G24 INSTA NWT_Climate NWT_Environment Research SCI

Global warming ‘hiatus’ is about to end, study says

A new study suggests that the global warming “hiatus” is about to come to an end and make way for even higher temperatures. While the past four years have been the warmest on record, the new data suggests that natural factors are going to push our already heating planet even further into extreme temperature ranges.

“It will be even warmer than the long-term global warming is inducing,” said Florian Sevellec, lead author of the study.

The recent “hiatus” is the result of natural variability of the planet, which has been running for almost a decade.

“I’m not at all surprised by the results,” said John Fyfe, senior research scientist at the Canadian Centre for Climate Modelling and Analysis at Environment and Climate Change Canada. “And the reason for that is that we have gone down this long slowdown period primarily due to internal variability, and the expectation was that we’d come out of it.”

However, it is important to note that these predictions are based on probabilities, not certainties. In particular, the study’s model suggests that temperatures will be higher than predicted due to increased carbon dioxide levels.

“Because we tested it over the last century, we know that we are accurate for the likelihood,” Sevellac said. “But the likelihood doesn’t mean it will occur … there exists a small chance of being cold.”

While the study shows that Earth’s natural variability can have short-term influence, it also points to future trends.

“I think it’s also a demonstration that global warming will still be there after all this natural variability,” Sevellac said.

The findings were published in Nature Communications.

NWT_Climate NWT_Environment SCI

Climate impact is evident in the seasons

Scientists have determined that people are responsible for global warming by looking at weather records. They also can dust for fingerprints (ecological footprints) in other places.

A new study led by Lawrence Livermore National Laboratory’s Ben Santer looked for prints in a new place: the seasonal cycle of temperatures. The perfect tool for analyzing this is the global temperature record satellites produce.

The satellites do not go back quite as far as weather-station records, but the dataset is now long enough to be useful for climate studies. Several groups maintain separate satellite temperature datasets.

A huge amount of work went into all the necessary processing to produce temperature maps. Therefore, the different datasets do not always line up perfectly with each other.

Santer’s study involved using the most recent two versions of three different datasets. Each one tracks different layers of the atmosphere.

One record covers the lower troposphere. The other one covers the middle troposphere that is a little higher.

By tracking the difference between the coldest months and warmest summer months, they were able to see interesting regional patterns. The team averaged together the Northern Hemisphere’s mid-latitude stripe and discovered a larger seasonal temperature swing than in the Southern Hemisphere. The reason for this is there is a much greater area of land.

Nevertheless, this seasonal cycle has also increased significantly since 1979. It is a result of summer temperatures in the atmosphere rising faster than winter temperatures.


NWT_Climate Research SCI

Great Barrier Reef ‘close to collapse’ due to climate change

A plan endorsed by Australian federal and state governments suggests that the current climate change path means that the Great Barrier Reef is heading toward a “collapse.” A “new and improved” Reef 2050 plan released on Friday attempts to acknowledge that climate change poses a huge threat to the reef.

“Coral bleaching is projected to increase in frequency … those coral reefs that survive are expected to be less biodiverse than in the past,” the plan says, recognizing that “holding the global temperature increase to 1.5°C or less is critical to ensure the survival of coral reefs”.

“Respected coral scientists have documented in peer-reviewed journals that most of the world’s coral reefs will not survive unless the global temperature increase is limited to 1.5 degrees Celsius above pre-industrial levels,” it continued.

WWF-Australia head of oceans Richard Leck claims that Australia’s emissions reductions are not in line with limiting warming to 2 degrees Celsius.

“It is simply not good enough for the revised plan to suggest the global community must work to limit warming when Australia is not doing its fair share,” he said.

Australian Marine Conservation Society’s reef campaign director Imogen Zethoven claims that increased climate change recognition must be followed by action, suggesting that bleaching events would happen less often under an average temperature increase of 1.6 degrees Celsius.

“The onset of twice-a-decade bleaching will then become the onset of annual bleaching and eventually [the entire reef] will be affected,” she said.

Whether or not Australia will be able to save the Great Barrier Reef in time is yet to be seen.

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Global warming might cause insects to eat more crops, study says

A new study suggests that climate warming will increase crop losses for critical food grains due to the increased metabolic rate and population growth of insect pests.

“Climate change will have a negative impact on crops,” said Scott Merrill of the University of Vermont, co-author of the study. “We’re going to see increased pest pressure with climate change.”

The team found that just a 2-degree increase in global temperature averages will cause total crop losses of around 213 million tons for rice, wheat, and maize crops. These losses will stem from increased insect metabolism.

“When the temperature increases, the insects’ metabolism increases so they have to eat more,” Merrill said. “That’s not good for crops.”

