P. A. Stott

Met Office · Hadley Centre

As the world warms, extremely hot days are becoming more frequent and intense, reaching unprecedented temperatures associated with excess mortality. Here, we assess how anthropogenic forcings affect the likelihood of maximum daily temperatures above 50 °C at 12 selected locations around the Mediterranean and the Middle East. We adopt a risk-based a...

The science of event attribution has developed considerably in recent years. There is now a growing interest in making this science operational. This perspective considers the challenges involved in doing this and suggests some priorities for further developments. It concludes that there is a requirement to deepen understanding of user needs for op...

GCM ensembles indicate that the October 2021 South Korean heatwave was extremely unlikely to occur without human influences, which corresponds to 2060s’ new normal without ambitious greenhouse gas mitigation.

Human influence and persistent low pressure are estimated to make extreme May rainfall in the United Kingdom, as in year 2021, about 1.5 and 3.5 times more likely, respectively.

Research into weather circulation changes over the UK for future climate has mainly focused on changes in the Summer and Winter seasons, with less analysis on seasonality and the transition seasons. Using the 30 Met Office weather patterns we examine the influence of climate change on seasonality through atmospheric circulation using a number of cl...

It sounds straightforward. As the Earth warms due to the increased concentration of greenhouse gases in the atmosphere, global temperatures rise and so heatwaves become warmer as well. This means that a fixed temperature threshold is passed more often: the probability of extreme heat increases. However, land use changes, vegetation change, irrigati...

The response of precipitation to global warming is manifest in the strengthening of the hydrological cycle but can be complex on regional scales. Fingerprinting analyses have so far detected the effect of human influence on regional changes of precipitation extremes. Here we examine changes in seasonal precipitation in Europe since the beginning of...

The full flowering of Kyoto’s cherry trees in 2021 was observed on the 26th of March, the earliest date recorded in over 1200 years. An early shift of the flowering season is consistent with Kyoto’s warming climate and could have serious repercussions for the local economy. It is therefore crucial to assess how human activity impacts flowering date...

Since the 1970s, scientists have developed statistical methods intended to formalize detection of changes in global climate and to attribute such changes to relevant causal factors, natural and anthropogenic. Detection and attribution (D&A) of climate change trends is commonly performed using a variant of Hasselmann’s “optimal fingerprinting” metho...

Research into weather circulation changes over the UK for future climate has mainly focused on changes in the Summer and Winter seasons, with less analysis on seasonality and the transition seasons. Using the 30 Met Office weather patterns we examine the influence of climate change on seasonality through atmospheric circulation using a number of cl...

Editors note: For easy download the posted pdf of the Explaining Extreme Events of 2020 is a very low-resolution file. A high-resolution copy of the report is available by clicking here . Please be patient as it may take a few minutes for the high-resolution file to download.

Probabilistic event attribution aims to quantify the role of anthropogenic climate change in altering the intensity or probability of extreme climate and weather events. It was originally conceived to calculate the costs associated with any increased likelihood of the meteorological event in question. However, only recently have such studies attemp...

Domestic energy consumption in the United Kingdom depends on both meteorological and socio-economic factors. The former are dominated by the effect of temperature during the colder months of the year, with the energy demand increasing as the temperature decreases. Warming of the UK climate under the influence of anthropogenic forcings is therefore...

We present results from the first 6 years of this major UK government funded project to accelerate and enhance collaborative research and development in climate science, forge a strong strategic partnership between UK and Chinese climate scientists and demonstrate new climate services developed in partnership. The development of novel climate servi...

A large number of recent studies have aimed at understanding short-duration rainfall extremes, due to their impacts on flash floods, landslides and debris flows and potential for these to worsen with global warming. This has been led in a concerted international effort by the INTENSE Crosscutting Project of the GEWEX (Global Energy and Water Exchan...

Abstract The breaking of the United Kingdom's daily rainfall record in October 2020 made a striking addition to the list of recent heavy precipitation events in the country. Mounting evidence from attribution research suggests that such extremes become more frequent and intense in a warming climate. Although most studies consider extreme events in...

A multimodel analysis indicates that the 2019 September record high number of typhoons affecting South Korea was contributed to mostly by the very strong convection over northwestern India with no discernible anthropogenic contribution.

Understanding the role of anthropogenic forcings in regional hydrological changes can help communities plan their adaptation in an informed manner. Here we apply attribution research methods to investigate the effect of human influence on historical trends in wet and dry summers and changes in the likelihood of extreme events in Europe. We employ a...

Editors note: For easy download the posted pdf of the Explaining Extreme Events of 2019 is a very low-resolution file. A high-resolution copy of the report is available by clicking here . Please be patient as it may take a few minutes for the high-resolution file to download.

The spring of 2018 was the hottest on record since 1951 over eastern China based on station observations, being 2.5°C higher than the 1961–90 mean and with more than 900 stations reaching the record spring mean temperature. This event exerted serious impacts in the region on agriculture, plant phenology, electricity transmission systems, and human...

