Flooding from sea level rise will double due to groundwater rise: UH scientists

As the sea level continues to rise, low-lying parts of Hawai`i will face attack on two fronts.

We can plan for driving through vast pools of brackish water throughout much of low-lying Honolulu, including much of Waikīkī.

(Image: Flooding in Māpunapuna. Credit: University of Hawaii.)

 The rising seas will push shoreward, but at the same time, groundwater will back up and further raise the water level, says a new study: “Assessment of groundwater inundation as a consequence of sea-level rise.”

The report, published in the journal Nature Climate Change, was written by Kolja Rotzoll of the Water Resources Research Center at University of Hawaii, and by Charles “Chip” Fletcher, of the University of Hawai`i School of Ocean and Earth Science and Technology.

“Besides marine inundation, it is largely unrecognized that low-lying coastal areas may also be vulnerable to groundwater inundation, which is localized coastal-plain flooding due to a rise of the groundwater table with sea level,” they write.

Their work suggests that sea level rise alone can’t be isolated as the source of flooding.

“The flooded area including groundwater inundation is more than twice the area of marine inundation alone,” they write.

Looking just at Honolulu, their work concludes that, particularly at high tide, there will be massive regions of flooding—ponds and lakes of standing brackish water that could represent 10 percent of all the low-lying land within a kilometer of the coast as sea level rise reaches one meter.

In many parts of the Islands, groundwater is already very near the surface in the lowest lying areas like Waikīkī and other parts of Honolulu. In some areas, including parts of Māpunapuna, the streets already flood during the highest tides. 

“With groundwater tables near the ground surface, excluding groundwater inundation may underestimate the true threat to coastal communities,” said Rotzoll.

 “Finding that the inundated areas double when including groundwater inundation in coastal flooding scenarios will certainly be a surprise for everyone assessing the effects of (sea level rise) without considering the local groundwater table,” Rotzoll said.

The authors recommend continuous groundwater level monitoring in the coastal zone, along with “rigorous planning” for the impacts of brackish water inundation.  And they recommend residents of coastal communities everywhere study their own potential situations.

“We hope other coastal communities use our research as the basis for conducting their own localized analysis,” Rotzoll said.

Fletcher, an associate dean at the University of Hawai`i and a coastal geologist who has been studying sea level rise and erosion issues statewide, said the planning won’t be easy.

“This research has implications for communities that are assessing options for adapting to (sea level rise). Adapting to marine inundation may require a very different set of options and alternatives than adapting to groundwater inundation,” Fletcher said.

The paper: Rotzoll, K. and Fletcher, C.H. Assessment of groundwater inundation as a consequence of sea-level rise. Nature Climate Change, DOI: 10.1038/NCLIMATE1725

The abstract can be viewed here.

Fletcher’s website on Hawaiian sea level rise impacts includes a virtual fly-through of those impacts. 

© Jan TenBruggencate 2012

Climate change: worse is more likely

Climate is changing faster than we’ve been told, and it’s going to get worse than the consensus estimates.

That’s a conclusion of a new report from the National Center for Atmospheric Research (NCAR).

Much of the science industry has been understating its science, perhaps because the most dire scenarios seem so outrageous, perhaps because they’re reeling from the denier attacks.

The Intergovernmental Panel on Climate Change’s 2007 report says its projections “do not include uncertainties in climate-carbon cycle feedbacks nor the full effects of changes in ice sheet flow, therefore the upper values of the ranges are not to be considered upper bounds for sea level rise.” 

Translation: We left out the really scary stuff.

For Hawai`i, where climate change predicts significantly reduced rainfall and coastal flooding from higher sea levels, it’s also important stuff.

Even so, IPCC in 2007 projected contracting snow cover, disappearance of Arctic summer sea ice, increase of extreme hot weather, increased hurricane intensity, less rainfall in subtropical land areas and more. Sound familiar? Let’s see. Glaciers are melting, you can now run ships over the north sides of both the Americas and Asia, Hurricanes Katrina and Sandy, the expanding Sahara and Gobi deserts.       

NCAR, in an article in this week’s issue of Science, is suggesting that the more severe estimates of global warming are more likely to be the accurate estimates.

“Our findings indicate that warming is likely to be on the high side of current projections,” say NCAR scientists John Fasullo and Kevin Trenberth.

The two researchers come to their conclusion based on global humidity patterns. Many earlier studies have tried to link climate change to cloud patterns, but clouds are notoriously ephemeral and difficult to model. On the other hand, humidity is well researched and provides a useful tool for analysis of climate patterns, they said.

They looked at relative humidity figures for cloud-free subtropical areas, which they said are “easier to observe than the cloud properties themselves.”

Why the subtropics? “The dry subtropics are a critical element in our future climate. If we can better represent these regions in models, we can improve our predictions and provide society with a better sense of the impacts to expect in a warming world,” said Fasullo.

“Because we have more reliable observations for humidity than for clouds, we can use the humidity patterns that change seasonally to evaluate climate models,” says Trenberth. “When examining the impact of future increases in heat-trapping gases, we find that the simulations with the best fidelity come from models that produce more warming.”

NCAR’s press release on the study says it “could provide a breakthrough in the longstanding quest to narrow the range of global warming expected in coming decades and beyond.”

© Jan TenBruggencate 2012

Election's over, let's get back to saving the planet

Now that the Presidential election is over, maybe we can get back to saving the planet.

Allen Hershkowitz, senior scientist with the Natural Resources Defense Council, is vacationing on Kaua`i, and took, the time to give a couple of talks.

