Global Warming

Many people have a clear picture of the "Little Ice Age" (from approx. 1300 to 1850). It's characterized by paintings showing people skating on Dutch canals and glaciers advancing far into the alpine valleys. That it was extraordinarily cool in Europe for several centuries is proven by a large number of temperature reconstructions using tree rings, for example, not just by historical paintings. As there are also similar reconstructions for North America, it was assumed that the "Little Ice Age" and the similarly famous "Medieval Warm Period" (approx. 700 -- 1400) were global phenomena. But now an international group led by Raphael Neukom of the Oeschger Center for Climate Change Research at the University of Bern is painting a very different picture of these alleged global climate fluctuations. In a study which has just appeared in the well-known scientific journal Nature, and in a supplementary publication in Nature Geoscience, the team shows that there is no evidence that there were uniform warm and cold periods across the globe over the last 2,000 years.

y different picture of these alleged global climate fluctuations. In a study which has just appeared in the well-known scientific journal Nature, and in a supplementary publication in Nature Geoscience, the team shows that there is no evidence that there were uniform warm and cold periods across the globe over the last 2,000 years.

Climate fluctuations in the past varied from region to region

"It's true that during the Little Ice Age it was generally colder across the whole world," explains Raphael Neukom, "but not everywhere at the same time. The peak periods of pre-industrial warm and cold periods occurred at different times in different places." According to the climate scientist from Bern, the now-debunked hypothesis of climate phases occurring at the same time across the globe came about because of an impression that is defined by the climate history of Europe and North America. In the absence of data from other parts of the earth, this notion was applied to the whole planet, raising expectations that relatively cold or warm periods throughout the last 2,000 years were globally synchronous phenomena. But it has now been shown that this was not the case.

The authors of the study in Nature see the explanation for that as being that regional climates in pre-industrial times were primarily influenced by random fluctuations within the climate systems themselves. External factors such as volcanic eruptions or solar activity were not intense enough to cause markedly warm or cold temperatures across the whole world for decades, or even centuries.

The researchers relied on a database from the international research consortium PAGES, which provides a comprehensive overview of climate data from the last 2,000 years, for their investigation of five pre-industrial climate epochs. In addition to tree rings, it also includes data from ice cores, lake sediments and corals. To really put the results to the test, the team led by Raphael Neukom analyzed these data sets using six different statistical models -- more than ever before. This allowed for the calculation of the probability of extremely warm or cold decades and centuries, and not just the calculation of absolute temperatures. The result was that no globally coherent picture emerged during the periods being investigated. "The minimum and maximum temperatures were different in different areas," says Raphael Neukom. So thermal extremes across the world cannot be inferred from regional temperature phenomena like the oft-mentioned "Medieval Warm Period" in Europe and North America.

The current warm period is happening across the world for the first time

The results look very different for recent history. Both studies show that the warmest period of the last 2,000 years was most likely in the 20th century. They also show that this was the case for more than 98 percent of the surface of the earth. This shows -- once again -- that modern climate change cannot be explained by random fluctuations, but by anthropogenic emissions of CO2 and other greenhouse gases. What we didn't know until now is that not only average global temperatures in the 20th century are higher than ever before in at least 2,000 years, but also that a warming period is now affecting the whole planet at the same time for the first time. And the speed of global warming has never been as high as it is today.

Strange bacteria hint at ancient origin of photosynthesis

Structures inside rare bacteria are similar to those that power photosynthesis in plants today, suggesting the process is older than assumed.

The finding could mean the evolution of photosynthesis needs a rethink, turning traditional ideas on their head.

Photosynthesis is the ability to use the Sun's energy to produce sugars via chemical reactions. Plants, algae, and some bacteria today perform 'oxygenic' photosynthesis, which splits water into oxygen and hydrogen to power the process, releasing oxygen as a waste product.

Some bacteria instead perform 'anoxygenic' photosynthesis, a version that uses molecules other than water to power the process and does not release oxygen.

Scientists have always assumed that anoxygenic photosynthesis is more 'primitive', and that oxygenic photosynthesis evolved from it. Under this view, anoxygenic photosynthesis emerged about 3.5 billion years ago and oxygenic photosynthesis evolved a billion years later.

