Effects Of Global Warming On Humans

We examine 8 major impacts of global warming. (1) Rise in sea-levels. (2) Damage to agriculture and other enterprises in low-lying coastal zones. (3) Extreme heat. (4) Air pollution and smog. (5) Disease. (6) Freshwater problems. (7) Interruption of power supply. (8) Refugees.
The spread of infectious diseases is one of the key effects of global warming
Climate change is helping the spread of infectious diseases like malaria and ebola. Image: WHO (CC BY 2.0)

Effects on Human Health

The effects of global warming on humans include: (a) the worsening of health problems that already exist; (b) increases in health complaints generally, but particularly in developing countries with low-income; and (c) a greater likelihood worldwide of injury, disease, and death. These risks stem directly from extreme weather events (heatwaves, droughts, flooding), urban pollution, under-nutrition caused by diminished food production in poor regions, the spread of vector- and water-borne diseases, as well as problems with water and power supplies.

Other consequences of global warming include major changes to livelihoods, especially those that depend on marine and coastal ecosystems. As well as this, human nutrition may be impacted by the diminution or disappearance of certain climate-sensitive crops, such as corn, numerous fruits, nuts and beans. 1 The big unknown is the potential rise in sea-level, which could lead to social upheaval among coastal towns and cities around the globe.

Full Effects of Global Warming on Humans are Yet to Come

Climate change is already having a profound effect on Planet Earth and its biological, geological and ecological systems. 2 But how is it affecting humans? What impact does it have on the health, wellbeing and livelihoods of ordinary people?

In 2014, the World Health Organization (WHO) forecast that – in the absence of effective climate action – global warming will result in roughly 250,000 extra deaths each year (in the period 2030-2050), due to malnutrition, heat stress and malaria alone.

This figure, however, is a conservative estimate, according to a new review in The New England Journal of Medicine, because it ignores other climate-related factors that could impact on death rates – such as population displacement as well as disruptions to food production and supply. 3

In addition, the WHO estimate took no account of deaths and illnesses due to disruptions in health services caused by extreme weather, the review said, citing an earlier estimate of 529,000 adult deaths by 2050, from reduced food production alone. 4

Global warming is also projected to have a huge impact on human poverty around the world. According to World Bank estimates, roughly 100 million people could be forced into extreme poverty by 2030, making them more vulnerable to the health effects of the changing climate. 5 Already, countries like Bangladesh are experiencing increases in climate-sensitive diseases, including malaria, dengue, childhood diarrhoea, and pneumonia, among vulnerable population groups. See also: the Ethics of Climate Change.

No matter how badly human health has been affected by climate-related factors to date, it is nothing compared to what may happen later this century if greenhouse gas emissions are not drastically reduced. One factor which is rarely given sufficient weight by those who downplay the dangers of global warming, is “climate inertia” – the slowness of Earth’s climate system to respond to change. In other words, the effects we are seeing – on temperature, sea levels, ice-sheets, and so on – may only relate to a small part of the damage we have done to the planet.

For example, we know that excess carbon dioxide (CO2) emitted since 1900 will remain in the atmosphere for centuries to millennia. 6 In fact, even if all emissions ceased tomorrow Earth’s temperature is not expected to decrease significantly for thousands of years. 7

Because of climate inertia, and also because temperatures are set to rise this century even if we hit the IPCC target of “net-zero” emissions by 2050, it is safe to assume that the full effects of climate change on human health, as well as their livelihoods, is yet to come.

What Do Scientists Say?

The issue of climate-related impacts on men, women and children was specifically addressed by Working Group II in the Fifth Assessment Report issued by the Intergovernmental Panel on Climate Change (IPCC) in 2014. The report summarizes the key climate-related risks, as follows:

