- Climate change refers to long-term shifts in weather patterns and average temperatures on Earth, primarily caused by human activities, such as the burning of fossil fuels, deforestation, and industrial processes.
- It is characterized by the increase in greenhouse gas emissions, particularly carbon dioxide, which traps heat in the Earth’s atmosphere and leads to global warming.
- Climate change impacts various aspects of the planet, including rising temperatures, changing precipitation patterns, melting glaciers and polar ice caps, sea-level rise, and altered ecosystems.
- These changes have far-reaching consequences for human societies, ecosystems, agriculture, water resources, and natural disasters, posing significant challenges to global sustainability and the well-being of future generations.
Climate Change status
IPCC predicts that increases in global mean temperature of less than 1-3o Celsius) above 1990 levels will produce beneficial impacts in some regions and harmful ones in others. Net annual costs will increase over time as global temperatures increase.
Cause of climate change
- Scientists attribute the global warming trend observed since the mid-20th century to the human expansion of the “greenhouse effect”.
- Human activities are changing Earth’s natural greenhouse effect. Burning fossil fuels like coal and oil puts more carbon dioxide into our atmosphere.
Impacts of Climate Change
- Hotter temperatures
- As greenhouse gas concentrations rise, so does the global surface temperature. The last decade, 2011-2020, is the warmest on record.
- Since the 1980s, each decade has been warmer than the previous one. Nearly all land areas are seeing more hot days and heat waves.
- Higher temperatures increase heat-related illnesses and make working outdoors more difficult. Wildfires start more easily and spread more rapidly when conditions are hotter.
- Temperatures in the Arctic have warmed at least twice as fast as the global average.
- More severe storms
- Destructive storms have become more intense and more frequent in many regions.
- As temperatures rise, more moisture evaporates, which exacerbates extreme rainfall and flooding, causing more destructive storms.
- The frequency and extent of tropical storms is also affected by the warming ocean.
- Cyclones, hurricanes, and typhoons feed on warm waters at the ocean surface.
- Such storms often destroy homes and communities, causing deaths and huge economic losses.
- Increased drought
- Climate change is changing water availability, making it scarcer in more regions.
- Global warming exacerbates water shortages in already water-stressed regions and is leading to an increased risk of agricultural droughts affecting crops, and ecological droughts increasing the vulnerability of ecosystems.
- Droughts can also stir destructive sand and dust storms that can move billions of tons of sand across continents.
- Deserts are expanding, reducing land for growing food. Many people now face the threat of not having enough water on a regular basis.
- A warming, rising ocean
- The ocean soaks up most of the heat from global warming. The rate at which the ocean is warming strongly increased over the past two decades, across all depths of the ocean.
- As the ocean warms, its volume increases since water expands as it gets warmer.
- Melting ice sheets also cause sea levels to rise, threatening coastal and island communities.
- In addition, the ocean absorbs carbon dioxide, keeping it from the atmosphere.
- But more carbon dioxide makes the ocean more acidic, which endangers marine life and coral reefs.
- Loss of species
- Climate change poses risks to the survival of species on land and in the ocean.
- These risks increase as temperatures climb. Exacerbated by climate change, the world is losing species at a rate 1,000 times greater than at any other time in recorded human history.
- One million species are at risk of becoming extinct within the next few decades.
- Forest fires, extreme weather, and invasive pests and diseases are among many threats related to climate change.
- Some species will be able to relocate and survive, but others will not.
- Not enough food
- Changes in the climate and increases in extreme weather events are among the reasons behind a global rise in hunger and poor nutrition.
- Fisheries, crops, and livestock may be destroyed or become less productive. With the ocean becoming more acidic, marine resources that feed billions of people are at risk.
- Changes in snow and ice cover in many Arctic regions have disrupted food supplies from herding, hunting, and fishing.
- Heat stress can diminish water and grasslands for grazing, causing declining crop yields and affecting livestock.
- More health risks
- Climate change is the single biggest health threat facing humanity.
- Climate impacts are already harming health, through air pollution, disease, extreme weather events, forced displacement, pressures on mental health, and increased hunger and poor nutrition in places where people cannot grow or find sufficient food.
- Every year, environmental factors take the lives of around 13 million people.
- Changing weather patterns are expanding diseases, and extreme weather events increase deaths and make it difficult for health care systems to keep up.
- Poverty and displacement
- Climate change increases the factors that put and keep people in poverty. Floods may sweep away urban slums, destroying homes and livelihoods.
- Heat can make it difficult to work in outdoor jobs. Water scarcity may affect crops.
- Over the past decade (2010–2019), weather-related events displaced an estimated 23.1 million people on average each year, leaving many more vulnerable to poverty.
- Most refugees come from countries that are most vulnerable and least ready to adapt to the impacts of climate change.
Impact of climate Change on Cryosphere
Significance of polar regions
- Global ocean circulation is influenced by polar processes. Polar Regions also affect drawdown of atmospheric heat and carbon.
- Sea ice influences climate, weather, marine ecosystems and human activities: Ice sheets and glaciers discharge freshwater that influences ocean circulation, ecosystems and sea level globally.
