Heatwaves in September #ClimateChange #auspol #StopAdani 

Late-September heat wave leaves climate experts stunned.
“Never been a heat wave of this duration and magnitude this late in the season,” reports NOAA
Sep 27, 2017, 4:06 pm

Places where temperatures are projected to be within one degree of a record high Wednesday. CREDIT: National Weather Service via WashPost/

Century-old records across the Midwest and East Coast are being shattered by a monster late-September heat wave — the kind of extreme weather we can expect to get much worse thanks to President Donald Trump’s policies to undermine domestic and global climate action.

[And Australian government’s determination to go ahead with the Adani Coal Mine] 
“There has never been a heat wave of this duration and magnitude this late in the season in Chicago,” the National Weather Service reported Tuesday evening.
From Wednesday through Tuesday, for example, Chicago sweltered through “the only occurrence on record of 7+ consecutive 90°[F] days entirely within September.”

 Every day of the heatwave was 92°F or above, and every one set a new record high for that date.
“Summer in some regions of the world will become one long heatwave even if global average temperatures rise only 2°C [3.6ºF] above pre-industrial levels,” finds a study published Monday in Nature Scientific Reports. 

The Paris climate agreement, which Trump has decided to pull out of, seeks to limit global warming to “well below” 3.6ºF.
On Wednesday, another study showed the connection between deadly heat waves and climate change. 

Scientists with World Weather Attribution (WWA) released an analysis of Europe’s blistering summer heat, which included the heat wave so deadly it was nicknamed “Lucifer.” 

The researchers found, “climate change increased the chances of seeing a summer as hot as 2017 by at least a factor of 10 and a heat wave like Lucifer by at least a factor of four since 1900″ (emphasis in original).
New study: ‘Super heat waves’ of 131°F coming if global warming continues unchecked
Back in the United States, the current heat wave has set records across the Midwest and East. 

On Monday, 92ºF was the hottest Burlington, Vermont had ever been that late in the year — by a full seven degrees, the Washington Post reported. On Sunday and Monday, Buffalo, New York saw its latest-ever consecutive 90ºF days. Records for hottest day or hottest series of days this late in the year were crushed in Minneapolis; northern Maine; Ottawa, Canada; and Green Bay, Wisconsin.
“It’s perhaps obvious that global warming means more frequent and intense heat waves,” climatologist Michael Mann noted in an email to ThinkProgress. “But what is less obvious is how climate change may be impacting the behavior of the jet stream in way that causes more persistent weather extremes, giving us even more extreme and longer-duration heat waves than we would otherwise expect.”
The National Weather Service tweeted out a chart showing this very effect.

The scientific evidence and analysis is getting stronger and stronger that carbon pollution is changing the jet stream in ways that cause high pressure ridges that block or stall weather patterns.

 A similar effect stalled Superstorm Harvey over Houston, leading to a once-in-25,000-year deluge.
“Many of the worst heat waves in recent history, including the 2003 European heat wave and the 2011 Texas/Oklahoma heat wave, were associated with this effect,” Mann said.
CO2 is changing the jet stream in ways that will create more Harveys
Climate science predicted a weaker jet stream, and Harvey stalled because of a weakened jet stream.
The latest science makes it very clear that stronger heat waves are becoming far more likely, thanks to global warming — and that the warmer it gets the worse the heat waves will get.
Indeed, the new Nature Scientific Reports study finds that for each additional 1.8°F of global warming during the summer, there would likely be:
15 to 28 more heat wave days each year

Heat waves would last 3 to 18 days longer

The peak intensity of heatwaves will increase 2.2°F to 3.4°F

But while the rest of the world is working to limit additional warming as much as possible, Trump’s policies would take us to upwards of 5.4°F or more additional warming. In the worst case, we can see as many as 80 more heat wave days, heat waves could be 50 days longer, and the peak intensity could be as much as 10°F higher than it is now.

Press link for more: Think Progress


Climate Change is an existential risk. 

Human-induced climate change is an existential risk to human civilisation: an adverse outcome that would either annihilate intelligent life or permanently and drastically curtail its potential.

Special precautions that go well beyond conventional risk management practice are required if the “fat tails” — the increased likelihood of very large impacts — are to be adequately dealt with.

 The potential consequences of these lower-probability, but higher-impact, events would be devastating for human societies.

The bulk of climate research has tended to underplay these risks, and exhibited a preference for conservative projections and scholarly reticence, albeit increasing numbers of scientists have spoken out in recent years on the dangers of such an approach.

Climate policymaking and the public narrative are significantly informed by the important work of the Intergovernmental Panel on Climate Change (IPCC).

 However, IPCC reports also tend toward reticence and caution, erring on the side of “least drama”, and downplaying more extreme and more damaging outcomes. 

 Whilst this has been understandable historically, given the pressure exerted upon the IPCC by political and vested interests, it is now becoming dangerously misleading, given the acceleration of climate impacts globally.

 What were lower-probability, higher-impact, events are now becoming more likely.

This is a particular concern with potential climatic “tipping points” — passing critical thresholds which result in step changes in the system — such as the polar ice sheets (and hence sea levels), and permafrost and other carbon stores, where the impacts of global warming are non-linear and difficult to model at present.

 Under-reporting on these issues contributes to the “failure of imagination” that is occurring today in our understanding of, and response to, climate change.

If climate policymaking is to be soundly based, a reframing of scientific research within an existential risk-management framework is now urgently required.

 This must be taken up not just in the work of the IPCC, but also in the UN Framework Convention on Climate Change negotiations if we are to address the real climate challenge.

Current processes will not deliver either the speed or the extent of change required.

Three decades ago, when serious debate on human-induced climate change began at the global level, a great deal of statesmanship was on display. 

 There was a preparedness to recognise that this was an issue transcending nation states, ideologies and political parties which had to be addressed proactively in the long-term interests of humanity as a whole, even if the existential nature of the risk it posed was far less clear cut than it is today.

As global institutions were established to take up this challenge, such as the UN Framework Convention on Climate Change (UNFCCC) at the Rio Earth Summit in 1992, and the extent of change this would demand of the fossil-fuel-dominated world order became clearer, the forces of resistance began to mobilise.

 Today, as a consequence, and despite the diplomatic triumph of the 2015 Paris Agreement , the debate around climate change policy has never been more dysfunctional, indeed Orwellian.
In his book 1984, George Orwell describes a double-speak totalitarian state where most of the population accepts “the most flagrant violations of reality, because they never fully grasped the enormity of what was demanded of them, and were not sufficiently interested in public events to notice what was happening. 

 By lack of understanding they remained sane.”
Orwell could have been writing about climate change and policymaking. 

 International agreements talk of limiting global warming to 1.5–2°C, but in reality they set the world on a path of 3–5°C.

 Goals are reaffirmed, only to be abandoned. 

 Coal is “clean”. 