However, by analysing structures inside an ancient type of bacteria, Imperial College London researchers have suggested that a key step in oxygenic photosynthesis may have already been possible a billion years before commonly thought.

The new research is published in the journal Trends in Plant Science.

Lead author of the study, Dr Tanai Cardona from the Department of Life Sciences at Imperial, said: "We're beginning to see that much of the established story about the evolution of photosynthesis is not supported by the real data we obtain about the structure and functioning of early bacterial photosynthesis systems."

The bacteria they studied, Heliobacterium modesticaldum, is found around hot springs, soils and waterlogged fields, where it performs anoxygenic photosynthesis. It is very distantly related to cyanobacteria, the main bacteria that performs oxygenic photosynthesis today.

It is so distantly related that it last had a 'common ancestor' with cyanobacteria billions of years ago. This means that any traits the two bacteria share are likely to also have been present in the ancient bacteria that gave rise to them both.

By analysing the structures that both H. modesticaldum and modern cyanobacteria use to perform their different types of photosynthesis, Dr Cardona found striking similarities.

Both structures contain a site that cyanobacteria and plants exclusively use to split water -- the first crucial step in oxygenic photosynthesis.

The evolution of cyanobacteria is usually assumed to also be the first appearance of oxygenic photosynthesis, but the fact that H. modesticaldum contains a similar site means that the building blocks for oxygenic photosynthesis are likely much more ancient than thought, as old as photosynthesis itself, and therefore could have arisen much earlier in Earth's history.

Dr Cardona also suggests that this might mean oxygenic photosynthesis was not the product of a billion years of evolution from anoxygenic photosynthesis, but could have been a trait that evolved much sooner, if not first.

Dr Cardona said: "This result helps explain in fantastic detail why the systems responsible for photosynthesis and oxygen production are the way they are today- but for it to make sense it requires a change of perspective in the way we view the evolution of photosynthesis.

"Under the traditional view -- that anoxygenic photosynthesis evolved first and was the only type for about a billion years or more before oxygenic photosynthesis evolved -- these structures should not exist at all in this type of bacteria."

The work was funded by the Leverhulme Trust and the Biotechnology and Biological Sciences Research Council

Climate changes

About a dozen megadroughts struck the American Southwest during the 9th through the 15th centuries, but then they mysteriously ceased around the year 1600. What caused this clustering of megadroughts -- that is, severe droughts that last for decades -- and why do they happen at all?

If scientists can understand why megadroughts happened in the past, it can help us better predict whether, how, and where they might happen in the future. A study published today in Science Advances provides the first comprehensive theory for why there were megadroughts in the American Southwest. The authors found that ocean temperature conditions plus high radiative forcing -- when Earth absorbs more sunlight than it radiates back into space -- play important roles in triggering megadroughts. The study suggests an increasing risk of future megadroughts in the American Southwest due to climate change.

Previously, scientists have studied the individual factors that contribute to megadroughts. In the new study, a team of scientists at Columbia University's Lamont-Doherty Earth Observatory has looked at how multiple factors from the global climate system work together, and projected that warming climate may bring a new round of megadroughts.

By reconstructing aquatic climate data and sea-surface temperatures from the last 2,000 years, the team found three key factors that led to megadroughts in the American Southwest: radiative forcing, severe and frequent La Niña events -- cool tropical Pacific sea surface temperatures that cause changes to global weather events -- and warm conditions in the Atlantic. High radiative forcing appears to have dried out the American Southwest, likely due to an increase in solar activity (which would send more radiation toward us) and a decrease in volcanic activity (which would admit more of it) at the time. The resulting increase in heat would lead to greater evaporation. At the same time, warmer than usual Atlantic sea-surface temperatures combined with very strong and frequent La Niñas decreased precipitation in the already dried-out area. Of these three factors, La Niña conditions were estimated to be more than twice as important in causing the megadroughts.

While the Lamont scientists say they were able to pinpoint the causes of megadroughts in a more complete way than has been done before, they say such events will remain difficult for scientists to predict. There are predictions about future trends in temperatures, aridity, and sea surface temperatures, but future El Niño and La Niña activity remains difficult to simulate. Nevertheless, the researchers conclude that human-driven climate change is stacking the deck towards more megadroughts in the future.

