Tag Archives: global warming

Eastern Mediterranean Drought The Worst To Hit The Region In 900 Years

Modeling the historic droughts that have hit the Mediterranean basin, scientists have found that the region’s latestdry period was the worst drought to have hit the area in the past 900 years. The study, published in the Journal of Geophysical Research, highlights the concerns that climate change may be contributing to observed drying trends, and that those impacts might already be being felt.

The researchers looked back at the records of droughts documented in tree rings from all around the Mediterranean, sampling trees from North Africa, Greece, Lebanon, Jordan, Syria, and Turkey, as well as using existing tree ring data from Spain, France and Italy. They found that the growth of the trees matched up with historical records written at the time of droughts to have hit the region between 1100 CE and 2012 CE. Although the variability between wet and dry periods was quite large, the most recent 1998-2012 drought was still found to be about 50 percent drier than the driest period in the last 500 years, and over 10 percent drier than any in the past 900.

For January 2012, brown shades show the decrease in water storage from the 2002-2015 average in the Mediterranean region. NASA

The scale of the project also allowed the researchers to look at how droughts affected different regions of the Mediterranean. They found that if the east was experiencing a dry period, then it was likely that the west was going through a similar spell. This is important,because it has all sorts of implications for food and water security withinthe region as a whole if everyone is experiencing a drought at the same time, and could help predict where conflict over these resources might arise.

But interestingly, when the researchers then looked at how dry periods affected the north and south of the region, they found an opposite relationship. When Greece, Italy, France and Spain were in drought, the eastern areas of North Africa tended to be wet. The differences between what happens in the east and west of the region when compared to the north-south are thought to be due to airflow patterns that move the weather systems around the Med.

Having such a longterm data set will be invaluable for any future events, as it in effect provides a baseline for comparison. This means that any variability can be checkedto see if drying conditions could be seen as a natural cycle, or iscaused by man-made climate change.

The magnitude and significance of human climate change requires us to really understand the full range of natural climate variability, explains Ben Cook, from NASA’s Goddard Institute for Space Studies and who led the research. If we look at recent events and we start to see anomalies that are outside this range of natural variability, then we can say with some confidence that it looks like this particular event or this series of events had some kind of human-caused climate change contribution.

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Read more: http://www.iflscience.com/environment/eastern-mediterranean-drought-worst-hit-region-900-years

How Myths And Tabloids Feed On Anomalies In Science

UNDERSTANDING RESEARCH: What do we actually mean by research and how does it help inform our understanding of things? What if research throws up a result that calls for a new way of thinking? How do we handle that?

There are many misconceptions about science, including how science advances. One half-truth is that unexpected research findings produce crises, leading to new theories that overturn previous scientific knowledge.

Sometimes science progresses in this neat tidy fashion. But not very often. Assuming science is always so simple fuels misunderstanding of science, and provides ammunition to those who attack science, from cosmology to climate change.

Contrary to the myth, most anomalous findings have modest consequences. The vast majority of peculiar findings are usually the result of errors in data, methodology or misunderstanding the implications of existing theories.

Even when anomalies do prompt radical change, it is rare for them to completely upend large swathes of scientific knowledge.

Strange forces and Pioneers
In the 1970s, NASA’s Pioneer 10 and 11 spacecraft flew by Jupiter and Saturn before speeding towards interstellar space. As they coasted away from the sun, a strange “Pioneer Anomaly” was observed to be gently slowing the Pioneers. What was going on?

The Pioneer Anomaly has led to hundreds of papers, with many speculating on modified forms of gravity and relativity.

An artist’s impression of Pioneer 10 racing from the Solar System. NASA Ames/Donald Davis

In principle the Pioneers could measure tiny accelerations, as they cruised through space. But they were never designed for precision tests of relativity, nor were they tested (prior to launch) to see if the spacecraft themselves produced tiny accelerations.

After decades of study, it appears the Pioneer anomaly had nothing to do with new physics. The Pioneers generate heat, and thus infrared light (photons), which were subtly pushing on the spacecraft (including via reflections). The Pioneer anomaly, rather than provoking a crisis and new physics, is a triumph of century old physics.

Other anomalies have appeared and disappeared in a similar fashion. But despite this history, media reporting of anomalous results often emphasises how the laws of physics could be overturned, rather than the likelihood of anomalous results disappearing. “Einstein Wrong!” works as click-bait for headlines, but is usually not true.

