Although it is problematic to attribute causal links between specific natural phenomena and climate change (1), global warming aggravated by human interference in climate ecosystems brings diverse consequences for human and natural systems (2). Rising temperatures interfere with slow onset changes such as glacier melt, increase in sea level rise, water salinisation and loss of biodiversity. The increase in global temperature is shrinking glaciers in different parts of the world (3) and the melted ice and thermal ocean expansion rise the sea level. Under these circumstances, coastal hazards such as inundations, storms and erosions are expected to be more frequent, especially on Small Islands, affecting humans and biodiversity (4). The number of people exposed to coastal floods that previously occurred once in 100 years could rise from 20% in conservative measures (considering 0,15 m global mean sea level rise in comparison to 2020 levels) to 60% in the more extreme scenario (of 1,4 m global mean sea level rise with no adaptation measures) (5). In fact, different types of climate-related hazards are expected to become either more intense or frequent and more uncertain to be predicted. 

It is very likely that hot extremes, heat waves and heavy precipitation events will become more frequent, while future tropical cyclones (typhoons and hurricanes) are likely to become more intense, with larger peak wind speeds and more heavy precipitation. Increases in the amount of precipitation are very likely in high latitudes, while decreases are likely in most subtropical land regions. (Tanner & Horn-Phathanothai, 2014, pp. 33–34)

Deviation from the expected climate has also been registered in variability and uncertainty in temperature and rainfall distribution (6). While the global average temperature change can be more easily predicted according to the expected greenhouse gas emissions level, indicating the local variation in each part of the world is much more complicated (7). Following, I explain that these consequences of climate change directly interfere with the factors that build human well-being and disproportionately affect vulnerable populations - who are generally the target of development projects. 
 
Disruption to livelihoods and undermined nutritional conditions 

The critical determinant of whether people will be able to cope with climate change and the extension of its effects on their well-being is the strength of their livelihoods (8). Developing countries’ populations, especially those living in rural areas, have more climate-dependant livelihoods based on agriculture, livestock, fisheries and forestry resources (9). This is evident in the case of Zimbabwe, when, in 2014, 35% of a house’s income was climate-dependent (10). 

Increased variation in rainfall and temperatures, as well as more extreme high temperatures, are seriously damaging to people who depend on growing food to nourish themselves. In 2020, half of the 295 billion potential lost work hours due to heat were suffered by agricultural workers in low and medium Human Development Index (HDI) countries (11). In addition to the loss of working hours, in rising temperatures, the time required for crops to reach maturity is shortened, and the yield potential is reduced. The “Lancet Countdown on Health and Climate Change” compared yields potential from 2020 in relation to 1981–2010 and revealed a “6·0% reduction for maize; 3·0% for winter wheat; 5·4% for soybean; and 1·8% for rice in 2020” (Romanello et al., 2021, p. 1619). In conditions of diminished production, food prices tend to rise, which affects disproportionally poor people who depend on buying food to eat. It has been calculated that every 1°C rising in temperature led to an increase of 1,64% in the global probability of severe food insecurity in 2019, which happens when a person is not able to have one single meal for at least one day over the last 12 months (12). 

Poorer health conditions

Damaged livelihoods and the growth of food insecurity impact health and security. Poor nutrition makes people more vulnerable to diseases and affects their ability to recover from hazards (13), which, as pointed out above, tend to be more frequent and extreme due to climate change. On a lower income due to disrupted climate-dependent livelihoods, people are also less able to afford health care (14). This condition of exacerbated vulnerability is further negatively affected by more favourable conditions for diseases transmitted by organisms through water, air, food, and vectors (15). 

The number of months suitable for malaria transmission has increased by 39% in highland areas of the low HDI country group and, during the past 5 years, the environmental suitability for the transmission of emerging arboviruses (e.g., dengue, chikungunya, and Zika) was between 7% and 13% higher than it was in the 1950s. (Romanello et al., 2021, p. 1653)

These circumstances of presumably increase in epidemics, especially caused by vector-borne diseases in some regions of the world such as Central and South America (16), make access to adequate health care even more essential to populations who might already have difficulties accessing it before considering climate change effects.  Building up once again on this aggravated vulnerable situation, people need to be prepared to face intensified hazards. 

