WITH the passage of time, concern prevails over the degradation of the earth in the form of global warming before unlocking its full potential for human welfare. Global warming leading to climate change severely affects humanity and other biological and non-biological components of the ecosystems. The prime cause of global warming is exceptionally high anthropogenic emission of greenhouse gas into the atmosphere throughout the neolithic revolution (clearing of forests for expansion of agriculture), the industrial revolution and the green revolution.
In 2023, global greenhouse ga semission was 52962.9 million tCO2e. Global luxury, particularly the north, leading to stronger climate change, biodiversity loss 鈥� desertification, land degradation and drought 鈥� nexus that severely affects the most vulnerable people who often lack even the basic amenities. This further deepen disparity in society and hamper peace and prosperity. The historic Paris agreement was adopted by the COP21 in Paris on December 12, 2015, which came into force on November 4, 2016, aimed at addressing climate change and its negative impact by limiting global temperature increase to well below 2掳C above pre-industrial (1850鈥�1900) levels, with efforts to limit it to 1.5掳C.
Till today, 195 parties have joined the agreement. This is a legally binding international treaty that includes commitments from all countries to reduce their emissions and work together to adapt to the impact of climate change, and calls on countries to strengthen their commitments 鈥� nationally determined contribution or NDC 鈥� over time. The agreement provides a pathway for developed nations to assist developing nations in their climate mitigation and adaptation efforts while creating a framework for the transparent monitoring and reporting of climate goals of countries. It marks the beginning of a shift towards a net-zero emissions world.
It also calls on governments to speed up the transition away from fossil fuels to renewable energy such as wind and solar power in their next round of climate commitments. To better frame the efforts towards the long-term goal, the Paris agreement invites countries to formulate and submit voluntary long-term strategies. The implementation of the agreement is also essential for the achievement of the Sustainable Development Goals. Despite all efforts, in 2024, for the first time, average temperature (1.6掳C) exceeded the limit of 1.5掳C. Global temperature was record high in the last 10 consecutive years indicating insufficiency of efforts to curve global warming.
A few fatal common consequences of climate change are water, land, the loss of biodiversity, human health, poverty and displacement, the productivity of terrestrial ecosystem, the productivity of aquatic ecosystem, temperature rise, etc.
Water: Water and climate change are inextricably linked. Climate change affects the world鈥檚 water in complex ways. From unpredictable rainfall patterns to shrinking ice sheets, rising sea levels, floods and droughts, most of the impact of climate change comes down to water. Only 0.5 per cent of water on the earth is usable and available freshwater; and, climate change is dangerously affecting that supply. Over 20 years, terrestrial water storage, including soil moisture, snow and ice, has dropped at a rate of 1 centimetre a year, with major ramifications for water security. Climate change is exacerbating both water scarcity and water-related hazards such as flooding, droughts and salinity as rising temperatures disrupt precipitation patterns and the entire hydrologic cycle.
About two billion people worldwide do not have access to safe drinking water today and roughly, a half of the world鈥檚 population is experiencing severe water scarcity for at least part of the year. These numbers are expected to increase, exacerbated by climate change and population growth. Temperature rise will cause the drying up of water bodies such as rivers, canals and bils that will reduce fresh water availability and make weather warmer and ultimately a quicker loss of water bodies. Evapotranspiration loss water absorbs huge heat and keep the environment cool. It also acts as the buffering capacity of environment against warming.
Land: Land, the foundation of lie, acts as the primary source of food and 99.9 per cent of the food of more than eight billion people still comes from land. Land and climate interact in complex ways through changes in forcing and multiple biophysical and biogeochemical feedbacks across different spatial and temporal scales. Globally averaged land surface air temperature has risen faster than the global mean surface temperature ie land surface air temperature plus sea surface temperature, from the pre-industrial period (1850-1900 to 2006-2015) by 1.53掳C. Changes in land conditions from human use or climate change, in turn, affect regional and global climate. A changing climate, in turn, exacerbates land degradation through drought, desertification resulting to the loss of soil organic carbon and other extreme weather events that are increasing in frequency and intensity as the planet gets warmer.
Land plays a key role in the climate system as an essential carbon sink as forests regulate the planet鈥檚 temperature and help to store carbon. In the last decade alone, land-based ecosystems absorbed around 30 per cent of the carbon emissions generated by humans. But our land is under a huge pressure from deforestation, urbanisation, industrial development, agricultural expansion and unsustainable farming practices that are lowering its capacity to sustain food production, maintain freshwater and forest resources as well as regulate the climate and air quality. Today, up to 40 per cent of the world鈥檚 land surface has been degraded. Land degradation impacts food security, water availability and ecosystem health, directly affecting a half of humanity and causing a loss of about $40 trillion worth of ecosystem services each year. Land degradation is also considered 鈥榯he single largest cause of terrestrial biodiversity loss,鈥� because of the destruction of the habitats of many animals and plants.