  • Risk of death, injury, ill-health in low-lying coastal zones, due to hurricanes, storm surges, coastal floods, and sea level rise.
  • Risk of severe ill-health and disruption for large urban populations due to inland flooding in low-lying coastal hinterlands.
  •  Systemic risks due to extreme weather events leading to breakdown of infrastructure networks and critical services such as electricity, water supply, and health and emergency services.
  • Risk of death and severe ill-health during periods of drought and intense heat, both for vulnerable urban populations and those working outside in rural areas.
  • Risk of food scarcity and the breakdown of food production and supply systems, because of higher temperatures, drought, flooding, and precipitation variability and extremes, particularly for poorer populations in urban and rural settings.
  • Risk of reduced agricultural productivity and financial loss due to lack of access to drinking and irrigation water in semi-arid regions.
  • Increased ocean warming and acidification are damaging marine biomes and fish habitats, with adverse consequences for fisheries and food security, and to the livelihoods of those in fishing communities. (See: How Do Oceans Influence Climate?)
  • Risk to livelihoods because of damage to terrestrial and inland water ecosystems and biodiversity.

This covers most, but not all, of the most serious climate related impacts on human life. For example, there is no specific reference to urban pollution which, says the World Health Organization (WHO, accounts for enormous numbers of health problems and about 1 million premature deaths every year. 8

Why are governments dragging their feet over global warming? For the answer, see: Root Cause of Climate Change.

8 Major Effects of Global Warming on Humans

(1) Rise In Sea-Levels

Of all the environmental hazards to human health, none is surely more serious than the possibility of a substantial rise in global sea level. It is caused by two things: ice-melt from glaciers and the Greenland and Antarctic ice sheets, and the thermal expansion of water.

Average sea level rose by about 20 centimeters (8 inches) during the 20th century. However, the rate in the last two decades has doubled, and the rate is accelerating every year. 9 What’s more, as satellite data and other forms of research lead to improved climate models, estimates of sea level rise have been continually revised upwards. 10

How High Will Sea Levels Rise?

The IPCC’s Fifth Assessment report projected a rise of up to 90 cm (3 feet). According to NASA, levels are projected to rise by 1-4 feet by 2100. 11 Some later studies by the U.S. National Oceanic and Atmospheric Administration have warned that a sea level rise of 200-270 cm (6.5 to 9 feet) this century, is plausible. 12

But if either of the polar ice sheets collapse, it will be a catastrophe. The smaller Greenland ice sheet would raise global mean sea levels by 24 feet (7m), while the Antarctic ice sheet would cause a rise of about 58 meters (190 ft).

Sea Level projections. Rising seas are among the most serious effects of global warming on humans.
Sea-Level Rise: Possible scenarios based on different emissions pathways. Source: © NOAA

Meanwhile another study of ice in Antarctica involving some top ice-sheet specialists concluded that, if emissions aren’t reduced, sea levels could rise up to 1.5 meters (5 feet) by 2100. 13

This degree of sea level rise would submerge land inhabited by more than 153 million people. Miami has been dubbed the “No 1 most vulnerable city worldwide” in terms of damage from storm-related flooding and rising sea-level. 14 Among other major cities affected by a rise of 1.5 meters (5 feet) are: Guangzhou (China), Mumbai (India), Osaka (Japan), New Orleans and New York City (both USA). Meantime, some Pacific Ocean island nations, including Tuvalu, Kiribati and Nauru, are planning to evacuate, as flood defence would be economically unrealistic. 15

Note: According to a study in Environment and Urbanization (April 2007), more than 630 million people live in coastal areas within 30 feet (9.1 m) of sea level. The study also reported that about two thirds of the world’s cities with over five million people are located in these low-lying coastal areas. 16

How Are Sea Levels Measured?

By satellite. In 2018, for example, NASA launched two new satellite missions to improve and fine-tune sea level projections: the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission, created in collaboration with GeoForschungsZentrum (GFZ) in Germany, focuses on the Greenland and Antarctic ice sheets; while the Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) measures the elevation of ice sheets and glaciers.

(2) Damage To Agriculture And Other Enterprises In Low-Lying Coastal Zones

Sea levels will severely affect inhabitants of coastal and island regions, and trigger widespread flooding, particularly if accompanied by storm surges and high tides. Loss of agricultural land and urban disruption will follow. In addition, rising levels of saline seawater will contaminate wetlands and aquifers, degrading the local ecology and damaging habitats for birds and plants. (See also: Effects of Global warming on Oceans.)

