July 2021 was the world's hottest month ever recorded as temperature reached 1.67 degrees Fahrenheit above the century average. It marked a milestone for climate change. Climate change refers to significant changes in global temperature, precipitation, wind patterns and other measures of climate that occur over several decades or longer. It is a formidable challenge for global ecosystem of present time. After industrial revolution in the 1700s climate changes cannot be explained by natural causes alone.

Natural changes in the earth's orbit and its axis of rotation appears to be the primary cause of past cycles of ice ages. That time much of Europe and North America was under more than one km of ice for long periods. Volcanic eruptions release large quantities of carbon dioxide and Sulphur into the upper atmosphere, where they can reflect enough sunlight back to space to cool the surface of the planet for several years. Again, melting of sea ice, have contributed to climate change in the past. Scientist found that about 3 million years ago global temperature was 3-5 degrees Fahrenheit higher than recent pre-industrial era. Then sea levels stood at least 20 feet above their current heights.

Global warming as a result of Greenhouse Gas (GHG) emission is one of the major effects of human-induced climate change. Unfortunately, the sharp increase in greenhouse gas concentrations caused by industrial activity during the past couple of hundred years has thrown the system out of balance, causing the planet to heat up. Main greenhouse gases are water vapor, carbon dioxide (CO2), methane, nitrous oxide, and chlorofluorocarbons. They have the ability to trap solar radiation in the earth's atmosphere like a blanket and heat up the planet acting the same way a greenhouse keeps plants warm and growing. Few other reasons of global warming are methane emissions, forest fires, deforestation, decomposing organic matters, and increase in usage of chemical fertilizers. Atmospheric CO2 has increased to the highest levels seen in 800,000 years due to human behavior which mostly include burning fossil fuel.2 Due to present Russia- Ukraine war flights from Europe to Asia are flying south of Russia or taking a long reroute over the Arctic. Boeing from Tokyo to London need now more 2.4 hours of flight time and burns around 20% more fuel than normal. So, each flight emit additional 60 tons of CO2 into the atmosphere. Certainly it will add with normal 2% CO2 contribution by aviation sector. Global CO2 emissions reached 36.3 gigatonnes in 2021 and it was the highest level in history.3 Methane the second largest contributor after CO2 also increased in the atmosphere by the largest amount in 2021. The invisible, odorless gas leaks into the atmosphere mainly from oil and gas operations. Methane has roughly 80 times more warming power than CO2. If the trend continues, these poisonous gases are expected to grow by over 50% by 2050. This in turn would cause world temperatures to rise by up to 6 degrees Celsius by the end of the 21st century.

The effects of climate change are land degradation, rise in sea levels, increasing temperature and irregular weather patterns. Factors contribute to global sea level rise are thermal expansion of seawater due to global warming, widespread melting of land ice and loss of mass from the polar ice sheets.

Greenland is losing around 286 billion tons of ice volume per year, while Antarctica shreds about 127 billion tons of ice.5 Greenhouse gas emissions contribute to warmer oceans and the resulting melting of the West Antarctic Ice Sheet. Other parts of the Antarctic ice sheet are also less stable. Again, Greenland lost more ice in 2019 than in any year on record.

The greatest impacts will be felt by developing and poor countries. 200 million people in the world will live below the sea level line by 2100. Researchers estimate that 70 percent will live in China, Vietnam, Indonesia, Thailand, Philippines, Japan, Bangladesh and India. An additional 160 million will be affected by higher annual flooding due to rising ocean levels. In Europe, the Netherlands would theoretically be the most affected though the country has one of the most effective flood control networks in the world. Here, more than 4 million people are expected to live below sea level in 2100. Other countries in Europe where rising sea levels could be a problem are the UK, Germany, Turkey, France and Italy.

It is predicted an average of 170 million people across six regions will be subjected to internal migration by 2050. The region of Sub-Saharan Africa will be impacted the most.

