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Freshwater, essential for ecosystems and human well-being, is becoming increasingly scarce.
Population growth, urbanisation and socioeconomic development are all driving greater demand for the world’s finite water resources. At the same time, climate change is altering precipitation patterns and affecting water availability.
Currently, approximately four billion people experience water scarcity for at least one month each year.
Irrigated agriculture – which accounts for nearly 90% of the world’s water consumption – is a major driver of this scarcity.
Without substantial reductions in greenhouse gas emissions, global temperatures could rise by 3C by the end of the century, exacerbating water shortages and impacting an additional 0.8 to 2.2 billion people.
In our new study, published in Nature Communications, we quantify and map current “water gaps” – shortfalls where water demand exceeds supply – around the world, and project how 1.5C and 3C of warming will impact water availability.
We find that under 1.5C of warming, the global water gap will increase by nearly 6%. But under 3C of warming, the gap will grow by almost 15%.
Our work shows that mitigating climate change can help lessen future water shortfalls, but robust adaptation methods will also be necessary to secure water security in a warmer world.
‘Water gaps’
Traditionally, scientists have quantified water scarcity with a variety of indicators, which help assess water availability relative to demand.
For example, the Falkenmark Indicator, or water stress index, is a simple indicator, measuring the per-capita water availability. However, this approach says nothing about the quality of the water, the soil moisture (which is critical for agriculture) or the environmental flows. Other indicators include the water use-to-availability ratio and the water poverty index.
These indicators have been instrumental in highlighting resource limitations, but they are no longer sufficient for modern water management needs because they do not provide a quantitative assessment of the water volumes overused by humans.
In our study, we introduce the concept of “water gaps”, defined as the difference in water volume when demand exceeds supply.
We used historical water use data and water availability from a water-resources model to map the average global water gap between 2001 and 2010.
This approach has some advantages over traditional indicators.
By actually quantifying the volumes of water needed to solve water scarcity in a given location, decisionmakers can be better informed when designing solutions to solve it. For example, given a certain water gap, they can figure out how much desalination would be needed to solve water scarcity.
Water gaps represent the difference between the availability of “renewable” water resources and water consumption within a specific region and timeframe – where renewable water is that which can be replenished naturally through the water cycle.
When water availability falls below consumption, it signals a critical shortage and leads to unsustainable water use. These shortages threaten human needs, agriculture, industry, energy production and ecosystems – potentially leading to severe social, economic and environmental consequences.
We found that the current global water gap is approximately 458 cubic kilometres (km3) per year. (One cubic kilometre is equivalent to 1bn cubic metres.) The countries with the largest individual gaps are India, the US, Pakistan, Iran and China, but water gaps exist on every continent.
The map below shows the baseline average water gap, with lighter colours representing smaller gaps and darker colours representing larger ones. Light blue areas are areas where there is no water gap, and white areas show regions without human water consumption.
In areas with water gaps, humans must make up the shortfall by depleting groundwater, rivers, lakes and aquatic ecosystems.
Future shortfalls
We also look forward, projecting how water gaps might grow under future climate change.
We use five climate models from the sixth Coupled Model Intercomparison Project (CMIP6) to obtain projections of climatic conditions, such as rainfall and temperature.We focus on two levels of warming: 1.5C, part of the long-term goal under the Paris Agreement, and 3C, which is a realistic level of warming for the end of the century under current climate policies.
Then, we use those climate outputs into a hydrological model to determine the availability of renewable water under each warming scenario.
Under 1.5C of warming, the global water gap is projected to increase by around 26.5km3 per year – an increase of 5.8% from the current baseline. A 3C warming scenario would see a more severe rise of 67.4km3 per year, or 14.7%.
The difference in the size of the water gap under these two warming scenarios underscores the critical need for ongoing climate change mitigation to minimise its impact on water resources.
Regional patterns
The regional variability in water gaps highlights the uneven impacts of climate change, with some countries and river basins facing significant vulnerabilities.
India, which has the largest baseline water gap of 124.3km3 per year, is also expected to see the most significant increase in water gaps. Other countries experiencing notable increases include China, Pakistan, the US, Spain and Turkey.