Salt water intrusion into coastal soils is already a serious problem for crops that are not salt-resistant. Farmland in the Nile Delta, for example, is affected by salt water flooding. 17 and salt levels are increasing in the soil and irrigation water in both the Red River Delta and the Mekong Delta in Vietnam. 18

The effects of global warming on humans are also severe in the delta areas of Bangladesh and China. For example, a recent study of coastal agriculture in Bangladesh showed that farming losses will be a large driver of migration. Researchers estimated that a farm would be expected to lose 21 percent of its crop revenue each year as a result of moderate salt contamination. In such a situation, farmers who have the necessary resources switch 60 percent of their cultivation from rice to shrimps. 19 “My concern is that the most vulnerable people will be the least resilient in the face of climate change, because they have limited resources to adapt their farming practices,” says lead author Joyce Chen of Ohio State University.

In addition, seaside low-lying zones will be exposed to increasing risk of coastal erosion. 20 By the 2080s, millions of people will experience floods every year due to rising sea levels, mostly in the densely populated, low-lying deltas of Asia (Ganges) and Africa (Nile).

Increased coastal salinity also presents a quandary in the United States. A recent study of the Chesapeake Bay region and Maryland’s Eastern Shore revealed that some farmers affected continue to cultivate fields in traditional rotations, while others are switching to more salt-tolerant crops, like sorghum. Meantime others are simply abandoning fields as they become damaged by salt. This can lead to colonization by agricultural weeds and native marsh plants, which might facilitate ecosystem adaptation, but may also expose lands to invasion by the common reed (Phragmites australis), a noxious species that compromises wildlife in wetlands as well as healthy ecosystems. 21

(3) Extreme Heat

In 2003, a scorching heatwave swept across Europe, accounting for the deaths of 70,000 people. Many were elderly and some already suffered from chronic conditions. Unfortunately, ongoing climate change is likely to make heatwaves even longer and more intense (witness the record-breaking highs of almost 109°F in Paris and 98°F in London in 2019), and their effects are not going to be limited to the old and sick.

Heat Map illustrating the extreme heatwave In Europe, 2019.
2019: The July 2019 heatwave across Europe set all-time high temperature records. Thousands of people died, along with thousands of animals when ventilation systems in barns were overwhelmed. A climatological study of the event 22 , found that the temperatures experienced during the heat wave would have been 1.5 to 3 °C lower had it not been for anthropogenic global warming. Source: NOAA

In France, for example, there were 15,000 deaths in 2003 due to excessive heat. Every summer since then, despite precautions, the country has recorded between 500 and 3,500 fatalities from extreme heat: 700 deaths in 2016, 475 in 2017 and 1,500 in 2018. 23

Furthermore, sweltering temperatures also affect productivity. A mind-boggling 153 billion hours of labor – 80 percent of them in agriculture – were lost because of excessive heat in 2017, notably in India, Southeast Asia, sub-Saharan Africa and South America. Intense heat levels also destroy crops – 30 countries have seen crop yields decline due to extreme heat – and lead to ideal conditions for the spread of infectious diseases. 24

“Overall, the report does suggest very serious concerns about the effects of global warming on humans, particularly human health,” says Andy Haines, a professor of environmental change and public health at the London School of Hygiene & Tropical Medicine, who was not involved in the 2018 report but has co-authored previous Lancet Countdown assessments.

Average temperatures have been climbing across the globe, driven by spikes of 90°F and higher. (See: Global Temperature Projections for 2100.)

In the United States, according to the Centers for Disease Control and Prevention in Atlanta, extreme heat now accounts for more deaths in cities than all other extreme weather events combined. One reason why the concept of ‘sponge cities‘ is taking root with city planners. These green infrastructure projects incorporate more greenery in order to absorb rainfall, minimize flooding and reduce the urban heat island effect. Meantime, the CDC report warned that more frequent heat waves are expected in the future due to global warming.

Summers have been deadly for urban dwellers in North America recently. In June 2018, dozens of fatalities were reported across the U.S. and in Canada – including 28 people in Montreal alone – in the wake of a 100°F heatwave. The following week, much of California experienced record-breaking temperatures, followed by yet another killer heat wave in the Southwest later in July. At one point, 44 out of 50 states were being flayed by temperatures of 90°F or more.

