New Delhi, Jan 14 : In the last few years, the world, including India, has witnessed extreme weather conditions. Be it severe heat, torrential rain or severe cold - there has been a significant change in the weather patterns. North India is witnessing severe cold conditions these days. People are troubled by fog at night and cold winds during the day. At the same time, a weather expert has warned of severe cold waves in the coming days. Meteorologist Navdeep Dahiya has said that from January 14 to 19, North India will be in the grip of a severe cold wave. Especially between January 16 and 18, the cold will be at its peak and the mercury can fall from minus 4 degree Celsius to two degrees. The changes in weather patterns were visible in 2022 as well. From the first month of the year till December, the weather pattern was completely different from previous years. Meteorologists believe that the biggest reason for this is climate change. Climate is the average weather of a place over a long period of time or a few years, and when these conditions change, it is called climate change. Current climate change is affecting both global warming and weather patterns. There has been instability in the monsoon as well, due to which the duration of the summer season is increasing and the duration of the rainy season is decreasing. "If we look at the change in weather on a large scale, 'La Nina' is the reason behind it. Because of this, the surface temperature of the Pacific Ocean becomes quite cold," Dahiya told IANS. He said that La Nina has started showing its effect since 2019. Because of this, it is getting colder here (North India). The same pattern is working in 2023 as well. He said that earlier the weather used to be stable. There was cold, heat and rain for a fixed time and quantity. But for the last 50 years, the trend is changing due to climate change. Both El Nino and La Nina have also experienced significant warming in the last decade. The terms El Nino and La Nina refer to periodic changes in the sea surface temperature of the Pacific Ocean, which have an impact on weather around the world. The weather becomes warmer due to El Nino and cooler due to La Nina. Both usually last for 9-12 months but can last for several years in exceptional cases. The effect of both of these can be seen in India. In the El Nino effect, the sea surface temperature becomes much higher than normal. This temperature can be 4 to 5 degree Celsius higher than normal. El Nino is a part of the climate system. It has a profound effect on the weather. Due to its arrival, there is an effect on the weather all over the world. In the La Nina effect, the sea surface temperature drops significantly. It has a direct effect on the temperature around the world and the temperature becomes colder than average. La Nina typically leads to cooler weather in the northwest and warmer weather in the southeast. During this period in India, it is very cold and the rains are also moderate. Human use of oil, gas and coal has increased in the last few years for domestic purposes, factories and operations, which has an adverse effect on the climate. Environmental scientist Chander Vir Singh told IANS, "When we burn fossil fuels, most of the greenhouse gas released from them is carbon dioxide. Due to the increasing presence of these gases in the atmosphere, the temperature of the earth starts increasing." According to available data, compared to the 19th century, the temperature of the earth has increased by about 1.2 degree Celsius and the amount of carbon dioxide in the atmosphere has also increased by 40-50 per cent. According to meteorologists, due to climate change, unusual weather conditions are seen in almost every season. The effect of climate change caused by human activities is coming out in the form of severe heat in summer and severe cold in winter. The last few years have also seen a change in the monsoon systems. In many parts of Gujarat, Madhya Pradesh, Rajasthan and Maharashtra, excess rainfall was recorded in 2022. Quite the opposite, there was no rain in West Bengal, Jharkhand and Bihar. In August 2022, two monsoon cycles formed in the Bay of Bengal, one after the other, affecting entire central India. /IANS