Sea level rise is rapid and unstoppable unless Paris Agreement targets met

Nature

Aggressive efforts to limit global warming will sharply reduce future sea-level rise, suggests a paper published in Nature. 

Icebergs in Sermilik Fjord, SE Greenland Credit: Donald Slater

A second paper, also published in Nature, indicates that warming of 3 °C could cause sea level to increase by 0.5 cm every year by 2100 as a result of melting Antarctic land ice. The findings provide further insight into the impact of melting land ice on global sea-level rises.

This animation shows the rate at which the ice thickness is changing in meters per year (more red/yellow means faster thinning and thus faster ice loss) as the Antarctic Ice Sheet responds to changes in the atmosphere and ocean due to one potential climate scenario. This simulation, using the BISICLES ice sheet model, represents one of hundreds of such simulations used for this work to characterize ice sheet response to changes in the climate. Credit: Daniel Martin and Courtney Shafer.

Since 1993, land ice has contributed to around half of all global sea-level rise and this contribution is expected to increase as the world warms. The Antarctic Ice Sheet is the largest land ice reservoir and its ice loss is accelerating. Complex ice sheet models can be used to project the contribution of land ice to sea-level rise, but they require massive computational power and cannot explore all possible outcomes, owing to uncertainties in the projections.

Tamsin Edwards and colleagues use a statistical and computationally efficient approach to emulate the behaviour of more-complex models to project glacier and ice sheet contributions to sea-level rise under a range of scenarios. They find that if the ambitious Paris Agreement target of limiting warming to 1.5 °C was met, the contribution of land ice to sea-level rise could be halved by 2100—from the median projected sea-level rise of 25 cm under current climate projections, to 13 cm. The authors also suggest that melting from the Greenland Ice Sheet would fall by around 70% and that the contribution of melting glaciers to sea-level rise would also halve. The authors indicate that there is no clear difference for Antarctica under different emissions scenarios, owing to uncertainties in the competing processes of snowfall accumulation and ice loss. However, if the most extreme ice sheet behaviour is assumed, Antarctic ice loss could be five times higher, which would increase median sea-level rise to 42 cm under current pledges.

In a separate modelling study, Robert DeConto and colleagues find that limiting warming to the Paris Agreement’s alternative target of 2 °C maintains roughly constant Antarctic ice loss at current rates. However, in a scenario with warming of 3 °C—the warming trajectory consistent with current fossil fuel emissions—the authors predict that the rate of ice loss will increase substantially from 2060, triggering sea-level increases of 0.5 cm per year by 2100. Once a threshold of rapid sea-level rise is reached, modelling of optimistic, yet theoretical, approaches to remove carbon dioxide from the atmosphere shows a reduction, but not cessation, of further sea-level rise over the coming centuries.

The two papers highlight that aggressive efforts to limit global warming will sharply reduce future sea-level rise. For Antarctica, Tamsin Edwards and colleagues find that the complexity of competing processes on the ice sheet make it difficult to make concrete predictions about its future, and Robert DeConto and colleagues show that it is keenly sensitive to warming of 3 °C and greater. Thus, for the largest body of ice on the planet, important uncertainties remain.

Unsettling currents: Warm water flowing beneath Antarctica’s ’Doomsday Glacier'

Science Daily

The calving front of Thwaites Ice Shelf looking at the ice below the water's surface as seen from the NASA DC-8 on Oct. 16, 2012. 

Data from underneath Thwaites Glacier, also known as the Doomsday Glacier. Story here.

Unprecedented mass loss expected for the Greenland Ice Sheet

Nature

(With some minor editing by PinP.)

The edge of the Greenland Ice Sheet.  Credit: Jason Briner

Mass loss from the Greenland Ice Sheet is predicted to be higher in this century than any time in the past 12,000 years. The simulations, published in Nature, are based on high-carbon-emission scenarios and consider the southwestern region of Greenland. The findings add to a body of evidence that suggests that reducing carbon emissions is needed to decrease the contribution of the Greenland Ice Sheet to sea-level rise.