Substantial water gaps can currently be found in the Ganges-Brahmaputra basin in India and Bangladesh, the Sabarmati basin in India and the Tigris-Euphrates basin, which covers much of the Middle East. Under both warming scenarios, notable increases in water gaps are expected in the Ganges-Brahmaputra basin and the Mississippi-Missouri basin in the US.
While the climate models we used agree on worsening water gaps in most regions, some countries, such as Nigeria, Niger, Chad, Sudan, Ethiopia, Vietnam and the Philippines, are projected to see modest reductions in water gaps. Modest decreases are anticipated in the Sabarmati and Nile river basins.
The maps below show the projected changes in global water gaps under 1.5C (top) and 3C (bottom) of warming. Areas in blue are projected to have a decreased water gap in the future, while areas in red are projected to have an increased one.
No single solution can ensure global water security – effective solutions require both reducing water consumption and increasing water availability.
Reducing consumption can involve switching to less water-intensive crops, minimising food waste and enhancing irrigation efficiency. On the supply side, expanding water storage infrastructure, investing in seawater desalination technologies, and reusing treated wastewater can help augment freshwater resources.
A combination of these approaches, tailored to local needs, is essential for tackling water scarcity and ensuring long-term water security.
Our findings underscore the urgent need for robust adaptation and mitigation strategies to manage escalating water scarcity. By quantifying these future water gaps, decisionmakers can better understand regional vulnerabilities and develop targeted interventions.
The post Guest post: How the global ‘water gap’ will grow under climate change appeared first on Carbon Brief.
Guest post: How the global ‘water gap’ will grow under climate change
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An older teaching about land acknowledgement
As I have come to understand the spirit and intention of land acknowledgement, I often return to fond memories of my grandmother and her words of wisdom. She taught that the health of the places we call home comes first, because the wellbeing of the people depends on it.
In her teaching, land acknowledgement began with the land. Long before it became a paragraph read at the start of a meeting, it was a way of recognizing a homeland: its waters, its species, its seasons, and the spirit that revealed whether the place was well.
Her teaching echoes a practice found across many Indigenous Nations. Haudenosaunee gatherings, for example, have long opened with the Ohén:ton Karihwatéhkwen, the Thanksgiving Address, often translated as “the words that come before all else.” The speaker greets and gives thanks to the people, the earth, the waters, the plants, the animals, the winds, the sun, the moon and the stars. Only after everything that sustains life has been acknowledged does the gathering turn to its own business.
That order changes what an acknowledgement is for. Its purpose was to share the story of a place with neighbours and to draw them into the work of tending it. People entered the story second, as the ones responsible for what had just been named.
Understood this way, an acknowledgement does more than open a meeting. It asks us to reconsider where we stand, and what we owe the ground beneath us.
Nations among nations
In her teaching, people are one nation among many. The salmon are a nation. So are the cedars, the bison, the medicine plants, and the pollinators. Each belongs to a place, carries its own responsibilities, and offers gifts no other nation can give.
This idea of kinship runs through many Indigenous philosophies. The phrase “all my relations,” heard in ceremonies and gatherings across Turtle Island, is a reminder that family extends beyond people to the animals, plants, waters and lands that make life possible. Some Indigenous languages carry the same understanding in their grammar, speaking of many plants, animals and natural forces as living beings rather than objects.
Sovereignty, understood through this relationship, is a kind of standing more than a form of control. Each nation belongs fully to its place and carries its share of that place’s life. No nation thrives alone, and none thrives by taking over the whole.
The land is also the source of instruction. Over generations, people watched how a river valley or a stretch of prairie kept itself well: who arrived when, who fed whom, and how much could be taken before the giving stopped. In my grandmother’s telling, those observations became instructions, and those instructions helped shape law and protocol. They guided when to harvest, where to camp, how to enter a neighbour’s territory, and what was owed in return.
Indigenous legal scholars today often describe this as law that comes from the land itself, learned by watching how living systems sustain one another. A plainer name for it is knowing how to live somewhere.
The host and the guest
One of the clearest teachings in this understanding of the world is the relationship between host and guest. My grandmother invited us to recognize that relationship in the lives of plants and animals.
A host prepares the place before anyone arrives. A beaver family dams a stream, and the pond becomes a home for fish, frogs, birds and plants. A fallen tree becomes a nurse log, feeding the next generation of seedlings as it returns to the soil.