"Because you increase the baseline aridity, in the future when you have a big La Niña, or several of them in a row, it could lead to megadroughts in the American West," explained lead author Nathan Steiger, a Lamont-Doherty Earth Observatory hydroclimatologist.

During the time of the medieval megadroughts, increased radiative forcing was caused by natural climate variability. But today we are experiencing increased dryness in many locations around the globe due to human-made forces. Climate change is setting the stage for an increased possibility of megadroughts in the future through greater aridity, say the researchers.

Strange bacteria hint at ancient origin of photosynthesis

Structures inside rare bacteria are similar to those that power photosynthesis in plants today, suggesting the process is older than assumed.

The finding could mean the evolution of photosynthesis needs a rethink, turning traditional ideas on their head.

Photosynthesis is the ability to use the Sun's energy to produce sugars via chemical reactions. Plants, algae, and some bacteria today perform 'oxygenic' photosynthesis, which splits water into oxygen and hydrogen to power the process, releasing oxygen as a waste product.

Some bacteria instead perform 'anoxygenic' photosynthesis, a version that uses molecules other than water to power the process and does not release oxygen.

Scientists have always assumed that anoxygenic photosynthesis is more 'primitive', and that oxygenic photosynthesis evolved from it. Under this view, anoxygenic photosynthesis emerged about 3.5 billion years ago and oxygenic photosynthesis evolved a billion years later.

However, by analysing structures inside an ancient type of bacteria, Imperial College London researchers have suggested that a key step in oxygenic photosynthesis may have already been possible a billion years before commonly thought.

The new research is published in the journal Trends in Plant Science.

Lead author of the study, Dr Tanai Cardona from the Department of Life Sciences at Imperial, said: "We're beginning to see that much of the established story about the evolution of photosynthesis is not supported by the real data we obtain about the structure and functioning of early bacterial photosynthesis systems."

The bacteria they studied, Heliobacterium modesticaldum, is found around hot springs, soils and waterlogged fields, where it performs anoxygenic photosynthesis. It is very distantly related to cyanobacteria, the main bacteria that performs oxygenic photosynthesis today.

It is so distantly related that it last had a 'common ancestor' with cyanobacteria billions of years ago. This means that any traits the two bacteria share are likely to also have been present in the ancient bacteria that gave rise to them both.

By analysing the structures that both H. modesticaldum and modern cyanobacteria use to perform their different types of photosynthesis, Dr Cardona found striking similarities.

Both structures contain a site that cyanobacteria and plants exclusively use to split water -- the first crucial step in oxygenic photosynthesis.

The evolution of cyanobacteria is usually assumed to also be the first appearance of oxygenic photosynthesis, but the fact that H. modesticaldum contains a similar site means that the building blocks for oxygenic photosynthesis are likely much more ancient than thought, as old as photosynthesis itself, and therefore could have arisen much earlier in Earth's history.

Dr Cardona also suggests that this might mean oxygenic photosynthesis was not the product of a billion years of evolution from anoxygenic photosynthesis, but could have been a trait that evolved much sooner, if not first.

Dr Cardona said: "This result helps explain in fantastic detail why the systems responsible for photosynthesis and oxygen production are the way they are today- but for it to make sense it requires a change of perspective in the way we view the evolution of photosynthesis.

"Under the traditional view -- that anoxygenic photosynthesis evolved first and was the only type for about a billion years or more before oxygenic photosynthesis evolved -- these structures should not exist at all in this type of bacteria."

The work was funded by the Leverhulme Trust and the Biotechnology and Biological Sciences Research Council.

More sensitive climates are more variable climates

A decade without any global warming is more likely to happen if the climate is more sensitive to carbon dioxide emissions, new research has revealed.

A team of scientists from the University of Exeter and the Centre of Ecology and Hydrology in the UK has conducted pioneering new research into why both surges and slowdowns of warming take place.

Using sophisticated climate models the team, led by PhD student Femke Nijsse, discovered if the climate was more sensitive to CO2 concentration also displayed larger variations of warming over a decade.

When combined with information from simulations without any carbon dioxide increases, the authors were able to assess the natural variability of each climate model.

The research is published this week in Nature Climate Change.