 Just 1°C of warming is already dangerous, but this cannot be said. 

 The planetary future is hostage to myopic national self-interest. 

 Action is delayed on the assumption that as yet unproven technologies will save the day, decades hence. 

 The risks are existential, but it is “alarmist” to say so.

 A one-in-two chance of missing a goal is normalised as reasonable.

Climate policymaking for years has been cognitively dissonant, “a flagrant violation of reality”.

 So it is unsurprising that there is a lack of a understanding amongst the public and elites of the full measure of the climate challenge. 

 Yet most Australians sense where we are heading: three-quarters of Australians see climate change as catastrophic risk and half see our way of life ending within the next 100 years.

Politics and policymaking have norms: rules and practices, assumptions and boundaries, that constrain and shape them. 

 In recent years, the previous norms of statesmanship and long-term thinking have disappeared, replaced by an obsession with short-term political and commercial advantage Climate policymaking is no exception.

Since 1992, short-term economic interest has trumped environmental and future human needs.  

The world today emits 48% more carbon dioxide (CO2 ) from the consumption of energy than it did 25 years ago, and the global economy has more than doubled in size.

 The UNFCCC strives ” to enable economic development to proceed in a sustainable manner”, but every year humanity’s ecological footprint becomes larger and less sustainable.

 Humanity now requires the biophysical capacity of 1.7 planets annually to survive as it rapidly chews up the natural capital.

A fast, emergency-scale transition to a post-fossil fuel world is absolutely necessary to address climate change. But this is excluded from consideration by policymakers because it is considered to be too disruptive. 

 The orthodoxy is that there is
time for an orderly economic transition within the current short-termist political paradigm. 

 Discussion of what would be safe –– less warming that we presently experience –– is non-existent. 

 And so we have a policy failure of epic proportions.

Policymakers, in their magical thinking, imagine a mitigation path of gradual change, to be constructed over many decades in a growing, prosperous world.

 The world not imagined is the one that now exists: of looming financial instability; of a global crisis of political legitimacy; of a sustainability crisis that extends far beyond climate change to include all the fundamentals of human existence and most significant planetary boundaries (soils, potable water, oceans, the atmosphere, biodiversity, and so on); and of severe global energy sector dislocation.

In anticipation of the upheaval that climate change would impose upon the global order, the Intergovernmental Panel on Climate Change (IPCC), was established by the UN in 1988, charged with regularly assessing the global consensus on climate science as a basis for policymaking.

 The IPCC Assessment Reports ( AR ), produced every 5–6 years, play a large part in the public framing of the climate narrative: new reports are a global media event.

 AR5 was produced in 2013-14, with AR6 due in 2022. 

 The IPCC has done critical, indispensable work of the highest standard in pulling together a periodic consensus of what must be the most exhaustive scientific investigation in world history. 

 It does not carry out its own research, but reviews and collates peer-reviewed material from across the spectrum of this incredibly complex area, identifying key issues and trends for policymaker consideration.

However, the IPCC process suffers from all the dangers of consensus-building in such a wide-ranging and complex arena.

 For example, IPCC reports, of necessity, do not always contain the latest available information.

 Consensus-building can lead to “least drama”, lowest-common-denominator outcomes which overlook critical issues. 

 This is particularly the case with the “fat-tails” of probability distributions, that is, the high-impact but relatively low-probability events where scientific knowledge is more limited. 

 Vested interest pressure is acute in all directions; climate denialists accuse the IPCC of alarmism, whereas climate action proponents consider the IPCC to be far too conservative. 

 To cap it all, the IPCC conclusions are subject to intense political oversight before being released, which historically has had the effect of substantially watering-down sound scientific findings.

These limitations are understandable, and arguably were not of overriding importance in the early period of the IPCC.

 However, as time has progressed, it is now clear that the risks posed by climate change are far greater than previously anticipated. 

 We have moved out of the twilight period of much talk but relatively limited climate impacts. Climate change is now turning nasty, as we have witnessed in 2017 in the USA, South Asia, the Middle East and Europe, with record-breaking heatwaves and wildfires, more intense flooding and more damaging hurricanes.

The distinction between climate science and risk is now the critical issue, for the two are not the same.

 Scientific reticence — a reluctance to spell out the full risk implications of climate science in the absence of perfect information — has become a major problem. 

 Whilst this is understandable, particularly when scientists are continually criticised by denialists and political apparatchiks for speaking out, it is extremely dangerous given the “fat tail” risks of climate change.

 Waiting for perfect information, as we are continually urged to do by political and economic elites, means it will be too late to act.

Irreversible, adverse climate change on the global scale now occurring is an existential risk to human civilisation.

 Many of the world’s top climate scientists quoted in this report well understand these implications — James Hansen, Michael E. Mann, John Schellnhuber, Kevin Anderson, Eric Rignot, Naomi Oreskes, Kevin Trenberth, Michael Oppenheimer, Stefan Rahmstorf and others — and are forthright about their findings, where we are heading, and the limitations of IPCC reports.

This report seeks to alert the wider community and leaders to these limitations and urges change to the IPCC approach, and to the wider UNFCCC negotiations. It is clear that existing processes will not deliver the transformation to a low-carbon world in the limited time now available.
We urgently require a reframing of scientific research within an existential risk-management framework. This requires special precautions that go well beyond conventional risk management. 

 Like an iceberg, there is great danger “In what lies beneath”.

Press link for more: What lies beneath Report

Climate Change: The Science 

By Justin Gillis
The issue can be overwhelming. 

The science is complicated. 

Predictions about the fate of the planet carry endless caveats and asterisk.

We get it.
So we’ve put together a list of quick answers to often-asked questions about climate change. 

This should give you a running start on understanding the problem.

1. How much is the planet warming up?

2 degrees is actually a significant amount.

As of early 2017, the Earth had warmed by roughly 2 degrees Fahrenheit, or more than 1 degree Celsius, since 1880, when records began at a global scale.

 That figure includes the surface of the ocean. 

The warming is greater over land, and greater still in the Arctic and parts of Antarctica.

The number may sound low. 

We experience much larger temperature swings in our day-to-day lives from weather systems and from the changing of seasons. 

But when you average across the entire planet and over months or years, the temperature differences get far smaller – the variation at the surface of the Earth from one year to the next is measured in fractions of a degree. 

So a rise of 2 degrees Fahrenheit since the 19th century is actually high.
The substantial warming that has already occurred explains why much of the world’s land ice is starting to melt and the oceans are rising at an accelerating pace.

 The heat accumulating in the Earth because of human emissions is roughly equal to the heat that would be released by 400,000 Hiroshima atomic bombs exploding across the planet every day.

Scientists believe most and probably all of the warming since 1950 was caused by the human release of greenhouse gases.

 If emissions continue unchecked, they say the global warming could ultimately exceed 8 degrees Fahrenheit, which would transform the planet and undermine its capacity to support a large human population.
2. How much trouble are we in?