In the UK where 90% of residents are projected to live in urban areas by 2050, projecting changes in urban heat islands (UHIs) is essential to municipal adaptation. Increased summer temperatures are linked to increased mortality. Using the new regional UK Climate Projections, UKCP18-regional, we estimate the 1981–2079 trends in summer urban and rur...

As European heatwaves become more severe, summers in the United Kingdom (UK) are also getting warmer. The UK record temperature of 38.7 °C set in Cambridge in July 2019 prompts the question of whether exceeding 40 °C is now within reach. Here, we show how human influence is increasing the likelihood of exceeding 30, 35 and 40 °C locally. We utilise...

In China, summer precipitation contributes a major part of the total precipitation amount in a year and has major impacts on society and human life. Whether or not any changes in summer precipitation are affected by external forcing on the climate system is an important issue. In this study, an optimal fingerprinting method was used to compare the...

We have investigated the effects of land use on past climate change by means of a new 15‐member ensemble of the HadGEM3‐A‐N216 model, usually used for event attribution studies. This ensemble runs from 1960 to 2013, and includes natural external climate forcings with the addition of human land use changes. It supports previously‐existing ensembles,...

Editors note: For easy download the posted pdf of the Explaining Extreme Events of 2018 is a very low-resolution file. A high-resolution copy of the report is available by clicking here . Please be patient as it may take a few minutes for the high-resolution file to download.

We examine whether significant changes in ocean temperatures can be detected in recent decades and if so whether they can be attributed to anthropogenic or natural factors. We compare ocean temperature changes for 1960–2005 in four observational datasets and in historical simulations by atmosphere-ocean general circulation models (AOGCMs) from the...

Increasing extreme temperatures linked to human influence amplify thermal stress and can lead to decreases in work productivity and increases in heat‐related mortality. However, studies assessing in a formal statistical way the contribution of climate change to such impacts remain sparse. Two new indices are introduced here that measure the effect...

A detailed analysis is carried out to assess the HadGEM3-A global atmospheric model skill in simulating extreme temperatures, precipitation and storm surges in Europe in the view of their attribution to human influence. The analysis is performed based on an ensemble of 15 atmospheric simulations forced with observed sea surface temperature of the 5...

Editors note: For easy download the posted pdf of the Explaining Extreme Events of 2016 is a very low-resolution file. A high-resolution copy of the report is available by clicking here. Please be patient as it may take a few minutes for the high-resolution file to download.

Anthropogenic influence has increased the chance of an extreme heavy precipitation event like that in June 2017 in southeastern China by about twofold, from a 0.6% probability to a 1.2% probability.

The benefits of limiting global warming to the lower Paris Agreement target of 1.5 °C are substantial with respect to population exposure to heat, and should impel countries to strive towards greater emissions reductions.

We present a substantial upgrade of the Met Office system for the probabilistic attribution of extreme weather and climate events with higher horizontal and vertical resolution (60 km mid-latitudes and 85 vertical levels), the latest Hadley Centre atmospheric and land model (ENDGame dynamics with GA6.0 science and JULES at GL6.0) as well as an upda...

This sixth edition of explaining extreme events of the previous year (2016) from a climate perspective is the first of these reports to find that some extreme events were not possible in a preindustrial climate. The events were the 2016 record global heat, the heat across Asia, as well as a marine heat wave off the coast of Alaska. While these resu...

Attribution analyses of extreme events estimate changes in the likelihood of their occurrence due to human climatic influences by comparing simulations with and without anthropogenic forcings. Classes of events are commonly considered that only share one or more key characteristics with the observed event. Here we test the sensitivity of attributio...

An attribution study has been performed to investigate the degree to which the unusually cold European winter of 2009/10 was modified by anthropogenic climate change. Two different methods have been included for the attribution: one based on large HadGEM3-A ensembles and one based on a statistical surrogate method. Both methods are evaluated by com...

The science of event attribution meets a mounting demand for reliable and timely information about the links between climate change and individual extreme events. Studies have estimated the contribution of human-induced climate change to the magnitude of an event as well as its likelihood, and many types of event have been investigated including he...

We compare the latest observational land surface humidity dataset, HadISDH, with the latest generation of climate models extracted from the CMIP5 archive and the ERA-Interim reanalysis over the period 1973 to present. The globally averaged behaviour of HadISDH and ERA-Interim are very similar in both humidity measures and air temperature, on decada...

Large differences in climate outcomes are projected by the end of this century depending on whether greenhouse gas emissions continue to increase or are reduced sufficiently to limit total warming to below 2 °C (ref.). However, it is generally thought that benefits of mitigation are hidden by internal climate variability until later in the century....

The East Asian summer monsoon (EASM) is important for bringing rainfall to large areas of China. Historically, variations in the EASM have had major impacts including flooding and drought. We present an analysis of the impact of anthropogenic climate change on EASM rainfall in Eastern China using a newly updated attribution system. Our results sugg...

