Hurricane coverage and awareness in the national media always seems to increase when a storm approaches the more populace east coast. But right now – post Hurricane Katrina – it seems to be in overdrive.
While Hurricane Irene is certainly disconcerting on an immediate humanitarian and public safety level, it does provide more of the country with an opportunity to learn about these phenomenon, and ask essential questions about the possible connection between these storms and climate change.
Recently the Union of Concerned Scientists released a short primer on the issue with an astonishing graphic about the change in storm intensities measured over the past 2-decades.
While the report does not assign causation of these event to climate change, it does outline processes that connect these issues and result in greater strengthening of these storms as well as other weather conditions.
Excerpt:
Two factors that contribute to more intense tropical cyclones -ocean heat content and water vapor-have both increased over the past several decades–ocean heat content and water vapor–have both increased over the past several decades. This is primarily due to human activities such as the burning of fossil fuels and the clearing of forests, which have significantly elevated carbon dioxide (CO2) levels in the atmosphere. CO2 and other heat-trapping gases act like an insulating blanket that warms the land and ocean and increases evaporation.The world’s oceans have absorbed about 20 times as much heat as the atmosphere over the past half-century, leading to higher temperatures not only in surface waters (e.g., depths of less than 100 feet) but also down to substantial depths, with the most severe warming occurring in the first 1,500 feet below the surface. As this warming occurs, the oceans expand and raise sea level. This expansion, combined with the inflow of water from melting land ice, has raised global sea level more than one inch over the last decade. In addition, observations of atmospheric humidity over the oceans show that water vapor content has increased four percent since 1970; because warm air holds more water vapor than cold air, these findings correlate with an increase in air temperature.
Source: Hurricanes and Climate Change (Union of Concerned Scientists)
As of this writing, Hurricane Irene seems to be hovering between a Category 1 & 2 storm and is still about 2 days away from predicted landfall. However, the media and public preparation it is getting is far better then this writer personally observed while living in Washington DC in 2003, when Hurricane Isabel came ashore along the mid-Atlantic coast. Although that storm came ashore at a level 2, it had been rated as a full Category 5 storm (winds in excess of 165mph) just a few days prior.