Tag Archives: sea level

‘Most ice on Earth is very close to melting conditions,’ glacier expert warns

Image credit – Sharada Prasad CS, licensed under CC BY 2.0.

Measuring ice melt and the unprecedented changes in our cryosphere – the frozen parts of the planet which regulate the climate by reflecting the sun’s heat – is crucial for understanding future situations, he says.

We spoke to Prof. Kääb about the importance of the cryosphere and what we know about how it’s changing. 

Why is the cryosphere important?

‘The cryosphere – that is glaciers and ice sheets, snow, sea ice, permafrost, and lake and river ice – and changes of the cryosphere affect the lives of hundreds (of) millions (of people) and many ecosystems in various direct and indirect ways. Seasonal or year-round snow covers around 45 million sq km, and glaciers and the Greenland and Antarctic ice sheets an additional 15 million sq km, together (constituting) around 40% of the Earth’s land area.

‘Importantly, most ice on Earth is very close to melting conditions, a few degrees below 0°C, and thus reacts very sensitively to changes in air temperatures. Small temperature changes can trigger melt and (large) environmental changes. Sea level change through increased melt of glaciers and ice sheets is certainly the most far-reaching effect of ice melt on Earth.’

How are sea levels changing?

‘Melting of glaciers, (and) the two ice sheets in Greenland and Antarctica contributes to more than half of the currently measured sea level rise and they are projected to contribute more. The other half is thermal expansion – as the ocean gets warmer it expands – and all this sea level change affects people around the world, especially in coastal areas, (and) even if living far away from the melting ice.

‘Mean sea level is projected to rise about 1 metre by 2100 and will threaten coastal societies. How much the ocean would rise in (the) case of an, unrealistic, complete melt of the Antarctic ice sheet is around 60m.’

What are the other impacts of ice melt?

‘In terms of more local effects, there are a number of hazards relating to glaciers and thawing permafrost that we expect to increase. For instance, if glaciers retreat they leave steep mountain flanks uncovered so there is debris and rocks that are set to destabilise. So, we expect more rockfalls or debris flows from such areas.

‘Greenhouse gas emissions from thawing permafrost are much less understood, but could have an equally wide, actually global, impact by enhancing manmade emissions.

‘Then there are also hazard situations that could actually improve. (Ice avalanches from glaciers)  can destroy infrastructure, houses and kill people. But (there’s) the extreme case (where) if a glacier retreats very much, then the hazard from related ice avalanches could actually reduce.’

Glaciers are typically found close to where people live and changes can directly affect people’s lives, says Prof. Kääb. Image credit – Andreas Kääb.

Do you think we have passed a tipping point when it comes to ice melt?

‘The term tipping point is a bit controversial, because in most cases we don’t really know. Another term that is better is what the IPCC (International Panel on Climate Change) uses – committed (climate) change. So, climate change that man has contributed to has committed changes to the future.

‘That means the excess energy that mankind has already caused (through greenhouse gas emissions capturing the sun’s heat) will commit a long-term change in glaciers, ice sheets and ocean temperatures. Change that, let’s say, over a hundred years is irreversible. Even if we change our emissions now, a lot of ice melting has been committed.’

‘Glaciers are typically found comparably close to where people live. That means their changes affect people quite directly.’

Professor Andreas Kääb, University of Oslo, Norway.

You focus on glaciers. Why do we need to understand glacier change?

‘Glaciers are typically found comparably close to where people live. That means their changes affect people quite directly. Understanding glacier change helps to adapt to related climate change impacts such as changes in dry-season run-off and water supply, changes in glacial landslides and avalanches, or changes in the touristic value of glaciers.

‘Glaciers reflect climate change in a very visible and clear way. Their shrinkage has become for good reason an icon of climate change. For scientists, glaciers are important to illustrate climate change and make it understandable for a large audience.’

You were the coordinator of ICEMASS, a project using satellite imagery to measure and analyse changes to glaciers. How did you analyse change?

‘We have increasingly more and more different satellite data, and what the satellites measure is very different. My main goal, my main achievement, of the ICEMASS project was actually bringing different data together and integrating them. For instance, we use optical satellite images repeatedly to measure glacier flow. This works perfectly fine unless you have cloud cover or polar night (24-hour darkness). Then we use radar images that penetrate through clouds for the same purpose. But this does not give us the volume of glaciers.

‘For that we use, among others, satellites that shoot laser beams, like your laser pointer, and they measure the return time of this signal. The signal is sent from a satellite, bounces (off) the glacier surface, and comes back to the satellite. The time difference is directly related to the distance from the satellite to the (glacier surface). So, if you know the satellite position very well, which we do, then you can measure the height. And if you do that, over time, repeatedly, you get also the changes in glacier thickness and volume.’