Femke Nijsse, from the University of Exeter, said: "We were surprised to see that even when we took into account that sensitive climate models warm more over the last decades of the 20th century, these sensitive models were still more likely to have short periods of cooling."

Climate sensitivity, which sits at the very heart of climate science, is the amount of global warming that takes place as atmospheric CO2 concentrations rise.

For many years, estimates have put climate sensitivity somewhere between 1.5-4.5°C of warming for a doubling of pre-industrial CO2levels.

The study found that cooling -- or "hiatus" -- decades were more than twice as likely around the turn of the century in high sensitivity models (models that warm 4.5 ºC after doubling CO2), compared to low sensitivity models (models that warm 1.5 ºC after doubling CO2).

Co-author Dr. Mark Williamson, A Research Fellow at Exeter: "This does not mean that the presence of a global warming slowdown at the beginning of the 21st century implies we live in a highly sensitive world.

"By looking at all decades together, we get a better picture and find observations are broadly consistent with a central estimate of climate sensitivity"

Ms Nijsse added: "We still don't exactly know how much the climate system will heat up, nor do we know exactly what the range of natural variability in trends will be over the coming decades. But our study shows that these risks should not be considered as separate."

The paper also studied the chance that a decade in the 21st century could warm by as much as the entire 20th century -- a scenario that the research team call "hyper warming."

Under a scenario where carbon dioxide emissions from fossil fuels continue to increase, the chance of hyper warming is even more dependent on climate sensitivity than the long-term global warming trend.

Increasing the climate sensitivity by 50% from a central estimate of 3ºC would increase the mean global warming to the end of this century by slightly less than 50%, but would increase the chance of a hyper warming decade by more than a factor of ten.

The research was supported by the European Research Council ('ECCL ES' project) and the UK's Natural Environment Research Council.

Metabolic factors likely contribute to anorexia

Metabolic factors likely contribute to anorexia

Scientists defined that anorexia nervosa as a metabolic as well as a psychiatric illness. They are suggested that treatments should address the hybrid nature of the potentially lethal eating disorder.

The international team with more than 100 researchers studied about the DNA of tens of thousands of people with and without anorexia nervosa.

A Nature Genetics paper describes that how they identified eight genes with a strong link to anorexia nervosa.

Some of the genes have common links with other psychiatric illnesses, such as schizophrenia, depression, anxiety, and obsessive-compulsive disorder.

However, the findings also reveal genetic links to physical activity, the metabolism of glucose, how the body uses fat, and body measurements. In addition, these links will appear to be independent of common genetic ties to body mass index (BMI).

However, the new findings about the role of metabolism could help explain why people with anorexia "frequently drop back to dangerously low weights, even after therapeutic re-nourishment," she adds.

They outlived mammoths and saber-toothed tigers. But without dramatic action to reduce climate change, new research shows Joshua trees won't survive much past this century.

They outlived mammoths and saber-toothed tigers. But without dramatic action to reduce climate change, new research shows Joshua trees won't survive much past this century.

UC Riverside scientists wanted to verify earlier studies predicting global warming's deadly effect on the namesake trees that millions flock to see every year in Joshua Tree National Park. They also wanted to learn whether the trees are already in trouble.

Using multiple methods, the study arrived at several possible outcomes. In the best-case scenario, major efforts to reduce heat-trapping gasses in the atmosphere would save 19 percent of the tree habitat after the year 2070. In the worst case, with no reduction in carbon emissions, the park would retain a mere 0.02 percent of its Joshua tree habitat.

The team's findings were published recently in Ecosphere. Project lead Lynn Sweet, a UCR plant ecologist, said she hopes the study inspires people to take protective environmental action. "The fate of these unusual, amazing trees is in all of our hands," she said. "Their numbers will decline, but how much depends on us."

To answer their questions about whether climate change is already having an effect, a large group of volunteers helped the team gather data about more than 4,000 trees.

They found that Joshua trees have been migrating to higher elevation parts of the park with cooler weather and more moisture in the ground. In hotter, drier areas, the adult trees aren't producing as many younger plants, and the ones they do produce aren't surviving.

Joshua trees as a species have existed since the Pleistocene era, about 2.5 million years ago, and individual trees can live up to 300 years. One of the ways adult trees survive so long is by storing large reserves of water to weather droughts.