A personal tale of dark matters

I measure how galaxies grow, and at the end of the 20th century something seemed very wrong with galaxy growth research.

Simulations predicted the biggest galaxies should grow rapidly, as their vast gravity dragged in gas and neighbouring galaxies. In contrast, many observational studies found massive galaxies weren’t growing at all. What happened to all that gravity?

Some speculated that the dark matter paradigm was in trouble. Perhaps galaxies were less massive than people imagined. But instead of prompting radical change, this “crisis” has slowly faded away.

In 2007, I used a vast sample of distant galaxies to detect the slow growth of massive galaxies, and others have mitigated errors that have hampered observational studies of galaxy growth. Observational evidence for dark matter also improved, including cosmic microwave background measurements and the mass distribution within colliding clusters.

As computing power improved and simulations incorporated more complicated astrophysics, including supernovae and black-holes, the growth of simulated galaxies slowed down. So the gulf between simulation and observation closed.

Not so fast big guy! The biggest galaxies don’t grow as quickly as astronomers originally expected. Sloan Digital Sky Survey/Michael Brown

The demise of this anomaly wasn’t as clean as that of the Pioneer anomaly. There were gradual improvements in both simulation and observation, and no single study tied up all the loose ends.

This gradual identification and resolution of anomalous results doesn’t always generate headlines, but it is often how science advances.

The scope for radical change

While most anomalous results fizzle and die, some do spark radical change.

The understanding of the world has been upended when scientific observations and theory have replaced pre-scientific ideas. For example, Galileo’s observations of planets resulted in heliocentric (sun-centred) models of the solar system replacing geocentric (Earth-centred) models.

Truly radical change can also happen when very limited data supports the previous hypothesis. Barry Marshall and Robin Warren won the 2005 Nobel Prize for Medicine for establishing that most stomach ulcers are caused by bacteria, not stress. While the stress causing ulcers had been widely accepted for decades, that hypothesis actually hadn’t been systematically tested.

Einstein’s theories had huge implications for physics, but didn’t upend all previous scientific knowledge. NASA

As a science becomes more mature, with a wealth of supporting data, the implications of anomalous results become more limited. An example of this is Einstein’s general theory of relatively, which was (in part) motivated by odd measurements of the speed of light and the behaviour of Mercury’s orbit.

While general relatively has had huge implications for physics, it didn’t completely upend all previous physics. Maxwell’s equations for electromagnetism are still in use and Newtonian mechanics provides a good approximation of how satellites orbit the Earth.

The apple may have fallen on Newton’s head, but Einstein didn’t make the apple fly away.

Icy anomalies and the tabloids

While anomalous scientific results may seem a curiosity, they are central to public debates about science. To see why, go south!

Temperatures have increased over the past century as a result of increasing atmospheric CO2. The evidence includes (but is not limited to) lab measurements of CO2, measurements of atmospheric CO2, the spectrum of light radiated the Earth, planetary temperatures, and the pattern of temperature increase across the globe.

Increasing sea ice around Antarctica has less implications for global warming that some imagine. Brocken Inaglory/Wikimedia Commons

As a consequence, Arctic sea ice is decreasing, Antarctica and Greenland are losing land ice and sea levels are rising, and yet sea ice area around Antarctica has increased.

The increase in Antarctic sea ice area has been the subject of numerous articles by Andrew Bolt in the Herald-Sun and David Rose in the Daily Mail, among others. Some journalists believe this increase in sea ice is a fundamental flaw in global warming. But what can we conclude from this anomalous result?

The world isn’t getting any colder, so that doesn’t explain the increase in Antarctic sea ice. While simulations didn’t predict the increase in Antarctic sea ice area, they also didn’t predict the unexpectedly rapid decrease in Arctic sea ice either.

Sea ice area depends on air temperature, winds, ocean temperatures and currents, complicating the modelling of sea ice area. A simulation correctly modelling the greenhouse effect can fail to predict sea ice area if it doesn’t correctly model polar winds and oceans. While scientists are aware of this, such nuance is often absent from the tabloid media and blogsphere.

The tabloid media and blogsphere too often falls back on the simplicity of the myth, assuming the anomalous results will upend well-established science. This approach makes for good headlines and political point scoring, but the history tells us that science is very rarely upended in the manner some are wishing for.

This article is part of a series on Understanding Research.

