The current world is facing various types of natural disasters due to climate change. Problems such as abnormal temperature increases and droughts are having adverse effects on our lives. The negative impact of climate change is gradually leading our green planet towards desertification. The most affected geographical areas due to desertification are Africa (Sahel region), Asia (Gobi Desert and Mongolia), and parts of South America. According to the United Nations, environmental disasters are causing desertification of approximately two square kilometers of land every year in various countries around the world. In Bangladesh, these problems are becoming severe. The impact on our country's economy, agriculture, food security, energy, biodiversity, health, potable water, and coastal areas is significant. Summer heatwaves are creating unbearable conditions for our daily lives. The increase in temperature and desertification is reducing water availability, significantly affecting agriculture and decreasing crop production, which can lead to food shortages. Prolonged periods without rain or inadequate rainfall reduce soil moisture. Consequently, the soil loses its natural characteristics or softness, becoming arid and leading to drought. Desertification is the process, by which fertile land gradually turns into desert due to climate change, drought, and various human activities. Drylands are generally very fragile from an environmental standpoint and are the ones most affected by desertification. As a result of desertification, the land loses its productive capacity and becomes barren. This desertification process significantly increases the atmospheric temperature, creating heatwaves, the consequences of which we are experiencing continuously. Therefore, with the slogan "Generation Restoration," Bangladesh, like other countries around the world, is observing World Environment Day 2024.

According to the United Nations IPCC report, the average surface temperature has increased by approximately 1.45 degrees Celsius in the last decade. If this trend of global warming continues, scientists fear that by 2050, the temperature of the Earth could increase by an additional 0.50 to 1.70 degrees Celsius. According to the Bangladesh Meteorological Department (BMD) report, the average temperature in the country has increased by about 1.5 degrees Celsius over the past 50 years. Due to changes in average temperature, the pattern and timing of rainfall have changed. Natural seasonal cycles are no longer occurring on time, and the number of seasons has decreased. Additionally, the arrival of winter and monsoon is delayed, or there is heavy rainfall or cold at unusual times. According to United Nations data, if global temperatures continue to rise, melting ice will increase sea levels, and by 2050, approximately 17% of Bangladesh's coastal areas could be submerged. The main causes of temperature increase are unplanned urbanization and industrialization, lack of coordination among various agencies in the city, poor environmental management, and indiscriminate deforestation. Deforestation increases the amount of carbon dioxide and greenhouse gases in the atmosphere, which is one of the main causes of temperature rise. These gases absorb solar radiation and re-emit it into the atmosphere, causing temperatures to rise. Unplanned industrial pollution is a major source of greenhouse gases. Heatwaves negatively impact biodiversity. Heatwaves adversely affect human health, increasing the incidence of heat strokes, dehydration, and skin diseases. A recent report by the US-based Adrienne Arsht-Rockefeller Foundation Resilience Center titled "Hot Cities, Chilled Economies: Impacts of Extreme Heat on Global Cities" states that high temperatures in Dhaka cause an annual loss of 600 million USD, which could exceed 8.4 billion USD by 2050.

Worldwide, drought is continually reducing crop production and threatening food security. Africa's Sahel region, Australia, and California in the United States are severely affected by drought. In Bangladesh, drought occurs annually in about 13 to 14 districts. The risk of drought is increasing due to lack of rainfall, insufficient afforestation, and encroachment on agricultural land and water bodies. According to the Bangladesh Agricultural Research Council report, drought has reduced crop production by approximately 20-30% in the northwest region of the country. According to the Department of Environment (DoE) report, soil salinity is increasing in these areas, posing a significant challenge to agricultural production. Indiscriminate deforestation is causing local climate changes, and the topsoil is being washed away by rainwater. Drought reduces rainfall, changes temperature and wind speed, accelerating desertification. Drought is lowering the water table, threatening the supply of drinking water.

