Tag Archives: climate change

Climate Change Killed The Last Ichthyosaurs

Ichthyosaurs became extinct in the Late Cretaceous about 90 million years ago thats roughly 28 million years before the mass extinction event that wiped out all non-avian dinosaurs at the end of the Cretaceous. According to a new Nature Communications study published this week, the extinction of these dolphin-shaped marine reptiles occurred in two phases driven by climate instability and reduced evolutionary rates.

Researchers have previously proposed that the earlier demise of ichthyosaurs after their 157-million-year reign was because of an increase in competition with other marine reptiles or a drop in their food resources, soft cephalopods in particular. But recent studies suggested that ichthyosaurs were richly diverse up to just a few million years before their extinction, so the overall cause of their disappearance is still a mystery.

To investigate, a team led by University of Oxfords Valentin Fischer estimated ichthyosaur diversity over time by studying their evolutionary relationships. They assembled this so-called phylogenetic dataset using 88 characters from 36 ichthyosaur groups, including three-fourths of all known species from the Late Jurassic and Cretaceous. The team also estimated ecological diversity in terms of diet using a series of measurements on skulls and teeth, and they examined the wide range of differences in ichthyosaur body shapes and forms. They then correlated these results with environmental data ranging from ocean chemistry to sea level change.

Ichthyosaurs were highly diverse throughout the Early Cretaceous, but they were evolving slowly. These findings support climate change as a main driver of changes in marine ecosystems, and they fit with the hypothesis that ichthyosaurs were outcompeted by other marine reptiles and fishes. Additionally, the team identified an earlier extinction event that occurred about 100 million years ago. The earlier event eliminated most of their ecological diversity, and a second event about 94 million years ago finished them off, Fischer explains to IFLScience.

Ichthyosaurs faced an abrupt two-phase extinction linked to reduced evolutionary rates and environmental volatility. The beginning of the Late Cretaceous was a peculiar period of numerous climatic and oceanic disturbances, the authors write, with no polar ice, extremely high sea levels, unique sedimentation, strong anoxia, and high temperatures and carbon dioxide concentrations.

Read more: http://www.iflscience.com/plants-and-animals/climate-change-killed-last-ichthyosaurs

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

NASA Satellites Capture Superstorm Jonas From The Skies

While the inches upon inches of snow caused joy, inconvenience and tragedy to millions of people on the East Coast, NASAs satellites were up above and taking full advantage of their front-row view.

NASAs Landsat 8 satellite captured to these natural-color images shown above and below of Virginia, Maryland, and Washington, D.C. in the early afternoon on January 24, 2016.

Image credit: NASA

Thisimage and video,below, were caught on NASAsAquasatellite at around the same time at1:30 p.m. EST on January 24, 2016.

AsNASA explains on itsEarth Observatory site, It is possible that the strength of the storm was amplified by global warming and the record warm temperatures this year.

Ocean temperatures in the North Atlantic are unusually high this winter, providing a deep well of moisture that was drawn into the storm system. Warmer air masses can carry more water to fall as snow or rain, makingextreme snow eventsmore likely even thoughoverall annual snowfallhas been dropping in recent decades.

Image credit: NASA

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Read more: http://www.iflscience.com/environment/nasa-satellites-captures-superstorm-jonas-skies

Wreckage Of Sunken Whaling Ships Discovered Off Alaskan Coast

The sunken remains of two ill-fated whaling ships have been found off the coast of Alaska, 144 years after they became crushed by pack ice, forcing all crew members to abandon their vessels. Though all were later rescued, the event marks one of the greatest catastrophes in the history of U.S whaling, and resulted in the loss of an entire fleet of 33 ships.

Back in the 18th and 19th centuries, whale oil was used around the world for heating, candle wax, soap, and a number of other purposes. As such, whaling was pretty big business, and attracted fleets from across the world to the Arctic each summer, when the ice relented and several species of whales migrated northwards.

However, the conditions at the top of the world can be unpredictable, as this particular fleet discovered to their peril in September 1871, when their ships became trapped in ice before they had a chance to manoeuvre away. Since the disaster, various artefacts from the sunken vessels have been discovered floating in the sea or washed up on the shore. Andresearchers have now located two of the ships for the first time.

Using sonar and other submarine-sensing equipment, a team of archaeologists from the National Oceanic and Atmospheric Association (NOAA) surveyed the waters along a 48-kilometer (30-mile) stretch of coastline near Wainwright, Alaska. In doing so, they were able to plot the outline of two flattened hulls, along with other items such as anchors, ballast and blubber-boiling equipment.