For future generations, big trouble.

The risks are much greater over the long run than over the next few decades, but the emissions that create those risks are happening now.

 This means the current generation of people is dooming future generations to a more difficult future. 

How difficult?
Over the coming 25 or 30 years, scientists say, the climate is likely to resemble that of today, although gradually getting warmer, with more of the extreme heat waves that can kill vulnerable people. 

Rainfall will be heavier in many parts of the world, but the periods between rains will most likely grow hotter and drier. 

The number of hurricanes and typhoons may actually fall, but the ones that do occur will draw energy from a hotter ocean surface, and therefore may be more intense. 

Coastal flooding will grow more frequent and damaging, as is already happening.

Longer term, if emissions continue to rise unchecked, the risks are profound. 

Scientists fear climate effects so severe that they might destabilize governments, produce waves of refugees, precipitate the sixth mass extinction of plants and animals in the Earth’s history, and melt the polar ice caps, causing the seas to rise high enough to flood most of the world’s coastal cities.
All of this could take hundreds or even thousands of years to play out, but experts cannot rule out abrupt changes, such as a collapse of agriculture, that would throw civilization into chaos much sooner. Bolder efforts to limit emissions would reduce these risks, or at least slow the effects, but it is already too late to eliminate the risks entirely.
3. Is there anything I can do about climate change?

Fly less, drive less, waste less.

You can reduce your own carbon footprint in lots of simple ways, and most of them will save you money. 

You can plug leaks in your home insulation to save power, install a smart thermostat, switch to more efficient light bulbs, turn off the lights in any room where you are not using them, drive fewer miles by consolidating trips or taking public transit, waste less food and eat less meat.
Perhaps the biggest single thing individuals can do on their own is to take fewer airplane trips; just one or two fewer plane rides per year can save as much in emissions as all the other actions combined.

 If you want to be at the cutting edge, you can look at buying an electric or hybrid car, putting solar panels on your roof, or both.

If you want to offset your emissions, you can buy certificates, with the money going to projects that protect forests, capture greenhouse gases and so forth. 

Some airlines sell these to offset emissions from their flights. You can also buy offset certificates in a private marketplace, from companies such as TerraPass; some people even give these as holiday gifts. 

In states that allow you to choose your own electricity supplier, you can often elect to buy green electricity; you pay slightly more, and the money goes into a fund that helps finance projects like wind farms.
Leading companies are also starting to demand clean energy for their operations. You can pay attention to company policies, patronize the leaders, and let the others know you expect them to do better.
In the end, though, experts do not believe the needed transformation in the energy system can happen without strong state and national policies.

 So speaking up and exercising your rights as a citizen matters as much as anything else you can do.

4. What’s the optimistic case?

Several things have to break our way.

In the best case that scientists can imagine, several things happen: Earth turns out to be less sensitive to greenhouse gases than currently believed; plants and animals manage to adapt to the changes that have already become inevitable; human society develops much greater political will to bring emissions under control; and major technological breakthroughs occur that help society to limit emissions and to adjust to climate change.
Some technological breakthroughs are already making cleaner energy more attractive. 

In the United States, for instance, coal has been losing out to natural gas as a power source, as new drilling technology has made gas more abundant and cheaper; for a given amount of power, gas cuts emissions in half. In addition, the cost of wind and solar power has declined so much that they are now the cheapest power source in a few places, even without subsidies.

Unfortunately, scientists and energy experts say the odds of all these things breaking our way are not very high. 

The Earth could just as easily turn out to be more sensitive to greenhouse gases as less.

 Global warming seems to be causing chaos in parts of the natural world already, and that seems likely to get worse, not better. 

So in the view of the experts, simply banking on rosy assumptions without any real plan would be dangerous. They believe the only way to limit the risks is to limit emissions.

5. Will reducing meat in my diet really help the climate?

Yes, beef especially.

Agriculture of all types produces greenhouse gases that warm the planet, but meat production is especially harmful — and beef is the most environmentally damaging form of meat. Some methods of cattle production demand a lot of land, contributing to destruction of forests; the trees are typically burned, releasing carbon dioxide into the atmosphere. Other methods require huge amounts of water and fertilizer to grow food for the cows.
The cows themselves produce emissions of methane, a potent greenhouse gas that causes short-term warming. Meat consumption is rising worldwide as the population grows, and as economic development makes people richer and better able to afford meat.
This trend is worrisome. Studies have found that if the whole world were to start eating beef at the rate Americans eat it, produced by the methods typically used in the United States, that alone might erase any chance of staying below an internationally agreed-upon limit on global warming. Pork production creates somewhat lower emissions than beef production, and chicken lower still. So reducing your meat consumption, or switching from beef and pork to chicken in your diet, are moves in the right direction. Of course, as with any kind of behavioral change meant to benefit the climate, this will only make a difference if lots of other people do it, too, reducing the overall demand for meat products.
6. What’s the worst case?

There are many.

That is actually hard to say, which is one reason scientists are urging that emissions be cut; they want to limit the possibility of the worst case coming to pass. 
Perhaps the greatest fear is a collapse of food production, accompanied by escalating prices and mass starvation. It is unclear how likely this would be, since farmers are able to adjust their crops and farming techniques, to a degree, to adapt to climatic changes. But we have already seen heat waves contribute to broad crop failures. A decade ago, a big run-up in grain prices precipitated food riots around the world and led to the collapse of at least one government, in Haiti.
Another possibility would be a disintegration of the polar ice sheets, leading to fast-rising seas that would force people to abandon many of the world’s great cities and would lead to the loss of trillions of dollars worth of property and other assets. In places like Florida and Virginia, towns are already starting to have trouble with coastal flooding.  
Scientists also worry about other wild-card events. Will the Asian monsoons become less reliable, for instance? Billions of people depend on the monsoons to provide water for crops, so any disruptions could be catastrophic. Another possibility is a large-scale breakdown of the circulation patterns in the ocean, which could potentially lead to sudden, radical climate shifts across entire continents.
7. ​Will a technology breakthrough help us?

Even Bill Gates says don’t count on it, unless we commit the cash.

As more companies, governments and researchers devote themselves to the problem, the chances of big technological advances are improving. But even many experts who are optimistic about technological solutions warn that current efforts are not enough. For instance, spending on basic energy research is only a quarter to a third of the level that several in-depth reports have recommended. And public spending on agricultural research has stagnated even though climate change poses growing risks to the food supply. People like Bill Gates have argued that crossing our fingers and hoping for technological miracles is not a strategy — we have to spend the money that would make these things more likely to happen. 
8. How much will the seas rise?

The real question is not how high, but how fast.

