Recent years have seen a rapid succession of climate-related records broken.
To name just a few, the world has witnessed record warmth in the Atlantic, unprecedented glacier melt, all-time low Antarctic sea ice extent, the Amazon’s worst drought since observations began and UK temperatures soaring past 40C for the first time.
In a review article, published in Nature Reviews Earth & Environment, my coauthors and I look at how the frequency of weather records is changing as the planet warms.
We find that the number of hot temperature records observed around the world since 1950 far exceed what would be expected in a million years in a world without human-caused climate change.
Specifically, we show that “all-time” daily hot records on land were more than four times higher in 2016-24 than they would have been in a world without climate change.
Meanwhile, daily maximum rainfall records were up 40% over the same time period and record cold events were twice as rare.
A key finding of our research is that it is the pace of global warming that controls the occurrence of records.
We show that, if the pace of warming were to slow down, the frequency of record-breaking hot events would start to decline – even if global temperatures continue to rise.
Counting records
By definition, records are supposed to be rare events, at least in a system that is not changing.
Statistics of record occurrence are remarkably simple. They are expected to become rarer the longer a measurement series gets.
The chance of observing a new record after 20 years of measurement is one in 20, or 5%. And after 100 years of observations, the chances of a new record drops to 1%.
For example, this is why it becomes increasingly difficult to break records in athletics as time goes by, unless training methods or sports equipment improve.
Record-breaking weather events – for example, the highest windspeed, most intense rainfall or hot and cold temperatures – also face these odds in a climate that is “stationary”.
However, today’s climate is not stationary, but warming at a very high pace. This has significant implications for the record count.
The plot below shows how the frequency of all-time hot records (dashed red line) and record cold events (dashed blue line) has changed since the 1960s. This is compared to the probability that would be expected under a stationary climate (black line).
(The plot uses ERA5, a reanalysis dataset, which combines observations and models from the European Centre for Medium-Range Weather Forecasts (ECMWF).)
It illustrates how the frequency of hot events declined more slowly than would be expected in a stationary climate since 1950, before increasing in the last 15 years. Meanwhile, the frequency of record cold events is declining more quickly than expected.
The record ratio
Tracking the ratio between the measured number of records and the one theoretically expected in a stationary climate – the “record ratio” – reveals the fingerprint of climate change.
Analysis of ERA5 data and Berkeley Earth surface temperature observations finds that the record ratio over the last decade for hot records over global land regions is more than four. For cold records, it is between 0.2 and 0.5, showing that record-breaking cold has declined
In other words, there were more than four times as many hot record events and less than half as many cold record events than would be expected without global warming.
In 2023 and 2024, the record ratio for hot events reached 5.5 and 6.2, respectively.
Record ratios tend to be higher over global oceans than on land. They are also higher for monthly or seasonal record temperatures than all-time daily records.
This is because natural variability in the climate tends to be smaller over oceans and for longer averaging periods, such as months and seasons.
Record counts directly relate to the relationship between rates of warming and natural fluctuations in the climate. This is sometimes referred to as the “signal-to-noise ratio”. (The “signal” being the long-term trend of climate change and “noise” referring to short-term fluctuations of natural variability.)
As a result, event types and regions with a higher signal-to-noise ratio tend to see a greater number of records.
Another way of illustrating the signal of climate change is by counting the total number of records in a measurement series.
In a stationary climate, there should be about five records in 100 years of temperature measurements, 7.5 in 1,000 years and less than 10 in 10,000 years.
However, our analysis of records in two measurement series shows how the number of record-breaking events has become significantly higher as the climate has changed.
For example, as the figure on the left below illustrates, a new annual record for average global temperature has been set 25 times over the past 175 years.
Meanwhile, the figure on the right shows how, in the Pacific north-west, a new five-day average heat record has been set 14 times within the last 75 years. The spike in temperature in 2021 reflects the brutal heatwave that killed hundreds of people and brought devastating wildfires that almost entirely destroyed the Canadian village of Lytton.
(In both figures, the warm records are marked by pink circles.)
According to fundamental laws of statistics, 14 new records would not be expected in more than a million years in a climate that is not warming.
It is worth noting that some climate variables, including ocean heat content, sea level rise and minimum glacier or ice sheet volumes, are changing so relentlessly that new record levels are currently set every year.