According to the United Nations Desertification Report, around 2 billion people worldwide are at risk of desertification. As a result of desertification, 40% of arable land in North America has turned into desert. In the southern part of the Sahara, 650,000 square kilometers of land have been lost to desertification over the past 50 years. Approximately 70% of the world's wetlands are already affected by desertification, and 44 hectares of arable land and 20 hectares of forest are becoming decertified every minute, equivalent to 7 million hectares annually. In Bangladesh, signs of desertification are evident in the climate of the southern coastal areas and the northwest regions known as the Baranda Tract, including Naogaon, Rajshahi, and Chapainawabganj. According to a survey conducted by the Ministry of Water Resources in 2020, around 140 rivers in the country are either dead or dying. The main cause of land turning into desert is deforestation. Drought and desertification are hindering crop production, threatening food security. Experts believe that the water table is falling by an average of two to three feet per year depending on the location, and if this rate continues, the northern region of the country could completely turn into a desert within the next 20 to 25 years.

There is now more research than ever on heatwaves, droughts, and desertification. Several scientists and organizations are working on solutions to these problems. NASA's research shows that if the current drought situation continues, the intensity of drought worldwide will increase by about 50% by the end of the 21st century. A study conducted by the Center for Atmospheric Pollution Studies (CAPS) on 36 locations in Dhaka city found that the highest average temperature of 42 degrees Celsius in April 2024 was recorded in Uttara Sector-13, while the lowest average temperature was recorded in Nayapaltan at 37 degrees Celsius. This means there was a 5-degree Celsius difference in average temperature between Uttara Sector-13 and Nayapaltan areas due to the presence of fewer trees and wetlands. CAPS research also observed that areas with green presence have comparatively lower temperatures, and the commercial regions have higher temperatures due to the lack of vegetation and wetlands. The study also found that the average temperature in 2024 increased by approximately 4 degrees Celsius compared to the average temperature in 2017. Desertification is causing a temperature rise, and again this temperature rise is accelerating desertification and soil degradation.

The first step to controlling the increasing temperature, drought, and desertification is extensive tree planting and increasing afforestation activities. Trees help control temperature and maintain soil moisture. Along with ornamental plants on road dividers, various beneficial trees, such as fruit trees, medicinal plants, and timber trees, should be planted based on land type. Roof gardening should be increased. Tree cutting should be reduced to zero. A forest area directly reduces heat and carbon emissions. Special measures should be taken to conserve water. Rainwater harvesting and modern irrigation methods should be used. Encroached wetlands should be recovered, and the number of new reservoirs should be increased. No structures should be built by filling wetlands. Nature based solution should be prioritized instate of promoting dam, cordon and sluice gate. Necessary measures should be taken through policy change and law enforcement if needed. Drought-resistant crops should be cultivated using sustainable technologies and methods. Modern irrigation methods should be applied to conserve water. White paint (SRI) can be used on roads to control temperature. Adequate passenger shelters and emergency heat relief centers should be arranged. Population control is necessary, and the excess population should be reduced from urban areas by decentralizing the administrative activities. Burning plastic and other waste indiscriminately should be avoided, and plastic waste should be managed properly. The use of fossil fuels should be, and the use of renewable energy should be increased. Urban planning should be done considering the local geographical characteristics, natural environment, and public policies. Awareness should be created about the harmful effects of heatwaves and drought, and preventive measures should be encouraged. Weather forecasts and climate change information should be collected using modern technology. This will allow us to be prepared in advance. With our collective efforts, we can fight against the disasters of heatwaves, drought, and desertification. We must move forward on the path of sustainable development while maintaining harmony with nature.

Professor Dr. Ahmad Kamruzzaman Majumder, Dean, Faculty of Science, Professor, Dept. of Environmental Science, Stamford University Bangladesh, Joint Secretary, Bangladesh Poribesh Andolon (BAPA) and Chairman, Center for Atmospheric Pollution Studies (CAPS).

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