Climate change adaptation

• 1. Introduction

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  Climate change adaptation is the work of surviving a world that is already shifting. As of 2022, global average temperatures sit 1.2 degrees Celsius above pre-industrial levels, and scientists project that figure could reach 2.5 to 2.9 degrees by the end of this century. That gap, between where we are and where we are headed, is the terrain that adaptation tries to cross.

  The word itself covers an enormous range of human activity. It can mean a farmer in Niger planting in small basins that trap rainwater and push millet yields three or four times higher than before. It can mean a bridge built at unusual height to keep ship lanes clear as seas rise. It can mean a city installing seawalls, rewriting its building codes, or planting trees to blunt the summer heat. Adaptation is, at its core, the art of adjusting to change before that change destroys what people depend on.

  But the story of adaptation is not simply one of ingenious engineering or bold policy. It is also a story of money that was promised and not delivered, of plans that exist on paper but not on the ground, and of communities that face the steepest risks with the fewest tools. The questions worth sitting with are these: Who gets to adapt, and who is left to absorb the damage? And what happens when adaptation itself runs into its limits?

• 2. Four Ways to Respond

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  Experts sort adaptation responses into four broad categories, and each one operates in a different register of human life.

  Infrastructural and technological options are the most visible. They include flood barriers, seawalls, upgraded drainage systems, and irrigation networks built to cope with rainfall that arrives differently than it once did. A survey across European Union member states found that 39% of respondents named infrastructure improvement as the top local priority. The SMART Tunnel in Kuala Lumpur offers one concrete example: a system designed to separate stormwater from wastewater so that heavy downpours do not flood the city with contaminated overflow.

  Institutional options work through rules and organisations rather than concrete and steel. Zoning laws that restrict building on floodplains, revised building codes requiring better insulation or higher foundations for waterfront properties, and new insurance products that trigger payouts when rainfall or temperature crosses a defined threshold all belong here. The U.S. National Flood Insurance Program illustrates the tensions in this category: it spreads risk across many policyholders, but critics argue it also gives landowners a perverse reason to build in hazardous places, raising overall risk rather than reducing it.

  Behavioural and cultural options shift how individuals, households, and communities act. Farmers switching crop varieties, adjusting planting schedules to match a shifted rainy season, or harvesting rainwater in planting basins are all examples. So are dietary shifts toward plant-based foods in regions with excess calorie consumption; plant-based options require substantially less water and energy than meat and dairy, which gives them a double benefit for both adaptation and mitigation.

  Nature-based solutions make up the fourth category. Mangroves, for instance, dampen storm energy and reduce flood risk for communities behind them. Restoring natural fire regimes makes catastrophic wildfires less likely. Giving rivers more room allows them to store more water, reducing flood peaks downstream. These solutions often deliver benefits to both human communities and the ecosystems they depend on.

• 3. Who Is Most at Risk

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  Rainfed agriculture accounts for 80% of global agriculture, and many of the 852 million poor people in the world depend on rainfall to grow food across parts of Asia and Africa.

  The distribution of climate risk is not random. Developing countries carry a disproportionate share of the exposure, yet they tend to hold the fewest resources to respond. The consequences fall hardest on the poorest populations, who face higher exposure to temperature extremes and droughts while having fewer assets, less access to funding, and limited political influence. People with disabilities, minority groups, and those who face gender discrimination are further disadvantaged within these already vulnerable populations.

  Coastal regions contend with sea-level rise and the threat of flooding made worse by storm surges. Arid zones face intensifying water scarcity and the slow spread of desertification. A 2020 study projected that without significant emissions reductions, regions inhabited by one-third of the human population could experience temperatures as extreme as the hottest parts of the Sahara within 50 years. The same study noted that the most affected regions had the least adaptive capacity.

  Cities carry their own concentration of risk. Urban heat islands amplify the warming that climate change drives, and dense development can make that effect more severe. Urban flooding, especially in coastal settlements, adds another layer. A survey of 812 global cities found that 93% reported being at risk from climate change, yet 43% had no adaptation plan as of 2021, and 41% had never completed a climate risk and vulnerability assessment.

  Rural areas are more exposed to food insecurity because limited access to financial resources and food markets leaves little buffer when harvests fail. In Niger, small planting basins that capture water have already demonstrated the difference that targeted adaptation can make, driving three to four-fold increases in millet yields regardless of whether rainfall is generous or scarce.

• 4. The Money Gap

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  At the 2009 Copenhagen Summit, wealthy nations committed to sending $100 billion per year to developing countries by 2020 to fund both mitigation and adaptation. That commitment was restated at the 2010 Cancun Summit and again at the 2015 Paris Conference. It was not fully delivered.

  In 2020, adaptation received only 21% of the public climate finance that was actually provided. The overwhelming majority went to mitigation. Global adaptation financing from multilateral development banks exceeded 19 billion euros in 2021, a figure that points to a rising trend but one that falls far short of assessed need.

  The Adaptation Gap Report published by the United Nations Environment Programme in November 2023 placed the annual adaptation finance gap at between $194 billion and $366 billion. Developing countries alone need between $215 billion and $387 billion per year, a figure that is 10 to 18 times the current international public finance flows for adaptation. The same report recorded a 15% decline in international public climate finance to developing countries, with flows down to $21.3 billion in 2021. To meet commitments made at COP26, international adaptation finance would need to grow at an average annual rate of at least 16% from 2022 through 2025.