The ocean is rising at a rate of about a foot per century. That causes severe effects on coastlines, forcing governments and property owners to spend tens of billions of dollars fighting erosion. But if that rate continued, it would probably be manageable, experts say.
The risk is that the rate will accelerate markedly. If emissions continue unchecked, then the temperature at the Earth’s surface could soon resemble a past epoch called the Pliocene, when a great deal of ice melted and the ocean rose by something like 80 feet compared to today. A recent study found that burning all the fossil fuels in the ground would fully melt the polar ice sheets, raising the sea level by more than 160 feet over an unknown period. Many coastal experts believe that even if emissions stopped tomorrow, 15 or 20 feet of sea-level rise is already inevitable.
The crucial issue is probably not how much the oceans are going to rise, but how fast. And on that point, scientists are pretty much flying blind. Their best information comes from studying the Earth’s history, and it suggests that the rate can on occasion hit a foot per decade, which can probably be thought of as the worst case. Even if the rise is much slower, many of the world’s great cities will flood eventually. Studies suggest that big cuts in emissions could slow the rise, buying crucial time for society to adapt to an altered coastline.
9. Are the predictions reliable?

They’re not perfect, but they’re grounded in solid science.

The idea that Earth is sensitive to greenhouse gases is confirmed by many lines of scientific evidence. For instance, the basic physics suggesting that an increase of carbon dioxide traps more heat was discovered in the 19th century, and has been verified in thousands of laboratory experiments.
Climate science does contain uncertainties, of course. The biggest is the degree to which global warming sets off feedback loops, such as a melting of sea ice that will darken the surface and cause more heat to be absorbed, melting more ice, and so forth. It is not clear exactly how much the feedbacks will intensify the warming; some of them could even partly offset it. This uncertainty means that computer forecasts can give only a range of future climate possibilities, not absolute predictions.
But even if those computer forecasts did not exist, a huge amount of evidence suggests that scientists have the basic story right. The most important evidence comes from the study of past climate conditions, a field known as paleoclimate research. The amount of carbon dioxide in the air has fluctuated naturally in the past, and every time it rises, the Earth warms up, ice melts and the ocean rises. A hundred miles inland from today’s East Coast of the United States, seashells can be dug from ancient beaches that are three million years old, a blink of an eye in geologic time.
These past conditions are not a perfect guide to the future, because humans are pumping carbon dioxide into the air far faster than nature has ever done. But they show it would be foolish to assume that modern society is somehow immune to large-scale, threatening changes. 
10. Why do people question the science of climate change?

Hint: ideology.

Most of the attacks on climate science are coming from libertarians and other political conservatives who do not like the policies that have been proposed to fight global warming. Instead of negotiating over those policies and trying to make them more subject to free-market principles, they have taken the approach of blocking them by trying to undermine the science.
This ideological position has been propped up by money from fossil-fuel interests, which have paid to create organizations, fund conferences and the like. The scientific arguments made by these groups usually involve cherry-picking data, such as focusing on short-term blips in the temperature record or in sea ice, while ignoring the long-term trends.
The most extreme version of climate denialism is to claim that scientists are engaged in a worldwide hoax to fool the public so that the government can gain greater control over people’s lives. As the arguments have become more strained, many oil and coal companies have begun to distance themselves publicly from climate denialism, but some are still helping to finance the campaigns of politicians who espouse such views.
11. Is crazy weather tied to climate change?

In some cases, yes.

Scientists have published strong evidence that the warming climate is making heat waves more frequent and intense. It is also causing heavier rainstorms, and coastal flooding is getting worse as the oceans rise because of human emissions. Global warming has intensified droughts in regions like the Middle East, and it may have strengthened a recent drought in California.
In many other cases, though, the linkage to global warming for particular trends is uncertain or disputed. That is partly from a lack of good historical weather data, but it is also scientifically unclear how certain types of events may be influenced by the changing climate.
Another factor: While the climate is changing, people’s perceptions may be changing faster. The Internet has made us all more aware of weather disasters in distant places. On social media, people have a tendency to attribute virtually any disaster to climate change, but in many cases there is little or no scientific support for doing so.
12. Will anyone benefit from global warming?

In certain ways, yes.

Countries with huge, frozen hinterlands, including Canada and Russia, could see some economic benefits as global warming makes agriculture, mining and the like more possible in those places. It is perhaps no accident that the Russians have always been reluctant to make ambitious climate commitments, and President Vladimir V. Putin has publicly questioned the science of climate change.
However, both of those countries could suffer enormous damage to their natural resources; escalating fires in Russia are already killing millions of acres of forests per year. Moreover, some experts believe countries that view themselves as likely winners from global warming will come to see the matter differently once they are swamped by millions of refugees from less fortunate lands.
13. Is there any reason for hope?

If you share this with 50 friends, maybe.

Scientists have been warning since the 1980s that strong policies were needed to limit emissions. Those warnings were ignored, and greenhouse gases in the atmosphere were allowed to build up to potentially dangerous levels. So the hour is late.
But after 20 years of largely fruitless diplomacy, the governments of the world are finally starting to take the problem seriously. A deal reached in Paris in late 2015 commits nearly every country to some kind of action. President Trump decided in 2017 to pull the United States out of that deal, saying it would unfairly burden American businesses. But other countries are promising to go forward with it anyway, and some states and cities have defied Mr. Trump by adopting more ambitious climate goals.
Religious leaders like Pope Francis are speaking out. Low-emission technologies, such as electric cars, are improving. Leading corporations are making bold promises to switch to renewable power and stop forest destruction.
What is still largely missing in all this are the voices of ordinary citizens. Because politicians have a hard time thinking beyond the next election, they tend to tackle hard problems only when the public rises up and demands it.
14. How does agriculture affect climate change?

It’s a big contributor, but there are signs of progress.

The environmental pressures from global agriculture are enormous. Global demand for beef and for animal feed, for instance, has led farmers to cut down large swaths of the Amazon forest.
Brazil adopted tough oversight and managed to cut deforestation in the Amazon by 80 percent in a decade. But the gains there are fragile, and severe problems continue in other parts of the world, such as aggressive forest clearing in Indonesia.
Scores of companies and organizations, including major manufacturers of consumer products, signed a declaration in New York in 2014 pledging to cut deforestation in half by 2020, and to cut it out completely by 2030. The companies that signed the pact are now struggling to figure out how to deliver on that promise.
Many forest experts consider meeting the pledge to be difficult, but possible. They say consumers must keep up the pressure on companies that use ingredients like palm oil in products ranging from soap to lipstick to ice cream. People can also help the cause by altering their diets to eat less meat, and particularly less beef.
15. Will the seas rise evenly across the planet?

Think lumpy.

Many people imagine the ocean to be like a bathtub, where the water level is consistent all the way around. In fact, the sea is rather lumpy — strong winds and other factors can cause water to pile up in some spots, and to be lower in others.
Also, the huge ice sheets in Greenland and Antarctica exert a gravitational pull on the sea, drawing water toward them. As they melt, sea levels in their vicinity will fall as the water gets redistributed to distant areas.
How the rising ocean affects particular parts of the world will therefore depend on which ice sheet melts fastest, how winds and currents shift, and other related factors. On top of all that, some coastal areas are sinking as the sea rises, so they get a double whammy.
16. What are ‘carbon emissions?’