A host offers first. A flowering plant sets out nectar. A berry bush ripens fruit. These provisions come in their own season, not whenever a visitor happens to want them.
A host also makes its presence known. Birdsong, scent and the marks left along a trail tell newcomers that a place is already inhabited. The visitor does not arrive in an empty world.
The guest has responsibilities too. A guest attends to the season and to what the place can offer. A guest does not assume that everything within reach is theirs to take. A guest leaves something that helps sustain the relationship.
A bee takes nectar and carries pollen. Read through this teaching, that exchange offers an image of visiting well: receiving a gift while helping the host continue its life.
Many Indigenous harvesting protocols carry the same ethic into daily practice: ask before taking, take only what is needed, offer thanks, and leave enough for others and for the plant or animal to recover.
None of this suggests that every relationship in nature is peaceful or generous. These are ways of seeing responsibilities that people can learn to carry.
Everyone is both
No being is only a host or only a guest.
A tree makes room for other life while depending on soil, water, sunlight, fungi, and relationships beyond itself. People, too, may welcome others into their homes while remaining dependent on the larger homeland that sustains them.
The distinction between host and guest is therefore about roles, not ranks. Everyone receives. Everyone has something to give.
The question is whether the exchange sustains the place.
A visitor who takes without restraint leaves less for those who come next. A host who neglects the place has less to offer. Both have responsibilities, and neither can fulfil them alone.
This is the heart of reciprocity, a principle found across Indigenous philosophies: relationships stay healthy when gifts move in both directions. The Haudenosaunee teaching of the seventh generation extends that exchange across time, asking that decisions made today leave the place well for those not yet born.
Mutual benefit begins here, with the recognition that different beings carry different gifts and obligations.
What people carry forward
My grandmother’s teaching connects these relationships to the ways people meet their neighbours.
The host prepares a place, offers food and rest, and explains where the visitor has arrived. The guest makes themselves known, explains why they have come, listens to the terms of the visit, and brings something in return. The gift may be material. It may also be labour, knowledge, news, or a commitment to help.
Nations around the Great Lakes carried this ethic into treaty. The Dish with One Spoon, an agreement among the Haudenosaunee, Anishinaabe and allied Nations, describes shared hunting grounds as a single dish. Everyone eats from it with one spoon, takes only what they need, leaves enough for others, and keeps the dish clean. The Two Row Wampum, between the Haudenosaunee and European newcomers, shows two vessels travelling side by side on the same river, each keeping its own ways and neither steering the other.
In this understanding, acknowledgement is more than naming the people associated with a territory. It is learning enough about a homeland to behave responsibly within it.
Whose home is this? What sustains it? What laws and agreements guide our presence? What can we receive, and what must we return?
These questions make acknowledgement a relationship rather than a recital.
They also make it diplomatic. A guest who recognizes the host’s homeland recognizes that they have entered a place with its own relationships and responsibilities. A host who welcomes the guest makes room for an encounter governed by those relationships.
Neither arrives without standing. Neither arrives without obligations.
Beginning with place
I write from the shores of the Bay of Quinte. Here, the teaching asks me to begin with the water, the shoreline, and the life they sustain. Before I describe myself, I must attend to where I am.
That does not make people or history less important. It places them within the homeland that gives them meaning. The people, their laws, their agreements, and their responsibilities all belong to the place.
In a time of longer fire seasons, troubled waters, and uncertainty about what the next season will bring, this teaching asks something difficult and useful of us: pay attention before you speak.
An acknowledgement cannot tell the story of a place if the speaker has stopped noticing it.
The land came first. Beginning there again means learning to name what sustains us, and accepting that what sustains us also asks something of us.
By Rye Karonhiowanen Barberstock
Photo by Andrik Langfield on Unsplash
The post The Land Came First appeared first on Indigenous Climate Hub.
Carbon dioxide (CO2) emissions from fossil fuels and cement are projected to fall by around 0.4% in 2026 to 38.2bn tonnes of CO2 (GtCO2), according to new figures from the Global Carbon Project.
This guest post is by:
- Dr Zeke Hausfather, Carbon Brief’s climate science contributor
- Prof Pierre Friedlingstein, chair of mathematical modelling of climate systems at the University of Exeter and part of the Global Carbon Project team.
