Dr. Mirianna Budimir is senior climate and resilience expert at Practical Action, and early warning systems lead for the Zurich Climate Resilience Alliance (ZCRA). Francisco Ianni is senior officer for climate resilience initiatives at the International Federation of Red Cross and Red Crescent Societies, and heat hazards lead for the ZCRA. Carolina Pereira Marghidan is a technical advisor at the Red Cross Red Crescent Climate Centre.
Across the world, instances of extreme heat are occurring more frequently than ever. News of temperature records being shattered – all too often accompanied by reports detailing tragic loss of life – appear with frightening regularity. The threats posed by heatwaves are considerable, and due to the climate crisis are expected only to get worse.
It’s hard to think of any aspect of daily life unaffected by an extreme heat event. Health services quickly become overstretched; power systems buckle; and economic productivity grinds to a halt.
A new study by Mercy Corps in the rural region of Madesh in Nepal reveals the impact heatwaves are having on children’s education. “The classrooms feel like furnaces,” said one student. “The air is thick with hot air and foul smell of sweat, the walls trap the heat, and all I can think about is when I can escape.”
Scientists predict global warming of more than 1.5C for 2025-2029 period
Today is Heat Action Day, a global moment for raising awareness of heat risks. While we welcome and encourage the sharing of practical advice for staying safe, there’s so much more that needs to be done.
Knowing when and where these extreme heat events will occur is key to tackling the problem, and early warning systems hold enormous potential to reduce losses, suffering and death across the world. So why do they often fall short?
The fragmented landscape of heat warnings
Given the risks presented by heatwaves, and the relative ease of predicting temperature well in advance, over a hundred meteorological services – more than half of the global total – do provide warnings for instances of extreme heat.
However, many of these are informed solely by maximum temperature, and don’t capture prolonged, intense periods of heat. When the mercury refuses to drop for consecutive days and nights, the dangers are far greater.
This points to a bigger problem with heatwave warning systems: the lack of standardization. Analysis led by the Red Cross Red Crescent Climate Centre has revealed stark inconsistencies in approaches to the monitoring, research and forecasting of heat across the world. This is in no small part due to the differing levels of capacity from region to region; but even the terminology varies wildly, with literally hundreds of definitions of extreme heat in use right now.
Then there’s an even greater concern, which is that many countries – particularly lower-income nations in Africa, Latin America, and parts of Southeast Asia – have no such warning system at all. As is too often the case, those most vulnerable to the risks are the ones with the least protection, with potentially lethal consequences.
Climate change-driven heatwaves hit Delhi’s Red Fort market traders
Break the silos to enhance resilience to heat
Closing these gaps requires the urgent scaling up of effective early warning systems for heatwaves. While national governments and donors have their part to play (particularly in the development and financing of low-cost solutions), improved coordination and cooperation at the global level would give these efforts a much-needed boost.
More standardization will certainly improve matters, and it is promising to see progress being made on this front. The World Meteorological Organization recently published a new definition for heatwaves, one that crucially captures their prolonged nature. In partnership with the World Health Organization, the WMO is also updating its decade-old guidance on heatwave warning system development. And a new handbook of extreme heat indicators, indices and metrics is expected later this year.
To continue this momentum, far greater transparency is required of all governments, institutions and organizations engaged in addressing heat-related risks. This should include the proactive sharing of knowledge, data and best practices, and collaborating wherever possible.
Low-income countries currently without protection from extreme heat events can use this information to rapidly build their capacity to assess their existing vulnerabilities, as well as develop and implement appropriate warning systems. Meanwhile, those already using such systems can make the necessary improvements to increase their effectiveness.
No one-size-fits-all solution for communities
A more coherent, coordinated approach to heatwave warning systems will be a massive step in the right direction. However, as with any such intervention, steps must be taken to avoid an overly top-down approach. If invaluable community insights go unheard, and potentially life-saving messages don’t reach the people they’re designed to help, we won’t see anything close to the levels of progress needed.
Only by taking a people-centred approach can the true potential of early warning systems be realized. Alerts need to be accessible and comprehensible to even the most remote and marginalized populations, and contain practical guidance informed by detailed, locally led risk assessments and response plans. The best way to do that is to ensure communities are active participants at every step of the process.
Women bear brunt of South Sudan’s heatwave made worse by climate change
One major flaw with the top-down model is that it rarely acknowledges how heat affects different people in different ways. Rather than issuing a blanket alert, early warning systems must target their messaging to those most at risk – be it pregnant women, elderly people, or outdoor labourers.
Where communities lack access to air-conditioned spaces and other opportunities for respite, that must also be taken into account. In every case, information on the likely impact of the heat, combined with guidance on how to mitigate it, is essential.