According to a 2017 NRDC study, by 2040, an estimated 30,000 Americans will die every summer because of global warming. Roughly twice the number of fatalities caused by gun violence. 25

Is Air Conditioning A Good Way To Cool Down? 

Yes and No! Air-conditioning may be a convenient and effective tool to combat extreme heat, but it generates an estimated half a billion metric tons of carbon dioxide emissions in the U.S. every year, thus generating an even bigger climate crisis for our children and grandchildren.

Health Effects Of Wildfires

In 2019, Arctic fires engulfed huge tracts of boreal forest across Canada, Greenland, Alaska and Siberia. By the time the fires died down, they had discharged huge amounts of carbon dioxide into the atmosphere. Scientists working at the Copernicus Atmosphere Monitoring Service (CAMS) estimated that in June alone 50 megatons of CO2 were emitted – roughly the equivalent of Sweden’s total annual carbon output.

In addition, the fires created a toxic cloud of smoke and soot approximately 5 million square kilometers in extent: about the same size as the area occupied by the 28 countries of the EU. As well as being exceptionally harmful to human health, Nasa scientists say the soot absorbs sunlight and warms the atmosphere. 26 27

Arctic fires have also been responsible for thawing the area’s permafrost, one of the world’s largest deposits of carbon. This could potentially lead to a disastrous release of methane, adding hugely to the levels of carbon dioxide and other greenhouse gases in the atmosphere.

In the southern hemisphere, Australian bushfires 2019-2020 destroyed 186,000 sq km (72,000 sq mi) of land in NSW and Victoria, causing air pollution and CO2 emissions to skyrocket.

(4) Air Pollution And Smog

Smog over Mexico City. Smog is one of the most unhealthy effects of global warming on humans in cities.
Aerial view of photochemical smog over Mexico City. Smog is one of the most unhealthy effects of global warming on humans. Image: Fidel Gonzalez (CC BY-SA 3.0)
  • When burned, fossil fuels – such as coal, oil and natural gas – emit a number of air pollutants that cause serious harm to human health. 28 Coal burning, for example, is a major contributor to air pollution through its emission of sulfur dioxide (SO2) and nitrogen oxide (NOx). Sulfur dioxide particles in the air contribute to chronic respiratory problems, like asthma and bronchitis, while nitrogen oxide reacts with other chemicals to form ground-level ozone, which itself promotes severe lung problems such as chronic pneumonia and emphysema. NOx is also emitted from vehicle exhausts and electricity power plants.
  • Coal combustion also spews out microscopically small particles known as “particulate matter” or “particulates”. These tiny aerosols are especially damaging to human health because they are small enough to pass through the human lungs’ natural filters. 29 These particles are emitted directly from coal-fired power plants or furnaces as tiny pieces of black carbon, or are formed in the lower atmosphere as a result of reactions between oxygen and either sulfur dioxide or nitrogen oxide.
  • The World Health Organization (WHO) has stated that, coal-produced particulates are responsible for about 1 million premature deaths per year, most of which occur in India and China. 30 One study shows that in 2011-2012, pollution from coal plants in India led to 80,000 to 115,000 premature deaths and more than 20 million asthma cases from exposure to PM10 particulate pollution. 31 In parts of Africa and Asia, where as many as 3 billion people rely on indoor open fires for cooking and heating, the use of solid fuels like wood and coal cause high levels of indoor air pollution from smoke and its deadly micro-particles.
  • Coal-fired power plants are the largest source of atmospheric mercury emissions in the United States, accounting for 42 percent of all emissions. Mercury is extremely harmful to human health with several irreversible toxic effects. 32 In India, coal-fired power stations are a major contributor both to urban smog and the strange Asian brown cloud that appears during the winter dry season.
  • Combustion of petroleum in petrol or diesel-powered vehicles emits greenhouse gases like carbon dioxide, which is the biggest single driver of global warming. But vehicle tail-pipe emissions also include a range of other pollutants that reduce air quality – notably in cities – by causing photochemical smog. All are harmful to public health. 33
  • These pollutants include particulates (e.g. black carbon), volatile organic compounds (another creator of ground level ozone), nitrous oxide, sulfur dioxide, and the highly poisonous carbon monoxide (CO). Vehicle exhaust fumes account for over a third of all carbon monoxide emissions. All these pollutants are linked to a host of respiratory conditions, such as asthma, choking, lung irritation, pneumonia and influenza.
  • Delhi has the worst air pollution of any urban area in the world, suffering about 10,500 pollution-related fatalities every year. 34 The city has the highest level of PM2.5, the most harmful type of particulate matter. Rising air pollution levels have led to a noticeable increase in lung-related ailments (notably asthma and lung cancer) among Delhi’s women and children. 35
  • Studies show that roughly 200,000 Americans each year die prematurely because of polluted air. 36 37 In 2018, the inhabitants of 532 American metro areas experienced a total of 4,134 days when the official air quality index exceeded 100. This means the air is unhealthy for anyone with heart and lung disease, the elderly and the very young. That’s an increase of 15 percent more than the average for 2013 to 2016. 38
  • The number of very bad air days climbed even more. On average, in 2017 and 2018, city air quality was classified as “very unhealthy” or “hazardous” nearly 140 times, with the air quality index exceeding 200. That’s more than two-and-a-half times as often as the 2013-2016 average of 55. 38

