than different emission scenarios. Finally, this study complements recent analyses of an international project (Rhineblick) by analysing the seasonality aspects of low flows and extends the scope further to understand the effects of hydrological model errors and climate change on three important low flow seasonality properties: regime, timing and persistence.

An article by William D. Nordhaus (2010) in this journal examined the economic impacts by hurricanes in the USA, and the potential impacts of climate change on future hurricane damages. His analyses show that hurricane damages normalized over time for changes in GDP have increased significantly since the year 1900, at a rate of about 3.1% per year. Moreover, the results of Nordhaus show that hurricane damages increase with the ninth power of maximum wind speed, which is considerably higher than findings of other studies. We perform similar statistical analyses with different data series of hurricane damage, which are more accurately corrected for changes in exposure of assets over time. Our results do not indicate an upward trend in hurricane losses since 1900, which is in line with earlier studies, and indicates that climate change has not increased hurricane damage in the past. Moreover, although the relation between damage and maximum wind speed appears to be considerably higher than assumed by other studies, this elasticity is more likely to be the eighth-power of maximum wind speed. This finding is relevant since it implies that future climate change impacts on hurricane damage may be considerably lower than Nordhaus indicates.

Highly unusual amounts of rainfall were seen in the 2020 summer in many parts of China, Japan, and South Korea. At the intercontinental scale, case studies have attributed this exceptional event to a displacement of the climatological western North Pacific subtropical anticyclone, potentially associated Indian Ocean sea surface temperature patterns and a mid-latitude wave train emanating from the North Atlantic. Using clusters of spatial patterns of sea level pressure, we show that an unprecedented 80% of the 2020 summer days in East Asia were dominated by clusters of surface pressure greater than normal over the South China Sea. By examining the rainfall and water vapor fluxes in other years when these clusters were also prevalent, we find that the frequency of these types of clusters was likely to have been largely responsible for the unusual rainfall of 2020. From two ensembles of future climate projections, we show that summers like 2020 in East Asia may become more frequent and considerably wetter in a warmer world with an enhanced moisture supply.2020 年夏季, 中国、 日本和韩国的诸多地区均出现了创纪录的极端强降水. 该事件的个例研究将这一特殊事件归因于西北太平洋副热带反气旋的位置移动, 可能与印度洋海表面温度异常和自北大西洋发出的中纬度波列有关. 本工作通过对东亚逐日海平面气压 (SLP) 空间场的聚类分析, 发现 2020 年夏季南海地区为正 SLP 异常的天气型出现天数达到整个夏季的 80%, 为 1979 年以来之最. 通过与其他环流型所对应的降水和水汽通量异常对比, 发现这类天气型的频繁出现很可能是造成 2020 年梅雨期降水偏多的主要原因. 该研究进一步分析了两个大样本集合气候模拟预估结果, 发现未来在全球进一步增暖、 水分供应相应增加的情景下, 像 2020 年这样的东亚夏季环流可能会出现得更加频繁, 中国降水也会更强.

Air and near-surface ground temperatures, late-winter snow conditions, and characteristics of the vegetation cover and soil were measured across the forest–tundra transition in the uplands east of the Mackenzie Delta, Northwest Territories, in 2004–2010. Mean late-winter snow depth decreased northward from 73 cm in the subarctic boreal forest near Inuvik to 22 cm in low-shrub tundra. Annual near-surface ground temperatures decreased northward by 0.1–0.3 °C/km near the northern limit of trees, in association with an abrupt change in snow depth. The rate decreased to 0.01–0.06 °C/km in the tundra. The freezing season is twice as long as the thawing season in the region, so measured differences in the regional ground thermal regime were dominated by the contrast in winter surface conditions between forest and tundra.

In the boreal forests of Alaska, recent changes in climate have influenced the exchange of trace gases, water, and energy between these forests and the atmosphere. These changes in the structure and function of boreal forests can then feed back to impact regional and global climates. In this manuscript, we examine the type and magnitude of the climate feedbacks from boreal forests in Alaska. Research generally suggests that the net effect of a warming climate is a positive regional feedback to warming. Currently, the primary positive climate feedbacks are likely related to decreases in surface albedo due to decreases in snow cover. Fewer negative feedbacks have been identified, and they may not be large enough to counterbalance the large positive feedbacks. These positive feedbacks are most pronounced at the regional scale and reduce the resilience of the boreal vegetation – climate system by amplifying the rate of regional warming. Given the recent warming in this region, the large variety of associated mechanisms that can alter terrestrial ecosystems and influence the climate system, and a reduction in the boreal forest resilience, there is a strong need to continue to quantify and evaluate the feedback pathways.

