From flooding in New Zealand and wildfires in Canada through to drought in the Middle East and extreme heat across the northern hemisphere, last year provided a powerful demonstration of the impacts of climate change.
With global temperatures over the past decade around 1.2C warmer than pre-industrial levels, the impacts already urgently demand adaptation investments to avoid mounting losses.
However, research suggests that existing limits and barriers to adaptation could take decades to overcome, particularly in vulnerable countries. And while adaptation measures are gradually being put in place, how might they be further affected by continued warming?
In our new study, published in One Earth, we investigate how the effectiveness of well-established adaptation options in relation to water changes as the world warms.
Our findings show that the effectiveness of water-related adaptation declines markedly once warming passes 1.5C above pre-industrial levels – from a central estimate (median) of 90% to 69%, 62% and 46% at 2C, 3C and 4C, respectively.
With the implementation of adaptation already lagging behind what is needed, our findings show that warming beyond 1.5C needs to be avoided for effective adaptation to be possible.
Measuring the effectiveness of adaptation
The latest assessment report from the Intergovernmental Panel on Climate Change (IPCC) shows that current adaptation efforts are insufficient to cope with the increasing severity of warming-related impacts across the world.
This “adaptation gap” – the difference between what is needed to reduce impacts and what has been implemented – is growing, despite increasing adaptation efforts across all world regions.
Where adaptation has been documented, many benefits – such as economic gains, better educational outcomes or infrastructure improvements – have been observed. However, we still have very limited evidence and knowledge about how effective adaptation is in reducing climate risks – arguably the key purpose of adaptation.
This is, of course, an inherently difficult thing to measure, as it is not possible to calculate impacts that have been avoided because of adaptation.
Different ideas of how to measure adaptation effectiveness have been put forward. In a very narrow sense, the IPCC defines adaptation effectiveness as the extent to which an adaptation option is anticipated or observed to reduce climate-related risk, an approach we use in our study. More encompassing definitions of effectiveness include the multiple benefits adaptation can have on a broader set of outcomes, such as human well-being and equality.
A better understanding of the risk reduction potential of adaptation is crucial, as climate impacts will become more severe over the next decades. With limited resources to invest, it is essential that informed decisions can be made.
Adaptation as the world warms
In our study, we look at a set of frequently used adaptation interventions in the water and agricultural sectors, which are central in current modelling approaches of future impacts.
We collated a set of published case studies distributed across all world regions. We grouped these options into nine different types of adaptation interventions – shown in the map below.
For example, adaptation measures under “changes in cropping patterns and crop systems” include approaches such as shifting planting dates or substituting different crops. Measures related to “water and soil moisture conservation” include approaches such as reduced tilling (turning of the soil) or introducing mulching (covering topsoil with plant material).
Each case study assesses in detail how a particular option could be implemented according to specific local conditions and provides results on its potential to reduce climate risks.
In many studies, different combinations of measures or different specifications of one measure – for example, shifting planting dates by 10, 20 or 30 days – are tested. Where this leads to different levels of effectiveness, we focus on those specifications that show to be most effective in reducing risk.
Declining effectiveness
To set these case study results into a global context and align them with important levels of warming, as in the IPCC reports, we translate all results into a representation of adaptation effectiveness at 1.5C, 2C, 3C and 4C. To represent effectiveness, we assess the proportion of projected risk that an adaptation option is able to avoid.
Our findings suggest a concerning picture: adaptation options are effective in reducing risks in most assessed settings up to 1.5C of warming, but with increased warming, effectiveness declines across all options and regions.
The central estimate (that is, the median) of adaptation effectiveness across all assessed measures at 1.5C is 90%. However, this declines to a median effectiveness of 69% at 2C and 62% at 3C – a level that current policies could still take warming close to.
At 4C, effectiveness declines even further to a median of 46%, indicating that less than half of projected impacts would be avoided under the adaptation measure.
The decline in effectiveness is most pronounced for adaptation options related to agriculture. For example, changes in cropping patterns and crop systems show high effectiveness at 1.5C, with more than 50% of data points in this category, but the share of highly effective adaptation decreases to 14% at 4C.
At the other end of the scale, we find that energy related adaptation (85%), flood risk reduction measures (78%) and urban water (78%) are the most likely categories to reduce 80% or more of projected risk across all warming levels.
As models do not account for adaptation limits and barriers, effectiveness in practice is likely to be lower than under idealised model conditions we assess in our study.
