Average temperature in Finland has risen by more than two degrees

Over the past 166 years, the average temperature in Finland has risen by more than two degrees. During the observation period, the average increase was 0.14 degrees per decade, which is nearly twice as much as the global average.

According to a recent University of Eastern Finland and Finnish Meteorological Institute study, the rise in the temperature has been especially fast over the past 40 years, with the temperature rising by more than 0.2 degrees per decade. "The biggest temperature rise has coincided with November, December and January. Temperatures have also risen faster than the annual average in the spring months, i.e., March, April and May. In the summer months, however, the temperature rise has not been as significant," says Professor Ari Laaksonen of the University of Eastern Finland and the Finnish Meteorological Institute. As a result of the temperature rising, lakes in Finland get their ice cover later than before, and the ice cover also melts away earlier in the spring. Although the temperature rise in the actual growth season has been moderate, observations of Finnish trees beginning to blossom earlier than before have been made.

Temperature has risen in leaps

The annual average temperature has risen in two phases, the first being from the beginning of the observation period to the late 1930s, and the second from the late 1960s to present. Since the 1960s, the temperature has risen faster than ever before, with the rise varying between 0.2 and 0.4 degrees per decade. Between the late 1930s and late 1960s, the temperature remained nearly steady. "The stop in the temperature rise can be explained by several factors, including long-term changes in solar activity and post-World War II growth of human-derived aerosols in the atmosphere. When looking at recent years' observations from Finland, it seems that the temperature rising is not slowing down," University of Eastern Finland researcher Santtu Mikkonen explains.

The temperature time series was created by averaging the data produced by all Finnish weather stations across the country. Furthermore, as the Finnish weather station network wasn't comprehensive nation-wide in the early years, data obtained from measurement stations in Finland's neighbouring countries was also used.

Finland is located between the Atlantic Ocean and the continental Eurasia, which causes great variability in the country's weather. In the time series of the average temperature, this is visible in the form of strong noise, which makes it very challenging to detect statistically significant trends. The temperature time series for Finland was analysed by using a dynamic regression model. The method allows the division of the time series into sections indicating mean changes, i.e. trends, periodic variation, observation inter-dependence and noise. The method makes it possible to take into consideration the seasonal changes typical of Nordic conditions, as well as significant annual variation.

Journal Reference:

S. Mikkonen, M. Laine, H. M. M?kel?, H. Gregow, H. Tuomenvirta, M. Lahtinen, A. Laaksonen. Trends in the average temperature in Finland, 1847–2013. Stochastic Environmental Research and Risk Assessment, 2014; DOI: 10.1007/s00477-014-0992-2

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Temperature anomalies are warming faster than Earth's average, study finds

It's widely known that Earth's average temperature has been rising. But research by an Indiana University geographer and colleagues finds that spatial patterns of extreme temperature anomalies -- readings well above or below the mean -- are warming even faster than the overall average.

And trends in extreme heat and cold are important, said Scott M. Robeson, professor of geography in the College of Arts and Sciences at IU Bloomington. They have an outsized impact on water supplies, agricultural productivity and other factors related to human health and well-being.

"Average temperatures don't tell us everything we need to know about climate change," he said. "Arguably, these cold extremes and warm extremes are the most important factors for human society."

Robeson is the lead author of the article "Trends in hemispheric warm and cold anomalies," which will be published in the journal Geophysical Research Letters and is available online. Co-authors are Cort J. Willmott of the University of Delaware and Phil D. Jones of the University of East Anglia.

The researchers analyzed temperature records for the years 1881 to 2013 from HadCRUT4, a widely used data set for land and sea locations compiled by the University of East Anglia and the U.K. Met Office. Using monthly average temperatures at points across the globe, they sorted them into "spatial percentiles," which represent how unusual they are by their geographic size.

Their findings include:

Temperatures at the cold and warm "tails" of the spatial distribution -- the 5th and 95th percentiles -- increased more than the overall average Earth temperature.Over the 130-year record, cold anomalies increased more than warm anomalies, resulting in an overall narrowing of the range of Earth's temperatures.In the past 30 years, however, that pattern reversed, with warm anomalies increasing at a faster rate than cold anomalies. "Earth's temperature was becoming more homogenous with time," Robeson said, "but now it's not."

