Climate is a perennial statistical weather pattern characteristic of a locality depending on its geographical position. It is studied by means of long-term measurements of the meteorological elements and the determination of their average state. Such measurements have been made for more than 250 years - on land, in the high atmosphere and in the deep ocean. The data collected are used to determine the average state of the multi-year weather regime.

Therefore, climate is a collection of meteorological elements that characterize the average state of the atmosphere of a place. The main climate-forming factors are solar radiation, atmospheric circulation and the underlying land surface. Other important climate features are climatic factors и the climatic elements.

The Earth's climate has been changing at different rates since its beginning, but always with relatively slow fluctuations that are nothing compared to the present. Accounting for the rate of change is important because it allows us to understand the different contributions of natural and anthropogenic activities to climate change.

The data shows that the 15 warmest years on Earth have been in the last 20 years. The global average temperature from 2011 to 2020 is 1.1 degrees above pre-industrial times. As a result of climate change, the weather in Bulgaria, for example, is becoming more extreme. There are more and longer periods of drought, followed by severe storms and severe flooding. The climate south of the Balkan Mountains is becoming increasingly Mediterranean, while in the north the fertile lands are slowly becoming deserted. Snowfall in the mountains is decreasing. Snow starts to fall after Christmas, and so the amount of water available during the year changes.

Earth's average temperature is regulated by the balance between incoming and outgoing energy, which determines the planet's energy balance. Therefore, any factor that changes the amount of incoming or outgoing energy over a long period of time (decades or longer) can cause climate change. Some of these factors are natural or "internal" to the climate system - volcanic activity, solar energy, or the Earth's orbit around the Sun. Changes in ocean currents or atmospheric circulation can also affect climate for short periods of time.

The others reasons are "external" to the climate system and they push the climate to a new long-lasting state. This state may be warmer or colder, depending on the cause of the change. Different forcings act on different timescales, and not all forcings of the earth's climate in the distant past are relevant to current climate change.

These factors mainly affect the amount of incoming energy. Large volcanic eruptions with emissions of huge amounts of dust and sulphates cool the atmosphere, but have episodic contributions and relatively short-term impacts on climate (a few months to a few years). Changes in solar radiation have contributed to climate trends in recent centuries, but since the industrial revolution increased levels of greenhouse gases in the atmosphere are almost ten times more powerful drivers of climate change than changes in solar radiation.

Scientists believe that natural variations alone cannot explain the temperature changes over the past 50 years. Earth's average temperature could rise by 1.5 degrees as early as 2030. This means that polar ice will continue to melt and sea levels will rise. It is likely that episodes of heavy rainfall will become more intense and more frequent as the climate warms further.

Active action is needed by governments, business, NGOs and citizens to mitigating climate change. Otherwise, we could end up with an irreparable increase in the Earth's temperature, which will irreparably and drastically worsen the way we live.