The ICEMASS project analysed glacier avalanches in Tibet, with satellite images showing before (left) and after (right) the events. Image credit – Contains modified Copernicus Sentinel data (2019)/processed by A. Kääb, Department of Geosciences, University of Oslo, 2019.

And what did you find?

‘For me, personally, the most important results are more regional scale results. We developed glacier volume changes over a number of areas where little was known before. One of the examples that made it into the Nature journal, for instance, was glacier volume changes over the Himalayas and Central Asia. There was a lot of different numbers around for these melting glaciers – some actually massively contradicted each other – from very little change to massive change. And we (really) narrowed this uncertainty down.’

What did your project reveal about the state of glaciers around the world?

‘We found glacier mass loss in almost all regions we looked at. Unexpected large losses we measured in the European Arctic, on Svalbard. The massive retreat of sea ice in this sector of the Arctic raises air temperatures at a rate of roughly double the global average. The result is glacier melt rates (that are) much higher than one would expect so far north. In addition, about half of the glacier mass loss comes not from direct glacier melt but from glaciers that massively increased their ice flow and thus their ice discharge into the ocean.

‘(We found) unexpected low changes in glacier mass, lower than the global average, in parts of Central Asia, in the Karakoram, Pamir, and western parts of Tibet. There is even a region where glaciers grow a little bit. By also measuring changes of lakes without direct river outflow, we could show that the region received in recent years more precipitation, which let the lakes and the glaciers grow, despite air temperatures increasing at the same time.’   

This year’s IPCC Special Report on the Ocean and Cryosphere says climate change will cause up to 80% loss of glaciers in some places by the year 2100. What can research do to help society prepare for this future melting?

‘Carbon dioxide levels are much higher than they have been for the last 1 million years or more. This means our climate is at a stage where we don’t have historical experience to build sound statistics on extreme events. So, we need to monitor more what is going on now and then we need to better model future scenarios.  

‘The EU has their own fleet of satellites, the Sentinels within the Copernicus programme. They are really a game changer because before them there were mostly occasional scientific satellites.

‘These EU satellite constellations, in my experience, help develop models and strategies for really long-term perspectives. (We need these) satellites to allow for the long-term, consistent, observations that we need to predict and adapt to climatic changes.’

This interview has been edited and condensed.

The research in this article was funded by the EU’s European Research Council. If you liked this article, please consider sharing it on social media.

This post ‘Most ice on Earth is very close to melting conditions’ was originally published on Horizon: the EU Research & Innovation magazine | European Commission.

Emiliana huxleyi

Humanity has contended with rising seas before — and it didn’t go well for us

Some 7,600 years ago, human civilization in Southeastern Europe suddenly came to a halt. New research sought answers as to why this happened, and the findings paint a stark reminder of the toll rising seas can inflict on our society.

Emiliana huxleyi

Coccolithophore Emiliana huxleyi.
Image credits Jörg Bollmann.

The Neolithic revolution was the first major transformation humanity had paused — the transition foraging to farming. Spreading out from the Middle East, this wave of change took peoples used to hunt and forage wherever they pleased and tied them down, hoe in hand, to sedentary — but oh so lucrative — farms and fields.

Can’t till the sea, though

Around 7,600 years ago, however, the revolution paused — no new agricultural settlements seemed to pop up in Southeastern Europe around the time, existing communities declined, and the progress of civilization as a whole came to a standstill. Up until now, we didn’t have any inkling as to why this happened, but new research from the Senckenberg Biodiversity and Climate Research Centre, the Goethe University in Frankfurt, and the University of Toronto sheds some light on this mysterious period.

According to their findings, this lull in progress was due to an abrupt rise in sea levels in the northern Aegean Sea. Evidence of this event was calcified in the fossils of tiny marine algae preserved in seafloor sediments.

The impact this event had on societal dynamics and overall development during the time highlights the potential economic and social threats posed by sea level rise in the future, the team says. Given that climate-change-associated changes in sea level are virtually unavoidable, the team hopes their findings will help us better prepare for the flooding ahead.

“Approximately 7,600 years ago, the sea level must have risen abruptly in the Mediterranean regions bordering Southeastern Europe. The northern Aegean, the Marmara Sea and the Black Sea recorded an increase of more than one meter. This led to the flooding of low-lying coastal areas that would have been ideal areas for settlement,” says lead author Professor Dr. Jens Herrle.

