Cut carbon now to avoid climate tipping points

Cut carbon now to avoid climate tipping points

The price to be paid for not cutting greenhouse gas emissions could push the planetary climate system closer to irreversible “tipping points”.

LONDON, 3 April, 2015 – An international team of scientists has tried a new approach to addressing the complex argument about the costs of climate change – and, once again, the prediction is that the costs of inaction will be so much greater than paying the bills now.

The researchers − from the UK, Switzerland and the US − conclude that policy-makers must apply the brakes and put a high price on carbon emissions “before it is too late”.

Much of the argument on this issue revolves around the perceived cost of carbon emissions and any tax that should be imposed on fossil fuel use. Social scientists and economists and climate modellers have tried a number of approaches.

One group tried to work out the interval between the burning of fossil fuels and the consequent greenhouse warming, and concluded it could be as little as 10 years.

Other groups have separately tried to calculate the true cost of emitted carbon dioxide. The US government works on the basis of $37 in social costs per tonne emitted, but two US scientists proposed that the true cost in future health and habitat losses was probably six times higher.

“The additional carbon tax that our model recommends can be thought of as an insurance premium levied on society”

And yet another researcher began to examine the costs of petrol, or coal, or methane gas if the long-term economic damage and health costs were factored in, and concluded that these made “expensive” renewables cheap by comparison.

Now researchers from the universities of Exeter in the UK, Zurich in Switzerland and Chicago and Stanford in the US report in Nature Climate Change that they considered the risk that emitted greenhouse gases from fossil fuels would push the planetary climate system closer to what climate scientists call “tipping points.”

These are outcomes that would irreversibly change regional climate patterns, disrupt agriculture, precipitate greater flooding in some places, more sustained droughts in others, and accelerate sea level rise.

And, once again, they find that governments have underestimated the price to be paid by society for carbon dioxide emissions from fossil fuels.

“We are calling on policy-makers to respond to the prospect of triggering future climate tipping points by applying the brakes now and putting a high price on carbon emissions before it is too late,” says one of the authors, Tim Lenton, professor of climate change and earth system science at the University of Exeter.

“The additional carbon tax that our model recommends can be thought of as an insurance premium levied on society to delay irreversible changes in the future.”

The researchers selected five potential tipping points − all of which have separately been in the news recently. They relate to:

The researchers say their act-now, save-future-costs model not only demonstrates the dangers of underestimating the cost of future climate change, but is the first one to emerge from a purely market-based approach. The considerations do not have to be based on moral judgements about sustainability and the wellbeing of future generations. – Climate News Network

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Two oceans may explain global warming pause

Two oceans may explain global warming pause

Temperatures may be rising more slowly than expected because of two natural oceanic cycles − the latest refutation of the global warming “pause”.

LONDON, 1 March, 2015 − US scientists have suggested yet another explanation for the so-called pause in global warming. They think it might all be down to the juxtaposition of two independent natural climate cycles – each with periods of half a century or more – one of which is blowing cold, and the other not very hot.

Between them, the phenomena known to meteorologists as the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation could account for the seeming slowdown in predicted temperature rises.

Any pause or hiatus in global warming is only apparent: in fact, 14 of the warmest years on record have happened in the last 15 years and 2014 was scored separately, by the World Meteorological Organisation, the US National Oceanic and Atmospheric Administration, and the US space agency Nasa,  as the warmest on record.

But overall, the palpable increases in average temperatures per decade recorded in the last 30 years of the 20th century have not been maintained, and climate scientists and meteorologists have been trying to work out why.

The latest proposal is from Byron Steinman, a geologist at the University of Minnesota Duluth, and Michael Mann and Sonya Miller of Pennsylvania State University.

Multiple theories

Professor Mann is the scientist who, much to the fury of people who deny climate change, first formulated the famous “hockey-stick graph” which highlights the magnitude of change that threatens to overtake global climate as greenhouse gas levels rise because of human activity.

They report in Science that the northern hemisphere is warming more slowly, not because of the Atlantic oscillation, which has been relatively flat, but because of a second, different but still natural downward trend in the Pacific cycle.

This is not the only explanation on the table. In the past two years Climate News Network has reported that climate scientists certainly expected a slowdown, but just not right now; or that planetary measurements might be incomplete or misleading; or that even though average levels were down, this masked a series of hotter extremes.