The study records separate results for the Northern and Southern Hemispheres. Temperatures are considerably more volatile in the Northern Hemisphere, an expected result because there's considerably less land mass in the South to add complexity to weather systems.

The study also examined anomalies during the "pause" in global warming that scientists have observed since 1998. While a 16-year-period is too short a time to draw conclusions about trends, the researchers found that warming continued at most locations on the planet and during much of the year, but that warming was offset by strong cooling during winter months in the Northern Hemisphere.

"There really hasn't been a pause in global warming," Robeson said. "There's been a pause in Northern Hemisphere winter warming."

Co-author Jones of the University of East Anglia said the study provides scientists with better knowledge about what's taking place with Earth's climate. "Improved understanding of the spatial patterns of change over the three periods studied are vital for understanding the causes of recent events," he said.

It may seem counterintuitive that global warming would be accompanied by colder winter weather at some locales. But Robeson said the observation aligns with theories about climate change, which hold that amplified warming in the Arctic region produces changes in the jet stream, which can result in extended periods of cold weather at some locations in the mid-northern latitudes.

And while the rate of planetary warming has slowed in the past 16 years, it hasn't stopped. The World Meteorological Organization announced this month that 2014 is on track to be one of the warmest, if not the warmest, years on record as measured by global average temperatures.

In the U.S., the East has been unusually cold and snowy in recent years, but much of the West has been unusually warm and has experienced drought. And what happens here doesn't necessarily reflect conditions on the rest of the planet. Robeson points out that the United States, including Alaska, makes up only 2 percent of Earth's surface.

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Glacier beds can get slipperier at higher sliding speeds

As a glacier's sliding speed increases, the bed beneath the glacier can grow slipperier, according to laboratory experiments conducted by Iowa State University glaciologists.

They say including this effect in efforts to calculate future increases in glacier speeds could improve predictions of ice volume lost to the oceans and the rate of sea-level rise.

The glaciologists -- Lucas Zoet, a postdoctoral research associate, and Neal Iverson, a professor of geological and atmospheric sciences -- describe the results of their experiments in the Journal of Glaciology. The paper uses data collected from a newly constructed laboratory tool, the Iowa State University Sliding Simulator, to investigate glacier sliding. The device was used to explore the relationship between drag and sliding speed for comparison with the predictions of theoretical models.

"We really have a unique opportunity to study the base of glaciers with these experiments," said Zoet, the lead author of the paper. "The other tactic you might take is studying these relationships with field observations, but with field data so many different processes are mixed together that it becomes hard to untangle the relevant data from the noise."

Data collected by the researchers show that resistance to glacier sliding -- the drag that the bed exerts on the ice -- can decrease in response to increasing sliding speed. This decrease in drag with increasing speed, although predicted by some theoreticians a long as 45 years ago, is the opposite of what is usually assumed in mathematical models of the flow of ice sheets.

These are the first empirical results demonstrating that as ice slides at an increasing speed -- perhaps in response to changing weather or climate -- the bed can become slipperier, which could promote still faster glacier flow.

The response of glaciers to changing climate is one of the largest potential contributors to sea-level rise. Predicting glacier response to climate change depends on properly characterizing the way a glacier slides over its bed. There has been a half-century debate among theoreticians as to how to do that.

The simulator features a ring of ice about 8 inches thick and about 3 feet across that is rotated over a model glacier bed. Below the ice is a hydraulic press that can simulate the weight of a glacier several hundred yards thick. Above are motors that can rotate the ice ring over the bed at either a constant speed or a constant stress. A circulating, temperature-regulated fluid keeps the ice at its melting temperature -- a necessary condition for significant sliding.

"About six years were required to design, construct, and work the bugs out of the new apparatus," Iverson said, "but it is performing well now and allowing hypothesis tests that were formerly not possible."

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In the mood to trade? Weather may influence institutional investors' stock decisions

Weather changes may affect how institutional investors decide on stock plays, according to a new study by a team of finance researchers. Their findings suggest sunny skies put professional investors more in a mood to buy, while cloudy conditions tend to discourage stock purchases.