After over a decade enhancing resilience to floods around the world (including via warning systems), the Zurich Climate Resilience Alliance is applying the same community-centred approach to tackling heatwaves. In Pakistan, Senegal, the Philippines and more, we’re partnering with communities and national actors to conduct in-depth assessments and provide country-specific recommendations to enhance Heat Early Warning Systems.
No time to lose
By necessity, the world is beginning to act with more urgency to address the risks presented by heatwaves; but as life-threatening heat events increase in both frequency and intensity, we can’t afford to wait for the next heat-related tragedy before taking action.
This year, Heat Action Day falls on the opening day of the Global Platform For Disaster Risk Reduction in Geneva, at which Early Warning Systems will take centre stage. This is an unmissable opportunity to collaborate across continents and sectors, as part of a renewed commitment to a world in which all are protected from heatwaves and other climate hazards by effective and equitable early warning systems.
As temperatures rise, so too must our ambitions.
The post Early warnings for heatwaves can save lives – and we need them now appeared first on Climate Home News.
Early warnings for heatwaves can save lives – and we need them now
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On the Historic Route From Selma to Montgomery, an AI Cloud Looms
The planet is heating up more quickly than ever before.
For decades, greenhouse gas emissions caused by human activity have been building up in the atmosphere and trapping ever-higher levels of heat.
The resulting asymmetry between incoming solar energy and energy radiated back out into space – known as “Earth’s energy imbalance” – provides a direct measure of the extent to which humans are disrupting the Earth’s climate system.
This imbalance is growing and in 2025 its 10-year average reached a record high, indicating that global temperatures could increase at even higher rates in the future.
This is among the headline findings of the latest “indicators of global climate change” (IGCC) report, published in the journal Earth System Science Data, which tracks changes in the climate system on an annual basis.
The report, now in its fourth iteration, has been produced by dozens of scientists from around the world.
Its findings are designed to fill the gap between Intergovernmental Panel on Climate Change (IPCC) science reports, which are published every 5-7 years.
In this article, we unpack the IGCC report, which explores how human activity is driving a growing energy imbalance and why monitoring systems to track global climate are so crucial.
(For more on previous IGCC reports, see Carbon Brief’s coverage in 2023, 2024 and 2025.)
Greenhouse gas emissions remain at an all-time high
Global greenhouse gas emissions are continuing to increase, mostly as a result of the use of fossil fuels. However, deforestation, agriculture and industrial processes also play an important role.
Over the most recent decade (2015-24), emissions stood at the equivalent of 54.6bn tonnes of carbon dioxide equivalent (GtCO2e) per year. In 2024, the most recent year for which we have complete data, emissions reached 56.8GtCO2e.
As the chart below shows, these emissions have pushed up atmospheric levels of CO2, methane and nitrous oxide. In 2025, concentrations of these gases reached 425.6 parts per million (ppm), 1936.3 parts per billion (ppb) and 339.4ppb, respectively.
This represents a rise of 3.8%, 3.8% and 2.2%, respectively, since the 2019 levels reported in the IPCC’s sixth assessment report (AR6).
At the same time, declines in emissions of aerosols such as sulphur dioxide, partly as a result of efforts to tackle air pollution, are increasing the Earth’s energy imbalance. This is because aerosols have a cooling effect on the Earth’s climate, counteracting warming from CO2 and other greenhouse gas emissions.
(Tackling sulphur dioxide, alongside other particulate emissions, remains critical because the immediate health and environmental damage they cause far outweighs their short-term cooling effect on the climate.)
The Earth’s energy imbalance is rising rapidly
The Earth’s energy imbalance has long been recognised as a key indicator of how the climate is being affected by human activities.
However, it is only in the last few decades that scientists have been able to record temperature changes deep enough in the ocean to accurately quantify it.
Earth’s energy imbalance measures how quickly excess heat is accumulating in every part of the Earth system, primarily in the ocean, but also in land, ice and atmosphere.
Through this accumulation of heat, the energy imbalance influences the rate of sea level rise and ice melt across the world, as well as increasing the frequency and intensity of extreme weather events, such as storms, floods and droughts.
Without human influence, the Earth’s energy imbalance would be close to zero.
But, as greenhouse gas emissions have built up in the atmosphere, the imbalance has been growing since the 1970s. Recent increases to Earth’s energy imbalance have outpaced those projections made by climate models — indicating the planet could see more warming than expected in the future.
As the right-hand chart below shows, the imbalance is now at a record high, having more than doubled over the past two decades.
It has increased by around 40% since 2019, from an average 0.79 watts per square metre (Wm2) over 2006-18, according to IPCC AR6, to 1.12Wm2 over 2013-25.
The left-hand chart shows how heat is accumulating in the ocean (blues), ice (grey), land (orange) and atmosphere (purple).
