Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Erratic, extreme day-to-day weather puts climate change in new light

16.11.2011
The first climate study to focus on variations in daily weather conditions has found that day-to-day weather has grown increasingly erratic and extreme, with significant fluctuations in sunshine and rainfall affecting more than a third of the planet.

Princeton University researchers recently reported in the Journal of Climate that extremely sunny or cloudy days are more common than in the early 1980s, and that swings from thunderstorms to dry days rose considerably since the late 1990s. These swings could have consequences for ecosystem stability and the control of pests and diseases, as well as for industries such as agriculture and solar-energy production, all of which are vulnerable to inconsistent and extreme weather, the researchers noted.

The day-to-day variations also could affect what scientists could expect to see as the Earth's climate changes, according to the researchers and other scientists familiar with the work. Constant fluctuations in severe conditions could alter how the atmosphere distributes heat and rainfall, as well as inhibit the ability of plants to remove carbon dioxide from the atmosphere, possibly leading to higher levels of the greenhouse gas than currently accounted for.

Existing climate-change models have historically been evaluated against the average weather per month, an approach that hides variability, explained lead author David Medvigy, an assistant professor in the Department of Geosciences at Princeton. To conduct their analysis, he and co-author Claudie Beaulieu, a postdoctoral research fellow in Princeton's Program in Atmospheric and Oceanic Sciences, used a recently developed computer program that has allowed climatologists to examine weather data on a daily level for the first time, Medvigy said.

"Monthly averages reflect a misty world that is a little rainy and cloudy every day. That is very different from the weather of our actual world, where some days are very sunny and dry," Medvigy said.

"Our work adds to what we know about climate change in the real world and places the whole problem of climate change in a new light," he said. "Nobody has looked for these daily changes on a global scale. We usually think of climate change as an increase in mean global temperature and potentially more extreme conditions -- there's practically no discussion of day-to-day variability."

The Princeton findings stress that analysis of erratic daily conditions such as frequent thunderstorms may in fact be crucial to truly understanding the factors shaping the climate and affecting the atmosphere, said William Rossow, a professor of earth system science and environmental engineering at the City College of New York.

"It's important to know what the daily extremes might do because we might care about that sooner," said Rossow, who also has studied weather variability. He had no role in the Princeton research but is familiar with it.

Rossow said existing climate-change models show light rain more frequently than they should and don't show extreme precipitation. "If it rains a little bit every day, the atmosphere may respond differently than if there's a really big rainstorm once every week. One of the things you find about rainstorms is that the really extreme ones are at a scale the atmosphere responds to," he said.

Although climate-change models predict future changes in weather as the planet warms, those calculations are hindered by a lack of representation of day-to-day patterns, Rossow said.

"If you don't know what role variability is playing now, you're not in a very strong position for making remarks about how it might change in the future," he said. "We're at a stage where we had better take a look at what this research is pointing out."

Medvigy and Beaulieu determined sunshine variation by analyzing fluctuations in solar radiation captured by the International Satellite Cloud Climatology Project from 1984 to 2007. To gauge precipitation, the researchers used daily rainfall data from the Global Precipitation Climatology Project spanning 1997 to 2007.

Medvigy and Beaulieu found that during those respective periods, extremes in sunshine and rainfall became more common on a day-to-day basis. In hypothetical terms, Medvigy said, these findings would mean that a region that experienced the greatest increase in sunshine variability might have had partly cloudy conditions every day in 1984, but by 2007 the days would have been either sunny or heavily cloudy with no in-between. For rainfall, the uptick in variation he and Beaulieu observed could be thought of as an area experiencing a light mist every day in 1997, but within ten years the days came to increasingly fluctuate between dryness and downpour.

The researchers observed at least some increase in variability for 35 percent of the world during the time periods analyzed. Regions such as equatorial Africa and Asia experienced the greatest increase in the frequency of extreme conditions, with erratic shifts in weather occurring throughout the year. In more temperate regions such as the United States, day-to-day variability increased to a lesser degree and typically only seasonally. In the northeastern United States, for instance, sudden jumps from sunny to bleak days became more common during the winter from 1984 to 2007.