Record-shattering events
Record-shattering events are a subset of record-breaking events whose magnitude exceeds the previous event by a large margin.
In our research, we define this as more than one standard deviation, which is a measure of how spread out data is from the average.
(The exact value of standard deviation varies for different parts of the world. For example, when it comes to year-to-year average temperatures, one standard deviation is typically 2-3C in the Arctic, but less than 0.5C over the ocean).
These events of unprecedented intensity are often very impactful as they strongly exceed the conditions that society or ecosystems have experienced in the past.
The 2021 heatwave in the Pacific north-west, mentioned above, is a forbidding example.
Our research finds that the large number of record-shattering events in the past three decades is the consequence of a very high warming rate.
Using a simple timeseries model, we illustrate why the pace of warming is the key factor explaining the occurrence of record-shattering events.
In the left-hand figure, we assume a 150-year period of no warming followed by some linear warming at three different rates, which is a very simplistic approximation of historical and future warming pathways.
The right-hand figure illustrates what happens to the probability of record-shattering events in the Pacific north-west region under these three simplified pathways. It shows that the probability of record-shattering events at first rapidly increases and then stabilises. And the level at which the probability stabilises is greater the higher the rate of warming.
We therefore conclude that the high frequency of record-shattering hot extremes in recent years is controlled by the very high rate of warming caused by human-caused greenhouse gas emissions.
This tight coupling of record counts to the rate or speed of warming implies that there will be early benefits of slowing down global warming.
In our research, we look at how the probability of hot and cold records changes under different emissions reduction scenarios. To do this, we analysed the occurrence of record hot and cold events in climate model projections in the CMIP6 archive.
The figure below shows how stabilising temperatures by achieving net-zero carbon emissions (SSP1-1.9 and SSP1-2.6) will lead to a rapid decline of records, even if temperatures remain higher than in the historical period.
(It is worth noting that, while the number of records will decline under this lower-emissions scenario, the number of heatwaves would remain higher than today.)
Under intermediate (SSP2-4.5), high (SSP3-7.0) and very high emission (SSP5-8.5) scenarios, the number of records would continue to increase to levels much higher than today.
Rainfall records
We would also expect rainfall records to become progressively rarer in a stationary climate.
However, we find that record-breaking heavy precipitation occurred about 40% more often in 2015-24 than would be expected in a stationary climate. Many record-shattering heavy rainfall extremes occurred in the mid-latitudes and led to flooding which had large impacts.
(Calculating the frequency of records is more challenging for rainfall than for temperature, given small-scale variations and uncertainties in rainfall observations.)
The greater number of record-breaking rainfall events is due to an increase in precipitation intensity over most land regions as the atmosphere warms, as well as larger variations of rainfall intensity on a day-to-day, season-to-season and year-to-year basis .
We also find that the margin by which previous rainfall records are broken tends to become larger and larger in time. This is due to the “non-symmetric” distribution of rainfall – where there are many days with little precipitation, less with heavy precipitation and very few with very extreme precipitation.
It is therefore not surprising to see record-shattering precipitation events exceeding previous records by 20-50% in intensity, even if overall precipitation intensity increases by roughly 7% per degree of warming.
Preparing for the future
Efforts to adapt to climate change are typically informed by the worst events observed in recent generations.
This means that society is often underprepared for record-shattering events – which by their very definition are of unprecedented intensity.
Qualitative and quantitative storyline methods can offer insight into the many record-breaking events to come into the future – and, thus, help society prepare for escalating climate impacts.
These methods combine information from historical and paleoarchives, long measurement series, targeted climate model experiments, statistical and machine learning methods and weather forecasting systems.
Ultimately, these methods can improve society’s preparedness to climate change, so that the next record-shattering extreme does not come as a surprise.
The post Guest post: How climate change is fuelling record-breaking extreme weather appeared first on Carbon Brief.
Guest post: How climate change is fuelling record-breaking extreme weather
Drought and heatwaves occurring together – known as “compound” events – have “surged” across the world since the early 2000s, a new study shows.
Compound drought and heat events (CDHEs) can have devastating effects, creating the ideal conditions for intense wildfires, such as Australia’s “Black Summer” of 2019-20 where bushfires burned 24m hectares and killed 33 people.
The research, published in Science Advances, finds that the increase in CDHEs is predominantly being driven by events that start with a heatwave.