In Canada, glacial isostatic adjustment (GIA) is the dominant process to cause vertical motion of the land surface. A GIA model is presented herein that can be used to predict slope changes at given locations in North America where GIA is the primary cause for vertical motion. Uncertainty in Pleistocene ice cover and viscosity in the Earth’s mantle prevent one from picking a single GIA model from the literature to predict uplift rates in the region. Therefore, in this study, a range of mantle viscosity values as well as two different ice-loading histories are used in a forward model of the GIA process. The combination of viscosities and ice model that gives the best fit to recently available continuous and episodic GPS observations is assumed to provide the best prediction of slope changes in North America. This model can be used to quantify GIA-induced vertical deformation in local geomorphologic studies. We show that the predicted differential uplift rate in the Nelson River with respect to Lake Winnipeg reaches 1 mm/year over a 200 km distance using the model that best fits the GPS data whereas the ICE-5Gv1.2/VM2 model gives a slightly larger value. The difference in uplift rate between the northern and southern shore of Lake Michigan amounts up to 3 mm/year (slightly larger than the ICE-5Gv1.2/VM2 model), which could lead to a change in shorelines of tens of metres horizontally over a period of 100 years.

Kirschbaum (Mitig Adapt Strat Glob Change 11:1151–1164, 2006) explores the climatic impact over time of temporarily sequestering carbon from the atmosphere. He concludes that temporary storage of carbon in the terrestrial biosphere “achieves effectively no climate-change mitigation”. His strongly worded statement begs for a response. This paper argues that Kirschbaum’s conclusion is an artifact of the specific perspective of his analysis and his choice of a definition for climate-change impact. Even temporary sinks put us on a lower path for climate change, a path that will not otherwise be accessible. For carbon sinks in the terrestrial biosphere, we argue that sooner is better and longer is better, but even known temporary sinks have value.

We present new temperature and precipitation reconstructions for the past 25 000 cal. years BP from across eastern Beringia based on a network of pollen diagrams, an updated modern pollen calibration database, and an improved methodology using the modern analogue technique (MAT). Time series show July temperatures were around 4 °C lower during full glacial and January temperatures were about 2 °C lower than present. Annual temperatures rose beginning around 16 000 cal. years BP, reaching a maximum around 12 000 cal. year BP. The warming was more rapid in southern Beringia. Annual precipitation varied by 250 mm during the past 25 000 cal. years BP. Maps of reconstructed precipitation patterns show increasingly drier conditions since 12 000 cal. years BP. that vary regionally, suggesting Holocene atmospheric circulation changes at multiple time and space scales. Orbitally forced seasonality changes during the late glacial and early Holocene resulted in reversed seasonal temperature reconstructions due to methodological constraints using the MAT and (or) non-analogue conditions. The magnitude of millennial-scale climate variability in this region was greater during the last glacial and late glacial periods than during the past 8000 years.

Two piston cores recovered from the Chukchi and the Beaufort seas document Arctic Holocene geomagnetic field behaviour and highlight the potential of secular variation and relative paleointensity as a regional chronostratigraphic tool. Several centennial- to millennial-scale Holocene declination and inclination features can be correlated in both cores, with other high-resolution western North American lacustrine and volcanic paleomagnetic records and with records of changes in Earth’s dipole moment, supporting the geomagnetic origin of these features and implying that they are associated with changes in Earth’s dipole moment.

The occurrence of long-lasting severe heat stress, such as in July–August 2003, July 2010, or in April–May 2018 has been one of the biggest meteorological threats in Europe in recent years. The paper focuses on the biometeorological and mortality effects of the hot June that was observed in Central Europe in 2019. The basis of the study was hourly and daily Universal Thermal Climate Index (UTCI) values at meteorological stations in Poland for June 2019. The average monthly air temperature and UTCI values from 1951 to 2018 were analysed as background. Grosswetterlagen calendar of atmospheric circulation was used to assess synoptic conditions of heat wave. Several heat strain measures were applied : net heat storage (S), modelled heart rate (HR), sultriness (HSI), and UTCI index. Actual total mortality (TM) and modelled strong heat-related mortality (SHRM) were taken as indicators of biometeorological consequences of the hot June in 2019. The results indicate that prolonged persistence of unusually warm weather in June 2019 was determined by the synoptic conditions occurring over the European region and causing advection of tropical air. They led to the emergence of heat waves causing 10% increase in TM and 5 times bigger SHRM then in preceding 10 years. Such increase in SHRM was an effect of overheating and overload of circulatory system of human organism. Supplementary Information The online version contains supplementary material available at 10.1007/s00484-021-02202-0.

