Climate Change And Global Warming
Climate change is a long-term shift in temperatures and weather patterns that means climate change involves not just a change in temperature but every other component of weather, including rainfall, humidity and wind speed. It may be natural but it is largely caused by human activities primarily the burning of fossil fuels such as coal, oil, gas and land-use changes, thereby human activities are considered the main driver of climate change since the start of the industrial revolution. Other sources of GHG emissions are deforestation and fertilizer use (primary source of nitrous oxide emission), livestock production and other industrial processes.
Since the time of industrial revolution, concentrations of greenhouse gases (GHGs) have been steadily increasing in the Earth's atmosphere causing average temperatures at earth’s surface to rise, driving global warming. Global warming is an aspect of modern climate change. Greenhouse gases absorb some of the heat that the earth radiates after it warms from sunlight. GHGs act as a blanket wrapped around the earth and tapping the heat in the earth's lower atmosphere and heating it.
The greenhouse gases trap heat in the atmosphere and warm the lower atmosphere of the earth. It is called the greenhouse effect. They are transparent to incoming sunlight but they absorb radiation emitted from earth and warm it. Primary greenhouse gases are water vapours, carbon dioxide, methane, nitrous oxide, ozone.
Carbon dioxide emissions come from the burning of fossil fuels (coal, natural gas and oil), solid waste, plants and trees and other biological materials and manufacturing of cement, production of fertilizers, and deforestation and other land uses.
Agriculture, oil and gas operations are major sources of methane emission. Methane is more potent at trapping the heat than carbon dioxide but does not stay as long in the atmosphere as carbon dioxide. Over a 20 year time period, a molecule of methane gas taps about 84 times more heat than a molecule of carbon dioxide but over a century, it goes down to trapping 28 times more heat as per molecule than carbon dioxide, according to the International Panel on Climate Change (IPCC) report.
Recently, Black carbon has become a major contributor to climate change, possibly the second largest contributor to climate change and global warming after carbon dioxide gas, a major Greenhouse Gas.
If carbon emissions were unchecked then half the planet would face severe droughts by the century end, said by NASA. Some of the effects of climate change would continue for centuries such as sea level rise, ocean heating, ocean acidification, even if efforts to limit global warming to 1.5°C or 2°C as enshrined in the Paris Agreement 2015 become successful.
The IPCC AR6 synthesis report confirms that human activity is 'unequivocally' driving temperature rise globally, which has reached approximately 1.1 degree Celsius above pre-industrial level. The United Nation Secretary General called this report 'a survival guide for humanity'.
The UN Secretary General also recommends that the developed nations should try to achieve targets of net-zero carbon emissions (carbon neutrality) as close as possible to 2040 and the developing countries must commit to reach net-zero carbon as close as possible to 2050.
According to the IPCC AR6 synthesis report, for limiting global warming to 1.5 degree Celsius requires GHG emissions to be reduced by 43% by 2030 and for limiting 2 degree Celsius requires 21% emissions cut by 2030.
The World Health Organization (WHO) has called climate change the greatest threat to global health in the 21th century.
By measuring the air temperatures, the scientists got some evidence of warming.
- Changes to the natural water cycle such as an increase in frequency and intensity of heavy precipitation, melting of snow and land ice, and increased atmospheric humidity.
- Flora and fauna are also behaving in a manner consistent with warming; for instance, plants are flowering earlier in spring.
- Cooling the upper atmosphere: Greenhouse gases trap the heat near the Earth’s surface, warming the lower atmosphere, and preventing this heat to radiate into space thus cooling the upper atmosphere.
- The decline of sea ice in the Arctic, both in extent and thickness, is further evidence of rapid climate change.
- One of the most visible signs of climate change is the warming impact on glaciers resulting in faster glacial retreat.
Effects of Global Warming And Climate Change
The increase in both sea surface temperature and ocean heat content is an important effect of climate change.
The permafrost thawing due to temperature rise, releasing long-trapped carbon into the atmosphere as carbon dioxide and methane which are major greenhouse gases. This carbon emission further contributing to global warming and climate change which again in turn facilitates thawing of permafrost.
