Climate change impacts stream life

Climate change is warming Welsh streams and rivers, affecting the number and variety of some of their smallest animals, a major Cardiff University study has found.

Rivers and streams are key ecosystems for many aquatic species and form important links with surrounding habitats, yet little emphasis has been given so far to the ecological effects of climate change on these running-waters.

Now a twenty-five year study at Llyn Brianne in central Wales, led by Professor Steve Ormerod and Dr Isabelle Durance of the Cardiff School of Biosciences, has examined for the first time the effects of climate change on stream species.

The study looked at the effects of climate change on stream macroinvertebrates – animals that can be seen with the naked eye such as crustaceans, snails and larval insects including stoneflies or mayflies.

Professor Ormerod, said: “Streams and rivers are likely to be highly sensitive to climate and yet long-term evidence of effects is scarce globally. Our study shows a clear climate-change signal over the last 25 years, with temperatures warming faster than could be explained by background variations. An ecological response to warming has also been clear.”

The study predicts that at the present rate the springtime abundance of macroinvertebrates in streams could decline by as much as 21 per cent for every 1 degree Celsius rise in temperature.

Dr Durance added “The numbers of species in the streams we examined might also fall by 12-25 per cent if trends continue as expected over the next 50 years”.

 

Ocean’s ‘twilight zone’ may be a key to understanding climate change

Carbon dioxide consumed before it sinks in deep ocean may re-enter atmosphere as greenhouse gas

Mike Tidwell comments -This article and many others supoort the idea that the deep ocean is a sink for atmospheric carbon as was once hoped. Actually, carbon dioxide levels have been much higher in the deep past, in some instances as much 4,000 ppmv versus the current level of 385 ppmv. There is no easy way out–the natural removal of CO2 from the atmosphere is on the order of hundreds of years, and because of negative feedbacks in the system, possibly much longer.

A major study sheds new light on the role of carbon dioxide once it’s transported to the oceans’ depths. The research indicates that instead of sinking, carbon dioxide is often consumed by animals and bacteria and recycled in the “twilight zone,” a dimly lit area 100 to 1,000 meters below the surface. Because the carbon often never reaches the deep ocean, where it can be stored and prevented from re-entering the atmosphere as a green-house gas, the oceans may have little impact on changes in the atmosphere or climate.
The research is the result of two international expeditions to the Pacific Ocean, and is published in the April 27, 2007, issue of Science.
“These results are particularly important to our efforts today to improve the predictive capacity of numerical models that relate ocean carbon to global climate change on different time scales,” said Don Rice, director of NSF’s chemical oceanography program.
It also adds a new wrinkle to proposals to mitigate climate change by fertilizing the oceans with iron–to promote blooms of photosynthetic marine plants and transfer more carbon dioxide from the air to the deep ocean.
“The twilight zone is a critical link between the surface and the deep ocean,” said Ken Buesseler, a biogeochemist at Woods Hole Oceanographic Institution and lead author of the new study, which is co-authored by 17 other scientists. “We’re interested in what happens in the twilight zone, what sinks into it and what actually sinks out of it. Unless the carbon goes all the way down into the deep ocean and is stored there, the oceans will have little impact on climate change.”
Buesseler was the leader of a project funded by the National Science Foundation (NSF) called VERTIGO (Vertical Transport In the Global Ocean).
The twilight zone acts as a gate that allows more sinking particles through in some regions and fewer in others, complicating scientists’ ability to predict the ocean’s role in offsetting the impacts of greenhouse gases.
Using new technology, the researchers found that only 20 percent of the total carbon in the ocean surface made it through the twilight zone off Hawaii, while 50 percent did in the northwest Pacific near Japan.
These sinking particles, often called “marine snow,” supply food to organisms deeper down, including bacteria that decompose the particles. In the process, carbon is converted back into dissolved organic and inorganic forms that are re-circulated and reused in the twilight zone and that can make their way to the surface and back into the atmosphere.
The problem, say scientists, is that particles sink slowly, perhaps 10 to a few hundred meters per day, but they are swept sideways by ocean currents traveling many thousands of meters per day. To collect sinking particles, oceanographers use cones or tubes that hang beneath buoys or float up from sea floor. That, Buesseler said, “is like putting out a rain gauge in a hurricane.”
While many studies have investigated the surface of the ocean, little research has been conducted on the carbon cycle below. The VERTIGO team examined a variety of processes to open a new window into the difficult-to-explore twilight zone. They successfully used a wide array of new tools, including an experimental device that overcame a longstanding problem of how to collect marine snow falling into the twilight zone.
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Other scientists involved in VERTIGO are David Karl of the University of Hawaii; Makio Honda of the Japan Agency for Marine-Earth Science and Technology; Deborah Steinberg of the Virginia Institute of Marine Sciences; Mary Silver of the University of California at Santa Cruz; David Siegel of the University of California at Santa Barbara; James Bishop of the University of California at Berkeley; Thomas Trull of the University of Tasmania, Australia; Philip Boyd of the University of Dunedin, New Zealand; and Frank Dehairs of Free University of Brussels, Belgium.
More than 40 biologists, chemists, physical oceanographers, and engineers from 14 institutions and seven countries participated in the two VERTIGO oceanographic research cruises in 2004 and 2005 to investigate how marine plants die and sink, or are eaten by animals and converted into sinking fecal pellets.