Rapid damage assessment of natural disasters is essential for the fast recovery and strategic post-disaster reconstructions. In the present study, National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite (NPP-VIIRS) day/night band (DNB)-extracted night-time lights (NTL) data were explored for damage assessment caused by extremely severe cyclonic storm ‘AMPHAN’ that struck one of the most populous regions in India. The disaster impact was measured on two parameters: population and crop land area, where NTL density and population density were found to be strongly correlated (r2 > 0.8). From power outage intensity, three ‘crisis zones’ indicating the severity of cyclone damage were identified. Finally, the assessment found that the total affected population and crop land area were nearly 70% and 66%, respectively, of the study area. Therefore, NPP-VIIRS DNB image-based rapid damage assessment is potentially a useful tool for generating first hand information about the physical damages caused by extreme events. Supplementary Information The online version of this article (10.1007/s11069-020-04477-9) contains supplementary material, which is available to authorized users.

Coastal Zone Color Scanner (CZCS) satellite images show extensive plumes of discolored water extending from South America into the western tropical Atlantic. The most conspicuous plumes originate at the mouths of the Amazon and Orinoco Rivers, and plumes originating at smaller rivers can also be seen from space. In a recent paper by Longhurst (1993), the plume associated with the Amazon River was attributed to phytoplankton blooms stimulated by nutrients supplied via eddy upwelling. We revisit the argument that this plume is of riverine origin, and offer evidence that material present near continental margins can be advected offshore and trace circulation patterns in the adjacent ocean.

The action required to stem the environmental and social implications of climate change depends crucially on how humankind shapes technology, economy, lifestyle and policy. With transport CO2 emissions accounting for about a quarter of the total, we examine the contribution of CO2 output by scientific travel. Thankfully for the reputation of the scientific community, CO2 emissions associated with the trips required to present a paper at a scientific conference account for just 0.003% of the yearly total. However, with CO2 emissions for a single conference trip amounting to 7% of an average individual’s total CO2 emissions, scientists should lead by example by demonstrating leadership in addressing the issue.

If stratospheric temperature trends are to be understood, coupled chemistry climate models will need to be run. Simulations with fixed ozone trends might provide a misleading indication of future temperature trends. Copyright © 2005 Royal Meteorological Society

The study group “Towards a New Ethical Imagination. Political and social values in a Cosmopolitan World Society” of the Nordic Summer University had its winter meeting at the University of Akureyri, Iceland, March 1-3, 2013. We discussed different topics in the fields of moral, political, economic, and social philosophy, with the addition of a special theme i.e. ethical, political and legal issues in the Arctic region. It was a very fruitful meeting and we would like to thank the organisers at the University of Akureyri, in particular Águst Thor Árnason, the Icelandic NSU Coordinator, for all the hard work done in Akureyri.

This note answers questions raised by Cracknell et al. (preceding paper) on total ozone records over Thessaloniki, Greece, It also explains the physical theory and experimental methodology which was used in the objective re-evaluation of the Thessaloniki ozone record, which was also deposited to the WMO/World Ozone Data Centre in Toronto.

Graphical abstract, The higher concentration of PM10 and PM2.5 in the lower atmosphere is severely harmful for human health and it also makes visibility diminution along with weather and climate modifications. The main objective is to find out the spatiotemporal variation and dispersal of PM10 and PM2.5 along with COVID-19 infection in the dusty city Kolkata. The consecutive two years PM10 and PM2.5 data of different stations have been obtained from State Pollution Control Board, Govt. of West Bengal. Forward trajectory analysis has been done through HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) model to find the path and direction of air particles. The result showed that the various meteorological or environmental factors (such as temperature, relative humidity, wind, wind speed, pressure and gusty wind) and geographical location regulate the spatiotemporal variation of PM10 and PM2.5. These factors like high temperature with relative humidity and strong wind influence to disperse the particulate matters from north to south direction from city to outside during summer in Kolkata metropolitan city. During summer (both pre and lockdown years), the height of particles is extended up to 1000 m owing to active atmospheric ventilation whereas in winter it is confined within 100 m. The HYSPLIT model clearly specified that the particles dispersed from south, south-west to north and north east direction due to strong wind. The constant magnification of PM10 and PM2.5 in the lower atmosphere leads to greater frequency of COVID-19 infections and deaths. In Kolkata, the one of the crucial reasons of high infection and deaths (COVID-19) is co-morbidity of people.

The authors and co-signers of the Terrestrial Planets Comparative Climatology (TPCC) mission concept white paper advocate that planetary science in the next decade would greatly benefit from comparatively studying the fundamental behavior of the atmospheres of Venus and Mars, contemporaneously and with the same instrumentation, to capture atmospheric response to the same solar forcing, and with a minimum of instrument-related variability. Thus, this white paper was created for the 2023-2032 Planetary Science Decadal Survey process. It describes the science rationale for such a mission, and a mission concept that could achieve such a mission., 8 pages including cover page with one figure on cover page