The researchers conclude that cloudier days increase the perception that individual stocks and the Dow Jones Industrials are overpriced, increasing the inclination for institutions to sell.

The research paper, "Weather-Induced Mood, Institutional Investors, and Stock Returns," has been published in the January 2015 issue of The Review of Financial Studies. The research was collaborated by Case Western Reserve University's Dasol Kim and three other finance professors (William Goetzmann of Yale University, Alok Kumar of University of Miami and Qin Wang of University of Michigan-Dearborn).

Institutional investors represent large organizations, such as banks, mutual funds, labor union funds and finance or insurance companies that make substantial investments in stocks. Kim said the results of the study are surprising, given that professional investors are well regarded for their financial sophistication.

"We focus on institutional investors because of the important role they have in how stock prices are formed in the markets," said Kim, assistant professor of banking and finance at Case Western Reserve's Weatherhead School of Management. "Other studies have already shown that ordinary retail investors are susceptible to psychological biases in their investment decisions. Trying to evaluate similar questions for institutional investors is challenging, because relevant data is hard to come by."

Building on previous findings from psychological studies about the effect of sunshine on mood, the researchers wanted to learn how mood affects professional investor opinions on their stock market investments.

By linking responses to a survey of investors from the Yale Investor Behavior Project of Nobel Prize-winning economist Robert Shiller and institutional stock trade data with historical weather data from the National Oceanic and Atmospheric Administration, the researchers concluded aggregated data shows that seasonably sunnier weather leads to optimistic responses and a willingness to buy.

The research accounts for differences in weather across regions of the country and seasons. They show that these documented mood effects also influence stock prices, and that the observed impact does not persist for long periods of time.

A summary of the research was also recently featured at The Harvard Law School Forum on Corporate Governance and Financial Regulation.

Journal Reference:

W. N. Goetzmann, D. Kim, A. Kumar, Q. Wang. Weather-Induced Mood, Institutional Investors, and Stock Returns. Review of Financial Studies, 2014; 28 (1): 73 DOI: 10.1093/rfs/hhu063

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Small volcanic eruptions partly explain 'warming hiatus'

The "warming hiatus" that has occurred over the last 15 years has been caused in part by small volcanic eruptions.

Scientists have long known that volcanoes cool the atmosphere because of the sulfur dioxide that is expelled during eruptions. Droplets of sulfuric acid that form when the gas combines with oxygen in the upper atmosphere can persist for many months, reflecting sunlight away from Earth and lowering temperatures at the surface and in the lower atmosphere.

Previous research suggested that early 21st-century eruptions might explain up to a third of the recent warming hiatus.

New research available online in the journal Geophysical Research Letters (GRL) further identifies observational climate signals caused by recent volcanic activity. This new research complements an earlier GRL paper published in November, which relied on a combination of ground, air and satellite measurements, indicating that a series of small 21st-century volcanic eruptions deflected substantially more solar radiation than previously estimated.

"This new work shows that the climate signals of late 20th- and early 21st-century volcanic activity can be detected in a variety of different observational data sets," said Benjamin Santer, a Lawrence Livermore National Laboratory scientist and lead author of the study.

The warmest year on record is 1998. After that, the steep climb in global surface temperatures observed over the 20th century appeared to level off. This "hiatus" received considerable attention, despite the fact that the full observational surface temperature record shows many instances of slowing and acceleration in warming rates. Scientists had previously suggested that factors such as weak solar activity and increased heat uptake by the oceans could be responsible for the recent lull in temperature increases. After publication of a 2011 paper in the journal Science by Susan Solomon of the Massachusetts Institute of Technology (link is external) (MIT), it was recognized that an uptick in volcanic activity might also be implicated in the warming hiatus.

Prior to the 2011 Science paper, the prevailing scientific thinking was that only very large eruptions -- on the scale of the cataclysmic 1991 Mount Pinatubo eruption in the Philippines, which ejected an estimated 20 million metric tons (44 billion pounds) of sulfur -- were capable of impacting global climate. This conventional wisdom was largely based on climate model simulations. But according to David Ridley, an atmospheric scientist at MIT and lead author of the November GRL paper, these simulations were missing an important component of volcanic activity.