- Polar Regions are resource rich. There is increasing focus on resource extraction. Commercial activity is increasing bringing risks, opportunities and governance challenges.
- Very high albedo which reflects all the heat and keeps temperature cooler.
Impact of climate change on cryosphere
1. Sea ice
- Reflects a high proportion of incoming solar radiation back to space
- Provides thermal insulation between ocean and atmosphereInfluences thermohaline circulation
2. Changes in Arctic climate
- Air temperature in Polar Regions has increased faster than global average.
- Reasons for increased warming of polar regions are:
- Reduced summer albedo due to sea ice and snow cover loss.
- Increase of total water vapour content in the polar region’s atmosphere.
- Changes in total cloudiness in summer.
- Additional heat generated by newly formed sea areas and more extensive open water areas in the autumn.
- Northward transport of heat and lower rate of heat loss to space from Arctic.
- According to projections, the Arctic will be practically ice-free during summers by 2050.
3. Changes in Antarctic climate
- The loss of ice in Antarctic region has not been as clear as in Arctic region.
4. Changes in Terrestrial cryosphere
- Thawing of Polar Permafrost: It refers to ground (soil or rock and included ice and organic material) that remain at or below 0°C for 21 at least two consecutive years. The permafrost region has locked vast amounts of carbon and methane, if released will further accelerate global warming.
- Glaciers are expected to reduce in ice-mass and thin.
Impact of changes in Polar Cryosphere
- The loss sea ice will be positive for shipping industry as it will find new shorter routes.
- Changes in the range of animals and biodiversity. This will create risks for some animals such as Polar Bears, Reindeers, and Snow Leopard which are totally dependent on the snow ecosystem.
- Thawing of snow will lead more tourists to access these areas, which can further add to their degradation.
Impact of changes in mountain cryosphere
- Changes in river runoff. It is expected that water yields of rivers will first increase to hit a peak as glaciers melt at an accelerated pace, and then decrease when no glaciers are there to feed perpetual rivers.
- Changes in river run-offs will also affect hydro-power generation.
- Agriculture sector will be affected adversely due to want to water for irrigation.
Snow avalanches can occur either spontaneously due to meteorological factors such as loading by snowfall or liquid water infiltration.
Impact of climate Change on Oceans
- Ocean Heat:
- Four independent analyses show that the amount of heat stored in the ocean has increased substantially since the 1950s.
- Ocean heat content not only determines sea surface temperature, but also affects sea level and currents.
- Sea Surface Temperature:
- Ocean surface temperatures increased around the world during the 20th century.
- Even with some year-to-year variation, the overall increase is clear, and sea surface temperatures have been consistently higher during the past three decades than at any other time since reliable observations began in the late 1800s.
- Enhanced Ocean Stratification:
- Ocean Stratification refers to the process of forming of layers of (ocean) water with different properties such as salinity, density and temperature that act as barrier for water mixing.
- The strengthening of near-surface stratification generally results in warmer surface waters, decreased oxygen levels in deeper water, and intensification of ocean acidification in the upper ocean.
- Sea Level:
- When averaged over all the world’s oceans, sea level has risen at a rate of roughly six-tenths of an inch per decade since 1880.
- The rate of increase has accelerated in recent years to more than an inch per decade. Changes in sea level relative to the land vary by region.
- Along the U.S. coastline, sea level has risen the most along the Mid-Atlantic coast and parts of the Gulf coast, where several stations registered increases of more than 8 inches between 1960 and 2020.
- Sea level has decreased relative to the land in parts of Alaska and the Pacific Northwest.
- Changes in ocean currents:
- Ocean currents will change due to changes in wind stress. Western boundary currents have already started shifting pole ward.
- For ex. Atlantic Meridional Ocean Circulation is expected to weaken in future affecting the Gulf Stream.
- A Closer Look: Land Loss along the Atlantic Coast:
- As sea level rises, dry land and wetlands can turn into open water. Along many parts of the Atlantic coast, this problem is made worse by low elevations and land that is already sinking.
- Between 1996 and 2011, the coastline from Florida to New York lost more land than it gained.
- Coastal Flooding:
- Flooding is becoming more frequent along the U.S. coastline as sea level rises. Every site measured has experienced an increase in coastal flooding since the 1950s.
- The rate is accelerating at most locations along the East and Gulf coasts. The East Coast suffers the most frequent coastal flooding and has generally experienced the largest increases in the number of flood days.
- Ocean Acidity:
- The Ocean has become more acidic over the past few decades because of increased levels of atmospheric carbon dioxide, which dissolves in the water.
- Higher acidity affects the balance of minerals in the water, which can make it more difficult for certain marine animals to build their protective skeletons or shells.
- Ocean deoxygenation:
- The loss of oxygen in the ocean. It results from ocean warming, which reduces oxygen solubility and increases oxygen consumption and stratification, thereby reducing the mixing of oxygen into the ocean interior.
- Deoxygenation can also be exacerbated by the addition of excess nutrients in the coastal zone.
- Marine Heatwaves:
- Marine heatwaves – sustained periods of anomalously high near-surface temperatures that can lead to severe and persistent impacts on marine ecosystems – have become more frequent over the 20th century.