As Chernobyl taught us, air pollution is a global problem. What happens in one country can affect many others. 39 40 For more about the health impacts of airborne pollutants, see: Health Effects of Air Pollution.

(5) Disease

Ever since the late-1970s, global warming has been helping to boost the prevalence of certain infectious diseases, especially vector-borne diseases such as malaria and dengue fever. The vector (disease-carrier) in both cases is a type of mosquito – the Anopheles mosquito (malaria) or the Aedes aegypti and Aedes albopictus mosquitoes (dengue). The breeding grounds for these mosquitoes are small streams, ground or forest pools, irrigated lands, freshwater marshes, or any other place with clean, slow-moving water. 24

Spread Of Dengue Fever

  • Warmer temperatures and new rainfall patterns caused by climate change have increased the geographical ranges of organisms that spread dengue fever, malaria and also cholera. 41 For example, the “vectorial capacity” (how easily a disease carrier can transmit a pathogen) of dengue virus reached a record high in 2016, while the length of coastline suitable for hosting cholera-spreading organisms increased from the 1980s to the 2010s in the Baltic region and northeastern United States by 24 and 27 percent, respectively. 24
  • The best example of how global warming affects the spread of vector-borne diseases concerns Africa’s Eastern Highlands: areas 1,500 meters above sea level where the mean annual temperature used to be in the range of 16-19°C. Historically, these areas used to be malaria-free since malaria transmission cannot take place below 18°C. But due to rising temperatures, environmental suitability for the malaria-causing Plasmodium falciparum parasite has increased by nearly 21 percent from the 1950s to the 2010s. 42
  • A wonderful modelling tool for scientists investigating mosquito-borne diseases is the Dynamic Mosquito Simulation Process (DyMSiM). This software projects mosquito distribution and activity based upon local climate conditions. 43
  • In 2015, there were 212 million cases of malaria with roughly 429 000 malaria deaths, 300,000 of which children under age 5. Climate models indicate that the risk of malaria will increase 5-15 percent by 2100 due to global warming. 44
  • Dengue fever is now considered to be the most critical vector-borne viral disease in the world, causing an estimated 50–100 million annual infections. Over the past 50 years, incidence of dengue fever has rocketed with a thirty-fold increase in new cases. 45 Previously confined to a handful of tropical habitats, dengue is now a regular feature in more than 100 countries, notably in Southeast Asia and the Western Pacific, but also across the Americas, Africa and the Eastern Mediterranean. What’s more, the disease has already reached Europe. The first reported (local) transmission of dengue occurred in France and Croatia in 2010. 46
  • In Asia, dengue fever has achieved its greatest success in Bangladesh. 47 With its teeming population, warm-wet weather, and susceptibility to flooding due to its low-lying nature, Bangladesh is an ideal host for dengue. Its capital, the city of Dhaka, is the country’s most likely location for contracting the disease, with its collection of 11.8 million human hosts. [44] During the period 2000-2010, there were more than 25,000 new cases reported in Dhaka, and researchers are forecasting a forty-fold increase by the year 2100. 48
  • Climate change is not the only reason why vector-borne and water-borne diseases are increasing so fast. There are several other important reasons for it.
Global warming allows malaria mosquitoes to extend their breeding grounds.
A malarial mosquito (Anopheles stephensi) shown here feeding on the blood of a human host, through its pointed feeding tube or proboscis. The IPCC warns against the risk of disease caused by rising temperatures. Climate change warms the environment which boosts the reproduction rates of malaria-carrying mosquitoes, allowing them to become active in entirely new locations. 49 Image: Centers for Disease Control and Prevention’s Public Health Image Library.