The findings are based on a sediment core retrieved from the sea floor of the northern Aegean Sea. Herrle and his team used this core to reconstruct salinity levels in this part of the Mediterranean from 11,000 and 5,000 years ago. However, the core was also rich in tiny, calcified fossils of Emiliania huxleyi, a coccolithophore (a species of photosynthesizing plankton that’s ubiquitous even today).

Analyzing them under a scanning electric microscope, the team observed significant size changes in these algae — which indicate a change in the salinity of surface water in the Aegean during their lifetime.

“These calcifying algae evidence two rapid decreases in the salt content, at approximately 8,400 and again 7,600 years ago, which can only be explained by the fact that a higher volume of low-saline surface water flowed from the Black Sea into the northern Aegean at these times,” Herrle explains.

Such a rapid rise in sea levels would need a source, and the team says, surprisingly, it can be traced back to North America:

“The source of this may have been Lake Agassiz in North America. This glacial meltwater lake was enclosed in ice and experienced a massive breach during this period, which emptied an enormous volume of water into the ocean.”

The evidence supports a link between the two timeouts in the Neolithic revolution and the flooding events. The event 8,400 years ago coincides with archaeological findings suggesting that settlements in low-lying areas were under significant hardship from encroaching seas and other associated climatic changes. The renewed rise just 800 years later likely amplified these communities’ woes, keeping them from making the transition to agriculture.

Past fluctuations in sea levels have already had a significant effect on human history during the early days of agriculture, the authors note, warning that it would be unwise to dismiss the challenges it will place in our path in the future.

“Due to climate change, we expect global sea levels to rise by up to one meter over the next 100 years,” Herrle adds. “Millions of people could thus be displaced from coastal regions, with severe social and economic consequences.”

The paper “Black Sea outflow response to Holocene meltwater events” has been published in the journal Scientific Reports.

The Greenland ice sheet is losing some 270 billion tons of ice each year, a new study finds

A new study focusing on the Greenland Ice Sheet found that the rate of ice loss has accelerated over the past few years, confirming previous measurements. To put it into perspective, the sheet is now losing some 110 million Olympic-size swimming pools of water every year.

Image credits NASA Goddard Space Flight Center / Flickr.

One direct consequence of all the greenhouse gases we’re emitting into the atmosphere is melting ice. Doesn’t sound so dramatic — ice on my front lawn melts every spring, there’s ice-covered lakes and ice-bergs that sometimes melt and a little water never hurt anybody, right? For those things, yes. It’s a small quantity of ice, and it’s already floating on bodies of water so it won’t affect the volume of the world’s oceans if it melts.

But our planet has one huge deposit of water that doesn’t take part in the liquid’s natural cycle — ice sheets. When these melt, the water finds its way into the ocean and raises the sea level of the world’s oceans. So knowing how melting happens every year is important not only to help us quantify our activity’s effect on climate, but also because it helps us estimate how much sea levels rise.

However, you can’t simply hammer a tap into the ice and measure how much water flows out. What we can do is measure the volume of ice. This requires high-precision measurements of the ice sheets’ sizes over a long period of time to yield reliable results. In a new study, an international team reports the findings of one such high-precision measurement of the Greenland Ice Sheet, and their results confirm previous estimates of its rate of melting.

Malcolm McMillan from the Centre for Polar Observation and Modeling and his colleagues mapped the ice-sheet with incredibly high resolution (5 km distances,) by using data from the CryoSat 2 satellite. It relies on a technique called radar altimetry to measure terrain height, and with it the team was able to track the behavior of Greenland’s ice sheets with more precision than ever before.

In theory, if an ice sheet gains in altitude, it means that it’s also gaining in volume, so there’s more ice. A drop in altitude would correspond to a thinning of the ice caused by melting. But the processes that create the sheets are a little more complex — the Greenland sheets are thousands of meters thick, but the top layers are made up of snow and firn which gradually compress into solid ice. Accounting for the constitution of the sheet thus becomes very important in determining how much water gets trapped or released into the ocean.

After accounting for changes in density, surface roughness, and water content the authors found how much ice Greenland is losing, and how this melt varies by location and time. For example, 2012 saw a huge amount of ice loss compared to other years. The western side of the ice sheet is also melting much faster than the eastern side. The team found that a small part of the ice sheet (less than 1% of the sheet) is responsible for more than 10% of the mass loss.

Rate of mass change between January 2011 and December 2014 from CryoSat-2 radar altimetry. The color wheel indicates ice mass lost each year, with the radius scaled according to the magnitude of the total losses. The boundaries between the four sectors are shown in gray. Image provided by authors.