Large amounts of biomass are stored in the permafrost, and as it thaws, long-dormant bacteria and viruses that were imprisoned there will be released, perhaps spreading disease. Anthrax outbreak in Siberia in 2016 was a result of permafrost thawing which led to the death of 200,000 reindeer.
Sea ice is melting due to global warming in the Arctic Ocean and the meltwater is entering the North Atlantic Ocean through Greenland sea, possibly disrupting the ocean current patterns globally and affecting the climate around the globe.
Current warming is not uniform across the planet. For example, the Arctic is warming at a faster rate than the global average and 'Polar amplification' is one of the reasons. Due to the alarming rate of warming of the Arctic Ocean, the sea ice and the Greenland ice sheet is melting at a faster pace (in the Arctic region), contributing to sea level rise across the globe. The sea level rise along the Indian coast is faster than the global average rate due to reduction of sea ice in the Arctic region.
Sea ice melting increases the amount of water which is absorbing more solar radiation as water absorbs more sunlight than ice thereby reducing the albedo effect of the planet and further contributing to global warming which will further melt more sea ice in the Arctic Ocean and this will create a feedback cycle.
The problems of siltation, land loss, and saltwater intrusion will increasingly affect deltas and estuaries on the coastal zones. Sea level rise will slow down the regrowth of wetlands, threatening their rich biodiversity. Sea level rise will have an impact on mangroves as well since it will alter the productivity and salinity distribution of those places.
Coastal and low-lying areas in Asian countries like India, Bangladesh, Myanmar and Cambodia will be hitted hard by the increasing frequency and intensity of severe cyclonic storms and rising sea level due to climate change.
In Asia, climate change is expected to have a significant impact on the agriculture sector. It will put more strain on water availability and increase the demand for more irrigation by reducing water supply and soil moisture during the dry season. Affected rice-growing regions would result in yield reductions, which would have a big impact on agricultural commerce, growth of economy, and several Asian countries' development objectives.
Temperature rise reduces the yields of many cereal crops directly and shortens the growing season, thereby threatening food security by impacting food availability and disrupting supply across the globe.
Antarctica is the most vulnerable region to climate change on the Earth.
Climate risks (and hazards) impact human population and the ecosystems depending on exposure, vulnerability and adaptation capability. For example, people and the ecosystems such as estuaries, lagoons, salt marshes, mangroves, seagrass beds and coral reefs along the coastal areas are more vulnerable to sea level rise due to climate change.
A record drought has occurred in the Amazon rainforests due to the effects of climate change which drained rivers, killed endangered dolphins and affected the lives of millions of people in the region.
Global warming made the drought 30 times more likely, drove extreme temperatures and contributed to lower rainfall, according to an analysis concluded by the scientists of World Weather Attribution.
The drought has reduced water levels in the Amazon river in parts of the region to their lowest points on record. The drought could worsen forest fires which when coupled with deforestation could push the Amazon rainforest to a point after which the biome dries out and ceases to be a lush rainforest. Around 178 endangered pink and gray Amazon river dolphins have died last year due to low water levels in the river and its tributaries and high temperatures, said by researchers.
Countries most vulnerable to climate change
All of us are impacted by climate change, but not equally. We also don't have the same capacity to respond to the changing climate.
The countries most susceptible to the effects of climate change are the Least Developed Countries (LDCs) and the Small Island Developing States (SIDS). Millions of people living in LDCs will be more vulnerable to poverty, hunger, and disease as a result of changing weather patterns, especially severe floods and droughts. Many SIDS are facing the risk of their survival due to rising sea level and other impacts of climate change.
Climate change is already having an impact on agricultural production, fragile ecosystems, water supply, health indices, and economic growth in these countries.
Low-lying island nations like Tuvalu, Kiribati, and the Maldives would be totally submerged as a result of sea level rise if the global temperature rose by 4 degrees Celsius, according to a report concluded by the IPCC in 2007.
Climate change will cause flooding of low-lying coastal areas, an increase in water scarcity, a drop in agricultural yields and fishery resources, and a loss of biological resources for the LDCs in Asia and Africa continents. Other social and political upheavals, such as forced migration and conflict, would result from water shortages and the reduction of land suited for agriculture.
