The Give and Take of Climate, Weather & Kīlauea Volcano
The following is this week’s edition of “Volcano Watch” from the USGS Hawaiian Volcano Observatory:
Variable weather and extreme weather events are familiar here in Hawaiʻi nei. While we were lucky in the gentle passing of tropical storm Flossie a few weeks ago, questions are being posed worldwide on how changes in global climate are affecting weather patterns and extreme weather events.
In Hawaiʻi, there are additional questions unique to this special place. For instance, how do changes in local weather patterns influence the impacts of Kīlauea Volcano’s long-running eruptions on surrounding human and natural environments? And alternatively, has Kīlauea’s eruptive activity influenced local and regional weather or global climate?
A rise in the amount of volcanic pollution (vog) from Kīlauea began in 2008, with the onset of the summit eruption in Halemaʻumaʻu Crater. The increased emission of volcanic gases and particles has affected agriculture, as well as the natural and human environments.
The severity of the impacts from Kīlauea’s volcanic plume is determined by the amount of toxic gases and particles emitted, and importantly, by local wind conditions. While, for some, the memory of frequent vog events during spring 2013 has largely been erased by more recent pictures of a fine summer, the frequent absence of trade winds during March through May caused environmental challenges for East Hawaiʻi residents and agricultural producers whose crops and livestock were impacted by volcanic plumes. Residents as far away as Oʻahu reported distress as the disruption of trades sent volcanic emissions north along the island chain. Kīlauea’s emissions were relatively constant during this period; the wind was the main culprit this time.
During this period, the EPA’s primary one-hour health standard for SO2 gas at the Jaggar Museum measurement site near Halemaʻumaʻu was exceeded for 37 hour-long time-spans, as compared to 9–19 hours for the same period during 2010, 2011, and 2012. This National Park site can be considered a good indicator of the higher frequency of poor air-quality events for East Hawaiʻi communities, in general. In considering potential changes in local weather patterns due to larger-scale climate change, it is practical to take into account how shifts in trade winds affect our island community.
There is evidence that the trade wind regime has already changed in the last 30 years. Researchers from the University of Hawaiʻi have recently shown a decrease in the frequency of the northeasterly trades, with a shift to more easterly winds. While Hawaiʻi residents are familiar with the effects of absent trade winds, the full impact of this more subtle change will be revealed with time. In addition to considering the effects of climate and weather on the distribution of Kīlauea’s emissions, it is also important to consider their potential impact on local and regional weather and climate, as well as on the Earth’s energy balance.
Aerosols (fine solid particles or liquid droplets suspended in a gas), like those associated with Kīlauea’s emissions, can directly modify the ability of the Earth to reflect radiation by absorbing and scattering incoming solar radiation. They can also indirectly affect the amount of incoming radiation reflected back into space (known as the planetary albedo) by increasing the amount of clouds and their ability to reflect radiation. These indirect processes, while not well quantified, have an important effect on the Earth’s energy balance.
Kīlauea’s eruptions are currently serving as a natural experiment for exploring the impact of aerosols on Earth’s climate. Recent space-based studies examining the atmospheric effects of Kīlauea’s plume have shown that trade-wind cumulus cloud patterns are very sensitive to the presence of aerosols; thus, continuous eruptions (such as Kīlauea’s) may have a greater effect on climate than previously thought. The studies have confirmed that Kīlauea’s plume is associated with an increased number and reduced size of cloud droplets, reduced precipitation, and increased cloud brightness, size, and coverage. Aerosol-cloud interaction results in an increase in the amount of solar radiation reflected back into space.
These new findings have potentially far-reaching implications: they can help shape our understanding of how continuously degassing volcanoes, like Kīlauea, contribute to regional and global climate and lead to improved climate models. In terms of impacts from volcanic emissions, our backyard volcano continues to play an important role, both on the local and the global stage. For more information concerning Kīlauea’s continuing eruption, visit http://hvo.wr.usgs.gov