Sea Level Rise Flooding may Have Some Marine Ecosystem Benefits

Due to climate change, sea levels are expected to rise and flood large low-lying areas in many regions of the world. The big question is how we should cope? Should we built dykes or let the sea in?

The choice is not easy, but we have to make it. If we build dykes, we can keep the land dry. But it is a costly and sometimes risky choice. According to biologists at University of Southern Denmark, it is worth considering letting the seawater take over. The results might be more beneficial than trying to keep the water out, they suggest.

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Many Atolls may be Uninhabitable by Mid Century

Sea-level rise and wave-driven flooding will negatively impact freshwater resources on many low-lying atoll islands in such a way that many could be uninhabitable in just a few decades. According to a new study published in Science Advances, scientists found that such flooding not only will impact terrestrial infrastructure and habitats, but, more importantly, it will also make the limited freshwater resources non-potable and, therefore, directly threaten the sustainability of human populations.

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Global Warming Dates to the Beginning of the Industrial Revolution (called it!)

When Charles Dickens, the English novelist, was detailing the "soft black drizzle" of pollution over London, he might inadvertently have been chronicling the early signs of global warming.

New research led by Australian scientists has pegged back the timing of when humans had clearly begun to change the climate to the 1830s.

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Sooooo called it.

Could Cirrus Clouds Have Warmed Early Mars?

Could Cirrus Clouds Have Warmed Early Mars?

Authors:

Rameriz et al

Abstract:

The presence of the ancient valley networks on Mars indicates that the climate at 3.8 Ga was warm enough to allow substantial liquid water to flow on the martian surface for extended periods of time. However, the mechanism for producing this warming continues to be debated. One hypothesis is that Mars could have been kept warm by global cirrus cloud decks in a CO2-H2O atmosphere containing at least 0.25 bar of CO2 (Urata and Toon, 2013). Initial warming from some other process, e.g., impacts, would be required to make this model work. Those results were generated using the CAM 3-D global climate model. Here, we use a single-column radiative-convective climate model to further investigate the cirrus cloud warming hypothesis. Our calculations indicate that cirrus cloud decks could have produced global mean surface temperatures above freezing, but only if cirrus cloud cover approaches ~75 - 100% and if other cloud properties (e.g., height, optical depth, particle size) are chosen favorably. However, at more realistic cirrus cloud fractions, or if cloud parameters are not optimal, cirrus clouds do not provide the necessary warming, suggesting that other greenhouse mechanisms are needed.

Obliquity-forced climate during the Early Triassic hothouse in China

Obliquity-forced climate during the Early Triassic hothouse in China

Authors:

Li et al

Abstract:

The start of the Mesozoic Era is marked by roughly 5 m.y. of Earth system upheavals, including unstable biotic recovery, repeated global warming, ocean anoxia, and perturbations in the global carbon cycle. Intervals between crises were comparably hospitable to life. The causes of these upheavals are unknown, but are thought to be linked to recurrent Siberian volcanism. Here, two marine sedimentary successions at Chaohu and Daxiakou (South China) are evaluated for paleoclimate change from astronomical forcing. In these sections, gamma-ray variations indicative of terrestrial weathering reveal enhanced obliquity cycling over prolonged intervals, characterized by a 32.8 k.y. periodicity with strong 1.2 m.y. modulations. These suggest a 22 h length of day and 1.2 m.y. interaction between the orbital inclinations of Earth and Mars. Comparing the 1.2 m.y. obliquity modulation cycles in these sections with Early Triassic records of global sea level, temperature, redox, and biotic evolution suggests that long-term astronomical forcing was involved in the repeated climatic and biotic upheavals that took place throughout the Early Triassic.

Bramble Cay melomy: First Mammal Species Recognized to Have Gone Extinct due to Global Warming

Climate change is by definition a global phenomenon, but there are few locations feeling its immediate impacts like Australia's Great Barrier Reef. Just a month after local scientists were left reeling as warming seas triggered the worst coral bleaching event in its history, researchers are now reporting the reef's only endemic mammal species has become extinct as a result of rising sea levels, describing its demise as the first mammal species to be killed off by human-induced global warming.

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Ichthyosaurs Went Extinct due to Extreme Global Warming

Why ichthyosaurs — marine Mesozoic reptiles — disappeared before the dinosaur extinction has remained a mystery. New research suggests they may have gone extinct stepwise, during one of the most extreme greenhouse periods in the history of complex life-forms.

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Antarctic coastline images reveal 4 decades of ice loss to ocean

Part of Antarctica has been losing ice to the ocean for far longer than had been expected, satellite pictures reveal.

A study of images along 2000km of West Antarctica's coastline has shown the loss of about 1000km2 of ice - an area equivalent to the city of Berlin - over the past 40 years.