The researchers found anchors, rigging equipment, and other structural features of the sunken ships. NOAA

Until now, attempts to uncover the downed fleet had been thwarted by the thick layer of pack ice that covers much of the Arctic for large periods of the year, although a steady decrease in the amount of ice present during the height of summer over the past four decades has opened up new opportunities for conducting the search. As a consequence, the team was finally able to locate the ships last September, when the Arctic sea ice reaches its yearly minimum.

Reacting to the exciting discovery, project co-director Bad Barr said in a statement: This exploration provides an opportunity to write the last chapter of this important story of American maritime heritage and also bear witness to some of the impacts of a warming climate on the regions environmental and cultural landscape, including diminishing sea ice and melting permafrost.

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Read more: http://www.iflscience.com/editors-blog/wreckage-sunken-whaling-ships-discovered-alaskan-coast

Why Arctic Melting Will Be Erratic In The Short Term


rctic sea ice melts each summer, reaching its minimum extent sometime in September, before refreezing through the winter. Over the past 35 years, the September sea ice extent has reduced by about 35% overall and this decline is projected to continue as global temperatures increase.

In 2007 and 2012 the summer ice extent was dramatically lower, causing some some media speculation that we would soon see a summer which was “ice-free” (meaning a year with less than 1 million km2 of sea-ice).

Most climate scientists were more cautious. The weather in 2007 and 2012 was warmer than usual and the winds were particularly favourable for melting sea ice. Although human influence on Arctic sea ice has been detected, there was no evidence that these weather patterns would continue each year.

In contrast, 2013 and 2014 had more sea ice than 2012, causing other speculation that a recovery was underway. Is this claim warranted?

The figure below shows Arctic sea ice extent (the black line) has undergone a long-term decrease, with the dashed line representing a linear trend. But there have also been shorter periods of rapid melt, no change, and apparent increases in extent during this decline – represented below by coloured trend lines for some deliberately chosen eight year periods.


Satellite observations of September Arctic sea ice extent. Ed Hawkins/University of Reading

The most recent eight-year period, starting from the extreme low of 2007, shows an upward trend. This does not mean that the Arctic sea ice is recovering. As with global temperature, these erratic changes are what we expect to see.

Bouncing Towards An Ice-Free Summer

Imagine a ball bouncing down a bumpy hill. Gravity will ensure that the ball will move downwards. But if the ball hits a bump at a certain angle it might move horizontally or even upwards for a time, before resuming its inevitable downward trajectory. This bouncing ball is an analogy for the changing Arctic sea ice.

The hill represents the long-term downward trend in Arctic sea ice due to increasing global temperatures and the bumps introduce changes from this smooth trajectory. These erratic bounces could be in either direction, causing an apparent acceleration or temporary reduction in melt rate. By only examining a small part of the trajectory you might conclude that the ball was moving against gravity. A longer term view would see it as a bounce.

There is no expectation that sea ice, or any other aspect of the climate, will change smoothly over time. The climate system simply does not work that way. Previous studies have suggested that natural climate variations (or “bounces”) play a key role in how sea ice evolves, and suggested that some of the rapid melt in the early 2000s was a temporary acceleration.


September minimum, 1984 and 2012. NASA

A new study I co-authored with a team of Canadian and American scientists, published in Nature Climate Change, highlights that the recent slower melt is a temporary, but not unexpected, deceleration. The complex climate models used to make projections of future climate also exhibit similar periods of little change and more rapid change in Arctic sea ice. The recent trends are well within the range of these expectations. We might even see a decade or more with little apparent change in sea ice.

The causes of these fluctuations in melt rate are still being explored. One suggestion is that slow variations in Atlantic sea surface temperatures are involved. More observations of the Arctic ocean, atmosphere and sea ice would help answer this question.

An Ice-Free Future?

When will the Arctic be ice-free – or equivalently, when will the ball reach the bottom of the hill? The IPCC concluded it was likely that the Arctic would be reliably ice-free in September by 2050, assuming high future greenhouse gas emissions (where “reliably ice-free” means five consecutive years with less than 1 million km2 of sea ice).

We expect the long-term decline in Arctic sea ice to continue as global temperatures rise. There will also be further bounces, both up and down. Individual years will be ice-free sometime in the 2020s, 2030s or 2040s, depending on both future greenhouse gas emissions and these natural fluctuations.