Here’s a quick explainer.

The greenhouse gases being released by human activity are often called “carbon emissions,” just for shorthand. That is because the two most important of the gases, carbon dioxide and methane, contain carbon. Many other gases also trap heat near the Earth’s surface, and many human activities cause the release of such gases to the atmosphere. Not all of these actually contain carbon, but they have all come to be referred to by the same shorthand.
By far the biggest factor causing global warming is the burning of fossil fuels for electricity and transportation. That process takes carbon that has been underground for millions of years and moves it into the atmosphere, as carbon dioxide, where it will influence the climate for many centuries into the future. Methane is even more potent at trapping heat than carbon dioxide, but it breaks down more quickly in the air. Methane comes from swamps, from the decay of food in landfills, from cattle and dairy farming, and from leaks in natural gas wells and pipelines.
While fossil-fuel emissions are the major issue, another major creator of emissions is the destruction of forests, particularly in the tropics. Billions of tons of carbon are stored in trees, and when forests are cleared, much of the vegetation is burned, sending that carbon into the air as carbon dioxide.
When you hear about carbon taxes, carbon trading and so on, these are just shorthand descriptions of methods designed to limit greenhouse emissions or to make them more expensive so that people will be encouraged to conserve fuel.

Press link for more: NY Times

How many reasons do we need to #StopAdani #Auspol ?

1. Fossil fuels are destroying the world’s coral UNESCO Report

2. Climate change driven by fossil fuels is causing global conflict. Breakthrough Online

3. Air pollution (mainly coal) is killing millions Washington Post

4. Clean renewable energy is cheaper than coal.

5. Clean energy creates more jobs

6. $56 billion reasons to #StopAdani and protect the Great Barrier Reef.

The Great Barrier Reef is too big to fail ABC


Rob Pyne Video

Humans are changing the climate #auspol 

Detailed look at the global warming ‘hiatus’ again confirms that humans are changing the climateGlobal warming ‘hiatus’ explained

A new analysis in the journal Nature shows that the global warming “hiatus” may not have been quite what it seemed.

By Amina Khan

 Contact Reporter Environmental Science Climate Change Scientific Research

For years, the global warming ‘hiatus’ from 1998 to 2012 puzzled scientists and fueled skeptics looking to cast doubt on the very idea that Earth’s temperature has been on the rise, largely because of human-produced greenhouse gas emissions such as carbon dioxide — and that significant policy changes would need to be made to keep that rise in check.
Recent papers have begun to chip away at the idea of the slowdown. 

Now, a new analysis in the journal Nature brings together many of those arguments to show that the hiatus may not have been quite what it seemed.
“A combination of changes in forcing, uptake of heat by the oceans, natural variability and incomplete observational coverage reconciles models and data,” the researchers from the Institute for Atmospheric and Climate Science in Switzerland wrote. “Combined with stronger recent warming trends in newer datasets, we are now more confident than ever that human influence is dominant in long-term warming.”

Below, we sort through a few of the issues with the hiatus — and the lessons scientists learned from it.
What was the hiatus, anyway?
That’s a good question. 

Part of the problem is that there doesn’t seem to be an agreed-upon definition. 

The hiatus has been defined in three main ways in the scientific literature:
A period in which there is no significant positive trend in global mean surface temperatures (when it’s essentially flat)

A shorter-term slowdown in rising temperatures compared to the preceding long-term warming trend

The rate of increase in temperatures is lower than scientific models predicted

So whether you call it the ‘hiatus’ or the ‘pause,’ both are arguably misnomers, depending on which meaning is used. 

After all, in the latter two definitions, temperatures are generally still rising — just not as much as expected. 

And depending on which definition you use, different models will be more accurate than others.
“All three of those are very different arguments …. so it often makes it fairly confusing to talk about this hiatus discussion,” said Zeke Hausfather, a climate scientist at Berkeley Earth and PhD student at UC Berkeley who was not involved in the paper.
“The only sort of ‘true’ definition of a hiatus would be if global warming actually stopped,” he added, “and there’s no evidence in any operational datasets today that that happened.”
Regardless of the definition, to whatever the extent the global warming slowdown existed, it’s definitely over now. 

Independent analyses by NASA and NOAA show that 2016 was the hottest year on record, marking the third year of record-breaking heat in a row. 

The causes remain linked to human produced greenhouse gas emissions.

So the hiatus is over? 

Then why do scientists care?
Scientists had to care because everyone else seemed to. 

The hiatus, which is marked from 1998 to 2012, was generally treated by climate scientists as a reflection of short-term variations that didn’t affect long-term trends.
“In leaked drafts of the Intergovernmental Panel on Climate Change (IPCC) Working Group I (WG1) Fifth Assessment Report (AR5), the global warming hiatus was considered to be consistent with natural variability, and hence not in need of a detailed explanation,” the study authors wrote. “At the time of the first draft, there was almost no literature on the hiatus to be assessed anyway. Scientists knew from observations and models that global temperatures fluctuate on timescales of years to decades.”
But the deviation from expectations was seized upon by the media as well as global warming skeptics, the study authors noted, turning it into a political football around the time that major policy decisions about how to deal with climate change were under discussion.
“The interest of the media and public grew, and groups with particular interests used the case to question the trust in both climate science and the use of climate models,” the authors wrote.
(The Times has reported on fossil fuel companies’ support of climate skepticism.)
Those short-term trends may be considered relatively minor fluctuations — but they matter on human timescales, and they’re still poorly understood.
“Now, in 2017 … after a wave of scientific publications and public debate, and with GMSTs [global mean surface air temperatures] setting new records again, it is time to take stock of what can be learned from the hiatus,” the authors wrote.
It is time to take stock of what can be learned from the hiatus.

— Authors of the Nature study

So what did this new analysis find?
This analysis in Nature pulls together many findings in the wake of several research efforts looking to address the hiatus conundrum. Some argued that global warming predictions didn’t match the actual data during that time period because they didn’t include complex short-term climate factors that are poorly understood. Others have argued that the hiatus didn’t really exist; that it was a problem with the instrumentation or the data analysis, for example.
The new Nature paper essentially works through several examples under both of these explanations and finds that it’s a combination of the two. For example:
Regions in the Arctic, where global warming is having marked effects, are actually sparsely monitored, and different analyses try to extrapolate from that limited data set in different ways.

The definitions of a pause are faulty, especially when you consider that “the data continue to show significant warming trends when the trend length exceeds 16 years,” James Risbey and Stephan Lewandowsky, who were not involved in the paper, wrote in a commentary on it. (Risbey is with the Oceans and Atmosphere Commonwealth Scientific and Industrial Research Organisation in Australia; Lewandowsky is from the University of Bristol.)