Further reading:
Why research beats anecdote in our search for knowledge
Clearing up confusion between correlation and causation
Where’s the proof in science? There is none
Positives in negative results: when finding ‘nothing’ means something
The risks of blowing your own trumpet too soon on research
How to find the knowns and unknowns in any research
The 10 stuff-ups we all make when interpreting research

The ConversationMichael J. I. Brown receives research funding from the Australian Research Council and Monash University, and has developed space-related titles for Monash University’s MWorld educational app.

The Conversation

Read more: http://www.iflscience.com/editors-blog/how-myths-and-tabloids-feed-anomalies-science

New Analysis Suggests Sixth Mass Extinction Could Occur By 2200

We’ve already been warned that our planet faces a sixth mass extinction, and some even believe that we are already in the early stages of such an event. Now, the harsh reality of the impending situation has been highlighted by the scientific journal Nature, with a special report detailing the threats that major animal groups face. According to the analysis, those predicted to take the greatest hit are amphibians, with an alarming 41% of species within this group facing extinction. But mammals and birds won’t get off lightly, with 26% and 13% of species similarly threatened, respectively.

Among the known critically endangered species are numerous different primates, such as the snub-nosed monkey, black rhinos, the yangtzee river dolphin, western gorillas and the Amur leopard. But many species that are currently only listed as endangered also face being wiped out, such as bonobos and loggerhead turtles.

The primary driver? Humans. According to the Living Planet Index, exploitation—such as hunting and fishing—is playing a major role in triggering the decline in animal species. Other human activities that are helping obliterate populations include agriculture and urbanization, whereby large areas of wild habitats are destroyed to make way for buildings, infrastructure, livestock and crops.

Climate change, which is primarily due to humans, is also threatening many sensitive animals, such as polar bears and corals, and will probably accelerate extinctions in ways that are currently unknown. Increasing CO2 emissions are not only warming our planet and seas, but they are acidifying our oceans, making them a more hostile environment for marine organisms. It’s estimated that 10% of all Earth’s coral reefs are already degraded beyond recovery, and if current pressures continue, 60% could be dead by 2050.

While we know that the situation is not good for many organisms on Earth, attempting to predict how quickly species are likely to disappear is extremely difficult, which only exacerbates the problem. Much of the uncertainty comes from the fact that we only know about a fraction of our planet’s biodiversity, and many unknown groups often reside in small areas that are already being demolished by humans and may never be assessed.

When scientists attempt to assess the number of species of animals, plants and fungi alive today, estimates are wildly varied, ranging from around two million to more than 50 million. Not only that, but approximations of the rate of extinction also vary, ranging from 0.01% to 0.7%, meaning the number of species disappearing is somewhere between 500 and 36,000 a year. If we use the upper rate, a mass extinction—or loss of 75% of species—could occur within the next few hundred years. At the lower rate, however, it may not arrive for thousands of years.

Five mass extinction events have occurred before, all of which were triggered by either natural planetary transformations or asteroid strikes. But the impending 6th event will be the work of humans, who have been gradually wiping out animals since mammoths and mastodons during prehistoric times.

So what can we do? According to the report, it’s of fundamental importance that countries start extending protected areas and devoting more resources to counting and evaluating stocks of life on Earth before they disappear.

[Via Nature, Nature, The Guardian and The Independent]

Read more: http://www.iflscience.com/plants-and-animals/new-analysis-suggests-sixth-mass-extinction-could-occur-2200

NASA and NOAA Agree: 2014 Was Hottest Year On Record

Though it might be hard to believe right now since the Northern Hemisphere is currently experiencing the coldest part of winter, our average global temperatures are increasing at a worrying rate. NASA and NOAA have analyzed the data independently of one another and yet have arrived at the same conclusion: 2014 is the warmest year on record since 1880. This is the 38th consecutive year with above average surface temperatures. The dataset has been released by NASA’s Goddard Institute for Space Studies (GISS).

“NASA is at the forefront of the scientific investigation of the dynamics of the Earth’s climate on a global scale,” NASA’s John Grunsfeld said in a press release. “The observed long-term warming trend and the ranking of 2014 as the warmest year on record reinforces the importance for NASA to study Earth as a complete system, and particularly to understand the role and impacts of human activity.”

Surface temperatures in 2014 averaged 0.8° C (1.4° F) warmer than 1880. This doesn’t mean that 1880 was a particularly hot year; it’s just where the instrumental record begins. It might not seem like a significant increase, but it can have an incredible impact on the environment. This increase has been largely attributed to carbon dioxide released into the atmosphere due to human activity.