However, the connection to population growth is more complicated. Since insects have optimal temperatures for population growth, losses will be highest in temperate regions and less severe in tropics.

“Temperate regions are not at that optimal temperature, so if the temperature increases there, populations will grow faster,” Merrill said. “But insects in the tropics are already close to their optimal temperature, so the populations will actually grow slower. It’s just too hot for them.”

Ultimately, farmers will have to find novel pest management methods, such as adding new crop rotations or boosting pesticide use. However, not all of these strategies will be available to every farmer.

“There are a lot of things richer countries can do to reduce the effect, by increasing pesticide use or expanding integrated pest management strategies,” Merrill said. “But poorer countries that rely on these crops as staple grains will have a harder time.”

The findings were published in Science.

NWT_Climate NWT_Environment SCI

Climate change could make Earth’s ecosystems unrecognizable

A new study suggests that dramatic changes in the Earth’s vegetation due to climate change could render the planet’s ecosystems unrecognizable.

“We’re already starting to see warning signs of big changes in vegetation across Australia, with declines in the Mountain Ash forests in Victoria and the Pencil Pine forests in Tasmania that are occurring, in large part, due to climate change,” said Simon Haberle from the Australian National University (ANU) Department of Archaeology and Natural History.

“Widespread and rapid changes to ecosystems are likely to have major knock-on effects for nationally important ecosystem services such as biodiversity, carbon storage and recreation,” he added.

“The palaeoecological data that was used for this study can be viewed as natural experiments exploring the response of ecosystems to drivers of change over time scales that can’t be captured by instrumental or historical records,” said Janelle Stevenson, co-author on the paper.

ANU analyzed datasets based on ancient pollen records from numerous sites in Australia and across the Pacific and South East Asia.

“Pollen reflects the changes in landscape and vegetation cover, and the beauty of these ancient pollen records is that they allow us to see these changes over thousands to millions of years,” Stevenson said. “The parts of Earth that had the biggest temperature increases over the time period analysed also had the most substantial changes in vegetation.”

“Our study provides yet another wake-up call that we need to act now to move rapidly towards an emission-free global economy,” she concluded.

The findings were published in Science.

Archaeology NWT_Climate SCI

Cold climates contributed to Neanderthal extinction, study says

A new study suggests that climate change likely played a bigger role in the extinction of Neanderthals than we thought. The effort was a collaboration between many American and European research institutions and created detailed new natural records from stalagmites that reveal changes in the European climate over 40,000 years ago.

In particular, many of the cold periods coincide with many of the periods with no archaeological Neanderthals artifacts, which suggests that climate changes impact the long-term survival of the species.

“The Neanderthals were the human species closest to ours and lived in Eurasia for some 350,000 years,” said Vasile Ersek, co-author of the study. “However, around 40,000 years ago — during the last Ice Age and shortly after the arrival of anatomically modern humans in Europe — they became extinct.”

“For many years we have wondered what could have caused their demise,” he added. “Were they pushed ‘over the edge’ by the arrival of modern humans, or were other factors involved? Our study suggests that climate change may have had an important role in the Neanderthal extinction.”

The team believes that modern humans were able to survive these cold periods due to better adaptation to the environment.

“The comparable timing of stadials and population changes seen in the archaeologic and genetic record suggests that millennial-scale hostile climate intervals may have been the pacesetter of multiple depopulation-repopulation cycles” Ersek said. “These cycles ultimately drew the demographic map of Europe’s Middle-Upper Paleolithic transition.”

The findings were published in the Proceedings of the National Academy of Sciences.

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Scientists discover ‘ticking time bomb’ heated ocean under Arctic

Scientists just discovered evidence of a massive “ticking time bomb” in the form of a heated ocean underneath the Arctic Ocean. The reservoir penetrates deep into the polar region and threatens to melt the ice frozen on top.

“We document a striking ocean warming in one of the main basins of the interior Arctic Ocean, the Canadian Basin,” said oceanographer Mary-Louise Timmermans from Yale University.

Timmermans and her team examined temperature data on the Canada Basin from the last 30 years. The findings revealed that the amount of heat in the warmest region of the water had doubled during the period of 1987 to 2017.

The basin is formed from mixed layers of ocean water, with the warmer, saltier water trapped beneath cold, fresh water flowing at the surface. Although this unique dynamic is not new, the rapid heating conditions of the water underneath are concerning.

“Presently this heat is trapped below the surface layer,” Timmermans said. “Should it be mixed up to the surface, there is enough heat to entirely melt the sea-ice pack that covers this region for most of the year.”

