Evaluate evidence and arguments that tropical storm characteristics have changed and may change in future as a response to global warming.
In recent decades, evidence suggests that the changing nature of tropical cyclones is related to global warming. Through amplified absorbed solar radiation, sea surface temperatures have increased, and this closely associates with hurricane potential intensity and destructive capacity. This is supported by the doubling of category 4 and 5 hurricane occurrences since 1970, linked to the 5% increase in maximum wind speeds with 0.5°C sea surface temperature increases. The IPCC suggest that amplified sea surface temperatures are certainly linked to anthropogenic greenhouse gas contribution, which is particularly prevalent in hurricane formation regions. Oceanic heat plays a significant role in tropical cyclone distribution as 26.7°C ocean temperature is required to fuel hurricane winds, resulting in global distribution falling between 15-20° north and south of the equator. As sea surface temperatures increase, this automatically widens the geographical latitude range for tropical cyclone formation, suggesting a future of increased tropical cyclones when considering global warming predictions.
However, the extent of future change is debatable, with various points countering the link between tropical cyclone changes and global warming. It is argued that hurricane variation could follow a natural cycle which is not influenced by global warming, with peak periods possibly linking to the El Nino and La Nina oscillations which effect global climate. Furthermore, research into weather patterns displays data limitations, especially in earlier years when technology was less developed. In the 1970s and 80s data collection presented uncertainty and limitation which could significantly affect trends and predictions for the future of tropical cyclones. Conversely, current improvements in global modelling and improved analysis will allow for more educated assessments in the future. Furthermore, changes surrounding tropical cyclones need to be analysed in relation to other affecting local, regional and global processes, such as; response, development level, coastal setting, rising sea level and more. Sea level rise will likely gain relevance, and the 0.17m gain in the 20th century is expected to increase more dramatically, becoming a greater risk when concerning tropical storms. At present, statistical methods project vast increases in tropical storm activity, up to 300%, arising from mechanisms such as oceanic warming and sea level rise, but this is a debatable figure with the current provided data.