Younger trees and seedlings aren't capable of holding reserves in this way though, and the most recent, 376-week-long drought in California left the ground in some places without enough water to support new young plants. As the climate changes, long periods of drought are likely to occur with more frequency, leading to issues with the trees like those already observed.

An additional finding of this study is that in the cooler, wetter parts of the park the biggest threat other than climate change is fire. Fewer than 10 percent of Joshua trees survive wildfires, which have been exacerbated in recent years by smog from car and industrial exhaust. The smog deposits nitrogen on the ground, which in turn feeds non-native grasses that act as kindling for wildfires.

As a partner on this project, the U.S. Park Service is using this information to mitigate fire risk by removing the invasive plants.

"Fires are just as much a threat to the trees as climate change, and removing grasses is a way park rangers are helping to protect the area today," Sweet said. "By protecting the trees, they're protecting a host of other native insects and animals that depend on them as well."

UCR animal ecologist and paper co-author Cameron Barrows conducted a similar research project in 2012, which also found Joshua tree populations would decline, based on models assuming a temperature rise of three degrees. However, this newer study considered a climate change scenario using twice as many variables, including soil-water estimates, rainfall, soil types, and more. In addition, Barrows said on-the-ground observations were essential to verifying the climate models this newer team had constructed.

Quoting the statistician George Box, Barrows said, "All models are wrong, but some are useful." Barrows went on to say, "Here, the data we collected outdoors showed us where our models gave us the most informative glimpse into the future of the park."

For this study, the UC Riverside Center for Conservation Biology partnered with Earthwatch Institute to recruit the volunteer scientists. Barrows and Sweet both recommend joining such organizations as a way to help find solutions to the park's problems.

"I hope members of the public read this and think, 'Someone like me could volunteer to help scientists get the kind of data that might lend itself to concrete, protective actions,'" Barrows said.

Golden Blood: Need to know about it

Golden Blood: Need to know about it

Golden Blood, or Rh-null blood is an extremely rare blood type that has only been identified in 43 people around the world in the last 50 years. It is sought after both for scientific research and blood transfusions, but also incredibly dangerous to live with for the people who have it, because of its scarcity. To understand golden blood, it’s important to understand how blood types work. Human blood may look the same in everyone, but it’s actually very different. On the surface of each one among our red blood cells we've got up to 342 antigens – the molecules that trigger the assembly of bound specialized proteins known as antibodies – and it’s the absence of certain antigens that determines a person’s blood type. Around 160 of these antigens are considered common, meaning they are found on the red blood cells of most humans on the planet. If someone lacks an antigen that is found in 99 percent of all humans then their blood is considered rare, and if they lack an antigen found in 99.99 percent of humans, their blood is considered very rare.

The 342 well-known antigens belong to thirty-five blood type systems, of which the Rh, or ‘Rhesus’, system is the largest, with 61 antigens.

It’s not uncommon for humans to be missing one of these antigens.

For example, around 15 percent of Caucasians miss the D antigen, the most significant Rh antigen,

making them RhD negative.

In contrast, Rh negative blood types are much less common in Asian populations (0.3 percent).

But what if somebody's is missing all of the 61 Rh antigens?

Until half a century ago, doctors believed that such an embryo couldn’t even survive in the uterus, let alone develop
into a normal, healthy adult. But in 1961, an Aboriginal Australian woman was identified as having Rh-null blood,
meaning she lacked all the antigens in the Rh blood system, which made no sense at the time. Since then, solely 
forty-three individuals with Rh-null blood are known.

Rh-null blood is named “golden blood” for 2 reasons.

The most important one is that its complete lack of Rh antigens means that it can be accepted by anyone with a rare
blood type within the Rh blood system. Its life-saving potential is so enormous that even though blood samples
donated at blood banks are anonymized, scientists often try to track the donors of Rh-null blood to directly ask
them to donate more. However, because of its scarcity, golden blood is only given to patience in the most extreme
cases, because it is almost impossible to replace.

But golden blood also holds immense scientific value as it could help researchers unravel the mysteries of the
physiological role of the intriguingly complex Rh system.