Space technology has long been used to help forecast weather and climate crisis. The next-generation German Satellite Environmental Mapping and Analysis Program, or EnMAP is a game changer for its ability to use more than 250 colors to produce the most precise data on water, soil and vegetation in satellite history. The highly sophisticated satellite was designed to study the environmental impact of the climate crisis, observe how environments respond to human activities and to monitor the management of the world's natural resources.

Somalia, located in the Horn of Africa of East Africa is experiencing its worst drought in more than a decade. Climate change has also played a dramatic role in altering weather patterns in the region. Flash flooding, rising temperatures, sandstorms and cyclones are somewhat the norm across Somalia. The number of people who need assistance and protection is forecast to rise by 30 per cent in 2022 than previous year. Over 70 per cent of all Somalis live below the poverty line.

Industrial agriculture is a key driver in the generation of GHGs. Synthetic fertilizers, pesticides, heavy machinery, monocultures, land change, deforestation, refrigeration, waste and transportation contribute greatly to global climate change. Rising carbon dioxide levels will also diminish nutrient levels of rice. An increase of 4 degrees Celsius could cut U.S. corn production by nearly half. Fishes in North Atlantic might allow larger catches, but marine productivity will decline in nearly all tropical waters, caused by warming and acidification. By 2030, climate change costs are projected to cost the global economy by USD 700 billion annually, according to the Climate Vulnerability Monitor.

International community agreed to keep global temperature increase well below 2°C and if possible, below 1.5°C by signing in Paris Agreement in 2015. The EU plans to cut emissions by 40% by 2030. Emission pricing mechanisms, such as emission trading schemes and border taxes, are already being implemented or becoming significant pieces of regulatory discussion.

The oceans cover over 70% of the Earth's surface. Around 25% of all CO2 emissions are absorbed by the ocean, making it one of the world's largest 'carbon sinks'. The carbon thus captured are named as blue carbon. But as the ocean continues to absorb more CO2, it becomes more acidic. For this the microorganisms are at risk, which in turn affect the entire food web. Again, CO2 is used by plants for photosynthesis.

Surprisingly, few researchers believe this whole idea is ridiculous as climate is not static. The planet gets hotter, it gets colder, sometimes quickly, sometimes over eons, and there are a bunch of reasons. Human-produced carbon might be one of the factors, but there's simply no evidence that it is a significant one. Considering that man produces a great amount of CO2 on a yearly basis carbon sinks are still taking care of the problem. Factors including variations in solar activity, changes in earth's orbit and axis, changes in cloud cover which are influenced by fluctuations in gamma ray activity and volcanic and tectonic activity in the earth's crust contribute in climate change. For humans to presume that they are more than a gnat on an elephant's rump in terms of impact on climate change is vain and delusive. 21st century changes are neither exceptional nor persistent, and the historical and geological records show many periods warmer than today. Again, increased levels of carbon dioxide has beneficial effects in both animals and plants. There is also 'fertilization' effect from increasing the ambient carbon dioxide. The pace of sea level rise remained relatively constant throughout the 20th century, even as global temperatures gradually rose. There has similarly been no increase in the pace of sea level rise in recent decades. Also, the alarmist assertion that polar ice sheets are melting is simply false. Although decline in Arctic ice sheet has been completely offset by ice sheet expansion in the Antarctic. Cumulatively, polar ice sheets have not declined at all. Icebergs break off the Antarctic ice sheet every year, with or without global warming, particularly in the Antarctic summer. However, breaking off a particular large iceberg in Antarctic ice sheet does not necessarily result in "Shrinking Glaciers". To the contrary, the Antarctic Ice Sheet has been growing at a steady and substantial pace ever since NASA satellites first began measuring the Antarctic ice sheet in 1979. The temperature of the earth has been going up and down for millions of years. It has nothing to do with carbon dioxide in the atmosphere. Apparently many believe that global warming or climate change is a hoax.

Unabated climate change will adversely affect particularly the coastal regions in developing countries and ecosystem. Again, sea-level rise and ocean acidification cause major risks. So, every year to show concerns for planet April 22 is celebrated as Earth Day.

Mohammad Mahmudur Rahman Niaz is a civil Engineer and a serving Military Officer. E-mail: niaz7m@yahoo.com

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