Global climate change
Over the last 50 years, the global climate is changing as the Earth becomes warmer. Atmospheric concentrations of both the natural and man-made gases have been rising over the last few centuries due to the industrial revolution. Human activities have released sufficient quantities of carbon dioxide and greenhouse gases to affect global climate.
Gases that trap heat in the atmosphere are called greenhouse gases. Many greenhouse gases occur naturally in the atmosphere, such as carbon dioxide, methane, water vapor, and nitrous oxide, while others are synthetic. Those that are man-made include the chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). Emissions of these gases have risen because of increased use of fossil fuels (such as coal, oil and natural gas).
The United Nations Framework Convention on Climate Change (UNFCCC) defines climate change as ‘a change of climate that is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and that is in addition to natural climate variability observed over comparable time periods’.
In the last 130 years, the world has warmed by approximately 0.85oC. Each of the last 3 decades has been successively warmer than any preceding decade since 1850.
There are significant impacts of climate change in the form of changing weather pattern, rising sea levels, melting of glaciers, forest fires, changing precipitation patterns and more extreme weather events, such as Kashmir floods (2014), Uttarakhand flash floods (2013), Tsunami (2004) are some vivid examples. Globally an estimated 12.6 million deaths are caused by avoidable environmental risk factors every year.
Who is at risk?
All populations are affected by climate change, but certain regions and groups have higher susceptibility to climate-sensitive health impacts owing to their age (children and elderly), gender (particularly pregnant women), social marginalization (associated in some areas with indigenous populations, poverty or migration status), or pre-existing medical conditions or other health conditions like HIV. The socioeconomic impact of health problems caused by climate change are considerable.
People living in small island developing states (group of small island countries that tend to share similar sustainable development challenges) and other coastal regions, megacities, and mountainous and polar regions are more vulnerable to climate change.
In developing countries with weak health infrastructure, damage due to climate change is more and they need assistance to prepare and respond.
Climate change can affect human health in number of ways:
Climate change affects the social and environmental determinants of health – clean air, safe drinking water, sufficient food and secure shelter- for instance changing the severity and frequency of health problems already exiting in that area, creating unanticipated health problems in places where they have not previously occurred, disturbing food-producing ecosystem and increasing the frequency of extreme weather events.
Between 2030 and 2050, climate change is expected to cause approximately 250 000 additional deaths per year, from malnutrition, malaria, diarrhoea and heat stress.
Water problems and increased risks of water borne diseases:
Water borne diseases are sensitive to climate and also show seasonal variation. Diarrheal diseases are more common during rainy season. Increasingly variable rainfall patterns due to climate change are likely to affect the supply of fresh water. Globally, water scarcity already affects 4 out of 10 people. A lack of safe water can compromise hygiene and increases the risk of diarrhoeal diseases (which kills approximately 2.2 million people every year), trachoma (an eye infection that can lead to blindness) and other illnesses.
People are forced to carry water from long distances and store supplies in their homes. House hold water storage can further increase the risk of contamination of water. In extreme cases, water scarcity leads to drought and famine. By the late 21st century, climate change is likely to increase the frequency and intensity of drought at regional and global scale.
Floods are also increasing in frequency and intensity. Floods contaminate freshwater supplies, and increase the risk of water-borne diseases. Both drought and floods are risk factor for water borne diseases (cholera, and various diarrhoeal diseases). When floodwaters become contaminated with animal waste, outbreaks of leptospirosis may occur. Outbreaks of rotavirus, cholera are also reported in past after floods. Lack of basic sanitation is also a contributory factor for increase in water borne diseases.
Changes in vector ecology and vector borne diseases:
India is afflicted with six major vector borne diseases (VBDs) namely malaria, dengue, chikungunya, filariasis, Japanese encephalitis and leishmaniasis. A vector is any organism – such as fleas, ticks, or mosquitoes – that can transmit a pathogen, or infectious agent, from one host to another.
Climate change enhances the transmission season and expands the geographical distribution of vector-borne diseases (like dengue, malaria), as warmer temperature and humidity favours the breeding of insect vectors and also alters the geographic distribution of existing vectors. Warmer average temperatures can mean longer warm seasons, earlier spring seasons, shorter and milder winters, and hotter summers, conditions might become more favourable for many carriers of vector-borne diseases.
Malaria which is transmitted by Anopheles mosquitoes is strongly influenced by climate, collection of stagnant water provides breeding grounds for mosquitoes. These conditions are potentially aiding in the spread of malaria.
The Aedes mosquito, vector of dengue and chikungunya fever is also highly sensitive to climate conditions, and studies suggest that climate change is likely to continue to increase exposure to dengue.