The oceans have certainly been under suspicion. One group has already identified the cooling Pacific as a damper on global warming. Another has suggested that in fact the “missing heat” is collecting in the Atlantic depths.

Yet another has questioned the role of the trade winds, while still another has pointed to an upswing in volcanic activity that could have delivered a fine smear of sunblock aerosols to the atmosphere.

“The North Atlantic and North Pacific Oceans appear to be drivers of substantial natural… climate variability on timescales of decades”

Any or all of these could have some role in the big picture. The climate would vary anyway, and the question in every case is: how much would any or all natural variation affect the overall path of change because of increasing carbon dioxide levels in the atmosphere?

The latest study is based on sophisticated climate models that match the predicted impact of the great ocean-atmosphere cycles with the pattern of climate shifts recorded in the past.

“We know that it is important to distinguish between human-caused and natural climate variability so we can assess the impact of human-caused climate change, including drought and weather extremes,” Professor Mann said.

“The North Atlantic and North Pacific Oceans appear to be drivers of substantial natural, internal climate variability on timescales of decades.” – Climate News Network

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Ancient shells offer evidence of how Ice Age ended

Ancient shells offer evidence of how Ice Age ended

Ocean sediment reveals that release of carbon stored deep in the sea is linked to the rise in atmospheric CO2 that caused the world to warm.

LONDON, 13 February, 2015 − Scientists believe they may have cracked the mystery of the end of the last ice age. The temperatures suddenly soared, and the glaciers went into retreat, because the deep southern ocean released huge quantities of carbon dioxide.

And the convincing answers have been delivered by analysis of the composition of calcium carbonate shells of ancient marine organisms.

The link between human burning of fossil fuels and the steady rise in atmospheric carbon dioxide levels was proposed more than a century ago and firmly established in the last 30 years.

But the ups and downs of planetary temperatures before the emergence of human civilisation are harder to explain. Fossil evidence suggests a link with carbon dioxide levels, but not necessarily a cause.

Bygone climates

Now paleoceanographer Miguel Martínez-Botí, from the University of Southampton, UK, and ocean and climate change researcher Gianluca Marino, from the Australian National University, report in Nature that they found their evidence in sediment cores – in effect, annual records of bygone climates – rich in the shells of tiny foraminifera called Globigerina bulloides.

This is a species that flourishes in conditions of high nutrients, acting as a kind of biological pump, gulping carbon from the atmosphere.

They found that high concentrations of carbon dioxide dissolved in surface waters of the southern Atlantic Ocean and the eastern equatorial Pacific coincided with rises in atmospheric CO2 at the end of the last ice age.

The implication is that these regions were the source of the carbon dioxide to the atmosphere.

“Our findings support the theory that a series of processes in the Southern Ocean changed the amount of carbon in the deep sea”

At their coldest, during the ice ages, carbon dioxide levels fell to 185 parts per million. During the interglacials, when the world warmed and lions and hyenas roamed the plains of Europe, the carbon dioxide levels rose to 280 ppm.

Right now, thanks to human activity, CO2 levels are rising ominously towards 400 ppm.

The oceans are home to about 60 times more carbon than the atmosphere and can, it seems, surrender it rapidly.

“The magnitude and rapidity of the swings in atmospheric CO2 across the ice age cycles suggest that changes in ocean carbon storage are important drivers of natural atmospheric CO2 variations,” Dr Martínez-Botí says.

“Our findings support the theory that a series of processes operating in the southernmost sector of the Atlantic, Pacific and Indian oceans, a region known as the Southern Ocean, changed the amount of carbon in the deep sea.

Into the abyss

“While a reduction in communication between the deep sea and the atmosphere in this region potentially locks carbon away from the atmosphere into the abyss during ice ages, the opposite occurs during warm interglacial periods.”

To arrive at their conclusion, the scientists had to analyse subtle evidence from the isotopic composition of the carbonate shells, and then use mathematical techniques to reconstruct a story of a great, faraway sigh of carbon dioxide from the ocean to the atmosphere.

The finding, based on calculated probabilities, is incomplete as there may have been other forces also at play.

Gavin Foster, associate professor in isotope geochemistry at the University of Southampton, says: “While our results support a primary role for the Southern Ocean processes in these natural cycles, we don’t yet know the full story. Other processes operating in other parts of the ocean, such as the north Pacific, may have an additional role to play.” – Climate News Network

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Surfers fear climate will wipe out big waves

Surfers fear climate will wipe out big waves

Dedicated surfers, deeply involved with monitoring the natural coastal environment around the world, warn that climate change now poses a major threat to this booming leisure industry.