Those living in the Midwest or East Coast of the United States will remember last year’s Polar Vortex, which brought extreme winter weather to hundreds of millions of people. However, other parts of the country experienced record-setting temperatures during the summer, offsetting the cold experienced during the winter.

Overall, the planet has been growing increasingly warmer for several decades. Variations in weather patterns have created slight cooling periods, but looking at the larger picture shows that temperatures are definitely looking up, and not in a good way. In fact, nine out of the 10 warmest years since the record began have happened after 2000. The exception is 1998, due to the intense effects of El Niño. 2014 was not affected by El Niño.

Image credit: NASA, Hansen et al. (2010)

“This is the latest in a series of warm years, in a series of warm decades. While the ranking of individual years can be affected by chaotic weather patterns, the long-term trends are attributable to drivers of climate change that right now are dominated by human emissions of greenhouse gases,” noted Gavin Schmidt, GISS Director.

Though NASA and NOAA have agreed that 2014 was the warmest year since the Industrial Revolution, they used different methods for data collection. Researchers at GISS combined data from 6,300 weather stations to get land temperatures, while ocean temps were retrieved via ships, buoys, and from the Antarctic. NOAA’s conclusion also came from data collected by ships and buoys, though it made use of satellite and radar data as well.



Read more: http://www.iflscience.com/environment/nasa-and-noaa-agree-2014-was-hottest-year-record

Deep Ancient Water Is Stopping The Antarctic Ocean From Warming

The waters around the Antarctic may be one of the last places on Earth to feel the effects of man-made climate change. According to researchers at the University of Washington (UW) and the Massachusetts Institute of Technology (MIT), ancient seawater upwelling from the depths explainwhy the sea surface has remained roughly the same temperature while most of the planet has experienced temperature rises.

Using a combination of observations from floating ocean current trackers and cutting-edge computer simulations, the new Nature Geoscience study shows that this centuries-old seawater hasnt been to the surface since the dawn of the Industrial Revolution. Although the cooler waters around the Antarctic were previously blamed on ocean currents drawing sea surface heat down to the depths, it appears that cold water yet to experience the newly-warmed atmosphere is currently rising up to the surface.

With rising carbon dioxide you would expect more warming at both poles, but we only see it at one of the poles, so something else must be going on, the studys lead author Kyle Armour, a UW assistant professor of oceanography and of atmospheric sciences, said in a statement. We show that it’s for really simple reasons, andocean currentsare the hero here.

Observed warming over the past 50 years, as measured in degrees Celsius per decade. Its clear that the Southern Ocean has warmed by only a fraction, and it appears ocean currents are to blame for this unusual refrigeration mechanism. Kyle Armour/UW

Seawater from the deepest depths of the worlds oceans upwell at different times, and they do so when they become less dense than the water above them. This can happen for many reasons, including a reduction in salt concentrationor an influx of heat at depth, both of which make them more buoyant. On occasion, there can be a mechanical driver of seawater upwelling, such as persistent winds.

This is whats happening in the Southern Ocean, where extremely powerful westerly winds keep pushing warming surface water northwards; this gives the deeper, older water space to upwell into. The novel aspect of the waters here is that they have to upwell from depths of several thousand meters, far beyond the depths that most other oceanic currents reach. This means that it takes them an incredibly long time to reach the surface and interact with the atmosphere.

According to the models run by the team, the water only just beginning to reach the surface off the coast of Antarctica last experienced the Earths atmosphere centuries ago in the North Atlantic, before any serious man-made climate change had the chance to significantly heat it up. In fact, their simulations show that the oceanic currents that have experienced the most warming appear to be gathering at the North Pole, which also partly explains why Arctic sea ice is disintegrating so rapidly.

When we hear the term ‘global warming,’ we think of warming everywhere at the same rate, Armour added. We are moving away from this idea and more toward the idea of regional patterns of warming, which are strongly shaped by ocean currents.

The fact that Antarctic sea ice has been growing just as the Arctics has been disintegrating has baffled scientists for some time; irritatingly, this discrepancy is often cited by climate change deniers as proof that climatologists dont know what theyre talking about. It was only a matter of time before several explanations emerged, and this new study represents one of two corroborating theories helping to explain why the sea ice around Antarctica has been unexpectedly growing.