The observed global mean temperature data takes into account both ocean and surface air temperatures, but model predictions have often only used air temperatures. This leads to apples-and-oranges comparisons between predictions and reality, Risbey and Lewandowsky said.

Short-term ocean dynamics patterns, such as those of El Niño, the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation, move and store heat in ways that lead to surface temperature fluctuations that can last years or even decades. This does not mean that the heat’s gone, just that it’s out of range of sensors. And because we don’t fully understand those patterns, and when exactly one will start and when it will end, short-term predictions can be a little off — even though they’re right in the long-term.“The models have their own El Niño events but they’re not necessarily happening at the same time as the real-world El Niño events,” Hausfather said.

Climate change models did not perfectly characterize all the right complicating factors — how much solar radiation there was in a given year, for example, or the extent of the cooling effect from volcanic activity and human-produced aerosols. When those estimates are updated to reflect what actually happened, the models get much closer to reality.

Recent studies showed the need to better account for temperature detection changes that happened as ocean temperature monitors switched from ships to buoys. The buoys may have made temperature readings look a little cooler than expected, even when they were not. (In the older method, water would be heated by the ship’s engine on its way to be measured, while the buoys would measure water temperatures in the open ocean.)

“If you do all of these things you end up getting observations that match models pretty exactly,” Hausfather said of all the mitigating factors included by the Nature study authors. “Each of these things is a little part of the divergence between models and observations.”
Another problem? Marking the beginning of the hiatus from 1998, which was a year of record-breaking heat.
“Picking a large El Niño event as the starting year, you’re necessarily going to have a lower rate of warming after that, even in a warming world,” Hausfather said.
The problem, ultimately, is that studies looking at long-term change simply aren’t especially good at predicting short-term variation. That doesn’t mean that the long-term trend isn’t there; human-caused carbon dioxide emissions continue to fuel global warming.
“In short, some data, tools and methods that were good enough when looking at longer-term climate change proved to be problematic when they were focused on the problem of explaining short-term trends,” Risbey and Lewandowsky wrote. “Small differences in GMST data that are inconsequential for climate change are amplified when short-term trends are calculated. Climate-model projections are blunt tools for the analysis of short-term trends.”
What new light does this paper shed on the hiatus?
This analysis isn’t a “bombshell,” pointed out Michael Mann, a climate scientist at Penn State University.
“The work of many groups (including our own) has shown that models and observations are consistent in terms of long-term warming, and that this warming — and recent extreme warmth — can only be explained by anthropogenic (human-caused) activity, namely the burning of fossil fuels,” Mann said in an email. “The fact that there is substantial internal variability that can mask this warming on decadal and multidecadal timescales is also something established by us in previous work.”
But it does offer a holistic explanation of all the research that has been chipping away at this climate conundrum, Hausfather pointed out.
“I think it does a really good job at tying a bow on the last five years or so of hiatus arguments,” he said.
Is there a lesson to be learned from the controversy around the hiatus?
The study authors seem to think so. For example, scientists were forced to better understand these short-term variations, which helped them pin down factors such as how sensitive the climate was to additional carbon dioxide, the dominant greenhouse gas in Earth’s atmosphere.
“As a consequence, after a surge of scientific studies on the topic, we have learned more about the ways in which the climate system works in several areas,” the authors wrote.
And then there are other evergreen lessons — particularly with respect to science and its interface with public discourse.
“Social sciences might find this an interesting period for studying how science interacts with the public, media and policy,” they wrote. “In a time coinciding with high-level political negotiations on preventing climate change, sceptical media and politicians were using the apparent lack of warming to downplay the importance of climate change…. This will not be the last time that weather and climate will surprise us, so maybe there are lessons to be learned from the hiatus about communication on all sides.”

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Climate change has been underestimated. #auspol #science

Science has underestimated Earth’s sensitivity to CO2 changes, study finds
By Jim Shelton

April 7, 2016

Global warming

A Yale University study says global climate models have significantly underestimated how much the Earth’s surface temperature will rise if greenhouse gas emissions continue to increase as expected.

Yale scientists looked at a number of global climate projections and found that they misjudged the ratio of ice crystals and super-cooled water droplets in “mixed-phase” clouds — resulting in a significant under-reporting of climate sensitivity. The findings appear April 7 in the journal Science.
Equilibrium climate sensitivity is a measure used to estimate how Earth’s surface temperature ultimately responds to changes in atmospheric carbon dioxide (CO2). Specifically, it reflects how much the Earth’s average surface temperature would rise if CO2 doubled its preindustrial level. In 2013, the Intergovernmental Panel on Climate Change (IPCC) estimated climate sensitivity to be within a range of 2 to 4.7 degrees Celsius.
The Yale team’s estimate is much higher: between 5 and 5.3 degrees Celsius. Such an increase could have dramatic implications for climate change worldwide, note the scientists.
“It goes to everything from sea level rise to more frequent and extreme droughts and floods,” said Ivy Tan, a Yale graduate student and lead author of the study.
Trude Storelvmo, a Yale assistant professor of geology and geophysics, led the research and is a co-author of the study. The other co-author is Mark Zelinka of Lawrence Livermore National Laboratory’s Program for Climate Model Diagnosis and Intercomparison.

A key part of the research has to do with the makeup of mixed-phase clouds, which consist of water vapor, liquid droplets, and ice particles, in the upper atmosphere. A larger amount of ice in those clouds leads to a lower climate sensitivity — something known as a negative climate feedback mechanism. The more ice you have in the upper atmosphere, the less warming there will be on the Earth’s surface.
“We saw that all of the models started with far too much ice,” said Storelvmo, an assistant professor of geology and geophysics. “When we ran our own simulations, which were designed to better match what we found in satellite observations, we came up with more warming.”
Storelvmo’s lab at Yale has spent several years studying climate feedback mechanisms associated with clouds. Little has been known about such mechanisms until fairly recently, she explained, which is why earlier models were not more precise.
“The overestimate of ice in mixed-phase clouds relative to the observations is something that many climate modelers are starting to realize,” Tan said.
The researchers also stressed that correcting the ice-water ratio in global models is critical, leading up to the IPCC’s next assessment report, expected in 2020.
Support for the research came from the NASA Earth and Space Science Fellowship Program, the National Science Foundation, and the U.S. Department of Energy.