LONDON, 5 October, 2014 − The world’s oceans are alive with surfers enjoying one of the fastest growing leisure activities. It is estimated there are now at least 35 million people around the globe who regularly ride the waves, and many thousands of people are employed in what has grown into a multi-billion dollar industry.

A warming world should be good news for all those artists of the waves. Warming oceans mean more storms, and the theory goes that more storms will lead to ever bigger waves. So why then are surfing websites – the internet is waterlogged with them – full of concern about changes in the climate?

Two studies appearing in the journal Nature Climate Change have made surfers stand up on their boards and reconsider the situation.

A study led by Dr Andrew Dowdy, a researcher at the Centre for Australian Weather and Climate Research (CAWCR) predicts that rising temperatures will in fact reduce the number of storms causing big waves by the end of the century on the central east coast of Australia.

Potentially destructive

The storms that do occur could be more intense and potentially destructive – but the consistency of wave patterns will be reduced.

That’s bad news for surfers of the future in that area – one of the world’s surfing hotspots. They’ll just have to move elsewhere. Dowdy told the Climate News Network that his projections only relate to that particular region, and they are not necessarily applicable to other coastal regions.

But another study, led by Mark Hemer, a senior research scientist at CAWCR, indicates that surfers might be having to ride smaller waves in future in other parts of the world as well.

Using ocean modelling techniques, Hemer and his colleagues predict a decrease in annual wave height over more than 25% of the global ocean area by the end of the century. The North Atlantic is likely to see a decrease in wave heights during all seasons, and waves are likely to be smaller in the winter months in the North Pacific and Indian Ocean.

But all is not lost. The study predicts that some regions − including  the waters off the south coast of Australia and New Zealand − will see bigger waves of between 5% and 10% above present size averages during winter months.

Surfers are worried about other climate change related threats to their activities. There are fears that rising sea levels could threaten key surfing areas.

Surfers regularly monitor water conditions – everything from acidity levels to rubbish content and sewage levels in the seas.

Surf zone

The Save the Waves Coalition − a US-based group that lobbies to protect the coastal environment, with a particular focus on what it calls the surf zone − monitors development activities in surfing areas worldwide.

Its “endangered waves” campaign lists projects that threaten key surfing areas – from plans to construct a nuclear power station on the coast of South Africa to a series of coal-fired power plants proposed for the coast of Chile.

And Climate change is seen as a major challenge facing the surfing industry.

“The unfortunate truth is that the threats to surfing habitat are now growing exponentially due to the impacts of man-made climate change,” says the California-based Sustainable Surf organisation. – Climate News Network

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May days’ heat sets up record El Niño

May days’ heat sets up record El Niño

Scientists believe that soaring global temperatures during an unusually hot month of May may have created the ideal conditions to provide a warm welcome for an El Niño weather phenomenon that will break records

LONDON, 20 June, 2014 − Last month was the third warmest May since NASA satellites began taking the temperature of the planet 35 years ago, and was also the warmest May that did not fall within an El Niño Pacific warming event – which could mean a record-breaking appearance this year by the fearsome “Child”.

Scientists in the US says the global average was 0.33°C warmer than the seasonal norms for the month. The warmest May ever was in 1998 during the “El Niño of the century”, when global average temperatures rose by 0.56°C, and the second warmest at 0.45°C was in 2010, another El Niño year.

So if indications are correct that an El Niño event is taking shape in the Pacific right now off the equatorial coast of South America, then it could become a record-setter − even if it isn’t a very spectacular event − just because it will get a warmer start, according to John Christy, professor of atmospheric science at the University of Alabama in Huntsville, US.

Temperature patterns

An El Niño (Spanish for The Child, because it was first observed by Peruvian fishermen around Christmas) is a shift in the temperature patterns of the Pacific, as a blister of equatorial ocean heat moves eastwards. It is a natural cyclic event that tends to reverse the prevailing Pacific weather patterns, often damagingly, and is not connected with climate change  although its effects could be made worse by climate change.

“The long-term baseline temperature is about three tenths of a degree warmer than it was when the big El Niño of 1997-1998 began, and that event set the one month record,” Christy said. “With the baseline so much warmer, this upcoming El Niño won’t have very far to go to break that 0.66°C record. That isn’t to say it will, but even an average-sized warming event will have a chance to get close to that level.”