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Read more: http://www.iflscience.com/environment/deep-ancient-water-stopping-antarctic-ocean-warming

Greenland’s Ice Sheet Is Melting Ridiculously Early

Greenlands colossal ice sheet is melting early, and guess what were to blame. According to the climatologists at the Danish Meteorological Institute (DMI), 12 percent of the ice sheets surface area is already showing signs of melting, and this is, without a doubt, due to unseasonably warm temperatures and rain induced by man-made climate change.

This degree of melting would be expected in any scenario at the onset of summer, but is completely unprecedented halfway through April. In fact, this finding means that it has destroyed the record for early Greenland melting by over three weeks. Even in 2012, when 95 percent of the ice sheet was melting, it still began later in the year.

It’s disturbing, Peter Langen, a climatologist at DMI, said in a statement. Something like this wipes out all kinds of records, you can’t help but go this could be a sign of things we’re going to see more often in the future.

This frigid mass which at 1.7 million square kilometers (656,000 square miles)makes it roughly the same size as Mexico melts and refreezes on an annual summer-winter cycle. However, what is currently being observed can only be due to the year-on-year increases in sea surface, land and atmospheric temperatures.

The capital of this Danish territory, Nuuk, reached 16.6C (62F) this Monday, crushing the previous high-temperature record for that month by 3.5C (6.5F). Further inland, temperatures were warmer than San Francisco.

Left: Maps showing the unprecedented early melting extent (red) along the Greenland Ice Sheet. Right: Ice melt as a percentage of total area. The gray-shaded area denotes the average melt for each month from 1990-2013; the blue line marks the current melting extent. DMI

As in the summer months, higher temperatures cause the top of the ice sheet to melt, while warmer waves chip away at the baseof icy dams, keeping land-based ice from falling into the ocean. A warmer climate also encourages greater rates of precipitation; consequently, pools of warmer water delivered by increased rainfall help to break apart huge masses of ice.

All of these mechanisms conspire to disintegrate Greenlands Ice Sheet and thanks to man-made climate change, things are happening fair earlier, and far worse, than expected. The Greenland Ice Sheet has shed about 3.5 billion tonnes (3.9 billion tons) of ice since 2003, and this early April melting could be a sign that the annual rate of ice shedding is due to increase.

Things are getting more extreme and they’re getting more common, noted NASA ice scientist Walt Meier. One freakish thing every once in a while you might expect. But we’re getting these things more often and that’s an indication of climate change.

Unlike the collapse of ice shelves, the melting of ice sheets directly and immediately contributes to sea level rise. Within the next century, Greenlands melting is set to contribute at least 6meters (20 feet) in sea level rise.

Studies confirmthat the terrestrial advance of the oceans can only be halted by 2100 if the Paris climate agreement warming target of 2C (3.6F) is adhered to; otherwise, researchers have all but confirmed that it will doom coastal metropolises like New York City and Miami to eventual oblivion.

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Read more: http://www.iflscience.com/environment/greenlands-ice-sheet-melting-ridiculously-early-thanks-man-made-climate-change

Cloud Contributions Could Make Global Warming Even Worse

It has been a bad fortnight for climate change news, from the heat-induced devastationof coral reefs to warnings that sea levels could rise much faster than we thought. This unfortunate pattern continues with the announcement that we have been miscalculating the feedback between global warming and cloud formation, suggesting most climate projections have been too optimistic.

Clouds are among the hardest aspects to incorporate into models of how the atmosphere will respond to inputs such as increased carbon dioxide. This is because not all clouds behave alike. We know that the warming induced by carbon dioxide emissions will cause the atmosphere to hold more water vapor, leading to more clouds. However, with high clouds warming the planetand lower-altitude clouds havinga cooling effect, it is hard to know which will dominate.

Yale University graduate student Ivy Tanhas looked at clouds from both sides nowand her conclusions, published in Science,are disturbing. Sadly, it turns out they won’t block the Sun nearly as much as we would like.

Clouds are formed from ice crystals and supercooled liquid droplets, and the balance between these components is important. For a fixed amount of cloud water, spherical liquid droplets tend to be smaller in size and also to outnumber ice crystals, because ice nuclei are relatively scarce in Earths atmosphere in comparison to cloud condensation nuclei, Tan noted in the paper. As a consequence, clouds that consist of a higher fraction of liquid are optically thicker and hence more reflective of sunlight.

Tan pointed to previous workthat showed certain clouds contain fewer crystals and more droplets than previously realized. The crucial question is how this will change in a world where the atmosphere contains both more carbon dioxide and more heat.