Even when it reaches the bottom of the hill the ball will continue to bounce. Similarly, not every future year will be ice-free in summer. But if global temperatures continue to increase the bounces will become smaller and the ice-free periods will spread from late summer into autumn and early summer.

Commercial Arctic shipping is already increasing to exploit shorter journey times from Europe to Asia, while oil, gas & mineral extraction possibilities are being explored and Arctic tourism is growing. Decisions about such activities need to assess both the risks and opportunities. The important role of natural sea ice fluctuations needs to be considered in such assessments.

The Conversation

Read more: http://www.iflscience.com/environment/why-arctic-melting-will-be-erratic-short-term

Greenland’s Ice Is Getting Darker, And That’s Very Bad News

Satellites have been collecting data on the Greenland ice sheet since 1981. But since the mid-’90s, scientists have noticed the sheet has become progressively darker.

The satellites have been measuring the albedo of the Greenland ice sheet, essentially how much sunlight is reflectedback from the surface towards space. The process is not viewable with the human eye, butthe level of albedo is detectablethrough satellite instruments. Researchers from Columbias Earth Institute have collected and analyzed the data in a study recently published in the journal The Cryosphere.

Their findings state that if the current trend of darkening continues, parts of the sheet will be 10 percent less reflective by the end of the 21st century than they are today.

So what exactly is going on?

The study said soot from wildfires in China, Siberia,and North Americagetting into the ice is no doubt contributing. However, using the Global Fire Emissions Database, they found there was no increase in the number of wildfiresfrom the mid-nineties, suggesting another culprit was at play.

They found that the real driver for the change was rising temperatures. From 1996 onwards, the ice began absorbing about 2 percent more solar radiation per decade. This is in line with the findings that the near-surface temperatures in Greenland have been increasing by0.74Cper decade.

The snowpack of the sheet undergoes a constant processof thawing and refreezing throughout the seasons. However, the warmer and brighter summers are producing a bigger thaw in the ice. With each of these refreezings, the grains of ice get larger and larger. The larger the grains get, the less reflective a surface they have, hence they become darker.

The real issue with this darkening is the vicious circle itcreates. As youll know if you touch the bonnet of a black car on a hot day, darker colors are less reflective so absorbmorelight and, importantly, heat. The darker the icegets, the more vulnerable it is to melting, so it gets darker, and the cycle continues.

“It’s a complex system of interaction between the atmosphere and the ice sheet surface. Rising temperatures are promoting more melting, and that melting is reducing albedo, which in turn is increasing melting,”lead author Professor Marco Tedesco, from the Columbia University’s Lamont-Doherty Earth Observatory and NASA, said in a statement.

“As warming continues, the feedback from declining albedo will add up. It’s a train running downhill, and the hill is getting steeper,” Tedesco added.

Read more: http://www.iflscience.com/environment/greenlands-ice-getting-darker-and-its-not-good-news

World’s Largest Canyon System Discovered Beneath Antarctic Ice Sheet

Antarctica wasnt always a vast, frozen desert. 100 million years ago, this huge land mass was covered in lush, dense rainforests, and it contained many landscape features that nowadays have been concealed by blankets of ice. For decades, scientists have been trying to image the bedrock hidden underneath the surface, and as part of this endeavor, a team of researchers may have discovered a crevasse that is over twice the size of the Grand Canyon in the U.S. Their remarkable discovery has been described in the journal Geology.

East Antarctica has two fairly underexplored regions: Princess Elizabeth Land (PEL) and Recovery Basin. Known by scientists as Poles of Ignorance, they are both the target of intense study, particularly in regards to what may lie beneath them. After all, understanding the bedrock of Antarctica is vital if researchers are to understand how the icy continent will behave as the world continues to warm. Ice moves across the land according to the landscape its sitting on, so mapping any subglacial geological features is a necessity for climatologists.

In the same way, the surface shape of the ice is influenced by what it is resting on, so by looking at the surface, we can infer what may be hiding underneath it. With this in mind, an international team of scientists used a complex combination of satellites, including radar, to image the ice sheets on PEL; a few elongated linear features, previously unspotted, immediately got their attention.