We compare the latest observational land-surface humidity dataset, HadISDH, with the latest generation of climate models extracted from the CMIP5 archive and the ERA-Interim reanalysis over the period 1973 to present. The globally averaged behaviour of HadISDH and ERA-Interim are very similar in both humidity measures and air temperature, at decada...

Anthropogenic climate change increased the probability that a short-duration, intense rainfall event would occur in parts of southeast China. This type of event occurred in May 2015, causing serious flooding.

This year's event types include tropical cyclones, extreme sunshine, nuisance tidal flooding, snowpack drought, forest fires, and Arctic sea ice extent in addition to heat, cold, precipitation, and drought. The Summary Table (Table 28.1) is provided to give readers a general overview of the results. However, it is a highly simplified categorization...

Editors note: For easy download the posted pdf of the Explaining Extreme Events of 2015 is a very low-resolution file. A high-resolution copy of the report is available by clicking here. Please be patient as it may take a few minutes for the high-resolution file to download.

Extreme winter sunshine in the United Kingdom, as observed in the record high 2014/15 season, has become more than 1.5 times more likely to occur under the influence of anthropogenic forcings.

Changes in precipitation characteristics directly affect society through their impacts on drought and floods, hydro-dams, and urban drainage systems. Global warming increases the water holding capacity of the atmosphere and thus the risk of heavy precipitation. Here, daily precipitation records from over 700 Chinese stations from 1956 to 2005 are a...

We present a new method that allows a separation of the attribution of human influence in extreme events into changes in atmospheric flows and changes in other processes. Assuming two data sets of model simulations or observations representing a natural, or 'counter-factual' climate, and the actual, or 'factual' climate, we show how flow analogs us...

Detection and attribution studies have demonstrated that anthropogenic forcings have been driving significant changes in temperature extremes since the middle of the 20th century. Moreover, new methodologies have been developed for the attribution of extreme events that assess how human influence may have changed their characteristics. Here we comb...

Understanding how the overall risks of extreme events are changing in a warming world requires both a thermodynamic perspective and an understanding of changes in the atmospheric circulation.

Using optimal detection techniques with climate model simulations, most of the observed increase of near surface temperatures over the second half of the twentieth century is attributed to anthropogenic influences. However, the partitioning of the anthropogenic influence to individual factors, such as greenhouse gases and aerosols, is much less rob...

Understanding how human influence on the climate is affecting precipitation around the world is immensely important for defining mitigation policies, and for adaptation planning. Yet despite increasing evidence for the influence of climate change on global patterns of precipitation, and expectations that significant changes in regional precipitatio...

Although it is critical to assess the accuracy of attribution studies, the fraction of attributable risk (FAR) cannot be directly assessed from observations since it involves the probability of an event in a world that did not happen, the "natural" world where there was no human influence on climate. Instead, reliability diagrams (usually used to c...

Extreme weather and climate‐related events occur in a particular place, by definition, infrequently. It is therefore challenging to detect systematic changes in their occurrence given the relative shortness of observational records. However, there is a clear interest from outside the climate science community in the extent to which recent damaging...

A succession of storms reaching southern England in the winter of 2013/2014 caused severe floods and £451 million insured losses. In a large ensemble of climate model simulations, we find that, as well as increasing the amount of moisture the atmosphere can hold, anthropogenic warming caused a small but significant increase in the number of January...

Apart from global scale surface warming, anthropogenic forcings also lead to warming and thermal expansion of the lower atmosphere. Here we investigate these effects using the geopotential height at 500hPa, an indicator of the combined thermodynamic and dynamic climatic response to external forcings. We employ optimal fingerprinting, which uses inf...

We investigate the relative contribution from natural and human-caused forcings to the 2014 hot spring with high mean temperatures in northern China using a two-step attribution procedure. We show that the spring temperature increase during the period 1958-2014 could be explained by the combined effects of anthropogenic and natural forcings with hu...

We investigate the relative contribution from natural and human-caused forcings to the 2014 hot spring with high mean temperatures in northern China using a two-step attribution procedure. We show that the spring temperature increase during the period 1958-2014 could be explained by the combined effects of anthropogenic and natural forcings with hu...

An improved understanding of how changes in extremes can be relevant and applied to improved decision making is discussed. The early onset of the 2014 dry season in California fueled an extraordinary jump in wildfires. Between 1 January and 20 September, the California Department of Forestry and Fire Protection reported thousands more fires than th...

This special supplement on explaining extreme events has now published 79 papers over the past four years. Over half of these papers have shown that human-caused climate change influenced an event's frequency and/or intensity in a substantial manner. It could be argued that because all of these events occurred in the context of a warmer world, ther...

Extreme winter rainfall in the United Kingdom becomes eight times more likely when the atmospheric circulation resembles winter 2013/14, whereas anthropogenic influence is only discernible in extremes with a shorter duration.