Using 79 months of data from NASA’s Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite observations, Tan concluded that models have over-estimated the current rate of ice crystal growth. When she ran what she sees as more realistic processes through climate models, the results were terrifying:A model that previously predicted 4.0C (7.2F) of warming now produced 5.0to5.3C (9.0to9.5F).

Calin Tatu/Shutterstock

An initial doubling of CO2 concentrations causes the entire troposphere to deepen, the paper reported. This in turn increases the altitude at which a particular temperature is reached, with consequent effects on the crystal/droplet ratio.

The impact on cloud formation is greatest over the Southern Ocean, the paper noted. However, additional heat captured there will make its way around the entire globe.

The paper expresses confidence thatshould the low [ice formation] bias be eliminated from global climate models, the estimation of temperatures for a particular concentration of carbon dioxide will increase. Whether the extra warming will be as large as Tan’s initial estimates remains to be seen; the paper acknowledges that other models may be affected by different amounts.

However, even if the additional warming turns out to be only half as large as Tan’s model shows, our problems just got bigger.

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Read more: http://www.iflscience.com/environment/cloud-contributions-could-make-global-warming-even-worse

2015 Was The Hottest Year Since Records Began By An Enormous Margin

Climatologists have been predicting it for the last few months, but with all the data now analyzed, its official: 2015 was the hottest year since records began in 1850. The news comes after three of the worlds major organizationshave concluded their independent analysis of their climate data and unanimously drewthe same conclusion. This is the second year in a row that global temperatures have broken the record, and if current trends continue, then it looks like 2016 will make it a third.

The results were released by NASA, the National Oceanic and Atmospheric Administration (NOAA), and the U.K. Met Office, who all agree the data showaworrying trend. Althoughthe heads of state all gathered in Paris at the end of last year to agree to limit global warming to below 2C (3.2F), while striving to prevent average temperatures to rise above 1.5C (2.7F), it may already be too late for that. 2015 was a record-breaking year for our climate. Global mean temperatures reached 1C [1.6F] above pre-industrial levels for the first time and the year’s average global temperature was the highest ever recorded, says Peter Stott, from the Met Office in the U.K.

The consequences of the mercury creeping ever higher have already started to be felt across the globe, although due to nuances in the weather and climate patterns, some places are being hit harder than others. India, for example, experienced the second-worst heat wave in the countrys history last year, claiming more than 2,300 lives when temperatures reached up to an unforgiving 48C (118F) in some cities. China, on the other hand, was severely hit by flooding, costing the nation an estimated $25 billion (16.6 billion) and affecting 75 million people.

This all occurred even before we take into account what could be one of the worst El Nio events the world has seen in a century, which has only acted to exasperate what was already set to be the hottest year. With its continuation into 2016, its putting things in place to make this year equally warm, if not hotter. Such a large El Nio not only impacts the Americas, playing a hand in the flooding in South America and the record warm December across much of the United States, but might also create problems as far away as Africa, causing droughts and potentially famine.

Normally when heat records are set, they are reached gradually, but this year saw the average global temperaturejump by a staggering quarter of a degree fahrenheit, adding to the thoughts that temperatures are rising at an increasingly rapid rate. According to the Mets figures, 2015 was a whopping 0.75C higher than the average from 1961 to 1990. While there are slight discrepancies between the meteorological organizations due to differences in methods and data sets, they all converge on the overall outcomes.

Climate change is the challenge of our generation, and NASAs vital work on this important issue affects every person on Earth, explains Charles Bolden, NASAs administrator, in a statement. Todays announcement not only underscores how critical NASAs Earth observation program is, it is a key data point that should make policy makers stand up and take noticenow is the time to act on climate.

Read more: http://www.iflscience.com/environment/2015-officially-hottest-year-records-began

Greenland’s Meltwater Rivers Are The Largest Contributor to Rising Sea Levels

Over 80% of Greenland’s surface is covered with ice, which features vast crystal blue rivers of meltwater. As gorgeous as the scenery is, a new study has indicated that meltwater from this ice sheet is the largest contributor to rising sea levels. The water from the streams drains more water into the ocean than the combination of Greenland’s meltwater lakes and chunks of ice that break off and fall in, which were previously believed to play the biggest role in rising sea levels. Laurence Smith of UCLA served as the lead author of the paper, which was published in the Proceedings of the National Academy of Sciences.