Meanwhile, according to new research in Nature Climate Change, people in the northern hemisphere can also expect warmer temperatures in autumn and winter – in spite of last winter’s spectacular ice storms in the US north-east that shut down cities from the Atlantic to the Midwest, and where − to the joy of headline writers − the town of Hell in Michigan froze over.

Extremes of cold

The report’s author, James Screen, Natural Environment Research Council research fellow at the University of Exeter, UK, says that even though there will be extremes of cold, these will be less frequent and less severe. The Arctic is warming, and a study of autumn and winter temperature variations shows that variability in the temperate zone overall has in fact decreased.

“Autumn and winter days are becoming warmer on average, and less variable from day to day,” Dr Screen said. “Both factors reduce the chance of extremely cold days.

“Cold days tend to occur when the wind is blowing from the north, bringing Arctic air south into the mid-latitudes. Because the Arctic air is warming so rapidly, these cold days are now less cold than they were in the past.” – Climate News Network

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Trade winds draw ‘missing’ warmth to deep ocean

Trade winds draw 'missing' warmth to deep ocean

FOR IMMEDIATE RELEASE
Contrary to some reports, global warming hasn’t stopped or slowed at all, new research suggests. The trade winds have simply carried the heat into the Pacific Ocean – temporarily.

LONDON, 10 February – Australian and US scientists think they know where a lot of global warming has been concentrated: it has been tucked away below the surface waters of the western Pacific Ocean. And the agency that took the heat out of the atmosphere and transferred it into a liquid form could have been the equatorial trade winds.

Matthew England from the Australian Centre of Excellence for Climate System Science and colleagues report in Nature Climate Change that a dramatic acceleration in the winds has drawn heat from the atmosphere and transferred it to the ocean: cooler waters have risen to the surface to mask the transaction.

Climate sceptics – and some climate scientists – talk about a slowdown, or a pause, or a hiatus in global warming. In fact, temperatures have gone on rising and 13 of the 14 warmest years ever recorded have all occurred since 2000. But the rate of rise in global average temperatures since 2000 has not been as fast as the rate during the 1980s and 1990s.

Since greenhouse gas levels have continued to rise, and since scientists are sure of their atmospheric physics, then there was some “missing heat” to be accounted for.

Researchers have variously suggested that a puzzling increase in deep ocean temperatures could be one explanation or that perhaps the unevenness of temperature measurements around the planet might be another. But both suggestions were hypotheses: nobody had an answer that could be tested by any kind of experiment.

Slower rate

Professor England and colleagues worked with observed winds, surface air temperatures, and a set of ocean climate models to calculate what may have happened.

The global warming story has always been one of fits and starts: a warming that ought to have been observed 70 years ago stalled between 1940 and 1970, and when it resumed, did so in fits and starts. The overall trend continued upward, but the rate of rise slowed noticeably during the last decade.

Ocean circulation loops are driven by winds, and speed up as the winds intensify. Cool waters well up, warm waters descend. And intensify is just what the trade winds have done. They began strengthening during the 1990s, a process which continues today. Once the researchers added the trade winds to their calculations, the global average temperatures looked very like the observations during the hiatus.

They also found that four-fifths of the surface temperature cooling occurred after 2000, which confirmed that wind acceleration was the key contributor.

“Scientists have long suspected that extra ocean heat uptake has slowed the rise of global average temperatures, but the mechanism behind the hiatus remained unclear”, said Professor England.

Rapid rise on the way

“But the heat uptake is by no means permanent: when the trade wind strength returns to normal – as it inevitably will – our research suggests heat will quickly accumulate in the atmosphere. So global temperatures look set to rise rapidly out of the hiatus, returning to the levels projected within as little as a decade.”

The same mechanism could explain the slowdown between 1940 and 1970. In 1938, the British scientist G S Callendar argued that rising carbon dioxide levels should mean global warming but the evidence proved elusive, perhaps because the trade winds accelerated during those decades.

Richard Allan, professor of climate science at the University of Reading in the UK, said the current slowdown was only a temporary reprieve.

“Measurements from satellites and ocean buoys show that the planet is absorbing more heat than it is radiating out to space and the heat is building up in the oceans.

“This new research suggests that when the trade winds weaken again, the planet can expect rapid warming of the surface to resume, as greenhouse gas concentrations continue to rise.” – Climate News Network

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