Global warming is now significantly perturbing weather patterns and climatic trends to change globally, but it is yet unclear how hurricanes are being impacted by this changing environment. Strong tropical cyclones (TCs), which form in the warm ocean waters of our planet, are known as hurricanes. In the West Pacific, they are referred to as typhoons, and in the Indian Ocean, as cyclones.
Warm tropical seas are the primary source of energy for hurricanes, and it is well known that since the middle of the 20th century, ocean temperatures in regions where tropical storms occur have been rising. Numerous factors related to climate change can affect cyclones e.g. sea level rise, warmer sea surface temperature, atmospheric changes, the warming of mid-latitudes etc.
Higher sea surface temperatures increase the pace of tropical storms, increasing their potential to do more damage should they make landfall. Over the past forty years, there has been a rise in major hurricane activity in the United States accompanied by a decline in lesser storm activity. The average sea level has increased by more than half a foot worldwide since 1900, and this century, it is predicted to rise by one to 2.5 feet. These effects will be most severe in coastal areas. Sea level rise has exacerbated the effects of some recent storms and raised the possibility of coastal flooding. Coastal storms are already becoming more destructive due to sea level rise, and this trend is predicted to increase. There may be an increase in tropical cyclone activity at higher latitudes as a result of the mid-latitude warming. Although to make a precise relationship the research in these aspects along with the atmospheric changes is underway.
Climate change and the case of North Atlantic Ocean cyclones
Numerous investigations have been conducted to investigate the relationship between hurricane severity and frequency in the North Atlantic basin and climate change. The findings of these analyses point to a key contributing element in the rising frequency of hurricanes: greater sea surface temperatures brought on by climate change. According to research, there are more big storms overall in the North Atlantic, and this is correlated with warmer sea surface temperatures and more humid weather overall. So, it is obvious that the chief reason behind the rise in the sea surface temperature is the rise in the global average temperature.
The increase in the total number of tropical cyclones and major hurricanes in the North Atlantic may be explained by both climatic variability like El Nino Southern Oscillation (ENSO), North Atlantic Oscillation, Atlantic Meridional Mode and Atlantic Multidecadal Oscillation (AMO) and climate change (higher ocean heat, sea surface temperature, and cloud cover moisture), with climate change factors being more statistically significant. It is currently unclear how much of the rise in activity and intensity of tropical cyclones in the North Atlantic can be related to climate change, despite recent research indicating that the total number of these storms has increased.
According to a scientific study, the United States' hyperactive hurricane seasons, like the one in 2020, are typically linked to stronger wind shear environments, positive phases of the Atlantic Multidecadal Oscillation and the Atlantic Meridional Mode, lower sea level pressure patterns, higher sea surface temperatures, and higher cloud cover development. Ocean temperatures were greater and wind shear settings were less during seasons with a larger number of significant hurricanes. Scientists studying strong cyclones such as Hurricane Maria (2017) have discovered that the storm's precipitation was more intense than usual due to climate change. Nevertheless, opinions on whether climate change is causing or will cause more storms to occur remain divided. But one thing that all experts agree on is that trends in the strength of tropical cyclones are significantly influenced by climate change. Additionally, scientists are beginning to agree on the part of how climate change affects the intense precipitation linked to storms. But a recent study in 2021 suggests that, in Tropical Cyclone-prone areas, especially in the Northwestern Pacific and Northern Atlantic basins where the increasing trends are more pronounced, the increasing rainfall rate induced by warmer and moister environments has the potential to generate more severe impacts associated with Tropical Cyclone rainfall events.
Does climate change affect the Nor’easter storm? Â
A large-scale extratropical cyclone in the western North Atlantic Ocean is known as a nor'easter or northeastern storm. The name comes from the direction in which the northeastern winds blow. At present, the Northeastern United States including New York, Pennsylvania, and Massachusetts is bracing for possibly the heaviest and most intense snowstorm in the last two years. Higher rates of two to three inches per hour are predicted by meteorologists for the Hudson Valley, northern New Jersey, eastern Pennsylvania, northern Connecticut, and northern Rhode Island. Although nor’easter storms are a common climatic phenomenon, their intensity is affected by climate change.
Strong low-level winds and low surface pressures of extratropical cyclones (ETCs), which regularly form during the North American cool-season months, are the primary causes of storm surges along the northeastern coast of the United States. Winter storms, such as nor'easters, can produce storm tides, or high water levels, along the northeast coast of the United States during the cool season, which runs from November to March. This can potentially cause coastal flooding.
A study in 2021 based on highly resolved computer models suggests there is a link between winter storm tides in northeastern states and climate change scenarios. The study discovered that under the associated climate change scenario, changes to storm tides are often less significant than predicted sea level rise. On the other hand, counties along the Delaware, Hudson, and northern Chesapeake Bay rivers show signs of rising storm tides, while counties around the mid-Atlantic Bight coastal region show signs of declining storm tides. The unpredictable nature of storms and the higher daily tide level in the northern regions (New England, Long Island Sound, New York Bight, and Delaware Bay) make alterations to storm tides more unpredictable. More studies like these are needed to establish a sound relationship between climate change and winter storms like nor’easter.