LDCs and SIDS use comparatively less fossil fuels than industrialised (rich) and other developing states, which means they make little contributions to the climate change crisis. Despite this fact, the SIDS and LDCs will be the most affected. For LDCs and SIDS, therefore, climate change adaptation is critical.
Historically, developed nations are accountable for a major share of GHG emissions, therefore they should take more responsibility and implement climate action.
According to the United Nations, the richest 1% of the global population emits more than two times the emissions of the bottom 50%. Clearly, net zero or carbon neutrality by 2050, and the cap on emissions it implies, applies only to countries with high per capita emissions, GDP and well-being.
Since developing countries are more vulnerable to climate change-induced extreme weather events and they have rising energy needs. Food security and agriculture-dependent economies like India were the most vulnerable to the impacts of global warming as per IPCC reports. Hence they need financial support to low-carbon transformations and to build resilience to climate change. The Russia-Ukraine conflict has further sparked an energy crisis threatening climate goals.
Climate change threatens people, particularly in developing countries and islands, with extreme weather events such as floods, droughts, heat stress, and food and water scarcity in alignment with vector-borne diseases, malnutrition and economic loss. It also causes human migration and conflicts.
Cyclones and Climate Change
Rapid intensification of tropical cyclones has been driven by climate change. The high sea surface temperature and high ocean heat content are potentially crucial factors to rapidly intensify tropical cyclones.
Warm sea surface temperature is required in order to form and strengthen tropical cyclones. And the high ocean heat content helps these cyclones to achieve higher intensity. Both these factors also contribute in making storms bigger, long-lasting and causing flooding rains.
Tropical cyclones use warm and moist air as their source of energy or fuels and climate change is warming the oceans or increasing sea surface temperatures, potentially fuelling the tropical cyclones.
Warm ocean water is the primary source of energy for these tropical cyclones and oceans are warming mainly because of two factors: first, the global ocean has absorbed over 90% of earth’s excess heat as a result of increased concentrations of greenhouse gases in recent decades, which raised the heat content in the ocean. Second, increase in sea surface temperatures.
Tropical cyclonic storms are strongest near or over water as they receive fuels constantly from warm ocean waters but when they encounter or move over land, they abruptly lose their fuel source and rapidly dissipate. That’s why the coastal regions are particularly vulnerable to tropical storms as compared to inland regions.
The North Indian Ocean is experiencing stronger and slow-moving cyclones over the past two decades. An abnormal warming of oceans due to climate change is the primary reason for this because in addition to making cyclones more powerful and slow-moving, the warm oceans also cause cyclones to stay for longer duration as extreme weather events which can disturb rainfall patterns or cause longer dry periods.
The number of severe cyclonic storms in the North Indian Ocean comprising both the Arabian sea and Bay of Bengal, has increased to 16 between 2004-2023 from 10 occurred between 1984-2003. And extremely severe cyclonic storms have also increased in these last two decades. The reason is primarily attributed to rapid warming of the Indo-Pacific Warming Pool (IPWP) due to global warming. IPWP is located in the western Pacific Ocean and eastern Indian Ocean in the tropical ocean region. IPWP is increasing sea surface temperature (SST) over the North Indian Ocean basin, affecting weather over Asia and the Indian subcontinent.
Heat Waves and Climate Change
A heatwave is defined as a period of unusually hot weather with above normal temperature that typically lasts three or more days. Climate change and global warming have increased the probability of heat waves in the past three decades, current research shows. Increased concentrations of GHG gases increases the air temperature which can lead to more intense heat waves.
The heatwave has become a recurrent and long-lasting phenomenon in India and the Indian subcontinent. Recent study shows More states in India have become vulnerable to climate change due to heat waves than previously estimated with Climate Vulnerability Index (CVI). The heat waves in India are mostly prevalent over two areas: Central and Northwest India, and coastal areas of Andhra Pradesh and Odisha.
Example: The 2003 European heat wave killed over 70,000 people. The years 2015-19 have globally been the warmest years on record. The Amazon fire of 2019, the bush fires of 2019-20 in Australia were unprecedented in their scale and devastation.
Oceans warming as a result of temperature rise is leading to an increase in frequency and intensity of marine heat waves which in turn are degrading or even destroying marine habitats and forcing marine species to change their habitat ranges.
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