The global area affected by such “heatwave-led” compound events has more than doubled between 1980-2001 and 2002-23, the study says.
The rapid increase in these events over the last 23 years cannot be explained solely by global warming, the authors note.
Since the late 1990s, feedbacks between the land and the atmosphere have become stronger, making heatwaves more likely to trigger drought conditions, they explain.
One of the study authors tells Carbon Brief that societies must pay greater attention to compound events, which can “cause severe impacts on ecosystems, agriculture and society”.
Compound events
CDHEs are extreme weather events where drought and heatwave conditions occur simultaneously – or shortly after each other – in the same region.
These events are often triggered by large-scale weather patterns, such as “blocking” highs, which can produce “prolonged” hot and dry conditions, according to the study.
Prof Sang-Wook Yeh is one of the study authors and a professor at the Ewha Womans University in South Korea. He tells Carbon Brief:
“When heatwaves and droughts occur together, the two hazards reinforce each other through land-atmosphere interactions. This amplifies surface heating and soil moisture deficits, making compound events more intense and damaging than single hazards.”
CDHEs can begin with either a heatwave or a drought.
The sequence of these extremes is important, the study says, as they have different drivers and impacts.
For example, in a CDHE where the heatwave was the precursor, increased direct sunshine causes more moisture loss from soils and plants, leading to a drought.
Conversely, in an event where the drought was the precursor, the lack of soil moisture means that less of the sun’s energy goes into evaporation and more goes into warming the Earth’s surface. This produces favourable conditions for heatwaves.
The study shows that the majority of CDHEs globally start out as a drought.
In recent years, there has been increasing focus on these events due to the devastating impact they have on agriculture, ecosystems and public health.
In Russia in the summer of 2010, a compound drought-heatwave event – and the associated wildfires – caused the death of nearly 55,000 people, the study notes.
The record-breaking Pacific north-west “heat dome” in 2021 triggered extreme drought conditions that caused “significant declines” in wheat yields, as well as in barley, canola and fruit production in British Columbia and Alberta, Canada, says the study.
Increasing events
To assess how CDHEs are changing, the researchers use daily reanalysis data to identify droughts and heatwaves events. (Reanalysis data combines past observations with climate models to create a historical climate record.) Then, using an algorithm, they analyse how these events overlap in both time and space.
The study covers the period from 1980 to 2023 and the world’s land surface, excluding polar regions where CDHEs are rare.
The research finds that the area of land affected by CDHEs has “increased substantially” since the early 2000s.
Heatwave-led events have been the main contributor to this increase, the study says, with their spatial extent rising 110% between 1980-2001 and 2002-23, compared to a 59% increase for drought-led events.
The map below shows the global distribution of CDHEs over 1980-2023. The charts show the percentage of the land surface affected by a heatwave-led CDHE (red) or a drought-led CDHE (yellow) in a given year (left) and relative increase in each CDHE type (right).
The study finds that CDHEs have occurred most frequently in northern South America, the southern US, eastern Europe, central Africa and south Asia.
Threshold passed
The authors explain that the increase in heatwave-led CDHEs is related to rising global temperatures, but that this does not tell the whole story.
In the earlier 22-year period of 1980-2001, the study finds that the spatial extent of heatwave-led CDHEs rises by 1.6% per 1C of global temperature rise. For the more-recent period of 2022-23, this increases “nearly eightfold” to 13.1%.
The change suggests that the rapid increase in the heatwave-led CDHEs occurred after the global average temperature “surpasse[d] a certain temperature threshold”, the paper says.
This threshold is an absolute global average temperature of 14.3C, the authors estimate (based on an 11-year average), which the world passed around the year 2000.
Investigating the recent surge in heatwave-leading CDHEs further, the researchers find a “regime shift” in land-atmosphere dynamics “toward a persistently intensified state after the late 1990s”.
In other words, the way that drier soils drive higher surface temperatures, and vice versa, is becoming stronger, resulting in more heatwave-led compound events.
Daily data
The research has some advantages over other previous studies, Yeh says. For instance, the new work uses daily estimations of CDHEs, compared to monthly data used in past research. This is “important for capturing the detailed occurrence” of these events, says Yeh.
He adds that another advantage of their study is that it distinguishes the sequence of droughts and heatwaves, which allows them to “better understand the differences” in the characteristics of CDHEs.