As the Arctic warms, the Greenland Ice Sheet has been losing mass and contributing to sea-level rise. That loss rate has increased dramatically since the 1990s. But are those rates and ones projected for the future unexpected? Or, are they just related to "natural variability?" To answer that question, Jason Briner and colleagues produced high-resolution simulations based on geological observations covering southwestern Greenland for the past 12,000 years that extend continuously into the future up to 2100.

The Greenland Ice Sheet.  Credit: Jason Briner

The simulations suggest that mass loss from the Greenland Ice Sheet in the twenty-first century will exceed the maximum mass-loss rates from the past 12,000 years. They find the largest losses in the past (between 10,000 and 7,000 years ago) were at rates of around 6,000 billion tonnes per century. That's similar to the estimated rates of the first two decades of this century. 

However, future losses are expected to exceed those maximum rates. Projected mass losses for the rest of this century are in the range of 8,800 to 35,900 billion tonnes. Those are based on the lowest and highest greenhouse gas emissions scenarios, respectively - that is, the amount of ice losses this century could reverse 4,000 years of cumulative ice growth and exceed previous mass-loss rates by about fourfold. The authors conclude that unprecedented rates of mass loss will occur unless a low-carbon-emission scenario is followed.

Climate Change: Life’s a beach - a disappearing one!

natureresearch

A Pexels photo.

Half of the world's beaches, many of which are in densely populated areas, could disappear by the end of the century under current trends of climate change and sea level rise, suggests a paper published in Nature Climate Change. 

Sandy beaches occupy more than one third of the global coastline and have high socio-economic value. Beaches also provide natural coastal protection from marine storms and cyclones. However, erosion, rising sea levels and changing weather patterns threaten the shoreline, its infrastructure and populations.

Michalis Vousdoukas and colleagues analysed a database of satellite images showing shoreline change from 1984 to 2015. The authors extrapolated historical trends to predict future shoreline dynamics under two different climate change scenarios. They determined the ambient shoreline change, driven by physical factors (geological or anthropogenic) and shoreline retreat due to sea level rise. They also examined how erosion from storms may change under climate change and impact shorelines.  

The results of these analyses indicate that around 50% of the world’s sandy beaches are at risk of severe erosion. The risk for erosion is particularly high in certain countries under both climate scenarios, including The Gambia and Guinea-Bissau, where over 60% of sandy coastline may be lost. When the total length of sandy beach projected to be lost is analysed, Australia would be the worst affected with nearly 12,000 km at risk. Canada, Chile, Mexico, China and the United States would also be greatly affected. Additional research could further improve these estimates, which may be impacted by human intervention.

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Rising sea levels pose threat to homes of 300m people – study

The Guardian

Photo by Christian Ferrer

Figure based on new analysis of coastlines is more than three times previous estimate. Story here.

Lancet Study Warns of Global Health Crisis and 1 Billion Climate Refugees by 2050

CommonDreams

"We are only just beginning to feel the impacts of climate change." Story here.

Waves crash against the International Airport of Nauro, 
a small Pacific island country. Photo - Matt Robertson 

Global fingerprints of sea-level rise revealed by satellites

NATURE|NEWS

Geological processes send more meltwater from glaciers and ice sheets to Earth's mid-latitudes. Story here.

Greenland. Photo by Uffe Wilken

Satellite snafu masked true sea-level rise for decades

nature.com

Revised tallies confirm that the rate of sea-level rise is accelerating as the Earth warms and ice sheets thaw. Story here.

RELATED: 

• Angry Oceans. How Sea Level Rise is Impacting the World, including Atlantic Canada. (Story & Audio Podcast)
• Angry Oceans...the Second in a Series Looking at the Impact of Climate Change and Sea-Level Rise on Atlantic Canadians. (Video)

Planet in Peril. Famine in Africa. Sea-Level Rise in Atlantic Canada. (Video)

Angry Oceans...the Second in a Series Looking at the Impact of Climate Change and Sea-Level Rise on Atlantic Canadians. (Video)

RELATED: Episode One: "Angry Oceans. How Sea Level Rise is Impacting the World, including Atlantic Canada. (Story & Audio Podcast)"

Angry Oceans. How Sea Level Rise is Impacting the World, including Atlantic Canada. (Story & Audio Podcast)

by Larry Powell

NEEPAWA, MB: Even tho I live in a little landlocked town on the Canadian prairies, I’ve long been fascinated with the role our oceans play in the evolution of manmade climate change. And, as a science writer, I also do lots of research, trying to keep on top of the issue. 