Rate of mass change between January 2011 and December 2014 from CryoSat-2 radar altimetry. The color wheel indicates ice mass lost each year, with the radius scaled according to the magnitude of the total losses. The boundaries between the four sectors are shown in gray.
Image credits Malcolm MacMillan et. al, 2016.

They estimate that between 2011 and 2014, some 270 gigatons of ice have melted away from Greenland — that’s enough water to fill 110 million Olympic swimming pools each year. This matches other independent measurements almost perfectly, helping to confirm the numbers.

“Using high resolution satellite data from ESA’s CryoSat-2 mission, we have produced a detailed and comprehensive picture of how Greenland has changed in recent years. In particular, we have been able to map the changing ice sheet in fine detail, and pinpoint where, and when, the greatest ice losses have occurred,” McMillan said in an interview for The Guardian.

The measurements allow scientists to calculate how much ice has been lost every year and determine the relationship between mean temperatures and melt — by looking at melt during the record summertime temperatures of 2012, for example. The variations in ice quantity show to what extent Greenland contributes to the sea level rise we’ve seen in recent years. And, thanks to their high resolution, researchers can also highlight which glaciers are experiencing the most melt.

The duration of this study was a relatively short 4 years. Hopefully, the team will continue their measurements in the following years, so we can get a better understanding of how sea levels will evolve in the future.

The full paper, titled “A high-resolution record of Greenland mass balance” has been published online in the journal Geophysical Research Letters.

More than 13 million Americans could be at risk from sea level rise by 2100

A new study analyzing sea level rise forecasts as well as population growth projections found that we’ve underestimated just how many people would be impacted by rising waters. Anywhere from 4.3 to 13.1 million people from the US alone will face the risk of inundation by 2100, according to their estimate.

Brackish sea water washes over the center line of a street in Charleston Oct. 1, 2015.
Image credits Stephen B. Morton/AP.

The team, with members from the University of Georgia and Stetson University in Florida used population trends and sea level rise estimates to establish a county-by-county risk assessment across the US. Their results suggest that previous research, based on current population numbers, underestimates the risk coastal states face.

An important implication of this is the estimated cost of adapting to sea level rise might be too low, since it doesn’t take population growth and the associated installation of more long-lasting, vulnerable infrastructure into account.

“There are 31 counties where more than 100,000 residents could be affected by 6 feet of sea level rise,” said study co-author Mathew E. Hauer, of the University of Georgia in a press release.

The southeastern U.S. coast is a hotspot for inundation risk related to sea level rise, the authors say. This is partly due to the high population growth that the area is experiencing. Over 10 percent of coastal populations in states such as Georgia and South Carolina will be affected by a global sea level increase of 1.8 meters (5.9 feet) by 2100. A similar rise would affect an estimated one million people in California and Louisiana each. Florida faces the most risk, with up to 6 million residents affected under the same scenario.

Densely populated counties in coastal areas, such as Broward or Miami-Dade Counties in Florida, San Mateo in California or Jefferson in Louisiana are expected to see more than 100,000 residents “potentially impacted” by a 0.9 meters (around 3 feet) rise in sea levels.

The study also identified three counties as having an “extreme exposure” to inundation: North Carolina’s Tyrrell and Hyde Counties, and Monroe County in Florida. Tyrell and Hyde Counties are home to abundant nature preserves on North Carolina’s Outer Banks, while Monroe County is located at the southwestern tip of Florida, encompassing a swath of Everglades National Park as well as the Florida Keys. People living in these areas will suffer “catastrophic impacts” by 2100 if steps aren’t taken to address the issue.

Image credits misterfarmer/pixabay

The authors also warn that the lack of protection for coastal residents could lead to a population migration on par with the “Great Migration” of southern African Americans after the first World War. They estimate that the cost of relocating all the people affected by sea rise by 2100 would exceed $14 trillion dollars.

“The impact projections are up to three times larger than current estimates, which significantly underestimate the effect of sea level rise in the United States,” Hauer added.

Compared to previous estimates, these are worrying numbers. The team’s estimates revolve around those 1.8 meters of sea rise used in their calculations. The study also doesn’t take factor in regional variations in the rate of sea level rise. But, while the consensus seems to be set around a 1 meter (3.6 feet) rise by 2100, there is growing concern around the stability of the Greenland and West Antarctic ice sheets in today’s warmer oceans. Faster melting of these ice sheets would rise the waterline significantly, possibly way above the 1.8 meter level the team set.

