Mention the global occurrence of volcanic eruptions in 2021 and their impact on the regional environment.

A volcanic eruption is when lava and gas are released from a volcano, sometimes explosively. On an average there are around 20 to 25 volcanic eruptions every year. However, in 2021, this number went almost double.

Some of the eruptions of 2021 are:

1. Fajradalsfjall in Iceland

2. Kilauea in the Hawaiian Islands.

3. Nyiragongo in Democratic Republic of Congo

4. Mt. Etna in Europe

5. La Palma in Canaries.

Impact on regional environment:

1. Eruptions can produce such features as pyroclastic flows and mudflows that can cause major loss of life within minutes.

2. Volcanic ash reflects incoming solar radiation leading to localized cooling effect in the temperature. E.g., Mt. Krakatau brough a mini-ice-age.

3. Plumes of volcanic ash can spread over the large areas of the sky, reducing visibility. 

4. It also leads to the deterioration of water quality, fewer periods of rain, crop damages, and the destruction of vegetation.

However, such volcanic eruptions also provide new opportunities for Geothermal Energy, and also the Lava and ash is a good source of Nutrients for the soil. A report by the Intergovernmental Panel on Climate Change predicts a major volcanic eruption can counteract anthropogenic global warming to a small extent. Tough, volcanoes cannot be avoided, steps can be taken to mitigate their effects.