Researchers were surprised to find that the region has been losing ice for such a length of time. Their findings will help improve estimates of global sea level rise caused by ice melt.

A research team from the University of Edinburgh analysed hundreds of satellite photographs of the ice margin captured by NASA, the United States Geological Survey (USGS) and the European Space Agency (ESA).

They found that ice has been retreating consistently along almost the entire coastline of Antarctica's Bellingshausen Sea since satellite records began.

The team also monitored ice thickness and thinning rates using data taken from satellites and the air. This showed that some of the largest changes, where ice has rapidly thinned and retreated several miles since 1975, correspond to where the ice front is deepest.

Scientists suggest the loss of ice is probably caused by warmer ocean waters reaching Antarctica's coast, rather than rising air temperatures. They say further satellite monitoring is needed to enable scientists to track progress of the ice sheet.

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Russia Opposed to US-China on Global Warming Pact

Russia set itself at odds with a drive by China and the United States for rapid ratification of a global agreement to slow climate change when a senior official said on Wednesday that Moscow first wanted a clear set of rules.

Negotiating a detailed rule book for the 2015 Paris Agreement for shifting the world economy from fossil fuels could take years, in the worst case, delegates said at May 16-26 U.N. talks in Bonn on implementing the pact.

Top greenhouse gas emitters China and the United States say they plan to join the Paris Agreement this year and almost all other nations say they will ratify as rapidly as possible -before the rules are in place.

But Russia, the number three greenhouse gas emitter, questioned the plan in a rare sign of disagreement about implementation.

The Agreement can still enter into force without Russia, because it requires at least 55 nations representing 55 percent of global greenhouse gases to gain legal force. Russia, the number three emitter, only accounts for 7.5 percent.

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Cephalopods may be Spreading due to Climate Change

Humans have changed the world's oceans in ways that have been devastating to many marine species. But, according to new evidence, it appears that the change has so far been good for cephalopods, the group including octopuses, cuttlefish, and squid. The study reported in the Cell Press journal Current Biology on May 23 shows that cephalopods' numbers have increased significantly over the last six decades.

"The consistency was the biggest surprise," says Zoë Doubleday of Australia's Environment Institute at the University of Adelaide. "Cephalopods are notoriously variable, and population abundance can fluctuate wildly, both within and among species. The fact that we observed consistent, long-term increases in three diverse groups of cephalopods, which inhabit everything from rock pools to open oceans, is remarkable."

According to the researchers, there has been growing speculation that cephalopod populations were proliferating in response to a changing environment, based partly on trends in cephalopod fisheries. Cephalopods are known for rapid growth, short lifespans, and extra-sensitive physiologies, which may allow them to adapt more quickly than many other marine species.

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Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate

Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate

Authors:

Anagnostou et al

Abstract:

The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago)1, was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period2, 3, 4. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500–3,000 parts per million5, 6, 7, and in the absence of tighter constraints carbon–climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments8, 9, 10, 11 to generate a new high-fidelity record of CO2 concentrations using the boron isotope (δ11B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates6. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene12. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period13, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene14. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed2, 3, 4, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the canonical range (1.5 to 4.5 degrees Celsius15), indicating that a large fraction of the warmth of the early Eocene greenhouse was driven by increased CO2 concentrations, and that climate sensitivity was relatively constant throughout this period.

Iron Fertilization Will NOT Work in the Pacific

Over the past half-million years, the equatorial Pacific Ocean has seen five spikes in the amount of iron-laden dust blown in from the continents. In theory, those bursts should have turbo-charged the growth of the ocean's carbon-capturing algae - algae need iron to grow - but a new study shows that the excess iron had little to no effect.

The results are important today, because as groups search for ways to combat climate change, some are exploring fertilizing the oceans with iron as a solution.

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Regrowing Latin American Forests Could Significantly Help With Global Warming

Forests re-grown on lands that had been cleared for agriculture in Latin America could play a key role in trapping carbon from the atmosphere and mitigating climate change if they are managed properly, researchers said in a study published on Friday.

Over the next 40 years, such second-growth forests have the potential to sequester greenhouse gas emissions equivalent to all fossil fuel and industrial emissions from Latin America in the past two decades, said the study by scientists at the University of Connecticut.

While preventing deforestation is the best protection against releasing climate-changing gases, the study published in the journal Science Advances shows that re-grown forests have a bigger impact in combating global warming than previously thought.

"Avoiding deforestation and supporting forest regeneration are complementary and mutually reinforcing activities," said Robin Chazdon, a professor of evolutionary biology at the University of Connecticut and lead author of the study.