Ridley and colleagues found the missing piece of the puzzle at the intersection of two atmospheric layers, the stratosphere and the troposphere -- the lowest layer of the atmosphere, where all weather takes place. Those layers meet between 10 and 15 kilometers (six to nine miles) above Earth.

Satellite measurements of the sulfuric acid droplets and aerosols produced by erupting volcanoes are generally restricted to above 15 km. Below 15 km, cirrus clouds can interfere with satellite aerosol measurements. This means that toward the poles, where the lower stratosphere can reach down to 10 km, the satellite measurements miss a significant chunk of the total volcanic aerosol loading.

To get around this problem, the study by Ridley and colleagues combined observations from ground-, air- and space-based instruments to better observe aerosols in the lower portion of the stratosphere. They used these improved estimates of total volcanic aerosols in a simple climate model, and estimated that volcanoes may have caused cooling of 0.05 degrees to 0.12 degrees Celsius since 2000.

The second Livermore-led study shows that the signals of these late 20th and early 21st eruptions can be positively identified in atmospheric temperature, moisture and the reflected solar radiation at the top of the atmosphere. A vital step in detecting these volcanic signals is the removal of the "climate noise" caused by El Ni?os and La Ni?as.

"The fact that these volcanic signatures are apparent in multiple independently measured climate variables really supports the idea that they are influencing climate in spite of their moderate size," said Mark Zelinka, another Livermore author. "If we wish to accurately simulate recent climate change in models, we cannot neglect the ability of these smaller eruptions to reflect sunlight away from Earth."

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Hurricane-forecast satellites will keep close eyes on the tropics

A set of eight hurricane-forecast satellites being developed at the University of Michigan is expected to give deep insights into how and where storms suddenly intensify--a little-understood process that's becoming more crucial to figure out as the climate changes, U-M researchers say.

The Cyclone Global Navigation Satellite System is scheduled to launch in fall 2016. At the American Geophysical Union Meeting in San Francisco this week, U-M researchers released estimates of how significantly CYGNSS could improve wind speed and storm intensity forecasts.

CYGNSS--said like the swan constellation--is a $173-million NASA mission that U-M is leading with Texas-based Southwest Research Institute. Each of its eight observatories is about the size of a microwave oven. That's much smaller than a typical weather satellite, which is about the size of a van.

The artificial CYGNSS "constellation," as researchers refer to it, will orbit at tropical, hurricane-belt latitudes. Its coverage will stretch from the 38th parallel north near Delaware's latitude to its counterpart in the south just below Buenos Aires.

Because of their arrangement and number, the observatories will be able to measure the same spot on the globe much more often than the weather satellites flying today can. CYGNSS's revisit time will average between four and six hours, and at times, it can be as fast as 12 minutes.

Conventional weather satellites only cross over the same point once or twice a day. Meteorologists can use ground-based Doppler radar to help them make predictions about storms near land, but hurricanes, which form over the open ocean, present a tougher problem.

"The rapid refresh CYGNSS will offer is a key element of how we'll be able to improve hurricane forecasts," said CYGNSS lead investigator Christopher Ruf, director of the U-M Space Physics Research Lab and professor of atmospheric, oceanic and space sciences.

"CYGNSS gets us the ability to measure things that change fast, like extreme weather. Those are the hardest systems to measure with today's satellites. And because the world is warmer and there's more energy to feed storm systems, there's more likelihood of extreme weather."

Through simulations, the researchers quantified the improvement CYGNSS could have on storm intensity predictions. They found that for a wind speed forecast that is off by 33 knots, or 38 miles per hour--the average error with current capabilities--CYGNSS could reduce that by 9 knots, or about 10 mph.

Considering that the categories of hurricane strength ratchet up, on average, every 20 mph, the accuracy boost is "a very significant number," Ruf said.

"I'd describe the feeling about it as guarded excitement," he said. "It's preliminary and it's all based on models. People will be really excited when we get up there and it works."

The numbers could also improve as scientists update weather prediction tools to better use the new kind of information that CYGNSS will provide.