Rh-null blood can be given to anyone with a negative Rh blood type, which is why scientists often say that it’s worth
its weight in gold, but what if a person born with this unusual blood type ever needs a blood transfusion. That would
be a downside, as they might solely receive Rh-null blood.This makes it very dangerous to live with. If they receive
blood from someone who is ‘positive’ for one of the 61 Rh antigens they lack, their own antibodies could react with
the incompatible donor blood cells, triggering a potentially lethal immune system response.

In 2014, The Atlantic wrote about Thomas, one of the only 43 people known to have Rh-null blood, and the precautions he had taken throughout his life to avoid finding himself in situations where he would require blood transfusions. As a child, his parents didn’t allow him to go to summer camp for fear that he might have an accident, and as an adult, he always drove very cautiously and never travelled to countries that lacked modern hospitals. He also carried with him a special card that confirmed his ultra-rare blood type, in case he was ever hospitalized.

I guess you could look at having golden blood as both a blessing and a curse. On one hand, you have the power to save countless lives through a simple blood donation, but you also live with the terrifying thought of ever needing a blood transfusion yourself.

Huntington's disease: Could a cancer drug hold the key?

Huntington's disease: Could a cancer drug hold the key?

Medication which is used to treat cancer could potentially be an effective therapy for Huntington's disease, according to new research led by Duke University School of Medicine in Durham, NC. Even the drug may also offer a pathway to treat other neurodegenerative diseases.

Huntington's disease is an inherited disorder that may also leads to the degeneration of certain nerve cells in the brain. The condition is progressive and affects movement, cognition, and behavior.

There is no cure, no therapies for Huntington's disease to stop or slow down its progression. People with Huntington's often die within 15 to 20 years of being affected by diagnosed.

Previous researchers found that a compound known as KD3010, tested in the treatment of diabetes, was effective in reducing disease progression and overall neurodegeneration and improving motor function.

The new study explores about treating mice with the equivalent of Huntington's disease with bexarotene, a cancer treatment for advanced skin lymphomas.

Laughter: The medicine for Heart

Laughter: The medicine for Heart

It’s true: laughter is strong medicine.

In recent years, studies have shown a powerful link between our emotions and heart health.

Research has shown that laughter strengthens your immune system, boosts mood, diminishes pain, and protects you from the damaging effects of stress.
Nothing works quicker or dependably to bring your mind and body back to balance than an honest laugh.

Studies have shown that positivity and optimism have similar impacts on heart health, and frequent laughter may be a sign of this positive outlook. It is also true that laughing forces you to feel
better—even momentarily—which can be extremely important, especially for people who may be lonely or isolated.

Physiologically, laughter reduces the secretion of stress hormones, which dilate blood vessels and allow more blood to flow to all parts of your body, providing your body with more oxygen and
nutrients. This makes it easier for your heart to work and pump enough oxygen and nutrients to your cells.

Laughter increases the amount of HDL cholesterol in your blood. HDL cholesterol is often called “good” cholesterol because it prevents or reverses the processes involved in plaque formation. In addition, laughter reduces inflammation in your blood vessels. When inflammation is decreased,
plaque is less likely to be deposited in your blood vessels. These changes are similar to the benefits obtained from exercising or using drugs to lower cholesterol levels. The difference is laughter is spontaneous and the effects of laughter can last 24 hours.

By creating laughter as a daily a part of your life, you'll be able to have a giant impact on your own heart health.

Could gut bacteria play a role in high blood pressure?

Could gut bacteria play a role in high blood pressure?

In this Spotlight feature, Scientists investigate whether the bacteria that live in our guts could influence our blood pressure. If so, could they guide future treatment?

Scientists are growing interested in the role of gut bacteria.

Every week, journal’s publish lot’s study papers that examine how these microscopic visitors might play a role in health and disease.

As it stands why because the microbiome is a relatively new field of study and the full scope of gut bacteria's role in health is still up for debate.

However, it is becoming increasingly clear that the bacteria in our gut can open new avenues in our understanding of a wide range of conditions.

Scientists have learned about the role of gut bacteria in conditions as varied as obesity, Parkinson's disease, depression, and blood pressure.

This Spotlight focuses on their role in hypertension. Elevated blood pressure causes risk factor for cardiovascular disease and it affects almost 1 in 3 adults in the United States.

Because of all of this, it is vital that medical scientists unearth the various mechanisms that underpin blood pressure regulation.