So, when I learned that “The Science Media Centre of Canada,” was sponsoring a “webinar” on climate change and sea level rise, I jumped at the chance to take part. (A webinar is a live, online event, a bit like a modern day teleconference.) So I tuned in and listened eagerly as four leading experts, three Canadians and an American, laid out in ways that were at once matter-of-fact and alarming, how the phenomenon of rising ocean levels is impacting our planet. 

Please read on, listen to the podcast below, or both!

Predictions surrounding rising sea levels around the world and the threat they pose to millions of coastal dwellers are sounding more and more ominous. This was evident as panel members told their stories. The moderator was Brigitte Nyan (sp? - r.).  

“Sea levels are on the rise. But they will not rise at equal levels around the world. As the climate changes and the planet warms, rising sea levels are now becoming one of the greatest threats to the world’s populations. The latest research published just 2 weeks ago shows rises in sea levels will double the frequency of severe coastal flooding in most of the world, with dire consequences for major cities that sit on coastlines, including those in Canada. The social and political fallout of displaced populations can prove to be one of the greatest challenges for future generations.

“According to a recent study in “Nature,” more than 13 million Americans will lose their homes to sea level rise by the end of this century. And Canada could face a similar fate. 

“When you hear about the global impacts from one of our panelists, 13 million might sadly begin to sound like a few drops in the ocean when it comes to how many will be affected. The repercussions of rising sea levels will challenge the way countries make planning decisions about climate change.”

 

Dr. Adam Fenech (l.), director of the Climate Lab at the University of Prince Edward Island, warns that some of the higher sea level rises anywhere are expected for much of the eastern seaboard of North America. And that includes his home, PEI and Atlantic Canada. He adds, many experts now fear they could rise by between 2 and 2.6m there by century's end. That's way more than  

the IPCC itself had been predicting just four years ago.

In a visual presentation, Dr. Fenech told the webinar,“How important is it to PEI? Well this yellow arrow was pointing to Emmett McKenna’s property back in 1959 he purchased 3 acre from his Uncle for $55/acre & now it’s completely underwater. So almost during my lifetime, people on PEI have had waterfront property that’s now completely under water, both from a combination of sea level rise as well as coastal erosion. 

“We conducted a study a few years ago that looked at the coastline we looked at every single metre of PEI from the year 1968 to 2010 &, when you took that thin strip of land and added them all up, you could see that, overall there was 35 k2 of land that was eroded or lost. There was almost 15 k2 that were gained, & overall there was a net loss of 20 k2. That’s about 5,000 acres. That’s about half the size of Charlottetown. So the island’s not going anywhere fast. Under those rates of erosion, it’s going to take 10 thousand years for Prince Edward Island to completely disappear. But it is the most important part of PEI. Everybody loves to be close to the shoreline. There’s a lot of infrastructure that’s close to the shoreline. So when we look at all those metre changes that I talked about  between 1968 & 2010, and we looked at the average change that happened, we multiply that by 30, 60 & 90 yrs just to get a sense of what kind of infrastructure is going to be vulnerable. 

"Now we all think that the rates of erosion are going to increase because sea levels are increasing, the land itself is falling little bit. We’re getting more storms in terms of frequency in terms of magnitude, but just under current rates of erosion, things that we’ve seen over the last 40 yrs or so, there’s at least a thousand homes & cottages that are threatened or vulnerable. We have 17 lighthouses one of them is actually half in the water already. We even have wind turbines, ones that we’ve put in in the last 10 yrs or so, are vulnerable to coastal erosion. I think the big message here is, let’s not build so darn close to the shore.” 

Dr. Fenech adds, a waste water treatment plant, even the First Nations Community of Lennox Island, just off PEI, are in the path of the rising waters, too.

More about "The Science Media Centre of Canada."