 

Arctic ice retreating more quickly than computer models project

Article here;

http://www.ucar.edu/news/releases/2007/seaice.shtml

 

Plants do not emit methane

Mike Tidwell comments – That plants emit a diverse number compounds, including a very small amount of hydrocarbons, is well documented. But keep in mind that even if plants were emitting a great deal of methane into the atmosphere, this still would not constitute a source of climate change. All carbon emitted by plants originated from the atmosphere. In the long view, the great majority of carbon held by plants is returned to the atmosphere as they die and decompose. Only deep-earth atoms moved from below ground to the atmosphere are a true addition of greenhouse gases to our atmosphere. There is a tendency to blame other earth processes for climate change, but the reality is that the blame rests squarely on our shoulders. It is we who are moving carbon-based molecules, safely locked up underground, into our atmosphere on a massive scale.

Scientists disprove a recent study that suggests plants emit the potent greenhouse gas methane

 

A recent study in Nature¹ suggested that terrestrial plants may be a global source of the potent greenhouse gas methane, making plants substantial contributors to the annual global methane budget. This controversial finding and the resulting commotion triggered a consortium² of Dutch scientists to re-examine this in an independent study. Reporting in New Phytologist, Tom Dueck and colleagues present their results and conclude that methane emissions from plants are negligible and do not contribute to global climate change.

 

The consortium brings together a unique combination of expertise and facilities enabling the design and execution of a novel experiment. Plants were grown in a facility containing atmospheric carbon dioxide almost exclusively with a heavy form of carbon (¹³C). This makes the carbon released from the plants relatively easy to detect. Thus, if plants are able to emit methane, it will contain the heavy carbon isotope and can be detected against the background of lighter carbon molecules in the air.

 

Six plant species were grown in a ¹³C-carbon dioxide atmosphere, saturating the plants with heavy carbon. ¹³C-Methane emission was measured under controlled, but natural conditions with a photo-acoustic laser technique. This technique is so sensitive that the scientists are able to measure the carbon dioxide in the breath of small insects like ants. Even with this state-of-the-art technique, the measured emission rates were so close to the detection limit that they did not statistically differ from zero. To our knowledge this is the first independent test which has been published since the controversy last year.

 

Conscious of the fact that a small amount of plant material might only result in small amounts of methane, the researchers sampled the ‘heavy’ methane in the air in which a large amount of plants were growing. Again, the measured methane emissions were neglible. Thus these plant specialists conclude that there is no reason to reassess the mitigation potential of plants. The researchers stress that questions still remain and that the gap in the global methane budget needs to be properly addressed.

 

^1’Methane emissons from terrestrial plants under aerobic conditions’ by Keppler F, Hamilton JTG, Braβ M, Rockmann T. Nature 439: 187–191

 

²The Dutch consortium includes scientists from Plant Research International, IsoLife and Plant Dynamics in Wageningen, Utrecht University, and the Radboud University in Nijmegen.

 

ENDS

Notes to Editors

1. The article referred to is available Online Only via Blackwell Synergy:
’No evidence for substantial aerobic methane emission by terrestrial plants: A 13C-labelling approach’ Tom A. Dueck, Ries de Visser, Hendrik Poorter, Stefan Persijn, Antonie Gorissen, Willem de Visser, Ad Schapendonk, Jan Verhagen, Jan Snel, Frans J. M. Harren, Anthony K. Y. Ngai, Francel Verstappen, Harro Bouwmeester, Laurentius A. C. J. Voesenek and Adrie van der Werf

New Phytologist. Article published online: 27-April-2007.

2. For further information, please contact Lucy Mansfield, email: lucy.mansfield@oxon.blackwellpublishing.com or telephone: +44 (0) 1865 476241

 

3. New Phytologist is an international journal offering rapid publication of high quality original research in plant science. Owned by a not-for-profit organisation, the New Phytologist Trust is dedicated to the promotion of plant science.

 

Satellites shed light on global warming

Mike Tidwell comments -Modern satelite data has not only ended long-standing controveries about ice and climate, but it has also spurred new ones such as the waves mentioned in this article. I do not have a comment on the influence of long waves on our environment at the present time. This is an new idea for me and something I want to think about before commenting.