In the 23 years that sunshine variability rose for tropical Africa and Asia, those areas also showed a greater occurrence of towering thunderstorm clouds known as convective clouds, Medvigy said. Tropical areas that experienced more and more unbalanced levels of sunshine and rainfall witnessed an in-kind jump in convective cloud cover. Although the relationship between these clouds and weather variations needs more study, Medvigy said, the findings could indicate that the sunnier days accelerate the rate at which water evaporates then condenses in the atmosphere to form rain, thus producing heavy rain more often.

Storms have lasting effect on daily weather patterns

Although the most extreme weather variations in the study were observed in the tropics, spurts of extreme weather are global in reach, Rossow said. The atmosphere, he said, is a fluid, and when severe weather such as a convective-cloud thunderstorm "punches" it, the disturbance spreads around the world. Weather that increasingly leaps from one extreme condition to another in short periods of time, as the Princeton research suggests, affects the equilibrium of heat and rain worldwide, he said.

"Storms are violent and significant events — while they are individually localized, their disturbance radiates," Rossow said.

"Wherever it's raining heavily, especially, or variably is where the atmosphere is being punched. As soon as it is punched somewhere in the tropics it starts waves that go all the way around the planet," he said. "So we can see waves coming off the west Pacific convection activity and going all the way around the planet in the tropical band. The atmosphere also has the job of moving heat from the equator to the poles, and storms are the source of heat to the atmosphere, so if a storm's location or its timing or its seasonality is altered, that's going to change how the circulation responds."

These sweeping atmospheric changes can interact with local conditions such as temperature and topography to skew regular weather patterns, Rossow said.

"Signals end up going over the whole globe, and whether they're important in a particular place or not depends on what else is happening," he said. "But you can think of storms as being the disturbances in an otherwise smooth flow. That's why this is a climate issue even though we're talking about daily variability in specific locations."

The impact of these fluctuations on natural and manmade systems could be as substantial as the fallout predicted from rises in the Earth's average temperature, Medvigy said. Inconsistent sunshine could impair the effectiveness of solar-energy production and — with fluctuating rainfall also included — harm agriculture, he said. Wetter, hotter conditions also breed disease and parasites such as mosquitoes, particularly in tropical areas, he said.

On a larger scale, wild shifts in day-to-day conditions would diminish the ability of trees and plants to remove carbon from the atmosphere, Medvigy said. In 2010, he and Harvard University researchers reported in the journal the Proceedings of the National Academy of Sciences that erratic rain and sunlight impair photosynthesis. That study concluded that this effect upsets the structure of ecosystems, as certain plants and trees — particularly broad-leafed trees more than conifers — adapt better than others.

In the context of the current study, Medvigy said, the impact of variability on photosynthesis could mean that more carbon will remain in the atmosphere than climate models currently anticipate, considering that the models factor in normal plant-based carbon absorption. Moreover, if the meteorological tumult he and Beaulieu observed is caused by greenhouse gases, these fluctuations could become self-perpetuating by increasingly trapping the gases that agitated weather patterns in the first place.

"We have not yet looked for direct ties between weather variability and increased carbon dioxide concentration in the atmosphere, but I would not be surprised if they are connected in some way," Medvigy said.

"Increases in variability diminish the efficiency with which plants and trees remove carbon dioxide from the air," he said. "All of a sudden, the land and the atmosphere are no longer in balance, and plants cannot absorb levels of carbon dioxide proportional to the concentrations in the environment. That will affect everybody."

The study was published online Oct. 14 by the Journal of Climate, and was funded by grants from the Princeton Carbon Mitigation Initiative and the Fonds Québécois de la Recherche sur la Nature et les Technologies.

Morgan Kelly | EurekAlert!
Further information:
http://www.princeton.edu

More articles from Studies and Analyses:

nachricht Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung

nachricht Scientists reveal source of human heartbeat in 3-D
07.08.2017 | University of Manchester

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>