  The concept of additionality sits at the centre of many debates about how this finance is counted. Additionality refers to the principle that climate finance should represent new money, not existing aid relabelled. In practice, the line is often blurred. Denmark provides an instructive case: from 2010 to 2020, it increased its adaptation aid from 0.09% of GDP to 0.12% of GDP. But those funds came from existing foreign assistance budgets rather than new money. A Danish newspaper reported that the shift effectively moved resources away from other forms of poverty aid.

  The IPCC estimates that adaptation will cost between $15 billion and $411 billion per year for climate change impacts through 2030, with most estimates well above $100 billion. Because this range so substantially exceeds available finance, an adaptation gap persists, and it continues to widen.

• 5. When Adaptation Goes Wrong

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  The IPCC introduced the term maladaptation in 2001, and the concept has grown more important as adaptation efforts have scaled up.

  Maladaptation describes an action taken in the name of adaptation that ends up increasing vulnerability or reducing the overall capacity to adapt in the future. Most often, the IPCC notes, it is unintended. The expansion of irrigation in Egypt into the Western Sinai desert after a period of higher river flows offers one example: given longer-term projections of drying in the region, that investment locked in infrastructure suited to conditions that would not persist.

  Air conditioning illustrates the same tension. Installing cooling systems helps people survive heat waves. But if the electricity powering those systems comes from carbon-intensive sources, the resulting emissions accelerate the very warming that made the cooling necessary. The growing use of fertilizers and pesticides to cope with shifting agricultural conditions carries a similar contradiction: both are associated with additional greenhouse gas emissions during their production.

  Seawalls, often treated as a straightforward engineering fix for coastal flooding, can waterlog adjacent fields and reduce soil fertility, creating new agricultural problems while solving the immediate flood risk. Top-down technical interventions, the source notes, carry higher maladaptation risk than community-driven, bottom-up approaches that take a more holistic view of local conditions.

  The IPCC Sixth Assessment Report in 2022 drew a further distinction between soft and hard adaptation limits. Soft limits are those where adaptation is still technically possible but faces social, financial, or institutional barriers. Hard limits are those where no adaptation can prevent loss. The report identified human systems in Australia, small islands, the Americas, Africa, and Europe as already reaching soft limits, and noted that some natural systems, including parts of coral reefs, wetlands, rainforests, and ecosystems in polar and mountain regions, have already reached hard limits. At 1.5 degrees of additional warming, regions dependent on glaciers and snowmelt would join that list.

• 6. Governing the Response

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  The Paris Agreement of 2015 requires countries to keep global temperature rise this century below 2 degrees Celsius above pre-industrial levels, and to pursue efforts to limit it to 1.5 degrees. Under that agreement, a Global Goal on Adaptation was established, built around three core components: reducing vulnerability to climate change, enhancing adaptive capacity, and strengthening resilience. The specific targets and indicators for that goal were still in development as of 2023.

  Adaptation plans, policies, or strategies are in place in more than 70% of countries. By 2020-72% of countries had a high-level adaptation instrument of some kind. But having a plan and implementing it are different things. As of 2022, adaptation efforts had focused more on planning than on execution across all regions and sectors, and the gap between current needs and current implementation continued to grow. Around 21% of countries had sub-national plans and 58% had sectoral plans. Only about a quarter had a monitoring and evaluation framework in place as of 2020.

  Cities occupy a critical position in this governance structure. They often hold substantial responsibility for land use, public health, and disaster management. Institutional adaptations occur more frequently in cities than in other sectors, and many cities have developed integrated city-wide adaptation strategies that draw together civil authorities, economic actors, and infrastructure services. Research consistently finds that such strategies work better when implemented in genuine partnership with local communities, national governments, research institutions, and the private sector.

  In 2022, nations agreed on a proposal to create a loss and damage fund to support communities in situations where adaptation comes too late or is simply not enough. That fund addresses the frontier of what adaptation can be expected to achieve, and points toward the questions that will define the field in the decades ahead.

• 7. Pushing Nature to Move

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  Assisted migration is one of the more unusual tools in the adaptation toolkit: the deliberate movement of plants or animals to new habitats before their current ones become uninhabitable.

  A 2023 multi-author review paper examined 204 species, mostly plants, that had been subject to intentional, experimental, or inadvertent assisted migration. The authors observed that controversy around the practice sits in some tension with actual human behaviour: "Despite hesitancy around the tactic, humans have a long history of relocating plants and animals for a variety of reasons (e.g., agriculture, horticulture, forestry, pet trade). Further, Indigenous peoples have been translocating species for millennia."

  The core argument for assisted migration is straightforward. Climate change can outpace natural selection, particularly for species with poor dispersal abilities. If a habitat becomes unsuitable faster than a species can migrate on its own or evolve to cope, extinction becomes the default outcome. Moving the species preempts that.

  The objections are also real. Introducing a species into a new ecosystem carries risks of disruption, including the possibility of introducing invasive behaviour or disease into habitats that were previously healthy. Scientists and land managers have not resolved these tensions in the abstract; they have largely proceeded species by species, weighing the risks of intervention against the near-certainty of loss without it.

  The broader framework that contains assisted migration is ecosystem-based adaptation, which works with natural systems rather than around them. Restoration of coastal and river systems reduces flood risk while improving water quality. Expanding green areas in cities reduces temperatures. Reinstating natural fire regimes lowers the probability of catastrophic fire events. These approaches share a logic: that intact and recovering ecosystems provide services to human communities that engineered alternatives struggle to replicate, and that protecting those systems is itself a form of climate adaptation. The Great Green Wall project, which aims to halt the southward expansion of the Sahara desert, had by 2018 restored over 12 million acres of degraded land in Nigeria and planted roughly 30 million acres of drought-resistant trees across Senegal.