For re-growing forests to live up to their potential in sucking carbon out of the atmosphere in the tropics, governments across Latin America need to work with local communities to ensure the land is protected, Chazdon said.

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Climate Change Likely to Cause Mass Exodus From Middle East

The number of climate refugees could increase dramatically in future. Researchers of the Max Planck Institute for Chemistry and the Cyprus Institute in Nicosia have calculated that the Middle East and North Africa could become so hot that human habitability is compromised. The goal of limiting global warming to less than two degrees Celsius, agreed at the recent UN climate summit in Paris, will not be sufficient to prevent this scenario. The temperature during summer in the already very hot Middle East and North Africa will increase more than two times faster compared to the average global warming. This means that during hot days temperatures south of the Mediterranean will reach around 46 degrees Celsius (approximately 114 degrees Fahrenheit) by mid-century. Such extremely hot days will occur five times more often than was the case at the turn of the millennium. In combination with increasing air pollution by windblown desert dust, the environmental conditions could become intolerable and may force people to migrate.

More than 500 million people live in the Middle East and North Africa - a region which is very hot in summer and where climate change is already evident. The number of extremely hot days has doubled since 1970. "In future, the climate in large parts of the Middle East and North Africa could change in such a manner that the very existence of its inhabitants is in jeopardy," says Jos Lelieveld, Director at the Max Planck Institute for Chemistry and Professor at the Cyprus Institute.

Lelieveld and his colleagues have investigated how temperatures will develop in the Middle East and North Africa over the course of the 21st century. The result is deeply alarming: Even if Earth's temperature were to increase on average only by two degrees Celsius compared to pre-industrial times, the temperature in summer in these regions will increase more than twofold. By mid-century, during the warmest periods, temperatures will not fall below 30 degrees at night, and during daytime they could rise to 46 degrees Celsius (approximately 114 degrees Fahrenheit). By the end of the century, midday temperatures on hot days could even climb to 50 degrees Celsius (approximately 122 degrees Fahrenheit). Another finding: Heat waves could occur ten times more often than they do now.

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Oceanic Hypoxia to Become Readily Apparent in 2030s

A reduction in the amount of oxygen dissolved in the oceans due to climate change is already discernible in some parts of the world and should be evident across large regions of the oceans between 2030 and 2040, according to a new study led by the National Center for Atmospheric Research (NCAR).

Scientists know that a warming climate can be expected to gradually sap oceans of oxygen, leaving fish, crabs, squid, sea stars, and other marine life struggling to breathe. But it's been difficult to determine whether this anticipated oxygen drain is already having a noticeable impact.

"Loss of oxygen in the ocean is one of the serious side effects of a warming atmosphere, and a major threat to marine life," said NCAR scientist Matthew Long, lead author of the study. "Since oxygen concentrations in the ocean naturally vary depending on variations in winds and temperature at the surface, it's been challenging to attribute any deoxygenation to climate change. This new study tells us when we can expect the impact from climate change to overwhelm the natural variability."

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Does Climate Change Threaten the Primates?

This is the battle that nobody wins. According to a new study, climate change will adversely affect every single primate species on Earth. That’s every ape, monkey, gibbon, lemur and loris, no matter how super or strong they might be.

The study, published in the International Journal of Primatology, reveals that primate habitats will, on average, feel the pinch of a warming world 10 percent more severely than non-primate habitats. Not only will temperatures change, so will rainfall, with some species experiencing 7.5 percent more or less precipitation per degree C of global warming.

This is troubling news for the world’s primates, as many species rely on narrow habitats or have extremely specialized diets. Some primates only eat one or two things, so their food and habitats are particularly sensitive to disruption. Many primates are already endangered by habitat loss, hunting, or the illegal pet trade, so this additional threat could push several species over the brink.

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The Importance of Atmospheric Carbon in the end of the Last Glaciation

As the Earth emerged from its last ice age several thousand years ago, atmospheric carbon dioxide increased and further warmed the planet. Scientists have long speculated that the primary source of this CO2 was from the deep ocean around Antarctica, though it has been difficult to prove.

A new study published this week in Proceedings of the National Academy of Sciences confirmed that the ocean played a significant role in the rise of atmospheric carbon dioxide, but also documents the signature of land-based carbon sources in Antarctic ice cores that contributed to abrupt increases in CO2.

"There wasn't a steady rate of rising carbon dioxide during the last deglaciation," said Edward Brook, an Oregon State University paleoclimatologist and co-author on the PNAS study. "It happened in fits and starts. With the new precise techniques we developed to fingerprint the sources, it is apparent that the early carbon largely came from the ocean, but we think the system got a jolt from an influx of land-based carbon a few times as the climate warmed."