“That heat isn’t going to go away,” said oceanographer John Toole from the Woods Hole Oceanographic Institution. “Eventually … it’s going have to come up to the surface and it’s going to impact the ice.”

Although it’s not an immediate threat, it could severely impact Arctic ice, and as of now, the ramifications are unclear.

“It remains to be seen how continued sea ice losses will fundamentally change the water column structure and dynamics,” the authors wrote, although they note that excess heat “will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.”

“We’re seeing more and more open water as the sea ice retreats in the summertime,” Timmermans said. “The Sun is warming up the ocean directly, because it’s no longer covered by sea ice.”

The findings were published in Science Advances.

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Corals in deeper waters are stressed too, study says

A new study suggests that corals in deeper waters are exposed to episodic thermal stress. Researchers previously believed that corals at a depth of 30 to 150 meters were safer than their shallow-water counterparts. But although the intervals of thermal stress they experience are different than corals at the surface, they still feel the effects of ocean warming.

The team reached their conclusions using almost two decades of data sets that include sea-surface temperature, sea level, and temperature observations that range from the surface to deep in the mesophotic zone. Using their unique approach, they were able to measure and predict the thermal stress of coral reefs at many depths.

“We’re now adding the dimension of depth into the problem where before we were only skimming the surface of what temperature stress meant for corals,” said Travis Schramek, lead author of the study. “We see that the heat-induced stress penetrates all the way into the mesophotic zone during larger bleaching events.”

“A surprising outcome of the study is that the oceanic conditions along the dramatic reef walls that are the boundaries of Palau are very representative of the broader Western Pacific,” said Scripps oceanographer Eric Terrill, senior author of the study. “As a result, we had a surprising amount of success in predicting the vertical structure of the temperature fields that the coral communities would be exposed to, even during El Niño conditions.”

The new insights from the study can help researchers predict the temperature stress on deep corals. Not only that, they can shed light on how the effects contribute to our understanding of the reef system as a whole.

The findings were published in Geophysical Research Letters.

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Earth at risk of heading toward ‘hothouse’ conditions

A new study suggests that even if we meet the carbon emission reductions outlined in the Paris Agreement, the Earth is still at risk of entering “hothouse” conditions. Given the findings, the authors believe that it is critical that we quickly move toward an emission-free world economy.

“Human emissions of greenhouse gas are not the sole determinant of temperature on Earth,” said lead author Will Steffen from the Australian National University and Stockholm Resilience Centre. “Our study suggests that human-induced global warming of 2 degrees C may trigger other Earth system processes, often called feedbacks, that can drive further warming—even if we stop emitting greenhouse gases. Avoiding this scenario requires a redirection of human actions from exploitation to stewardship of the Earth system.”

As of now, global average temperatures are sitting just over 1 degrees Celsius past pre-industrial and increasing at 0.17 degrees Celsius each decade.

In order to avoid a “Hothouse Earth,” we must reduce carbon dioxide and greenhouse gas emissions and enhance biological carbon stores through methods such as improved forest management and biodiversity conservation.

“Climate and other global changes show us that we humans are impacting the Earth system at the global level,” said study co-author Katherine Richardson from the University of Copenhagen. “This means that we as a global community can also manage our relationship with the system to influence future planetary conditions. This study identifies some of the levers that can be used to do so,”

The findings were published in the Proceedings of the National Academy of Sciences.

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Scientists uncover new connections between climate change and ocean warming

A new study by scientists from the University of California, Santa Cruz and University of Toronto suggests that an increase in carbon dioxide (CO2) in the Earth’s atmosphere over 50 million years ago changed the chemistry of the planet’s oceans drastically.

“Our study shows that global warming is not only about extreme weather events, or hotter summers, but it has the potential to alter the ocean structure with unknown consequences for fisheries,” said Uli Wortmann, co-author of the study.

And the scary thing is this: it’s not the first time that this has happened over the course of history.

“We show that the last time large amounts of CO2 were injected into the atmosphere, not only did the planet get hot—which is known as the so called Paleocene-Eocene Thermal Maximum, about 55 million year ago—but it also changed the chemistry of the ocean quite markedly,” Wortmann said.

“Increased atmospheric CO2 concentrations go hand in hand with oxygen loss in the ocean, and this is the first demonstration that the CO2 release from human activity could be large enough to turn parts of the ocean into a toxic brew,” he added.

Although it’s uncertain how long it takes for increased CO2 levels to become apparent in ocean chemistry, the team believes it is likely a fast transition.

“Our study is another piece in the puzzle,” Yao said. “It highlights an often overlooked aspect of the global climate change debate: what will happen to marine fisheries in a warming world?”

The findings were published in Science.