Satellite data from MODIS (Moderate Resolution Imaging Spectroradiometer) revealed surface features indicative of a massive, hidden canyon system. Grantham Institute/Imperial College London

These surface lineations appear to trace out the shape of a vast canyon system over 1,000 kilometers (620 miles) long, and in places up to one kilometer (0.62 miles) deep. This would make it the largest canyon system in the entire world. Although further geophysical surveys are required to confirm that the bedrock beneath these features actually take the form of a canyon, the researchers are fairly confident of their claims.

Where we have good bed data coverage [elsewhere in Antarctica], we see these type of surface features above them, so we have confidence that the new surface features are from a subglacial structure, Prof. Martin Siegert, a coauthor of the paper and researcher at Imperial College London, told IFLScience. Indeed, knowledge from other areas inform us that they should be valleys/canyons.

The researchers understanding of subglacial water drainage, along with the discovery of this canyon and its incredible dimensions, hasled them to hypothesize the existence of a vast, connected lake also concealed beneath the ice. This lake could be up to 1,250 square kilometers (483 square miles) in area.

Both the lake and the canyon theories are supported by initial results from new radar scanning, which is able to see through the ice layers. In order to definitively confirm the existence of both of these phenomenal features, additional radar surveys across thousands of kilometers of Antarctic ice sheets are taking place between British, American and Chinese scientists.

A previous survey on the Antarctic revealed complex underlying bedrock. NASA/GSFC

When completed, they will have a truly comprehensive view of the bedrock a project that has essentially been over five decades in the making. The region in question is the last part of Antarctica to be explored in this way, and so the canyon will likely be the last major geomorphological feature left to be discovered, Siegert noted.

Indeed it is likely to be the last major geomorphological feature on the land surface of our planet to be discovered.

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Read more: http://www.iflscience.com/environment/worlds-largest-canyon-system-discovered-beneath-antarctic-ice-sheet

Snowshoe Hare’s Camouflage Thwarted By Climate Change

The forest-dwelling snowshoe hare (Lepus americanus)has the remarkable ability to change the color of its fur from brown in summer to white in winter in order to camouflage itself. However, as a new study in the journal Ecology Letters reveals, human activity is causing a snowfall reduction, leaving the wintry white hares standing out to predators like light bulbs, and increasing their mortality rate.

A recent study has suggested that two-thirds of all recent dangerous climatic events are directly attributable to human-produced (anthropogenic) greenhouse gas emissions. These impacts include the rapid alteration of ecosystems, including the types of forests inhabited by the snowshoe hare.

As the new study outlines, the snowshoe hare is remarkably well adapted to its North American environment. It is herbivorous in summer, but when resources are scarce in the winter, it is known to opportunistically become carnivorous to satiate its hunger. A nocturnal animal, it has specialized feet that prevent it from sinking into the winter snow and that protect it from very low temperatures.

A major predator of the hare is the lynx, a fast hunter over twice the size of the average domestic cat. Fortunately, the snowshoe hare has a clever defense mechanism: It is able to change its fur to white to match the color of the snowfall in winter, and brown to match the earthy ground in summer. These changes take about 10 weeks to completely occur, and are related to the production of melanin, a pigment, in its body. The more melanin in the fur, the darker it will be.

The summer morph of the snowshoe hair. Walter Siegmund/Wikimedia Commons; CC BY-SA 3.0

The rabbits detect the changes in the seasonal light through specialized retina cells, which let the brain know when to alter the production of melanin to match the fur coat color to the season. However, previous research has recognized that a decrease in snow due to increasing global temperatures has caused a mismatch between when the white fur appears and the start of a snowy winter.

In order to investigate if this causes an increase in mortality rate, the researchers of this new study tagged 186 snowshoe hares with radio collars in two large swaths of hare territory in Western Montana. These hares were monitored once a week for several years, particularly during the seasonal transitions from summer to winter.

As the light levels remained the same as global temperatures rose, the hares do indeed change their fur color too early for the increasinglydelayed snowfall; consequently, as the radio collars showed, their survival rate has been dropping for some time. In fact, their weekly survival rate suffers a 7 percent drop when snow arrives late or leaves too early.

This paper shows that the mismatch costs are severe enough to cause hare populations to steeply decline in the future unless they can adapt to the change, said Marketa Zimova, lead author of the study, in a statement.

Only time will tell whether or not individuals are able to change their fur color at slightly different times to adapt to the changing snow, and if they can survive long enough to pass on this ability to their offspring. Either way, the evolutionary clock for the snowshoe hare is ticking.

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Read more: http://www.iflscience.com/plants-and-animals/snowshoe-hares-camouflage-being-thwarted-climate-change

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

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