Polovina to Discuss Climate Change at Annual Dinner of Environment Hawai‘i

posted in: October 2019 | 0

On November 8, Jeff Polovina will be the featured speaker at our annual benefit dinner. Polovina is the author of the Oceans and Marine Ecosystem section of the Hawai‘i chapter of the 4th National Climate Assessment. Until his retirement two years ago, he was senior scientist and chief of the Ecosystem and Oceanography Division of the Pacific Islands Fisheries Science Center, a research arm of the National Oceanic and Atmospheric Administration. His ecosystem modeling of the food chain, ECO-PATH, has become a standard analytical tool for anyone wanting to understand the interrelatedness of marine organisms.

Polovina is also well known for his work studying regime shifts and climate impacts on marine ecosystems. His current research uses climate and ecosystem models and data to identify potential fishing and climate impacts on ecosystems, particularly those in the central North Pacific.

Although most of his work focuses on the central North Pacific and Pacific islands, Polovina has received two Fulbright Senior Research awards for work in Kenya and the Galapagos Islands. He holds faculty appointments in the Oceanography and Marine Biology departments at the University of Hawai‘i and also serves as senior fellow at the Joint Institute of Marine and Atmospheric Research in Hawai‘i. He is a recipient of the 2010 Wooster Award from the North Pacific Marine Sciences Organization.

Fun fact: Polovina is also the author of two children’s books, The Case of the Fish with the Curious Bite and The Case of the Outlaw Dolphins.

In anticipation of Polovina’s talk, Environment Hawai‘i editor Patricia Tummons posed several questions to him:

In recent weeks, the news from Greenland and the polar regions has been grim, with both land and sea ice showing signs of melting at rates faster than anything anticipated by the Intergovernmental Panel on Climate Change in its most recent report. Are changes in the global environment outpacing not only our ability to deal with them – through changes in policy and funding of new infrastructure – but also our ability to grasp their full implications?

Yes. The IPCC, in its attempt to be as rigorous as possible with the best available models, conveyed climate change as a gradual change. However, what we are seeing is that many of the models and IPCC projections underestimated the rate of change we are now observing. But now, with all the wildfires, heat waves, stronger and wetter storms, etc., people are becoming more aware of how serious a crisis climate change is. The challenge remains. As you’ve stated, these changes are outpacing our ability to address them with policy and infrastructure and our forecasts of future impacts still are not able to capture the full complexity of the climate system and future damaging impacts.

Another recent event, Hurricane Dorian, practically leveled the Bahamian islands where it sat for several days. Those flat islands differ from the populated islands of Hawai‘i but the prospect of more numerous and more severe hurricanes, fueled by warming ocean waters, is still one that Hawai‘i needs to take seriously. Should the state now be preparing for hurricanes that match Dorian in intensity?

That would be prudent and hopefully that is being done.

Following up on that, is it possible that ever-stronger storms and hurricanes could render the atolls of the Northwestern Hawaiian Islands unable to support the wildlife assemblages found nowhere else? Hurricane Walaka caused East island in French Frigate Shoals to disappear in 2018. Should we expect to see more of this type of storm in the future?

In the past the NWHI was exposed to hurricanes and strong North Pacific winter storms/waves and in the past coral reefs have recovered from the damage. Now they face additional stressors – bleaching, acidification, and sea level rise – all making recovery more difficult.

2015 and 2016 were the warmest years on record in Hawai‘i. But this summer, weather stations across the islands were reporting record-high temperatures or record-matching temperatures. Over the 30-day period in Kahului from August 17 to September 16, records were set or tied on 29 days. Reported temperatures at all four airport weather stations showed daily highs and lows higher by several degrees from historical average highs and lows. Across the state, from August 24 through September 17 (today), a high temperature record was set or tied somewhere in Hawai‘i every single day. In August, the maximum temperature at the Honolulu airport exceeded 90 degrees on 27 days – which is 20.3 days more than the normal value of 6.7 days. In the same period, Kahului saw 24 90-plus degree days, 19.7 more than the normal value of 4.3. At Lihue, the 10 90-plus degree days was 100 times the normal value of 0.1. As a layperson, I’m alarmed by these records. At what point do we say this isn’t just the weather, but it’s a dramatically, and quickly, changing climate?

Yes. I’ve been tracking these developments closely as they resemble those of 2015. I’ll talk about the large-scale ocean and atmosphere changes that appear to be contributing to this 2019 heat wave. There’s a perception that temperature will slowly and gradually increase over time but the climate system is complicated and tipping points occur that can give rise to large shifts. For example, coral reef bleaching is a classic example of a tipping point where temperature increases gradually and not much happens then suddenly, with just a little more warming, widespread bleaching occurs. The recent heat wave may be the result of such a tipping point in the jet stream impacting mid-latitude ocean temperatures with links to Hawai‘i trades and sea surface temperatures. I’ll explore this in my talk.

Coral bleaching has been given quite a bit of attention with the movement of warm ocean water coming down from the north to Hawai‘i. A website set up by Greg Asner’s lab allows citizens to report locations of bleached coral around the islands and note the severity of bleaching, and bleached corals have been reported on all inhabited Hawaiian islands, from Hilo to Ni‘ihau, and on up the Hawaiian chain all the way to Kure. It’s known that repeated episodes of bleaching make it difficult for corals to recover. But when you add the increasing acidity of ocean waters to the mix, won’t that exacerbate the problem?

Yes, the recent repeated bleaching is really stressing many corals and it is unclear if some can adapt quickly enough to adjust. Some species or some locations may prove resilient. However, the evidence is not comforting as the 2015-2016 bleaching off West Hawai‘i resulted in substantial mortality to corals. Adding to the thermal stress is the long-term decline in pH that increases coral mortality and reduces growth adding to the thermal stress.

A study published earlier this year by Phoebe Woodworth-Jefcoats and others concluded that “a decline in Hawai‘i’s longline fishery yield may be inevitable” as a result of both fishing pressure and climate change, but the effect of climate change on fish populations can be lessened if fishing pressure is reduced. The Hawai‘i longline fleet has grown in recent years, as have efforts by vessel owners and the Western Pacific Fishery Management Council to increase the allowable catch of bigeye in the Western Pacific. Do you see any encouraging signs that both the industry and its regulators may curb their short-term interests in the hope of protecting the resource over the long term?

So far I haven’t seen any evidence that the two Regional Fisheries Management Organizations, Inter-American Tropical Tuna Commission and the Western and Central Pacific Fisheries Commission, have developed climate-informed reference points in their management. Part of the challenge is that there is so much we don’t know about how the entire food web and highly mobile fishes at the top will respond to climate change. For example, virtually all the studies project declines at the base of the food web but changes in the food web structure, and/or the species mix in the middle of the food web could greatly impact the energy flow to apex species.

Polovina will speak at Environment Hawai‘i’s dinner, November 8, 5:30 p.m., at the ‘Imiloa Astronomy Center in Hilo. Reservations are $75 per person and may be made by calling our office at 808 934-0115. (The cost includes a $35 donation to Environment Hawai‘i.) Please make your reservations by November 5.

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