Hurricanes and SST

Current studies investigating the possible link between more frequent or more intense hurricanes and global climate change have been quite contradictory. Not enough time has passed for researchers to accurately and definitively assess hurricane trends for anomalies and their possible connections to global warming. We can observe these trends, but it is extremely difficult at this point to separate anthropogenic effects from natural oscillations. Evidence on both ends of the debate can be convincing in different ways. A few things must be understood about hurricanes before their relevance to climate change can be discussed. To put it simply, hurricanes are caused by a combination of wind shear and ocean temperatures. Warm water fuels hurricanes, and they are more destructive the higher the temperatures rise (Realclimate.org). It is this characteristic that can put hurricanes in danger of being affected by climate change. Some studies have found that the sea surface temperature (SST) of our earth’s oceans has increased by .6⁰C (Realclimate.org). Even a rise as small as this can have major effects on weather events (Xie et al). The question then becomes, is climate change responsible for this rise in SST? Hopefully I will be able to investigate this further in the coming weeks. For now, I leave you with a study published in Science a decade ago, simulating the possible increase of hurricane intensity as CO₂ levels rise in our atmosphere. Researchers compared 51 Western Pacific storms under present climate conditions with 51 storms under high CO₂ conditions. They found that when SST was raised by 2.2⁰C, they simulated hurricanes whose wind speed increased by 5-12%. Surface pressure was also found to increase (Knutson et al).

Sources: 

RealClimate.org: "Hurricanes and Global Warming- Is there a connection?"

Xie et al, "Global Warming Pattern Formation: Sea Surface Temperature and Rainfall," Journal of Climate, September 2009. 

Knutson et al, "Simulated Increase of Hurricane Intensities in a CO2-Warmed Climate," Science, February 1998. 

Introduction

It seems that the past few years have seen quite a few more extreme weather events than most of us bargained for. Who can forget Hurricane Katrina, or the recent tsunami in Japan? And how about that Indian summer we just experienced here in the UK? It is possible that unusual temperature fluctuations and the occasional extreme weather event are natural occurrences stemming from normal changes in our Earth's oceans and atmospheres. Other evidence points to a more worrisome conclusion: that climate change is affecting and perhaps even causing some of these weather events. This brings forth many new questions: How do we define 'extreme' as it pertains to weather? Can global warming really be blamed, and to what extent? Have weather events actually become more extreme, or is the recent global discourse on climate change causing us to attach too much meaning to them? Is this the new normal?