For people who live in common hurricane or typhoon paths, closer wind speed predictions could translate into more accurate estimates of the storm surge at landfall, Ruf said. That's the main way these systems harm people and property.

"The whole ocean gets higher because the wind pushes the water. That's really hard to forecast now and it's an area we hope to make big improvements in," Ruf said.

Researchers expect the satellite system to give them new insights into storm processes. Hurricanes evolve slowly at first, but then they reach a tipping point, says Aaron Ridley, a professor of atmospheric, oceanic and space sciences.

"The hurricane could be meandering across the Atlantic Ocean and then something happens." Ridley said. "It kicks up a notch and people aren't exactly sure why. A lot of scientists would like to study this rapid intensification in more detail. With a normal mission, you might not be able to see it, but with CYGNSS, you have a better chance."

The satellites will operate in a fundamentally different way than their counterparts do. Rather than transmit a signal and read what reflects back, they'll measure how GPS signals from other satellites bounce off the ocean surface. Each of the eight CYGNSS nodes will measure signals from four of the 32 Global Positioning System satellites.

They'll also be able to take measurements through heavy rain--something other weather satellites are, surprisingly, not very good at.

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Hurricane sandy increased incidents of heart attacks, stroke in hardest hit New Jersey counties

Heart attacks and strokes are more likely to occur during extreme weather and natural disasters such as earthquakes and floods. Researchers at the Cardiovascular Institute of New Jersey at Rutgers Robert Wood Johnson Medical School have found evidence that Hurricane Sandy, commonly referred to as a superstorm, had a significant effect on cardiovascular events, including myocardial infarction (heart attack) and stroke, in the high-impact areas of New Jersey two weeks following the 2012 storm. The study, led by Joel N. Swerdel, MS, MPH, an epidemiologist at the Cardiovascular Institute and the Rutgers School of Public Health, was published in the Journal of the American Heart Association.

Utilizing the Myocardial Infarction Data Acquisition System (MIDAS), the researchers examined changes in the incidence of and mortality from myocardial infarctions and strokes from 2007 to 2012 for two weeks prior to and two weeks after October 29, the date of Hurricane Sandy. MIDAS is an administrative database containing hospital records of all patients discharged from non-federal hospitals in New Jersey with a cardiovascular disease diagnosis or invasive cardiovascular procedure.

In the two weeks following Hurricane Sandy, the researchers found that in the eight counties determined to be high-impact areas, there was a 22 percent increase in heart attacks as compared with the same time period in the previous five years. In the low impact areas (the remaining 13 counties), the increase was less than one percent. 30-day mortality from heart attacks also increased by 31 percent in the high-impact area.

"We estimate that there were 69 more deaths from myocardial infarction during the two weeks following Sandy than would have been expected. This is a significant increase over typical non-emergency periods," said Swerdel. "Our hope is that the research may be used by the medical community, particularly emergency medical services, to prepare for the change in volume and severity of health incidents during extreme weather events."

In regard to stroke, the investigators found an increase of 7 percent compared to the same time period in the prior five years in areas of the state impacted the most. There was no change in the incidence of stroke in low-impact areas. There also was no change in the rate of 30-day mortality due to stroke in either the high- or low-impact areas.

"Hurricane Sandy had unprecedented environmental, financial and health consequences on New Jersey and its residents, all factors that can increase the risk of cardiovascular events," said John B. Kostis, MD, director of the Cardiovascular Institute of New Jersey and associate dean for cardiovascular research at Rutgers Robert Wood Johnson Medical School. "Increased stress and physical activity, dehydration and a decreased attention or ability to manage one's own medical needs probably caused cardiovascular events during natural disasters or extreme weather. Also, the disruption of communication services, power outages, gas shortages, and road closures, also were contributing factors to efficiently obtaining medical care."

Journal Reference:

J. N. Swerdel, T. M. Janevic, N. M. Cosgrove, J. B. Kostis. The Effect of Hurricane Sandy on Cardiovascular Events in New Jersey. Journal of the American Heart Association, 2014; 3 (6): e001354 DOI: 10.1161/JAHA.114.001354

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