They include social factors, such as: patterns of human travel and migration, the effectiveness of public health standards and systems, as well as the underlying health and nutrition of the population group concerned. 50 Environmental factors include: deforestation, expansion of wetlands and water development projects (all of which can increase mosquito breeding habitat), as well as increased urbanization. To take just two of these factors – deforestation and cultivation of natural swamps – both help to create favorable conditions for the survival of mosquito eggs and larvae. 51

(6) Freshwater Problems

Water shortages are a major effect of global warming on humans. In simple terms, due to changes in weather patterns, wet areas are getting wetter and dry areas are becoming dryer.

  • Studies are already projecting a 10–40 percent increase in water availability and surface runoff in northern latitudes and in wetter regions of the tropics by 2050, while decreases of a similar size are expected in dryer parts of the tropics and subtropics. Earlier and larger volumes of spring runoff are already being seen in western parts of the United States and other temperate zones served by glaciers or snow-fed rivers.
  • In the Northern Hemisphere, spring freshwater ice breakup now occurs 9 days earlier than it did 150 years ago, and autumn freeze-up 10 days later. 52 This seasonal change results in less water flow in the late summer undermining farmers’ ability to irrigate crops a problem which is particularly acute for irrigation in South America. 53
  • In Asia, too, farmers are going short of water because glaciers in the Himalayas are melting earlier. Harry Zekollari, from Delft University of Technology in the Netherlands, said most people did not understand quite how crucial glaciers were. “A glacier is a reservoir. A healthy glacier will typically melt in summer and become a bit bigger in winter. That means that when people need water most, they get water from the glacier,” he explained. Having extra water in the late winter or early spring is no use to them, he explained. 54
  • Water availability, too, is decreasing in dryer regions and has been over the past two decades. Bioregions such as the African Sahel, southern Africa, the Levant, western and southern Australia along with western parts of the United States, continue to be most at risk. In these regions drought is predicted to increase in both intensity and duration, with extremely negative impacts on agriculture and livestock. And the harder and more baked the earth becomes, the less water it can absorb, which is why droughts typically end in flash floods rather than the replenishment of moisture in the soil or an increase in water table levels. (See also: Why is Soil So Important to the planet?)
  • Fresh water, presently stored by mountain glaciers and snow in both the tropics and mid-latitudes beyond the tropics, is also predicted to decline, thus reducing its availability for 15 percent of the world’s population.
  • It is also expected that global warming – through its impact on biological activity in reservoirs, lakes, rivers and other watercourses – may have an adverse impact on water quality. Warmer waters, for example, are responsible for the development of algal blooms, which can present health risks to humans. Increased evaporation will also constrain the full operation of reservoirs.
  • More powerful tropical cyclones, combined with rises in average sea levels, have led to increasing coastal salinity and contamination of freshwater irrigation systems and streams.

(7) Interruption Of Power Supply


Global warming also affects power plants – especially nuclear power stations. This is because old reactors with water-cooled cores are obliged to operate at lower internal temperatures for safety reasons. Heatwaves typically raise river temperatures and increase evaporation, thus diminishing water flow. This situation has forced some nuclear reactors to shut down and is likely to continue doing so until the cooling systems of these plants are upgraded to provide more leeway.

Such shutdowns became a common occurrence in France during the heatwaves of 2003 and 2006, when 17 reactors were forced to reduce output or shut down. More than three quarters of French electricity is nuclear powered, and when another series of shutdowns took place in 2009, the French government were obliged to import electricity.

Similar cases have been reported from Germany, where high temperatures have curtailed nuclear power production a number of times at the Unterweser and Isar nuclear power plants between 1979 and 2007. Nuclear shutdowns have happened in several other plants in Europe during the summer and many more are predicted if global warming continues. (See also: Is Nuclear power a replacement for Fossil Fuels?)