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The Market is not Enough to end Fossil Fuel use

In recent years, proponents of clean energy have taken heart in the falling prices of solar and wind power, hoping they will drive an energy revolution. But a new study co-authored by an MIT professor suggests otherwise: Technology-driven cost reductions in fossil fuels will lead us to continue using all the oil, gas, and coal we can, unless governments pass new taxes on carbon emissions.

"If we don't adopt new policies, we're not going to be leaving fossil fuels in the ground," says Christopher Knittel, an energy economist at the MIT Sloan School of Management. "We need both a policy like a carbon tax and to put more R&D money into renewables."

While renewable energy has made promising gains in just the last few years -- the cost of solar dropped by about two-thirds from 2009 to 2014 -- new drilling and extraction techniques have made fossil fuels cheaper and markedly increased the amount of oil and gas we can tap into. In the U.S. alone, oil reserves have expanded 59 percent between 2000 and 2014, and natural gas reserves have expanded 94 percent in the same time.

"You often hear, when fossil fuel prices are going up, that if we just leave the market alone we'll wean ourselves off fossil fuels," adds Knittel. "But the message from the data is clear: That's not going to happen any time soon."

This trend -- in which cheaper renewables are outpaced by even cheaper fossil fuels -- portends drastic climate problems, since fossil fuel use has helped produce record warm temperatures worldwide.

The study concludes that burning all available fossil fuels would raise global average temperatures 10 to 15 degrees Fahrenheit by the year 2100; burning oil shale and methane hydrates, two more potential sources of copious fossil fuels, would add another 1.5 to 6.2 degrees Fahrenheit to that.

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American Southwest may Mimic Drought Conditions That Destroyed Anasazi/Ancestral Puebloans due to Global Warming

The weather patterns that typically bring moisture to the Southwest are becoming more rare, an indication that the region is sliding into the drier climate state predicted by global models, according to a new study.

"A normal year in the Southwest is now drier than it once was," said Andreas Prein, a researcher at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, who led the study. "If you have a drought nowadays, it will be more severe because our base state is drier."

Climate models generally agree that human-caused climate change will push the southwestern United States to become drier. And in recent years, the region has been stricken by drought. But linking model predictions to changes on the ground is challenging.

For the study, the researchers analyzed 35 years' worth of data to identify common weather patterns -- arrangements of high and low pressure systems that determine where it's likely to be sunny and clear or cloudy and wet.

They identified a dozen patterns that are usual for the weather activity in the contiguous U.S., then looked to see whether those patterns were becoming more or less frequent.

"The weather types that are becoming more rare are the ones that bring a lot of rain to the southwestern United States," Prein said. "Because only a few weather patterns bring precipitation to the Southwest, those changes have a dramatic impact."

The Southwest is especially vulnerable to any additional drying. The region, already the most arid in the country, is home to a quickly growing population that is putting tremendous stress on its limited water resources.

"Prolonged drought has many adverse effects, so understanding regional precipitation trends is vital for the well-being of society," says Anjuli Bamzai, program director in the National Science Foundation (NSF) Division of Atmospheric and Geospace Sciences, which funded the research. "These researchers demonstrate that subtle shifts in large-scale weather patterns over the past three decades or so have been the dominant factor in precipitation trends in the southwestern United States."

The study also found an opposite, though smaller, effect in the Northeast, where some of the weather patterns that typically bring moisture to the region are increasing.

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Human Caused Global Warming has Postponed the Next Glacial Cycle by at Least 50,000 Years

Humanity has become a geological force that is able to suppress the beginning of the next ice age, a study now published in the renowned scientific journal Nature shows. Cracking the code of glacial inception, scientists of the Potsdam Institute for Climate Impact Research found the relation of insolation and CO2 concentration in the atmosphere to be the key criterion to explain the last eight glacial cycles in Earth history. At the same time their results illustrate that even moderate human interference with the planet's natural carbon balance might postpone the next glacial inception by 100.000 years.

"Even without man-made climate change we would expect the beginning of a new ice age no earlier than in 50.000 years from now - which makes the Holocene as the present geological epoch an unusually long period in between ice ages," explains lead author Andrey Ganopolski. "However, our study also shows that relatively moderate additional anthropogenic CO2-emissions from burning oil, coal and gas are already sufficient to postpone the next ice age for another 50.000 years. The bottom line is that we are basically skipping a whole glacial cycle, which is unprecedented. It is mind-boggling that humankind is able to interfere with a mechanism that shaped the world as we know it."

For the first time, research can explain the onset of the past eight ice ages by quantifying several key factors that preceded the formation of each glacial cycle. "Our results indicate a unique functional relationship between summer insolation and atmospheric CO2 for the beginning of a large-scale ice-sheet growth which does not only explain the past, but also enables us to anticipate future periods when glacial inception might occur again," Ganopolski says.

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