Ocean News

Mass balance of the Greenland Ice Sheet from 1992 to 2018

Abstract
In recent decades, the Greenland Ice Sheet has been a major contributor to global sea-level rise, and it is expected to be so in the future...

Although the ice sheet was close to a state of balance in the 1990s, annual losses have risen since then, peaking at 335 ± 62 billion tonnes per year in 2011.

Cumulative ice losses from Greenland as a whole have been close to the IPCC’s predicted rates for their high-end climate warming scenario, which forecast an additional 50 to 120 millimetres of global sea-level rise by 2100 when compared to their central estimate.

 

Atmospheric Rivers Fuel Most Flood Damage in the U.S. West. Climate Change Will Make Them Worse.

Giant rivers of moist air that curl off from the tropics are responsible for most of the flooding in the Western United States, and scientists say these atmospheric rivers will become more intense as the planet warms.

"In a warmer climate, extreme ARs (atmospheric rivers) will become more intense as they become wetter, longer and wider; there is some indication that this is already happening in association with observed Pacific Ocean warming," they wrote in the scientific journal Science Advances.

"The upshot was, you will, if you're standing somewhere on the California coast (between 2070 and 2100), experience atmospheric river conditions 40 percent more than now. The number of events decreases, but they get about 20 percent longer and 25 percent wider than today. Even if you have a smaller number, you are more likely to be affected," he said.

 

The Arctic may have crossed key threshold, emitting billions of tons of carbon into the air, in a long-dreaded climate feedback

 

Climate tipping points — too risky to bet against

Politicians, economists and even some natural scientists have tended to assume that tipping points1 in the Earth system — such as the loss of the Amazon rainforest or the West Antarctic ice sheet — are of low probability and little understood. Yet evidence is mounting that these events could be more likely than was thought, have high impacts and are interconnected across different biophysical systems, potentially committing the world to long-term irreversible changes.

Here we summarize evidence on the threat of exceeding tipping points, identify knowledge gaps and suggest how these should be plugged. We explore the effects of such large-scale changes, how quickly they might unfold and whether we still have any control over them......

If current national pledges to reduce greenhouse-gas emissions are implemented — and that’s a big ‘if’ — they are likely to result in at least 3 °C of global warming. This is despite the goal of the 2015 Paris agreement to limit warming to well below 2 °C. Some economists, assuming that climate tipping points are of very low probability (even if they would be catastrophic), have suggested that 3 °C warming is optimal from a cost–benefit perspective. However, if tipping points are looking more likely, then the ‘optimal policy’ recommendation of simple cost–benefit climate-economy models4 aligns with those of the recent IPCC report2. In other words, warming must be limited to 1.5 °C. This requires an emergency response.......

Ice collapse.....

Biosphere boundaries.....

Global cascade......

We argue that the intervention time left to prevent tipping could already have shrunk towards zero, whereas the reaction time to achieve net zero emissions is 30 years at best. Hence we might already have lost control of whether tipping happens. A saving grace is that the rate at which damage accumulates from tipping — and hence the risk posed — could still be under our control to some extent.....

 

Top scientists warn of an Amazon ‘tipping point’

 

A 3C World Is Now “Business as Usual”

The world is on a path to warm around 3C above pre-industrial levels by 2100 under policies and commitments currently in place. This is a far cry from the 1.5C and 2C targets enshrined in the Paris agreements, but is also well short of the 4C to 5C warming in many “business as usual” baseline scenarios that continue to be widely used.......

Our business-as-usual projection of 3C of warming — rather than 4 or 5C — is a testament to the progress in global decarbonization over the last few decades. It also reflects the fact that rapid growth in coal use during the 2000s was not necessarily characteristic of longer-term energy use trends. The world has taken concrete steps to move away from coal in the past decade, and this progress should be reflected in our assessment of likely emissions pathways — and their resulting climate impacts — going forward.

The worst case outcomes of ten years ago appear far less likely today. But there is also a risk of overenthusiasm about progress; there is still an ever-growing gap between current emissions and what would be needed to limit warming below 2C. With every year of continued emissions growth and increased deployment of clean energy, we make both low warming (<2C) and high warming (>4C) increasingly unlikely......

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See also:

We’re Getting a Clearer Picture of the Climate Future — and It’s Not as Bad as It Once Looked

 

Guess somebody forgot to tell the Obama's

Why would Obama buy a doomed beach house for $15 million? http://www.politicaljack.com/threads/why-would-obama-buy-a-doomed-beach-house-for-15-million.124307/

 

Simulations show thousands of lakes in Himalaya Mountains at risk of flooding due to global warming

As climate change continues and glaciers melt, natural lakes form when one of their borders is a natural levee called a moraine. These barriers are made of loose rock and dirt held together by ice. If the ice melts, the moraine gives way, resulting in what the researchers describe as glacial lake outburst floods (GLOFs), several of which have already occurred in recent decades.......