Hydroelectric plants are even more vulnerable to climate change than nuclear installations. Because their output of electrical energy is directly affected by river flow. Lower river flows and reservoir water levels caused by reduced rainfall or higher temperatures and increased evaporation will reduce the amount of stored water thus reducing the amount of water that can be used for hydroelectricity. This will lead to power shortages in areas served by the hydroelectric plant.

Obviously, the likelihood of water and flow shortage will increase as a result of higher temperatures caused by climate change. Studies from the Colorado River in the United States – a river that runs 1,450 miles and drains parts of seven U.S. states – indicate that a 2°C rise in global temperature could cause a 10 percent drop in precipitation and might reduce river run-off by up to 40 percent. In Brazil, a country that relies heavily on hydroelectricity, global warming could reduce total energy production by 7 percent per annum by 2100.

(8) Displacement And Forced Migration Of People

Map showing climate refugees and where they will come from.
Map showing the Climate Refugee Hotspots, which are likely to be most affected by climate change and thus cause the most population displacement. Loss of homes and livelihoods is one of the worst effects of global warming on humans. Image: © CC BY-SA 3.0
  • Climate change leads to displacement of people for several reasons. First, extreme weather events (storms, floods, severe droughts, famine) can destroy homes or livelihoods turning local inhabitants into displaced people or economic migrants.
  • Second, climate-induced deterioration of the local habitat, due to desertification, the gradual collapse of agriculture due to a rise in sea-levels, or similar longer-term processes, will also force people to abandon their traditional homes for more secure environments. This situation is already happening in areas of Africa’s Sahel (Mali, Niger, Chad, Sudan), the dry belt spanning the continent between the Sahara to the north and the Sudanese Savanna to the south.
  • Third, climate change impacts on agriculture and the resulting impoverishment of local inhabitants can lead to the collapse of the local economy, a breakdown in the relationship between local and central government, or even the breakdown of law and order. Any of these events can uproot people or whole communities.
  • Due mainly to coastal flooding and agricultural disruption, the IPCC projects that 150 million environmental migrants will exist by mid-century.
  • According to data from the Internal Displacement Monitoring Centre, more than 40 million people were uprooted in Asia and the Pacific during 2010 and 2011, as a result of storms, floods, drought and extremes temperatures. Although most eventually returned home when conditions improved, a significant minority became migrants, usually inside their country, but some also crossed into neighboring countries.
  • With sea levels in the Asian and Pacific region threatening to submerge small islands and large river deltas, a climate-induced humanitarian disaster, spurring wholesale migration, is almost certainly looming if global warming goes unchecked. 55

Mitigation And Adaptation Strategies

Supported by international programs, set up by the United Nations Framework Convention on Climate Change (UNFCCC) and monitored by the Paris Climate Agreement secretariat, efforts are being made across the globe to identify and implement a wide range of climate change mitigation projects.

Examples of such international programs include the Clean Development Mechanism and Joint Implementation programs (providing bilateral assistance for mitigation projects), as well as the International Mechanism for Loss and Damage associated with Climate Change Impacts. Financial assistance is also provided by the Global Climate Change Alliance+, the EU External Investment Plan, the Green Climate Fund and other funds.

Education and training is also essential in order to enhance climate change adaptation strategies and thus reduce the effects of global warming on societies. Climate-related courses in disciplines like oceanography, atmospheric science, biogeoscience, geochemistry, paleoclimate and environmental science, are being developed and expanded in many countries. So too are specialist training programs in areas such as environmental protection and land planning, reef management, marine spatial planning, integrated water resources management, agroforestry and livelihood diversification.

Unfortunately, because it is difficult to classify environmental migrants as “refugees,” 56 neither the UN Framework Convention on Climate Change nor the subsequent Kyoto Protocol includes any provisions for specific assistance for those directly affected by climate change. 57

Frequently Asked Questions About Global Warming

For answers to popular questions on all aspects of climate and rising temperatures caused by man-made actions, see: 50 Climate Change FAQs, and 50 FAQs About Global Warming.


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