L9: Demographic Change & Climate Change – Social Change

Weather vs climate

• Weather = the temperature and precipitation at a specific time and place

• Climate = weather in a location averaged over long periods of time

Climate change vs climate variability

• Climate change = sustained change in the average long-term levels of temperature and precipitation

• Clime variability = sustained change in the long-term variance around these average levels

Environmental change

Broader concept, can result from oil spills, lang degradation, deforestation, etc.

When is climate change expected to take place?

Climate change is expected to be paralleled by increases in extreme weather events (e.g. heat waves), rising sea levels, more (intense) floods & droughts, resulting in degradation of land & fresh water resources, lower food security, etc.

Why does climate change matter to demographers?

Climate change is more concerning than other aspects of demography such as fertility or immigration

Demography’s role in climate change: Formula

I = PAT

• Impact = Population, Affluence, Technology

Demography’s role in climate change: Facts

• Population growth parallels increases in economic growth, energy consumption and greenhouse gas emissions

  • The net effect of a 1% increase in population growth on increases in carbon emissions has been estimated to be around 1% (keeping every other variable fixed)

  • Does, next to its size, the composition of a population also matter (through different consumption and emission behaviors)?

How (changes in) population composition mitigate climate change

• Population ageing should generally drive carbon emissions down (due to changes in consumption patterns and reduced labor productivity)

  • But: larger share of expenditures in carbon intensive items

  • Population aging may be good for climate change

Urbanization

• Increase in economic scale, technical innovation, action to information (eco-friendly actions), efficient land and energy use and lower fertility 

  • Reduction in carbon emissions

• Rising labor productivity and incomes, “urbanized” lifestyles and consumption patterns

  • Increase in carbon emissions

• Evidence/projections thus provide mixed results (dependence on period/region and short-vs long-term perspectives)

Education

• Positive association with more “eco-friendly” consumer choices at any given level of income

• Reduction in people’s vulnerability and strengthening of adaptive capacity (to less-favorable conditions)

• Fosters economic growth and – importantly – reduces fertility

Fertility decline

• Slows population growth

• Reduction of pressure on livelihoods

• Frees resources that can be used to cope with climate change

Population policies: a suitable response to climate change?

• Embedded in a broader set of development policies, population policies and programs promoting education + universal access to voluntary contraception and addressing demographic factors such as urbanization and aging will contribute to a more sustainable demographic future that plays a crucial role in climate change mitigation and adaptation

  • Maybe: European demographers are highly divided on the questions:

    • Whether the global population size should be reduced to lower CO 2 emissions 

    • Whether family planning is an effective policy instrument

Climate change & fertility

• Relatively little empirical research yet, but several plausible pathways linking climate change and fertility

  • Effects on economic development, such as sectoral change (agriculture)

  • Effects on (child) mortality and migration

  • Effects on armed conflicts

• Hajdu & Hajdu (2021) conclude that “exposure to heat in the pre-conception period has detrimental impacts on fertility”

Heat-related mortality

• Between 1991-2018, 37% of all warm-season heat-related deaths in 43 countries could be attributed to anthropogenic climate change

• By the end of this century, climate change (reflected in ‘very hot days’) is projected to increase age-adjusted US mortality rates by 3%

  • But: Between 1900-2004, the mortality impact of days by a mean temperature >27°C declined by 75% (almost exclusively post-1960)

• This decline in the US almost entirely results from the diffusion of residential air conditioning

  • Residential energy consumption is expected to increase by 11% over the course of this century

Cold-related mortality

Reductions in cold-related mortality may (initially) outweigh increases in heat-related mortality

Projections of temperature-related mortality for the UK

• By the 2050s, heat-related deaths would rise by around 257% (in the absence of adaptation); cold-related mortality would decline by 2%

  • But: cold burden remains higher than the heat burden in all periods!

• Population aging as an amplifier: oldest-old population at highest risk!

Climate change, air pollution and mortality

• Substantial global increase in e.g. ozone-related mortality due to climate change

  • Africa as exception, India & East Asia most affected by ozone-related mortality

• Amplifying effect of population aging

Climatic influences on infectious diseases

• If global warming amplifies “El Niño” type phenomena, regions surrounding the Pacific and Indian oceans are expected to be the most vulnerable ones with higher incidences of diseases

  • Malaria (South America), rift valley fever (East Africa), dengue fever (Thailand), cholera (Bangladesh), ...

• Adaptation: Early warning systems for heatwaves and for expected outbreaks of infectious diseases

3 categories of “environmental migrants”

• Temporarily displaced because of environmental stress (usually natural disasters)

• Permanently displaced and resettled in a new area

• Internal migrants due to deterioration of the resource base in their original habitat

“Environmental refugees”

People forced to leave their traditional habitat, temporarily or permanently, because of a marked environmental disruption (natural and/or triggered by mankind) jeopardizing their existence and/or seriously affecting their quality of life

Projected numbers

• Increase from ~25M at the turn of the millenium to ~200M in 2050

  • Evidence base is “varied and patchy”, ranging from “substantial” to “minor” impact of climate change on human migration

• Fielding (2011) concluded that the impacts of environmental change on internal migration in the UK will probably be relatively minor 

  • Exception that greater river and coastal flooding is likely to render some areas hazardous to settlement and/or very costly to protect

Environmental change has the potential to affect directly following aspects:

• The hazardousness of a place

• The migration indirectly through economic and political (e.g. conflicts about water) drivers

  • The effect of the environment is highly dependent on the economic, political, social and demographic context

Future consequences 

• Future environmental change will only have an incremental direct impact on (international) migration flows

  • It will rather amplify (or alter) existing demographic trends of migration. 

• In less developed countries adverse weather/climate conditions are more likely to stimulate internal and shorter distance moves or even to “trap” populations in place costs of migration

• Migration can be both a problematic outcome of climate change and a key element for the adaptation to and management of environmental risks

  • Adapt in place –help communities stay in place where local adaptation options are viable and sensible

  • Enable mobility–for people who need to move away from unavoidable climate risks (and ensure that sending and receiving areas are adequately prepared)