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Scientists up their projections for sea level rise. #auspol 

Scientists keep upping their projections for how much the oceans will rise this century

 A 30-mile-long meltwater river runs through Petermann glacier, Greenland, on August 27, 2016. (Whitney Shefte/The Washington Post)

A report by a leading research body monitoring the Arctic has found that previous projections of global sea level rise for the end of the century could be too low, thanks in part to the pace of ice loss of Arctic glaciers and the vast ice sheet of Greenland.
It’s just the latest in a string of cases in which scientists have published numbers that suggest a grimmer picture than the one presented in 2013 by an influential United Nations body, the Intergovernmental Panel on Climate Change.
The new Snow, Water, Ice and Permafrost in the Arctic report presents minimum estimates for global sea level rise by the end of the century, but not a maximum. This reflects the fact that scientists keep uncovering new insights that force them to increase their sea level estimates further, said William Colgan, a glaciologist with the Geological Survey of Denmark and Greenland, who contributed to the sea level rise section.
“Because of emerging processes, especially related to the Greenland ice sheet and the Antarctic ice sheet, it now looks like the uncertainties are all biased positive,” Colgan said.
The assessment found that under a relatively moderate global warming scenario — one that slightly exceeds the temperature targets contained in the Paris climate agreement — seas could be expected to rise “at least” 52 centimeters, or 1.7 feet, by the year 2100. Under a more extreme, “business as usual” warming scenario, meanwhile, the minimum rise would be 74 centimeters, or 2.4 feet.
The new findings were published Tuesday as part of a broader overview report by the Arctic Monitoring and Assessment Program, a working group of the intergovernmental Arctic Council, which unites eight Arctic nations, including the United States, and six organizations representing the indigenous peoples of the Arctic.
It is the work of 90 scientists and 28 peer reviewers and is expected to be presented in Fairbanks, Alaska, next month at the next summit of Arctic political leaders.
The report bluntly contrasts its sea level findings with a previous 2013 report from the U.N. Intergovernmental Panel on Climate Change, which had put the “likely” low end sea level rise number for these two scenarios at 32 centimeters (about 1 foot) and 45 centimeters (1.5 feet) for the period between 2081 and 2100. That global body — whose high end sea level rise number for the year 2100 was just shy of one meter, or 3.2 feet — has often seen its assertions on sea level rise faulted by scientists for being too conservative.
“These estimates are almost double the minimum estimates made by the IPCC in 2013,” said the new Arctic Council report, which is dubbed a “Summary for Policymakers” because the technical report underpinning it has not yet been released.
The new Arctic report is hardly the first of late to call the IPCC’s figures into question.
An influential study of Antarctica published last year in the journal Nature suggested that the frozen continent alone could nearly double the IPCC’s sea level projections for the end of the century.
(The IPCC did concede that sea levels could be higher than its “likely” forecast in the event of a “collapse of marine-based sectors of the Antarctic ice sheet” — but it added that “there is medium confidence that this additional contribution would not exceed several tenths of a meter of sea level rise during the 21st century.”)
And since then, several other scientific documents — presumably aware of this Antarctic research — have cited the possibility of particularly extreme sea level rise by 2100, even if they cannot necessarily quantify the likelihood of it occurring.
At the close of the Obama administration, a report from the National Oceanic and Atmospheric Administration suggested that, at least as an “extreme” case, seas could possibly rise by as much as 8 feet by century’s end.
And yet another report, prepared for the state of California and released this month by a team of climate researchers, has now also presented the possibility of extreme sea level scenarios by 2100 — albeit ones that have either a low or an unknown probability of occurring.
That document looked specifically at California coastlines, and found that for San Francisco, for instance, the “likely” range for sea level rise in the year 2100 under a high global warming scenario would be 1.6 to 3.4 feet. But it also said there was a 1-in-20 chance of 4.4 feet, a 1-in-200 chance of 6.9 feet, and even a chance, whose probability could not be estimated, of 10 feet.
“We’re learning an increasing amount about the instability of marine based ice, and the amount of marine based ice that there is in Antarctica,” said Bob Kopp, a sea level researcher at Rutgers University and one of the authors of the California report. “And as we take more of these processes into account, the extent of the things that we don’t know that much about and aren’t yet able to quantify well has become clearer.”
The report for the Arctic Council, by contrast, focuses on a growing Arctic contribution to sea level rise, rather than an Antarctic one. Antarctica has far greater potential to raise seas over all, but the Arctic report emphasizes that for now, Greenland is actually raising seas the most and that it too has a great deal of potential sea level rise to contribute.
“These estimates of higher sea level contributions from the Arctic will only add to the new, higher estimates of potential sea level contributions from Antarctica — which is not good news,” said Rob DeConto, a geoscientist at the University of Massachusetts at Amherst who published the aforementioned Antarctica study and also worked on the California study. He was not involved in the new Arctic report.
Here’s a figure that the Geological Survey of Denmark and Greenland’s Colgan provided, showing the new sea level projections for a modest and more severe warming scenario, as well as the different and changing components of sea level rise over time:

 The sources and amounts of sea level rise from 1850 to the present, and then projected to the year 2100. RCP4.5 represents a modest global warming scenario that’s not too much warmer than the goals contained in the Paris climate agreement, whereas RCP8.5 represents a more severe “business as usual” scenario (William Colgan)

The Arctic report states that Greenland, in particular, lost 375 billion tons of ice per year from 2011 through 2014, enough to single-handedly raise the global sea level by about a millimeter per year. That annual loss, the document states, is “equivalent to a block of ice measuring 7.5 kilometers or 4.6 miles on all sides.”
Meanwhile, the melting glaciers of the Alaskan, Canadian and Russian Arctic are all steadily raising seas as well and could also see their contributions grow. The report therefore estimates that 19 to 25 centimeters (0.6 to 0.8 feet) of sea level rise in this century will come from the Arctic alone, and that must be combined with all the sea level rise contributed by Antarctica, other glacier systems and the steady expansion of seawater itself as it gets warmer.
Because of the difference between the worst case and more moderate sea level rise scenarios, the report concludes that the Paris climate agreement could substantially reduce the global sea level rise seen by 2100, even though seas will still rise considerably under any scenario.
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“You have to have a deliberate and sustained implementation of Paris for 30 years before you see a significant difference in the rate of global sea level rise,” Colgan said.
The Trump administration has been divided over whether to stick with the president’s campaign pledge and withdraw the United States from that agreement. Because of the upcoming G-7 meeting in May, where Trump is likely to be pressed on climate change, many observers expect a decision relatively soon.
It is unclear how the United States may react to the new Arctic report at the upcoming Arctic council meeting — the U.S. is currently chairing the council — or whether this will also put any additional pressure on the Trump administration.
Meanwhile, scientists studying the planet’s ice and its seas continue their work.
“If you look at the history of sea level rise projections over the last 20 years, they’re going up through time,” said Colgan. “Not just because of sea level actually rising, but also because of our understanding of the processes improving through time.”

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Climate Outlook May Be Worse Than Feared. #auspol 

Climate Outlook May Be Worse Than Feared, Global Study Suggests
Newswise — As world leaders hold climate talks in Paris, research shows that land surface temperatures may rise by an average of almost 8C by 2100, if significant efforts are not made to counteract climate change.

Such a rise would have a devastating impact on life on Earth. It would place billions of people at risk from extreme temperatures, flooding, regional drought, and food shortages.
The study calculated the likely effect of increasing atmospheric levels of greenhouse gases above pre-industrialisation amounts. 