Carbon dioxide (CO2) emissions from fossil fuels and cement are projected to fall by around 0.4% in 2026 to 38.2bn tonnes of CO2 (GtCO2), according to new figures from the Global Carbon Project.
The 21st edition of the annual “global carbon budget” report, published today, says that this small decline is largely due to a 1.9% drop in emissions from oil and the energy shock triggered by the Iran conflict and the closure of the strait of Hormuz.
Emissions from coal continue to increase slightly.
The Global Carbon Project’s projections for fossil fuel and cement CO2 emissions in 2026 are preliminary, with a range that spans a fall of -1.5% to a rise of +0.6%.
This means a small increase in emissions can not be ruled out.
Emissions from land-use change, such as deforestation, are projected to rise in 2026.
This is primarily driven by peat fires and forest degradation in south-east Asia and is linked to the development of a strong El Niño event this year.
As a result, total CO2 emissions from fossil fuels and land use are projected to reach a record high of 43.3GtCO2 in 2026 – marginally above 42.8GtCO2 in 2025.
Research published alongside the report by the same team in Nature Climate Change finds that the growth in solar, wind and electric vehicles (EVs) now offsets around two-thirds of the emissions that would otherwise come from rising energy demand.
However, the deployment of these technologies is not yet enough to push global emissions into a sustained decline, according to the study.
The 2026 global carbon budget report also estimates that:
- Fossil emissions are projected to fall in China (-0.9%), the US (-1.3%) and the EU (-1.5%) in 2026, but rise by 4.4% in India.
- Oil emissions are projected to fall in every major region, with the largest drop in China (-4.6%).
- Land-use emissions averaged 4.9GtCO2 per year over 2016-25, around 21% lower than the decade before.
- Total CO2 emissions (fossil and land-use) grew by an average 0.3% per year over the past decade (2016-25), compared with 1.7% per year over the decade before.
- The remaining carbon budget to limit warming to 1.5C is 150GtCO2, or less than four years of current emissions.
- The land sink in 2025 was the highest on record, rebounding after being weakened during the 2023-24 El Niño. The current El Niño is expected to weaken the land sink in 2027.
- The concentration of CO2 in the atmosphere is set to reach 427.7 parts per million (ppm) in 2026, 54% above pre-industrial levels.
(For more on previous editions of the Global Carbon Project’s annual report, see Carbon Brief’s coverage in 2025, 2024, 2023 and 2022.)
Total emissions edge up as land-use emissions rise
Total global CO2 emissions, which combines fossil fuels and land-use change, are projected to reach a record high of 43.3GtCO2 in 2026, up from 42.8GtCO2 in 2025.
The increase in 2026 comes entirely from a projected rise in land-use emissions, which are more challenging to estimate than fossil emissions.
(The global carbon budget groups emissions from fossil fuels and cement production as “fossil emissions”. Carbon Brief follows this convention throughout this piece.)
If land-use emissions had stayed at 2025 levels, total emissions would have fallen slightly in 2026 to around 42.6GtCO2.
Each edition of the global carbon budget updates the historical record as new data and methods become available. The chart below shows total emissions in this year’s budget compared with the five previous editions.
This year’s estimates of historical fossil emissions are around 0.3GtCO2 per year higher than in last year’s budget.
This is largely because the report now estimates a smaller “cement carbonation” sink in the wake of research published this year in Communications Sustainability. In other words, it estimates that cement is able to slowly reabsorb less CO2 over its lifetime than previously thought.
Estimates of land-use emissions have also been revised, including a spike in 2018 – visible in the chart above – linked to updated cropland data for Colombia.
The updated numbers show that total emissions have grown by 0.3% per year over the past decade (2016-25), compared with 1.7% per year over 2006-15.
Fossil emissions grew about 0.9% per year in the past decade, compared with 1.9% the decade before. Over the same period, land-use emissions have declined.
While the slowdown reflects real progress, a plateau in emissions is still a long way from the rapid declines needed to reach net-zero emissions and stabilise global temperatures.
With human-caused warming reaching 1.37C above pre-industrial levels (1850-1900) in 2025, the report estimates that the remaining carbon budget to limit warming to 1.5C, with a 50% chance, is 150GtCO2 from the start of 2027. That is less than four years of 2026 emissions.
Meanwhile, the budgets for 1.7C and 2C are 510GtCO2 and 1,035GtCO2, respectively – or around 12 a