Ben Strauss told Mashable that the lack of regional variations in sea level rise would affect the results out to the year 2100, and the study also “assumes that people will be moving to the shore essentially just as briskly” in the latter half of the century as in 2020, despite the evident effects of sea level rise expected by 2070.

The full paper, titled “Millions projected to be at risk from sea-level rise in the continental United States” has been published online in the journal Nature Climate Change and can be read here.

Fiji becomes the first country in the world to ratify the Paris climate deal

This Friday, the tiny island nation of Fiji put up a big flag on the map by becoming the first country in the world to ratify the UN climate deal put together last December at the Paris COP21.

Global warming? More like global tanning, amirite?!
But no seriously, it’s gonna flood if we don’t get our act together.
Image via flickr

Most of you reading this already (hopefully) agree that human-induced global warming is real and that we need to stop it until it stop us. But for most of us climate change is still…out there. Very real, just not very palpable.

Not so if you happen to live in Fiji or a host of other pacific island nations; here, rising sea levels are already eating into the limited available land, causing major concern among both the people and the governing bodies. Fiji’s prime minister, Voreqe Bainimarama, told the nation’s parliament it was important to act now to protect the archipelago from floods, increasingly destructive tropical storms, and the loss of fish stocks as the surrounding seas warm.

Thankfully, there’s already a plan set up. At the Paris COP21 talks the nation of Fiji committed to a national plan meant to drastically cut into its carbon emissions. In this plan, the country pledged to have 100% of its electricity generated via renewable sources by 2030 and reduce its emissions by 30% in the meantime.

A pretty lofty goal for Fiji. For the island nation to be able to keep up its end of the agreement, more developed countries will have to offer financial. Should they be unable to secure the funds it needs to rebuild its energy production infrastructure, Fiji will still commit to a 10% cut in emissions.

The island nation of Fiji is now the first country in the world to ratify the new Paris climate agreement.
Image via wikimedia

While 195 nations agreed to the deal set up in Paris, it still needs to be formally ratified by at least 55 countries to take effect. While the document itself isn’t due to be signed until April, Fiji took the lead and officially ratified the deal.

Since all of the world’s major economies have already approved the agreement, it’s expected that more nations will soon follow Fiji’s suit.

sea level increase

Sea level rise of up to 1.6 meters projected for 2100

sea level increase

It is no longer a question if multi-meter sea level rises will happen, but only of when. According to the latest estimate from the Arctic Monitoring and Assessment Programme it seems the accelerated climate change in the Arctic including a thaw of Greenland’s ice could raise world sea levels by up to 1.6 meters by 2100.

“The past six years (until 2010) have been the warmest period ever recorded in the Arctic,” according to the Oslo-based Arctic Monitoring and Assessment Programme (AMAP), which is backed by the eight-nation Arctic Council.

“In the future, global sea level is projected to rise by 0.9 meters (2ft 11in) to 1.6 meters (5ft 3in) by 2100 and the loss of ice from Arctic glaciers, ice caps and the Greenland ice sheet will make a substantial contribution,” it said. The rises were projected from 1990 levels.

“Arctic glaciers, ice caps and the Greenland ice sheet contributed over 40 percent of the global sea level rise of around 3 mm per year observed between 2003 and 2008,” it said.

Back in 2007 the United Nations’ Intergovernmental Panel on Climate Change (IPCC) reported that they estimate an increase of sea levels between 18 and 59 cm by 2100, however these conservative numbers did not take in consideration the drastic acceleration of thaw in the arctic.

“It is worrying that the most recent science points to much higher sea level rise than we have been expecting until now,” European Climate Commissioner Connie Hedegaard told Reuters.

“The study is yet another reminder of how pressing it has become to tackle climate change, although this urgency is not always evident neither in the public debate nor from the pace in the international negotiations,” she said.

The UN is currently in entangling talks on how they can battle the increase in temperature and sea levels, but progress is sluggish described at best. But the climate doesn’t wait, actually it’s said the Arctic Ocean could be nearly ice free in summers within 30 to 40 years, earlier than projected by the IPCC.

RELATED: Soot responsible for rapid Arctic melting?

As reflective ice and snow shrink, ever bigger areas of darker water or soil get exposed filled with black carbon or soot. Those dark regions are extremely dangerous for the polar caps, as they soak up ever more heat from the sun, in turn stoking a melt of the remaining ice and snow.

“There is evidence that two components of the Arctic cryosphere — snow and sea ice — are interacting with the climate system to accelerate warming,” th IPCC said.

The AMAP report was due for release on Wednesday but AMAP officials released it a day early after advance media leaks.