The Climate and Health Nexus

By Modi Mwatsama, Wellcome Trust

Climate change is largely being driven by humans on the planet through actions which increase greenhouse gas emissions and destroy nature and natural carbon sinks such as rainforests. Among the major drivers of climate change, energy from burning fossil fuels accounts for 35% of global emissions, the food system accounts for 24% of emissions through agriculture and land-use change, and the transport sector accounts for 14% of emissions.

The climate change is driving human crises

We are already experiencing the consequences of global warming and without urgent action to halt this warming, things will get much worse. The consequences of global warming include rising sea levels, rainforests dying, lower agricultural yields in some regions and an increase in extreme weather events such as storms, floods and droughts. These climate-induced changes are in turn adversely impacting human health, health systems and welfare. For example, in 2018, 134 billion hours of labour were lost because of heat –  a rise than of 45 billion from 2000. In Pakistan, over 15 million people were affected by flooding in 2010. Six million of these people required urgent medical care, but the delivery of this care was hampered due to the destruction of over 200 health facilities. In 2019, drought-related food insecurity affected 14 million people in Africa.

Infectious diseases such as Covid-19 are becoming more common

Another example of the health-related consequences of climate change is a rise in emerging infectious diseases. Around 60% of these emerging conditions are zoonotic diseases which spread from animals to humans, such as bird flu. In addition to contributing to climate change through carbon-emissions, the food system is also an important direct source of these zoonotic diseases.  Clearing land to grow feed and raise livestock destroys natural habitats and brings wildlife into closer contact with humans, leading to a rise in zoonotic diseases. The first cases of Covid-19 were linked to a wildlife and livestock market, repeating a pattern observed for other recent zoonotic diseases such as swine flu, bird flu and SARS.

The poor and vulnerable are most affected by climate change

In all countries, the impacts of Covid-19 have disproportionately fallen on the poor and communities who are most at risk of suffering from the impacts of climate change. Examples of Covid-19’s disproportionate impact on the poor and vulnerable around the world during 2020 include:

  • Lost labour income is forecast to increase relative poverty by 56% among informal workers and their families in lower- and low-income countries
  • An additional 130 million people could face acute food insecurity as a result of retail price hikes and reduced incomes. This would mean that food insecurity would double compared to pre-crisis levels
  • In the UK women in the most deprived areas are 133% more likely to die from COVID-19 than those in the least deprived areas. Contributing factors include a higher prevalence of diet-related conditions such as hypertension and obesity, overcrowded housing conditions and occupations which increase exposure to the virus.

Nature-based solutions can help to tackle climate change and improve human health

Nature-based solutions to societal change have been defined as solutions that are “inspired and supported by nature, which simultaneously provide environmental, social and economic benefits and help build resilience.” These approaches can offer sustainable solutions to cope with climate change mitigation and adaptation challenges, while improving outcomes across multiple dimensions of health and generating economic benefits from reduced health and environmental costs. Examples of the co-benefits of nature-based solutions across different sectors are provided in Table 1. In summary, these include:

  • Nature-based ecosystem services can help to reduce greenhouse gas emissions and to conserve and expand carbon sinks in support of climate mitigation e.g. through protecting forests.
  • The ecosystem services that are necessary for human life are preserved and help to reduce the negative effects of climate change e.g. protecting coastal wetlands reduces the risk of flooding.
  • Protecting important ecosystem services enhances their resilience and wider benefits.
  • Nature based eco-system services can provide diverse co-benefits for health. On the mitigation side, the largest co-benefits arise from reduced risk of non-communicable diseases such as heart disease and diabetes, from changes such as increased physical activity and reduced air pollution.
  • Co-benefits on the adaptation side include reduced risk of infectious diseases including water-borne pathogens and zoonotic diseases such as Covid19, due to improved land and water-management.

Table 1: Examples of nature-based solutions which can deliver for both climate change and human health objectives

Sector Example solution Co-benefits of impacts
Climate and ecosystem services Health impacts
City planning and housing Urban green spaces such as parks, green roofs and walls and street trees Green spaces can help to absorb carbon emissions; they can also help to reduce the risk of flooding and provide shade and heat absorption to minimise the impacts of heatwaves Help to improve the aesthetics and quality of cities for residents. Access to green spaces and nature is linked to improvements in mental health
Transport Active transport infrastructure such as bicycle routes which reduce car use Providing infrastructure for active travel as an alternative to car use, means less land is used for roads and available for nature and the provision of ecosystem services. This can also help to lower emissions as a result of reduced car use Increased physical activity from active travel helps to reduce the risk of non-communicable diseases (NCDs) such as obesity, heart disease and diabetes and is also linked to improvements in mental health.

Improved air quality reduces levels of respiratory and other NCDs

Water management and land-use Integrating the protection of coastal wetlands such as tidal flats, mangrove forests in water-management and flood plans Provide protection against coastal erosion, help to absorb carbon emissions, and enhance biodiversity of plant and animal species – thereby building resilience. Protect against adverse impacts on human health and health systems which arise from flooding e.g. water-borne diseases, food insecurity, arising from loss of food crops and livelihoods.

Sources include Ecologic and WHO.

However, despite the potential benefits, a number of potential challenges and barriers to action hamper the adoption of nature-based solutions, including:

  1. The term nature-based solutions is not widely used outside of the environment community e.g. among health actors, and is also contested, minimising the likelihood of adoption.
  2. As the costs and benefits of nature-based solutions are often borne and accrued in different sectors, this can serve as a barrier to investments in the case where budgets and objectives are not co-owned.
  3. More integrated evidence is needed on the cost-effectiveness and co-benefits of nature-based solutions across multiple dimensions of health, climate change and nature.

Recommendations for G20 countries and stakeholders

The year 2021 will be significant for raising global ambitions and commitments towards tackling climate change, protecting nature and promoting human health. Major UN meetings including the climate COP26, biodiversity COP15 and UN food summit will review progress and set the agenda for action over the next 5 to 10 years. G20 nations, and allied stakeholders such as the Foundations Platform F20 will be critical to achieving these commitments as they account for 78% of global emissions. Key actions they should take to support to drive integrated solutions for climate, nature and health include:

  1. Raise awareness among policy makers, the public and other stakeholders of the links between climate change, nature and human health and the co-benefits of nature-based solutions.
  2. Promote cross-sector collaboration and solutions through joint funding and accountability mechanisms such as shared targets and goals
  3. Apply true cost accounting to the development, monitoring and evaluation policies, products and services, in order to enhance the benefits as well as minimize harmful externalities across multiple environment, health, social and economic dimensions.
  4. Ensure coherence and alignment of public and private sector financial investments, including taxes and subsidies across health and environment goals.



Arian Okhovat, Communications F20 |

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