More adverse conditions for dealing with natural disasters

The occurrence of hazards doesn’t necessarily lead to disasters. Although extreme weather events occurrence has risen significantly over the past 30 years, only low HDI groups have been considerably more affected (17). The latest IPCC report on Impacts, Adaptation and Vulnerability (2022, p. 12) highlights that “between 2010-2020, human mortality from floods, droughts and storms was 15 times higher in highly vulnerable regions, compared to regions with very low vulnerability (high confidence)”. This is because social – instead of natural – processes determine for whom hazards present more risk: the resistance of people’s livelihoods, the protection offered by the buildings they live in, the knowledge they access about hazards’ protection and their income (18). 

Thus, the effects of climate change and its consequences on the factors that build human well-being described above indicate that “climate change is a stress multiplier” (Srivastava, 2022). In most cases, climate change doesn’t create vulnerability. Instead, its effects depend on and deepen an existing vulnerable condition. This condition is highly uneven around the world, with some regions being considered by the IPCC as global hotspots of high human vulnerability:  the West, Central and East regions of the African continent, South Asia, Central and South America, Small Island Developing States and the Arctic (19). Between 2000 and 2004, a person's likelihood of experimenting adverse human impacts from climate hazards, for example, was 79 times higher in developing countries than in rich countries (20). This is not only because poor populations tend to live in areas more exposed to hazards.

This heightened vulnerability is rarely due to a single cause. Rather, it is the product of intersecting social processes that result in inequalities in socioeconomic status and income, as well as in exposure. Such social processes include, for example, discrimination on the basis of gender, class, ethnicity, age, and (dis)ability. (IPCC, 2014, p.6) 

Therefore, tackling the root causes of a population’s vulnerability is essential to increase people’s conditions to adapt to climate change (21).

The implications of climate change for development

Initiatives that aim to adjust “natural or human systems in response to actual or anticipated changes in climatic conditions and their effects” (IPCC, 2001, as cited in Tanner & Horn-Phathanothai, 2014, p. 64) are considered climate change adaptation. There is a significant overlap between adaptation and development efforts, although they are not always the same (22). McGray et al. (2007) place adaptation strategies in a continuum that has, in one extreme, “pure” development activities with emphasis on reducing vulnerability and, in the other, impact-focused measures that are directly targeted to specific climate change effects. The lower the existing capacity of a population to cope with the impact of climate change, the higher the priority for actions that focus on the causes of vulnerability. The better the current living conditions and the more reliable the information on climate impacts, the more feasible it becomes to invest in target-specific impacts. 

Within this framework, traditional development strategies are considered “low regret measures” since they benefit poor people independently of climate change specific local effects while simultaneously increasing people’s capacity to adapt. These are measures such as broadening access to education, diversifying livelihoods, and rising income, which improves people’s access to nutrition, health care, and security (23). However, taking advantage of this synergy between development and adaptation should not disregard that both “involve different time horizons and entail different inter-generational distributions of costs and benefits”  (Tanner & Horn-Phathanothai, 2014, p. 81). Addressing climate change is making investments at present aiming to benefit future generations, while development usually focuses on more short-term goals (24). Moreover, development in the context of climate change needs to consider the aggravated conditions that people in poverty will face due to climate change effects, as examined in the previous section. 

Whereas vulnerability reduction is essential to deal with climate change effects, it doesn’t solve all problems that arise with the overall increase in uncertainty. Anticipating climate change effects at the local level is essential to determine effective adaptation strategies. Still, existing climate models leave considerable space for uncertainty concerning localised implications, such as whether in a particular location rainfall is expected to increase or diminish (25). In this context, Ensor (2011) advocates for the centrality that leveraging populations’ conditions to deal with uncertainty should have in development. In practice, “this means working with communities in ways that strengthen their ability to cope with and recover from surprises, and strengthen their capacity to make changes to their lives as our knowledge of climate change and its likely impacts improves” (Ensor, 2011, p. 11). Thus, if development actions are to consider climate change effects, increasing communities ability to deal with uncertainty shouldn’t be a component of adaptation interventions but rather the ultimate goal for development itself (26).