Read article here;

http://www.esa.int/esaEO/SEMRLH12Z0F_planet_0.html

 

Fish growth enhanced by climate change

Mike Tidwell comments — This article is good example of a change in the environment, but which is difficult to say with certainty what caused it.  

Changes in growth rates in some coastal and long-lived deep-ocean fish species in the south west Pacific are consistent with shifts in wind systems and water temperatures, according to new Australian research published in the United States this week.

27 April 2007

“We have drawn correlations between the growth of fish species related to their environmental conditions – faster growth in waters above a depth of 250 metres and slower rates of growth below 1,000 metres,” says lead author, Dr Ron Thresher.

“These observations suggest that global climate change has enhanced some elements of productivity of shallow-water stocks but at the same time reduced the productivity and possibly the resilience of deep water stocks,” he says.

A biological oceanographer with CSIRO’s Wealth from Oceans Research Flagship, Dr Thresher said the research – published in the latest edition of the US science journal, Proceedings of the National Academy of Sciences – is based on the examination of fish earbones, or otoliths, which show similar characteristics to the growth rings used to date the age of trees.  The work was done in collaboration with the Victorian Marine and Aquatic Fisheries Research Institute, which has specialist skills in analysing otoliths.

Water temperatures have been obtained from a 60-year-long record at Maria Island on the Tasmanian east coast, and using 400-year-old deep-ocean corals to measure temperate at depth.

Dr Thresher said populations of large marine species are widely subject to two major stressors – commercial fishing and climate change. Heavy exploitation increases the sensitivity of species to environmental effects and could be magnifying the effects of long-term climate change and short-term climate variability on the viability of some species.

“Dr Thresher said slower growth in fishes has been correlated with a variety of life history traits – from higher mortality to reduced food availability and increased age or smaller size at sexual maturity.”

He said correlations for long-lived shallow and deep-water species suggest that water temperatures have been a primary factor in determining juvenile growth rates in the species examined – banded morwong, redfish, jackass morwong, spiky, black, smooth and warty oreo and orange roughy.  Because of the pervasive effect of temperature on the physiology and growth of marine animals, it was likely that similar effects would be seen in many other species.

The science team examined 555 specimens ranging in age from two to 128 years, with birth years from 1861 to 1993.

Growth rates of a coastal species, juvenile morwong, in the 1990s were 28.5 per cent faster than at the beginning of the period under assessment in the mid-1950s.  By comparison, juvenile oreos, a species found at depths of around 1,000 metres, were growing 27.9 per cent slower than in the 1860s. There was no or little change in the growth rates of species found between 500 and 1,000 metres.

Growth rates of the juveniles of the deep-water species all began decreasing well before the onset of commercial fishing.

Dr Thresher said slower growth in fishes has been correlated with a variety of life history traits – from higher mortality to reduced food availability and increased age or smaller size at sexual maturity.

He said comparisons of historical and modern oceanographic data indicate temperature trends very similar to the apparent changes in growth rates.  In the south west Pacific east of Tasmania sea surface temperatures have risen nearly two degrees, based on the results of a monitoring program at Maria Island.  Coinciding with this has been a southward shift in South Pacific zonal winds which has strengthened the warm, poleward-flowing East Australian Current.

“Modelling suggests that, with increasing global warming, temperatures at intermediate depths are likely to rise near-globally,” Dr Thresher said. “This could mean that over the course of time, the decrease in growth rates for the deep-water species could slow or even be reversed,” Dr Thresher said.

The paper: Depth-mediated reversal of the effects of climate change on long-term growth rates of exploited marine fish, was authored by Dr Thresher, Dr Tony Koslow, now of the Scripps Institute of Oceanography, Dr A.K. Morison, now at the Bureau of Resource Sciences,  and Dr David Smith, now of CSIRO.

 

U of Colorado researchers forecast 1 in 3 chance of record low sea ice in 2007

University of Colorado at Boulder researchers are forecasting a one in three chance that the 2007 minimum extent of sea ice across the Arctic region will set an all-time record low.

The researchers at CU-Boulder’s Colorado Center for Astrodynamics Research also say there is a 57 percent chance the 2007 sea-ice minimum will be lower than the 2006 minimum of 2.27 million square miles, now the second lowest on record. There is a 70 percent chance the 2007 sea-ice minimum will rank within the lowest five years on record, according to Research Associate Sheldon Drobot of CCAR’s Arctic Regional Ice Forecasting System group in CU-Boulder’s aerospace engineering sciences department.

Sea-ice extent is the area of an ocean covered by at least 15 percent ice. Declining sea ice in the Arctic is believed by researchers to be caused by higher winter temperatures due to greenhouse warming, said Drobot. Arctic sea ice has been declining since the late 1970s.