It finds that if emissions continue to grow at current rates, with no significant action taken by society, then by 2100 global land temperatures will have increased by 7.9C, compared with 1750.

This finding lies at the very uppermost range of temperature rise as calculated by the Intergovernmental Panel on Climate Change. 

It also breaches the United Nations’ safe limit of 2C, beyond which the UN says dangerous climate change can be expected.
Research at the University of Edinburgh first created a simple algorithm to determine the key factors shaping climate change and then estimated their likely impact on the world’s land and ocean temperatures. 

The method is more direct and straightforward than that used by the IPCC, which uses sophisticated, but more opaque, computer models.
The study was based on historical temperatures and emissions data. 

It accounted for atmospheric pollution effects that have been cooling Earth by reflecting sunlight into space, and for the slow response time of the ocean.
Its findings, published in Earth and Environmental Transactions of the Royal Society of Edinburgh, may also help resolve debate over temporary slow-downs in temperature rise.
Professor Roy Thompson, of the University of Edinburgh’s School of GeoSciences, who carried out the study, said: “Estimates vary over the impacts of climate change. 

But what is now clear is that society needs to take firm, speedy action to minimise climate damage.”

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Irreversible Threshold of #ClimateChange 

IN LATE 2015, a chilling report by scientists for
the International Cryosphere Climate Initiative

“Thresholds and closing windows: Risks of irreversible cryosphere climate change”

Warned that the Paris commitments will not prevent the Earth 

“crossing into the zone of irreversible thresholds”

In polar and mountain glacier regions, and that crossing these boundaries may 

“result in processes that cannot be halted unless temperatures return to levels below pre-industrial” 

The report says it is not well understood outside the scientific community that cryosphere dynamics are slow to manifest but once triggered “inevitably forces the Earth’s climate system into a new state, one that most scientists believe has not existed for 35–50 million years” 

Ian Howat, associate professor of earth sciences at Ohio State University, says: 

“It’s generally accepted that it’s no longer a question of whether the West Antarctic Ice Sheet will melt, it’s a question of when. 

This kind of rifting (cracking) behaviour provides another mechanism for rapid retreat of these glaciers, adding to the probability that we may see significant collapse of West Antarctica in our lifetimes.”

The scientists I have communicated with take the view that Rignot, Mouginot et al. is a credible paper and, together with the evidence published since, it would be prudent to accept that WAIS has very likely passed its tipping point for mass deglaciation, with big consequences for global sea level rise (SLR). 

DeConto and Pollard project more than a metre of SLR from Antarctica this century. 

This tallies with the Hanse, Sato et al scenario, which is also consistent with the findings of Phipps, Fogwill and Turney.

The reality of multi-metre SLRs is not if, but how soon. 

“The natural state of the Earth with present CO2 levels is one with sea levels about 70 feet (21 metres) higher than now” 

says Prof. Kenneth G. Miller. 

Other research scientists agree it is likely to be more than 20 metres over the longer term.

So how much could we expect sea levels to rise this century?


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An Atmospheric River Takes aim at #California Welcome to #ClimateChange

Atmospheric River Brings Historic Flood Risk to California
California is now experiencing its worst storm yet — with the potential to reshape its history.
By Eric Holthaus

A rainbow is made by spray from water coming down the damaged main spillway of the Oroville Dam on February 14th, 2017, in Oroville, California. (Photo: Elijah Nouvelage/Getty Images)

Amid the wettest start to a rainy season in state history, California is now experiencing its worst storm yet—with the potential to reshape its history.
An atmospheric river — a narrow band of tropical moisture — is taking aim at the central California coast on Monday and Tuesday, and providing a textbook meteorological scenario for major flooding. The National Weather Service office in Sacramento used dire language to describe the threat, urging residents to be prepared to evacuate with less than 15 minutes notice and warned of flooding unseen for “many years” in some places. More than a foot of rain is expected over a 36-hour period in higher elevations.

A weather model projection of the atmospheric river, as of Monday evening, with tropical moisture creating heavy rainfall as it hits the Sierra Nevada mountain range.

As of Monday morning, a cascade of flood warnings are in effect for the Bay Area and the Central Valley, as heavy rains reach the coastline. Dozens of lightning strikes have been detected offshore, and numerous landslides are being reported. A weather station near Big Sur, on the central coast of California, picked up more than an inch of rain in just an hour — a rainfall intensity more typical of a heavy tropical thunderstorm.
By Monday evening, damaging winds nearing hurricane force could spread across much of the central and northern part of the state, prompting the National Weather Service to warn of “long-lasting” power outages for thousands of households.
Heavy rains will continue on Tuesday, at which point serious problems could begin to emerge. The fragile Oroville Dam will again be tested, but dozens of other dams — like the one at Don Pedro Reservoir near Modesto — are also nearing capacity statewide and planning emergency contingencies.
By late Tuesday, the San Joaquin River — the main hydrologic thoroughfare of the vast Central Valley — is expected to exceed a level not seen since 1997, and then keep rising the rest of the week. The river is already in “danger” stage — the stage above flood stage when critical levees could begin to become compromised.
California’s levee network constrains the flow of water as it leaves the mountains of the Sierra Nevada and makes its way toward the Delta region near Sacramento. Overwhelming this system could bring a flood that, according to a study from the United States Geological Survey in 2011, could inundate hundreds of square miles and cost hundreds of billions of dollars, knocking out the water supply for two-thirds of Californians in the process; it would be the worst disaster in American history. That study, referred to as the “ARkStorm” scenario, was designed to anticipate the impact of a flood with an expected return period of about 300 years, similar to the one the region last experienced in 1862. A 2011 New York Times Magazine article about that scenario used the word “megaflood.”
Weather models on Sunday showed that rainfall intensity on Monday near the Sacramento-San Joaquin Delta could briefly reach levels not expected more than once a century — or even once per millennium if the slow-moving atmospheric river stalls completely, a scenario consistent with past levee breaches.

Making the impact of this storm even worse is the fact that Northern California has already racked up more than double the amount of rain it typically receives between October and late February. The rainy season is running about a month ahead of the previous record-setting pace set in 1983 — a rate not seen in at least a century of record-keeping. San Francisco has already eclipsed the total it typically receives in an entire “normal” rainy season in less than half the normal time.
The ARkStorm scenario was constructed without taking into account the effects of climate change, which helps to make atmospheric rivers more intense. A warmer atmosphere increases the rate of evaporation and causes more precipitation to fall as rain instead of snow. In California, the intensity of atmospheric rivers could double or triple by the end of the century.
Should this week’s atmospheric river morph into a megaflood — and it is still unlikely, though not impossible that it will do so — it will mean California has quickly transitioned from milliennial-scale drought to a millennial-scale deluge. Welcome to climate change.

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