“It’s the world’s biggest water park, with magnificent and beautiful — but deadly — rushing blue rivers cutting canyons into the ice,” Smith said in a press release, describing Greenland’s topography. 

During a six-day-long expedition in July of 2012, the research team studied these streams using a variety of equipment, including GPS-buoys, a drone boat, and extensive satellite imaging. These measured the location, length, and depth of the streams, as well as how much light was reflected off the water. The expedition was well-timed, as the amount of meltwater in 2012 was one of the highest of the last 700 years.

“It was a real preview of just how quickly that ice sheet can melt and the meltwater can escape,” Smith said.

They found that as the ice melts on the surface, it forms swift-moving rivers that quickly ferry the water away. The water then drains into an opening in the ice called a moulin, travels through the inside of the ice sheet, and emerges underneath, where it can then flow out into the ocean at a rate of 55,000 to 61,000 cubic feet per second. Before this study, not much was known about the ultimate fate of the meltwater rivers. It hadn’t been clear whether all of the meltwater drained into the ocean, or if some remained inside the ice. Though nearly all of the water in the 523 streams drained off of the surface, there does seem to be an unspecified amount getting hung up within the ice.

This study also examined the Isortoq River, which is an integral component of the IPCC’s MAR climate model and drains 20% of all Greenland’s meltwater. The river’s output was over 25% lower than previously believed, indicating that some gets held within the ice. Having a better understanding of the river’s true output and contribution to sea level will improve future climate models, though further research is necessary to determine exactly how much water stays inside the ice.

“If we can get better estimates, then we can have better projections for the extent and the impact of global warming,” added co-author Marco Tedesco of City College of New York. “Greenland is really the big player for sea level rise in the future, so improving climate models is extremely crucial.”

The team has dedicated the research to the memory of co-author Alberto Behar, who was a researcher at Jet Propulsion Laboratory and Arizona State University. He designed the drone boat used by the research team for data collection. Behar died on January 9 in a small plane crash in Los Angeles.

“The measurements we collected would not have been possible without the truly innovative instruments designed by Alberto Behar, and his steady hand during some very trying conditions in the field. The scientific outcomes of this study can be traced directly to him,” Smith told NASA.



Read more: http://www.iflscience.com/environment/greenland-s-meltwater-rivers-are-largest-contributor-rising-sea-levels

Climate Change Is Synchronizing Forest Growth Across Vastly Different Biomes

Researchers analyzing over a centurys worth of growth in tree rings have revealed that climate change is synchronizing forest growth across vast swaths of dramatically different habitats from frigid central Siberia to the mild, Mediterranean climes of Spain. The findings are published in Proceedings of the National Academy of Sciences this week.

Forests play a huge role in the carbon balance of the planets terrestrial ecosystems, but we have yet to figure out whether climate warming will result in longer, more effective growing seasons or worsen droughts, increase heat stress, and reduce productivity.

To better understand how climate change and increasing variability affect tree growth across continents,Jordi Voltasfrom the University of Lleida in Spainand colleagues examined 120-year tree-ring chronologies spanning 1890 through 2009. They studiedsix species of conifers (or evergreens) in two contrasting Eurasian settings: 45 chronologies from boreal forests in Siberia where tree growth is constrained by the cold, and 48 chronologies from Spain where Mediterranean forests are water-limited. Siberia has a prolonged cold season, large temperature variations throughout the year, and moderate amounts of precipitation. Spain, on the other hand, has mild to cool, wet winters and droughts in the summertime.

Spatial synchrony in tree growth refers to the extent of comparable changes in ring-width patterns among geographically disjoined tree populations. These tree ring samples reveal that synchrony in annual growth patterns peaked in the 21st century for these disparate biomes. Their response to climate change increased growth synchrony among forest stands separated by a thousand kilometers to levels wed expect of those within the same stand.

Enhanced synchrony is becoming a widespread, although regionally dependent, phenomenon related to warmer springs and increased temperature variability in high latitudes and to warmer winters and drier growing seasons in mid-latitudes, the team writes. In boreal forests, wood formation is getting an earlier start, for example, while Mediterranean forests are experiencing an advanced onset of growth.

High temperatures, as well as increasingly intense climate extremes, exert about as much influence as local drivers of tree growth such as topography, nutrient availability, and competition among trees. One day, large-scale synchrony may overwhelm regional differences.

Read more: http://www.iflscience.com/plants-and-animals/climate-change-synchronizing-forest-growth-across-vastly-different-biomes