Dr Meryem Tanarhte is a climate scientist at the University Hassan II in Morocco, and Dr Ruth Cerezo Mota is a climatologist and a researcher at the National Autonomous University of Mexico. Both scientists, who were not involved in the study, agree that the daily estimations give a clearer picture of how CDHEs are changing.
Cerezo-Mota adds that another major contribution of the study is its global focus. She tells Carbon Brief that in some regions, such as Mexico and Africa, there is a lack of studies on CDHEs:
“Not because the events do not occur, but perhaps because [these regions] do not have all the data or the expertise to do so.”
However, she notes that the reanalysis data used by the study does have limitations with how it represents rainfall in some parts of the world.
Compound impacts
The study notes that if CDHEs continue to intensify – particularly events where heatwaves are the precursors – they could drive declining crop productivity, increased wildfire frequency and severe public health crises.
These impacts could be “much more rapid and severe as global warming continues”, Yeh tells Carbon Brief.
Tanarhte notes that these events can be forecasted up to 10 days ahead in many regions. Furthermore, she says, the strongest impacts can be prevented “through preparedness and adaptation”, including through “water management for agriculture, heatwave mitigation measures and wildfire mitigation”.
The study recommends reassessing current risk management strategies for these compound events. It also suggests incorporating the sequences of drought and heatwaves into compound event analysis frameworks “to enhance climate risk management”.
Cerezo-Mota says that it is clear that the world needs to be prepared for the increased occurrence of these events. She tells Carbon Brief:
“These [risk assessments and strategies] need to be carried out at the local level to understand the complexities of each region.”
The post Heatwaves driving recent ‘surge’ in compound drought and heat extremes appeared first on Carbon Brief.
Heatwaves driving recent ‘surge’ in compound drought and heat extremes
Greenhouse Gases
DeBriefed 6 March 2026: Iran energy crisis | China climate plan | Bristol’s ‘pioneering’ wind turbine
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Energy crisis
ENERGY SPIKE: US-Israeli attacks on Iran and subsequent counterattacks across the Middle East have sent energy prices “soaring”, according to Reuters. The newswire reported that the region “accounts for just under a third of global oil production and almost a fifth of gas”. The Guardian noted that shipping traffic through the strait of Hormuz, which normally ferries 20% of the world’s oil, “all but ground to a halt”. The Financial Times reported that attacks by Iran on Middle East energy facilities – notably in Qatar – triggered the “biggest rise in gas prices since Russia’s full-scale invasion of Ukraine”.
‘RISK’ AND ‘BENEFITS’: Bloomberg reported on increases in diesel prices in Europe and the US, speculating that rising fuel costs could be “a risk for president Donald Trump”. US gas producers are “poised to benefit from the big disruption in global supply”, according to CNBC. Indian government sources told the Economic Times that Russia is prepared to “fulfil India’s energy demands”. China Daily quoted experts who said “China’s energy security remains fundamentally unshaken”, thanks to “emergency stockpiles and a wide array of import channels”.
‘ESSENTIAL’ RENEWABLES: Energy analysts said governments should cut their fossil-fuel reliance by investing in renewables, “rather than just seeking non-Gulf oil and gas suppliers”, reported Climate Home News. This message was echoed by UK business secretary Peter Kyle, who said “doubling down on renewables” was “essential” amid “regional instability”, according to the Daily Telegraph.
China’s climate plan
PEAK COAL?: China has set out its next “five-year plan” at the annual “two sessions” meeting of the National People’s Congress, including its climate strategy out to 2030, according to the Hong Kong-based South China Morning Post. The plan called for China to cut its carbon emissions per unit of gross domestic product (GDP) by 17% from 2026 to 2030, which “may allow for continued increase in emissions given the rate of GDP growth”, reported Reuters. The newswire added that the plan also had targets to reach peak coal in the next five years and replace 30m tonnes per year of coal with renewables.
ACTIVE YET PRUDENT: Bloomberg described the new plan as “cautious”, stating that it “frustrat[es] hopes for tighter policy that would drive the nation to peak carbon emissions well before president Xi Jinping’s 2030 deadline”. Carbon Brief has just published an in-depth analysis of the plan. China Daily reported that the strategy “highlights measures to promote the climate targets of peaking carbon dioxide emissions before 2030”, which China said it would work towards “actively yet prudently”.