After running the simulations, they report that they found approximately 5,000 lakes in the Himalayas are likely unstable due to moraine weaknesses. They also noted that those lakes with the highest risk of a GLOF were the ones with the largest volume of water......

 

The signal of human-caused climate change has emerged in everyday weather, study finds

 

Double-checking the science: Ocean acidification does not impair the behavior of coral reef fishes

Over the last decade, several high-profile scientific studies have reported that tropical fish living in coral reefs are adversely affected by ocean acidification caused by climate change—that is, they behave oddly and are attracted to predators as levels of carbon dioxide dissolved from air pollution increase.......

But when they tried to re-do those earlier studies with many of the same species, and by crunching the data in a new analysis, Clark and his team of Canadian and Scandinavian scientists—including UdeM biologists Sandra Binning and Dominique Roche—arrived at very different results......

But "by using rigorous methods, measuring multiple behaviours in multiple species, and making our data and analysis code openly available, we have comprehensively and transparently shown that ... ocean acidification has negligible direct impacts on the behaviour of fish on coral reefs," said Clark.......

 

BlackRock Sends Huge Warning Shot at Companies Ignoring Climate Risk

The world’s largest asset manager predicts a “fundamental reshaping of finance” as the climate threat comes into sharper focus.......

BlackRock CEO Larry Fink said in an open letter that his company will end support for thermal coal, screen fossil fuel investments more closely, and redesign its own investment approach to put sustainability at its core. As part of the shift, BlackRock will exit investments it decides have a high-sustainability-related risk........

Further, Fink wrote, “because capital markets pull future risk forward, we will see changes in capital allocation more quickly than we see changes to the climate itself. In the near future — and sooner than most anticipate — there will be a significant reallocation of capital.”.......

 

Meteorite impact 2 billion years ago may have ended an ice age

The Australian crater Yarrabubba, at about 2.23 billion years old, is the oldest known on Earth, according to new measurements, and it might be linked to the end of a “Snowball Earth” ice age.....

The meteorite impact that created Yarrabubba would have slammed into our planet at the end of one of our “Snowball Earth” ice ages, the researchers say, and it’s possible that the impact heated up our planet and ended that icy episode in Earth’s history....

They found that the crash would have instantaneously vaporized huge amounts of ice, potentially releasing as much water vapor as about 2 percent of what's currently in Earth’s atmosphere. Despite water being necessary for life, water vapor is a powerful greenhouse gas, so it’s possible that injecting so much extra water vapor into the atmosphere could have helped warm the planet and brought about the end of the “Snowball Earth” period that occurred roughly 2.2 billion years ago.....

 

Ozone-depleting gases might have driven extreme Arctic warming

 

As our oceans become more acidic they may corrode the skins of sharks


Climate change will make the oceans more acidic and could damage sharks’ skin. Increased acidity corrodes the sharks’ denticles – microscopic tooth-like scales that cover their skin – which may impair their swimming......

Shark teeth are made of the same material as their denticles, so this corrosion could also impair the shark’s feeding. Because denticles are found on all sharks, other species will probably be affected......

 

How the ocean is gnawing away at glaciers

The Greenland Ice Sheet is melting faster today than it did only a few years ago. The reason: it's not just melting on the surface—but underwater, too.......

For the purposes of the study, the researchers conducted the first extensive ship-based survey of the ocean floor near the glacier, which revealed the presence of a two-kilometre-wide trough, from the bottom of which comparatively warm water from the Atlantic is channelled directly toward the glacier. But that's not all: in the course of a detailed analysis of the trough, Janin Schaffer spotted a bathymetric sill, a barrier that the water flowing over the seafloor has to overcome. Once over the hump, the water rushes down the back of the sill—and under the ice tongue. Thanks to this acceleration of the warm water mass, large amounts of heat from the ocean flow past the tongue every second, melting it from beneath. To make matters worse, the layer of warm water that flows toward the glacier has grown larger: measured from the seafloor, it now extends 15 metres higher than it did just a few years ago......

In order to determine whether the phenomenon only manifests at the 79° North Glacier or also at other sites, the team investigated a neighbouring region on Greenland's eastern coast......"The readings indicate that here, too, a bathymetric sill near the seafloor accelerates warm water toward the glacier. Apparently, the intensive melting on the underside of the ice at several sites throughout Greenland is largely produced by the form of the seafloor."......