While the Centre has been around for nine years, I’d only heard about it recently. It is a non-profit, charitable organization “that helps journalists report on science issues.” I was delighted with my discovery. For years, I’ve been frustrated at the dearth of material readily available from Canadian sources. 

I especially remember an excellent article in an American publication recently. It warned of the growing seriousness of Lyme disease. Manmade climate change was resulting in an ever-expanding range for the tick which spreads it. The story documented the worsening situation in the U.S. and at least two places overseas. A map it displayed showed the vector spreading in the “lower 48,” then ending, magically, at the Canadian border! Nothing north of it. Nothing! Just a blank. The fact is, a very similar situation exists here in Canada, too. That article drove home to me, the pressing need for more and better access to scientific research in Canada - the kind now being provided by the Centre.

Oceans and Emotions. 

It’s tempting to ascribe human traits to our oceans, as you’ll see as you read on. If I appear to be doing that, I assure you, it’s only my feeble attempt at underlining the gravity of the crisis faced by both terrestrial and marine life in our modern age; not because of any “inner mystic” in me.

One might say, for example, that our oceans have actually been heroes, “saving our bacon,” as it were, and paying a terrible price in the process. 

How so? 

They’ve probably been absorbing more than 90% of the heat created by our profligate appetite for carbon fuels, sparing us from a home that might more closely resemble Venus, than Earth! Warmer water is not only disrupting many marine life-forms who depend on colder water to survive, it is causing the oceans to expand, worsening the scourge of sea-level rise.

As if that weren’t enough, it’s believed oceans are absorbing almost a third of the carbon dioxide, the main greenhouse gas, which human activity is producing. This is making oceans more acidic, threatening many marine life forms upon which we humans, and other sea-life, depend for survival.

So, are the oceans now "getting even" with us - biting back against the human population for treating them so shoddily? Of course not! The truth (which is often stranger than fiction) is this. Human behaviour is at the root of the profoundly disturbing state our earthly home is now in. And only we hold the key to the solution.

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Coming Soon. Planet in Peril Will Soon Provide You With a Valuable Insight Into the Impact Rising Sea Levels are Already Having on Canada. (Video Preview)

Sea level rise will double coastal flood risk worldwide

theguardian

Waves crash against the wall at the end of Nauru International Airport's runway. 

Rising sea levels pose a serious risk coastal erosion for small Pacific island countries, Photo: Matt Robertson / DFAT

Small but unstoppable increases will double frequency of extreme water levels with dire consequences, say scientists. Story here.

Slice of Greenland ice melts into oblivion

climate

news network

Eastern Greenland. Photo by Algkalv 

Coastal glaciers in terminal decline as Greenland ice runs into the ocean and threatens to raise sea levels by the end of the century. Story here.

Last Remnant Of North American Ice Sheet On Track To Vanish

News Network
Archaeology

Global sea ice has reached a record low – should we be worried?

NewScientist

It’s an internet sensation. An alarming graph showing the global area of sea ice falling to unprecedented lows for this time of year has gone viral. Story here.

Ghost Forests: How Rising Seas Are Killing Southern U.S. Woodlands

environment360

A steady increase in sea levels is pushing saltwater into U.S. wetlands, killing trees from Florida to as far north as New Jersey. But with sea level projected to rise by as much as six feet this century, the destruction of coastal forests is expected to become a worsening problem worldwide. Story here.

Scientists Nearly Double Sea Level Rise Projections For 2100

The Washington Post

Sea levels could rise nearly twice as much as previously predicted by the end of this century if carbon dioxide emissions continue unabated, an outcome that could devastate coastal communities around the globe, according to new research published Wednesday. 

The main reason? Antarctica. Details here.

Seas Are Rising at Fastest Rate in Last 28 Centuries

The New York Times

The worsening of tidal flooding in American coastal communities is largely a consequence of greenhouse gases from human activity, and the problem will grow far worse in coming decades, scientists reported Monday. Details here.

NOAA: Record Antarctic Sea Ice Growth Linked To Its Staggering Loss Of Land Ice

CLIMATEPROGRESS

NOAA said in a news release Tuesday that “as counterintuitive as expanding winter Antarctic sea ice may appear on a warming planet, it may actually be a manifestation of recent warming.” Details here.