In many cases, adaptation in a 1.5C world comes with potential co-benefits, where the adaptation option improves conditions more widely, relative to the baseline of current conditions. For example, shifting from rain-fed agriculture to irrigation systems produces co-benefits in multiple cases.
Our findings for adaptation across Africa show that co-benefits could be substantial in closing existing adaptation gaps: 54% of assessed studies indicate potential co-benefits at 1.5C. However, this potential declines to 12% at 4C.
Similarly, in Asia the potential for co-benefits declines from around 56% at 1.5C to 16% at 4C. In Central and South America, our data also shows a shift towards less effective adaptation outcomes. There is no apparent shift in the level of co-benefits that could be achieved, though it must be noted that much fewer studies were available for this region.
In some situations, adaptation becomes not just ineffective in reducing risk, but it actually aggravates the situation, leading to “maladaptation”.
Africa shows the largest share of maladaptive outcomes at all levels of warming. For example, intensifying the cultivation of maize and sorghum in west Africa or earlier planting of maize in Uganda further decreases yields – in addition to climate impacts – rather than reducing projected risk, even at 1.5C warming.
Models often overestimate the potential for adaptation
Currently, adaptation is not well represented in quantitative models. Integrated assessment models provide information on energy system transition pathways to limit warming, but they do not account for climate impacts or costs and potentials for adaptation.
Climate impact models assess the sectoral effects of warming – for example, on agriculture or the water system. Sectoral climate impact models implement selected adaptation measures, such as irrigation in the agricultural sector, for example, but do not account for limitations such as water availability.
But, even more importantly, models do not account for other constraints and limits to adaptation, which have been documented in practice.
Beside financial barriers, which are a fundamental impediment to effective adaptation, there are also constraints and limits related to governance and institutions, availability of information, awareness, human capacity and socio-cultural constraints. Similarly, adaptive capacity plays an important role in the ability to implement effective adaptation.
Consequently, where models include adaptation, they likely overestimate its potential. This is also true for our own assessment: we assess adaptation in a modelled context, where ideal conditions for implementing the respective option are assumed. If additional adaptation constraints and adaptive capacities were considered, the extent to which adaptation can effectively reduce climate risks may be further reduced.
Climate-resilient development requires limiting warming to 1.5C
Our study focuses on a limited set of adaptation options, which are currently frequently used and have direct entry-points into the modelling space. It can be assumed that progress and learning unlock further innovation for adaptation in the future, increasing the options and approaches available to adapt and reduce risk.
However, we also know that additional limits and constraints are likely to affect effectiveness as compared to a modelling environment that does not consider such aspects.
Our findings show that effective adaptation is only truly possible if it occurs alongside ambitious mitigation action that limits warming to 1.5C. Our study also emphasises that adaptation is not an alternative to mitigation, nor can it be seen as a way to allow for a delay in mitigation efforts.
The post Guest post: Climate adaptation becomes less effective as the world warms appeared first on Carbon Brief.
Guest post: Climate adaptation becomes less effective as the world warms
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”.
Around the world
- EU RULES: The European Commission has proposed new “made in Europe” rules to support domestic low-carbon industries, “against fierce competition from China”, reported Agence France-Presse. Carbon Brief examined what it means for climate efforts.
- RECORD HEAT: The US National Oceanic and Atmospheric Administration has said there is a 50-60% chance that the El Niño weather pattern could return this year, amplifying the effect of global warming and potentially driving temperatures to “record highs”, according to Euronews.
- FLAGSHIP FUND: The African Development Bank’s “flagship clean energy fund” plans to more than double its financing to $2.5bn for African renewables over the next two years, reported the Associated Press.
- NO WITHDRAWAL: Vanuatu has defied US efforts to force the Pacific-island nation to drop a UN draft resolution calling on the world to implement a landmark International Court of Justice (ICJ) ruling on climate, according to the Guardian.
98
The number of nations that submitted their national reports on tackling nature loss to the UN on time – just half of the 196 countries that are part of the UN biodiversity treaty – according to analysis by Carbon Brief.
Latest climate research
- Sea levels are already “much higher than assumed” in most assessments of the threat posed by sea-level rise, due to “inadequate” modelling assumptions | Nature
- Accelerating human-caused global warming could see the Paris Agreement’s 1.5C limit crossed before 2030 | Geophysical Research Letters covered by Carbon Brief
- Future “super El Niño events” could “significantly lower” solar power generation due to a reduction in solar irradiance in key regions, such as California and east China | Communications Earth & Environment
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)