Climate change might also affect other vector borne diseases endemic to South Asia. These include parasitic diseases such as leishmaniasis, lymphatic filariasis and onchocerciasis, and tick-borne diseases and the effect is due to the impact of climate on the relevant vector populations. Climatic factors might also influence human plague, a bacterial disease carried by rodents and transmitted by fleas.
Effects of extreme temperatures:
Climate change including heat waves, cold spells, and other extreme events will bring new and emerging health issues. Heat stress can make working conditions unfavaroubale and increase the risk of cardiovascular, respiratory and renal diseases and heat related illnesses. With 1.5°C warming, 350 million more people could be exposed to deadly heat stress by 2050.
Air pollution and increasing aeroallergen levels are also high in extreme heat that can trigger asthma and other respiratory diseases. Climate change may affect human health by increasing ground-level ozone and/or particulate matter air pollution. Ground-level ozone (a key component of smog) is associated with many health problems, including diminished lung function, increased hospital admissions and emergency department visits for asthma, and increases in premature deaths.
Fossil fuel combustion (for power, transportation and industry) responsible for climate change is also a major contributor to air pollution, which causes 7 million premature deaths worldwide every year. Black carbon, produced by inefficient combustion in sources such as cook stoves and diesel engines, is the second greatest contributor to global warming. Over 90% of the urban population of the world breathes air that exceeds WHO’s (World Health Organisation) guideline levels for outdoor air pollution.
Flooded materials in homes, schools, and businesses can cause mold to grow and when inhaled, contributing to respiratory problems.
Food supply problems:
Rising temperatures and variable precipitation are likely to decrease the production of staple foods in many of the poorest regions. This will increase the prevalence of malnutrition and undernutrition. These were highlighted as a concern for a number of developing countries in Africa, Asia and Latin America, with the impacts of climate change on food security, particularly in relation to floods and drought.
The meat and dairy industries contribute to approximately 15% of greenhouse gas emissions and diets that are high in meat and dairy increase risks of cancer and cardiovascular disease.
Severe weather events:
An increase in frequency of extreme events such as storms, floods, droughts, and cyclone directly affects the human health in terms of loss of life and injury (physical injuries and post-traumatic stress disorders) and affects indirectly through loss of houses; population displacement; contamination of water supplies; loss of food production; increased risk of epidemics of infectious diseases and damage to infrastructure for provision of health services.
It is estimated that 22.5 million people are displaced annually by climate or weather-related disasters, and these figures are expected to increase in the future. Climate-induced human mobility has a socioeconomic cost with mental and social problems to individual and community.
The human cost:
Climate and weather have direct and indirect impacts on human life. The most disadvantaged, vulnerable and poor populations are expected to be disproportionately affected by climate change, with rising food and water insecurity, higher food prices, loss of income and livelihood opportunities, negative health effects, and population displacement (including forced migration).
Protecting health from climate change
Climate change is a global challenge that needs the action from all people. In late 2015, to address climate change, more than 190 countries approved Paris Agreement at the 21st session of the Conference of the Parties (COP21) to the United Nations Framework Convention on Climate Change (UNFCCC) in Paris. In the agreement, all countries agreed to work to limit global temperature rise to well below 2 degrees Celsius and to make best efforts to keep it to 1.5 degrees Celsius, for the achievement of the Sustainable Development Goals. Meeting the goals of the Paris Agreement could save about a million lives a year worldwide by 2050 through reductions in air pollution alone.
In 2017 WHO launched a Special Initiative on Climate Change and Health in Small Island Developing States. While these countries contribute very little to causes of climate change, they are among the most vulnerable to climate change impacts.
India laid strong foundations for greater global cooperation on climate action through its pledge for Paris Agreement. India has committed to cut its emission intensity of gross domestic product (GDP) by 33-35% of 2005 levels by 2030.
Promotion of renewable energy by Indian government is a strong commitment towards climate change. There's a lot we can also do in our daily life to prevent climate change including use of climate friendly transportation, save energy, go solar, harvest rain water, reduce waste and promote urban green spaces.
Steps to reduce greenhouse gas emissions can have more immediate positive health effects, such as promoting the safe use of public transportation and active movement (biking or walking as alternatives to using private vehicles) reduces carbon dioxide emissions and air pollution; and helps prevent diseases like diabetes, heart disease and cancer.
We have a much better future in store for us if we act quickly and make significant changes in our lifestyle.
Some ways to save energy and reduce GHG emissions
“Rising global temperature, record levels of greenhouse emissions, and increasing impacts of climate change require urgent and measurable action on the part of everyone.”