Climate change impacts, including increases in extreme heat waves, droughts, and erratic rainfall, are only getting worse every day.
The latest report of IPCC Working Group I, Climate Change 2021: The Physical Science Basis, has clearly mentioned that climate change is already affecting every region on Earth in multiple ways.
Climate impacts are already more widespread and severe than expected.
The observed mean surface temperature increase has clearly emerged out of the range of internal variability compared to 1850-1900.
Impact of global warming on heatwaves
Heat extremes have increased while cold extremes have decreased, and these trends will continue over the coming decades.
It is indisputable that human activities are causing climate change, making extreme climate events, including heatwaves, heavy rainfall, and droughts, more frequent and severe.
It is now univocal that Earth’s climate is changing; global temperatures have already risen by about 1.1 °C from pre-industrial times, and it warns that the 1.5 °C threshold is likely to be reached by 2040.
This report projects with medium confidence that heatwaves and humid heat stress will be more intense and frequent during the 21st century.
The total number of days per year with a maximum temperature exceeding 35ºC will increase with the increase of global warming.
The latest IPCC Working Group II report mentioned that risks would escalate quickly with higher temperatures, often causing irreversible impacts of climate change.
We have already seen that millions of people in many parts of the South Asian region are experiencing a brutal heatwave that is threatening lives and livelihoods, and there is no relief in sight.
Possible causes of the heatwave in India and flash floods in Bangladesh
The Indian Meteorological Department (IMD) reported that the month of March this year was the hottest in 122 years since they started maintaining records.
Bangladesh Meteorological Department (BMD) mentioned that very little rainfall has been observed in March this year compared to the long-term average.
This year, western disturbances were weaker, which would cause little pre-monsoon rainfall in north-western and central India.
On the other hand, anticyclones with an area of high atmospheric pressure led to hot, dry weather over parts of western India in March, according to the media reports.
Interestingly, anticyclones formed over the Bay of Bengal push moisture-laden air towards the northeast direction of Bangladesh and cause heavy precipitation over the Meghalaya and Tripura hills.
Due to this intense heavy rainfall, we have observed flash floods in northeast Bangladesh which are located in the foothills of Meghalaya.
The standing Boro paddy crops were damaged in Sunamganj, Sylhet, and Netrokona districts of Bangladesh due to unusual early flash floods in the first week of April.
Some scientists mentioned that the pressure pattern associated with La Niña conditions, which are currently presiding over the Pacific, has persisted longer than expected.
This, along with warm waves coming from the Arctic, has caused heat waves to form.
Such prolonged La Niña conditions and their impact on dryness and heatwave during Spring and Summer seasons in Bangladesh and India are unexpected.
Cities and climate change
Urban areas are home to more than 50% of the world’s population and are the site of most of its built assets and economic activity.
By 2050, the population in urban areas is expected to increase by 2.5 to 3 billion and comprise two-thirds of the world population.
For the next three decades, nearly 70 million residents will move to urban areas every year.
The majority of these new residents will live in small- to medium-sized cities in the developing world.
Urban centres and cities are warmer than the surrounding rural areas due to what is known as the urban heat island effect.
The difference in observed warming trends between cities and their surroundings can partly be attributed to urbanization.
Despite having a negligible impact on global annual mean surface-air warming, urbanization has exacerbated the effects of global warming in cities.
Urbanization has exacerbated changes in temperature extremes in cities, in particular for nighttime extremes.