Severe degradation, eg drought and desertification, causes famine, leading to social and economic instability. Up to 250 million people could be displaced by 2050 as a result of climate change-induced desertification. Increased soil temperature will lead to soil organic matter depletion because of rapid decomposition of organic matter and land degradation. Inorganic soil becomes warmer quickly that increases soil respiration and ultimately affect soil biodiversity. It also increases respiration of crops leading to productivity loss. Soil temperature rise will increase evapotranspiration loss and case the drying up of soil, leading to drought and desertification, soil salinity, the loss of soil texture and structure, increase the need for irrigation and add to crop production cost or cause crop failures.
Loss of biodiversity: Biodiversity is often regarded as the defence against natural calamities, ie pest and disease infestation and famine. Global ecosystems and the biodiversity they contain act as natural carbon sinks, thus providing nature-based solutions to climate change. But nature is in crisis. Climate change is playing an increasingly important role in the decline of biodiversity. 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. Up to one million species are threatened with extinction, many within decades.
Climate change has altered marine, terrestrial and freshwater ecosystems around the world. It has caused the loss of local species, increased diseases and driven mass mortality of plants and animals, resulting in the first climate-driven extinction. On land, higher temperatures have forced animals and plants to move to higher elevations or higher latitudes, many moving towards the earth鈥檚 poles, with far-reaching consequences for ecosystems. The risk of species extinction increases with every degree of warming. With a 2掳C rise, 8 per cent of mammals will lose a half of their habitat.
Human health: Health and the climate are inextricably linked and today, the health of billions is endangered by the climate crisis. Climate change is undermining not only the health of our planet but also the health of people everywhere through toxic air pollution, diminishing food security, higher risks of infectious disease outbreaks such as Covid-19 and others, extreme heat, drought, floods and more. Between 2030 and 2050, climate change is expected to cause about 250,000 additional death a year from malnutrition, malaria, diarrhea and heat stress. And, by 2030, the direct health costs caused by climate change are estimated to be between $2 billion and $4 billion a year. Climate change also exacerbates many social and environmental risk factors for mental health. Exposure to extreme weather events, displacement, famine, malnutrition, anxiety and distress associated with climate change are all contributing to mental health issues.
Poverty and displacement: Climate change increases the factors that put and keep people in poverty and causes rural-urban migration. Floods may sweep away urban slums, destroying houses and the livelihood. Heat can make it difficult to work in outdoor jobs. In 2010鈥�2019, weather-related events, on an average, displaced an estimated 23.1 million people annually, leaving many more vulnerable to poverty. Most refugees from transboundary migration are most vulnerable and least ready to adapt to the impacts of climate change.
Productivity of terrestrial ecosystem: The productivity of terrestrial ecosystem will decline because of high respiration rates of plants and animals. Temperature rise also causes increased mid-day depression, the fall of photosynthetic rate. So, food security will be hampered.
Productivity of aquatic ecosystem: The productivity of aquatic ecosystem will decline because of low dissolved oxygen and a lower rate of photosynthetic process. Temperature rise in rivers, canals and bils will affect their waste accumulation capacity by reducing decomposition of wastes load and increase the magnitude of pollution. High temperature will increase soil and water salinity.
Temperature rise: Temperature rise affects beneficial bacterial activity. For example, bacteria bring fertilisers applied to the crop field into available form for crop plants. It causes the leaching loss of fertilisers and increases surface water and ground water pollution.
Along with global warming, local warming also affects humans and other living and non-living elements of the ecosystems. Local warming primarily depends on the extent of global warming, geographic location and topography, rural-urban ratio, terrestrial-aquatic ecosystem ratio, land quality and land cover, the magnitude of industrialisation, population density, etc.
Climate change is ground reality and countries, especially least developed countries, are suffering the most although their share of greenhouse gas emissions is negligible. The total greenhouse gas emissions of Bangladesh is 213.19 million tCO2e and per capita GHG emissions was 1.29 tCO2e in 2019, which was five times lower than the global average of 6.48 tCO2e. Irrespective of the extent of greenhouse gas emissions of a country, global warming escalates local temperature rise and causes immense sufferings. Bangladesh is an innocent victim of climate change. To face it effectively, Bangladesh must increase its adaptive capacity through environmental education and awareness, escalate research and development in relevant sectors, revitalise water bodies to increase water holding capacity, address issues of land degradation, optimise urbanisation and industrialisation, waste treatment following 3R strategy, optimise population, increase nature conservation activities, study solar energy influx and redistribute energy and water vapour between the land and the atmosphere, etc.
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Dr Md Sohrab Ali ([email protected]) is additional director general at the environment department.