Global temperature rise
The excess heat building up in the climate system from the energy imbalance is pushing up global temperatures at a record rate of 0.27C per decade.
We estimate that human-induced warming – the amount of observed global surface
temperature increase attributable to both the direct and indirect effects of human activities – reached 1.37C in 2025. This has risen from 1.0C in 2017, as reported in IPCC AR6.
While natural variability in the climate system – such as El Niño or La Niña events – can also influence temperatures year-to-year, the upward temperature trend we are seeing is being driven by the persistent imbalance in energy.
We now expect global temperatures to exceed the Paris Agreement limit of 1.5C above pre-industrial levels around the year 2030.
This is significant because 1.5C has been identified as the critical dividing line between manageable climate risks and catastrophic, potentially irreversible damage to global ecosystems and human societies.
Heat accumulating throughout the Earth system
While heat is accumulating throughout the Earth system, it is not being distributed evenly around the globe.
Since the 1970s, around 90% of this heat has been taken up by the ocean, affecting marine ecosystems, ocean circulation patterns, sea level rise and climate extremes.
For example, the number of marine heatwave days – periods of unusually high sea surface temperatures – has more than tripled globally since the early 1990s. The year 2025 alone saw 65 days of marine heatwaves – meaning they occurred, on average, more than one day a week.
Meanwhile, the cryosphere – the portion of the Earth made up of frozen water, including glaciers, ice sheets and permafrost – is experiencing widespread ice loss and thawing in response to the growing energy imbalance. This affects ecosystems, sea level rise and infrastructure in polar and high-latitude regions.
Rapid warming has also resulted in record extreme temperatures over land, with average maximum temperatures for any single day over 2016-25 around 1.92C above pre-industrial levels). This is an increase of almost half a degree compared to the previous decade (2006-15).
Sea level rise and the energy imbalance
Sea level rise provides one of the clearest long-term signals of a changing planet.
It is closely linked to Earth’s energy imbalance. As heat accumulates in the ocean, water expands, raising sea levels. Meanwhile, a warming land and atmosphere means addition of water to the oceans through melting of glaciers and ice sheets, also adding to sea level rise.
Over the long-term, sea levels have been rising, on average, at a rate of around 1.8mm per year since 1901, totalling a record 23cm in 2025. This is increasing the risk of coastal flooding, erosion and habitat loss in many low-lying areas around the world.
This rise can be seen in the left-hand chart below, which shows observed global sea level changes from tide gauges (grey and blue dashed lines) and satellites (red dashed lines) since 1901. The solid lines indicate the average across multiple datasets.
Sea level rise is accelerating consistent with the observed increase in Earth’s energy imbalance. Over 2006-25, sea levels have risen at a rate of 3.67mm per year – more than double the rate of 1.69mm per year seen over 1976-95.
This increasing rate is shown in the right-hand figure below, which shows four successive overlapping 20-year periods and the most-recent decade.
(Last year’s transition from El Niño to weak La Niña conditions affected global rainfall patterns and led to a small and temporary fall in global average sea level in 2025. This explains the slight decrease in rate of sea level rise for the most recent decade, which is affected more than the 20-year period 2006-25.)
The bigger picture
Despite greenhouse gas emissions not increasing as rapidly as in the 2000s, this year’s IGCC findings continue to show how far and how fast the climate is changing due to human activity.
A significant increase in decarbonisation efforts in the second half of this decade is required to slow down the rate of human-caused warming and limit the escalation of climate risks and impacts.
These findings, like many others produced by scientists across the globe, rely on international expertise, partnership and the maintenance and availability of global climate datasets and the global observing programmes that underpin them.
This year’s edition of IGCC used more than 40 global datasets produced by research teams around the world, including the NASA satellite record of the Earth’s energy imbalance and the ARGO deep ocean float network.
However, a number of long-term monitoring programmes could be threatened by funding decisions made by governments around the world, most notably the Trump administration in the US.
Local meteorological data and weather balloon measurement programmes in many countries have declined in recent years, especially in Africa, the west Pacific and South America. This reduces scientists’ ability to monitor and understand key indicators of climate change.
This is not just an issue for climate science. Many of these observations are key to weather forecasts and systems that provide early warning for extreme weather. For example, media reports have suggested that recent reductions in weather balloon measurements in Alaska led to a lack of warnings for a recent winter storm.
The continuity and integrity of the climate observations that scientists use to understand how the climate is changing depends on effective and sustained coordination by international organisations, such as the Global Climate Observing System, the World Meteorological Organization and World Climate Research Programme.
Without this data and its coordination, future assessments will be much more difficult at a time when urgent climate action is needed.
The post Guest post: How a record-high ‘energy imbalance’ is driving global warming appeared first on Carbon Brief.
Guest post: How a record-high ‘energy imbalance’ is driving global warming
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