His message: The planet needs saving, and the job is so huge that you might despair. His further message: You can’t do everything, but be sure to do something.

“We’re facing urgent ecological pressures,” he said. The climate is changing. Species are going extinct at a rate of one every 20 minutes. Forests are being destroyed at a rate of an acre per second (38 million acres last year). Most of the plastic in the world is not recycled, and a lot of it ends up in the ocean, where it outweighs a lot of biological organisms.

Hershkowitz is considered the father of the “greening” movement, which he describes as reviewing a business or industry’s operations with an eye to reducing impact.

Individuals and communities can “green” themselves, too. 

His message to his Kaua`i audiences: If you do one thing, recycle. The impact of using raw materials in manufacturing is immense, and recycling is an answer. It saves energy, it saves money, it creates jobs, it saves forests (does it make any sense at all to use virgin fiber for toilet paper?) and mountains (mountaintop-removal coal mining).

We’re cutting down tropical forests and destroying entire ecosystems for paper, when we could make the same paper out of agricultural waste like corn stalks.

That used plastic bottle is entirely lost if it goes into a landfill. It creates a tiny bit of energy if it’s burned in Honolulu’s HPOWER waste-to-energy plant. But if recycled, it saves far more energy than is used to make a bottle out of virgin materials—and it also saves raw.

Hershkowitz doesn’t much care whether your community separates your recyclables at home (more efficient waste stream with lower processing cost, but lower participation, higher collection cost) or uses a single stream system that separates the recyclables after collection (threat of recyclable contamination, higher participation, lower collection cost but higher processing cost).

He just wants you to do something. And indeed, the communities of Hawai`i have been stumbling along the path to doing something for some time. As an example, Kaua`i County has been talking about a Materials Recovery Facility for two decades.

“There’s no MRF on Kaua`i. That makes no sense to me,” Hershkowitz said. “There are companies that will come and build them and pay to do so.”

Here’s a YouTube piece on how a MRF works.  http://www.youtube.com/watch?v=7CFE5tD1CCI

© Jan TenBruggencate 2012

Climate's going to grind the coffee industry worldwide

The world’s coffee market will be severely and negatively disrupted by climate change in coming years, although the impact on Hawaiian growers might actually be moderated somewhat.

A new study, The Impact of Climate Change on IndigenousArabica Coffee (Coffea arabica): Predicting Future Trends and IdentifyingPriorities, suggests that much of the globe’s coffee-producing terrain may become unsuitable for growing the crop. 

“The evidence from coffee farmers, from numerous coffee growing regions around the world, is that they are already suffering from the influences increased warming,” the report says.

The homeland of coffee is in Africa, and that’s where the study assessed the impacts of climate change, modeling the impact at 2020, 2050 and 2080. It notes that coffee is a crop that does best in a fairly limited geographic range, and can’t take a lot of climate change: 

“Arabica coffee is confirmed as a climate sensitive species, supporting data and inference that existing plantations will be negatively impacted by climate change."

What that means in a time of climate change, is that coffee locked by its roots into a specific piece of land won’t do well as the climate zone around that land moves to another elevation or rainfall regime.

“Based on known occurrences and ecological tolerances of Arabica, bioclimatic unsuitability would place populations in peril, leading to severe stress and a high risk of extinction,” write authors Aaron P. Davis, Susana Baena and Justin Moat of the Kew Royal Botanic Gardens, and Tadesse Woldemariam  of the Environment and Coffee Forest Forum in Ethiopia.

This bad news isn’t entirely new. The scientific literature has been sniffing along this path for some time.

A 2006 study in the Brazilian Journal of Plant Physiology study appears to confirm the sensitivity of coffee to climate. Its abstract sets the tone: “Overall, drought and unfavourable temperatures ... are expected to become increasingly important in several coffee growing regions due to the recognized changes in global climate, and also because coffee cultivation has spread towards marginal lands, where water shortage and unfavourable temperatures constitute major constraints to coffee yield.”

Why doesn’t coffee do well in dry conditions? Probably because it evolved in conditions with reliable moisture, the Brazil study says: “The native home of coffee species is characterized by low-water-deficit conditions, which probably allowed evolution without the need to develop extensive mechanisms to cope with drought stress.”

Still another report, this one from 2007, also predicts hard times for coffee. it is entitled, Global Warming—the impact on global coffee. 

The authors argue that coffee farmers who want to respond to climate change need to start planting at higher elevations, where weather is cooler, and to do it soon.

“Since coffee is a perennial that may be in the ground for 20+ years, decisions on planting or replanting should now take climate change into account,” write authors Peter Baker and Jeremy Haggar.

The Hawai`i Data Book says that in 2010 the state had 8,000 acres in coffee production on 830 farms, with a farm value of $33.4 million.  http://hawaii.gov/dbedt/info/economic/databook/db2011/section19.pdf

Near half that acreage is in a single farm on Kaua`i, which mainly grows catuai varieties of arabica coffee. And some of the world’s most prized arabica coffee, generally of the typica variety, is grown on hundreds of small holdings in the Kona area of the Big Island. An arabica variety called mocha or mokka is grown extensively on Maui.

Will Hawaiian coffee respond negatively to climate change? Perhaps, although the moderating temperature impact of the surrounding ocean may help keep the coffee fields from warming too much. On the other hand, predictions of reduced rainfall as the climate warms pose a significant problem for coffee growers.

© Jan TenBruggencate 2012