Researchers pay particular attention to September and March because they generally mark the annual minimum and maximum sea-ice extents respectively, said Drobot. On April 4, researchers from CU-Boulder’s National Snow and Ice Data Center reported the maximum extent of this year’s March Arctic sea ice, 5.7 million square miles, was the second-lowest maximum on satellite record.

While regional sea ice declines were sharpest in the western Arctic over the past few years, large declines also occurred last year in much of the eastern Arctic, according to Drobot. Such regional variation is of interest to the maritime industry, including government agencies, international shipping companies, energy exploration corporations and tourism cruise lines active in the far North, he said.

“The practical offshoot here is that people operating ships in Arctic waters can use these forecasts to try to plan activities several months in advance,” said Drobot. The sea ice research by the CCAR group — the only research group in the world currently making seasonal Arctic sea ice forecasts based on probability — is funded by the National Science Foundation and NASA, he said.

The CCAR researchers used satellite data from the U.S. Department of Defense and temperature records from the National Oceanic and Atmospheric Administration for the forecasts, which they have been producing for five years, said Drobot. Updated forecasts will be provided throughout the spring and summer, he said.

 

Study says U.S. CO2 emissions rose 18% during the1990-2004 period

 

NEW YORK: Carbon dioxide emissions in the U.S. have risen by 18 per cent during the 1990-2004 period, a recent study by an advocacy group has indicated.

The state-wise study by the U.S. Public Interest Research Group showed that CO2 emissions came down in only two states — Delaware and Massachusetts — and the District of Columbia, while Texas and Nevada headed the list where the emissions grew at the highest rate.

The group used data from the U.S. department of energy for the study.

While Texas headed the list of states with emissions growing by 95.8 million metric tons during the period, Nevada with a 55 per cent growth ranked first in terms of percentage growth.

The group said electric power plants and the transportation sector — particularly cars and light trucks — contributed mainly to the increase in CO2 emissions nationwide — emissions from the electric power sector rising by 28 per cent and from the transportation sector by 23 per cent.

The study finds that the electric power sector accounted for 55 per cent of the increase in emissions. Increasing demand for electricity from residential, commercial and industrial consumers led to this rapid increase in emissions.

Coal-fired power plants accounted for most of the increase — three-fourths of the emissions increase in the electric power sector and 42 per cent in the overall increase in emissions.

CO2 emissions from natural gas consumption in the electric power sector increased by almost 70 per cent, accounting for 13 per cent of the nation’s overall increase in emissions.

The transportation sector accounted for 40 per cent of the overall increase in emissions. Emissions from motor gasoline consumption increased by 22 per cent, accounting for more than half of the emissions increase in the transportation sector.

The group released the report, titled “The Carbon Boom: State and National Trends in Carbon Dioxide Emissions Since 2007,” Thursday.

The top 15 states with the largest percentage increases in energy-related emissions are:

1 Nevada 55 per cent
2 Arizona 54 per cent
3 New Hampshire 50 per cent
4 South Carolina 45 per cent
5 Colorado 39 per cent
6 Idaho 38 per cent
7 Oregon 37 per cent
8 Florida 37 per cent
9 Mississippi 36 per cent
10 North Carolina 36 per cent
11 Alaska 35 per cent
12 Missouri 34 per cent
13 Virginia 34 per cent
14 Nebraska 31 per cent
15 Vermont 29 per cent

Copyright © 2007 Respective Author

 

Warming’s biggest wallop aimed at wildlife, not people

 “With the small climate change we’ve already had, 59 percent of the world’s species have shown a response – on all continents, in all major oceans, and across taxonomic groups,” says Dr. Parmesan.

 

Global warming will affect societies around the world through more prolonged droughts, more intense rains and flooding, changes in the timing of seasonal rainfall and snowmelt, and a projected increase in the spread of animal- and insect-borne diseases, scientists say.

But it will affect plant and animal species even more dramatically. A shift in climate zones could lead to extinction of some species and the spread of others, according to a report set to be released Friday by the Intergovernmental Panel on Climate Change.

In turn, many of these ecological shifts will affect humans, writes Chris Field, founding director of the Carnegie Institution’s department of global ecology at Stanford University, in an e-mail from the IPCC talks in Brussels. “A large fraction of the impacts of climate change on people are transmitted through ecosystems.”

If the average temperature rises by 1.8 degrees C (3.2 degrees F.) by the end of this century – the low end of the IPCC’s projected range – it would still be possible to set up preserves and maintain almost all of the planet’s major ecosystems and the species they contain, says Camille Parmesan, a biologist at the University of Texas in Austin. But if temperatures rise much higher than that, “We’re going into a realm Earth hasn’t seen for a very long time. Most of the species we have on Earth did not evolve under that warmer climate.”

Already, the global climate has warmed an average of 0.7 degrees C during the 20th century, she notes. So far, the ecological changes have been relatively benign.

What’s worrisome is if heat-trapping greenhouse-gas emissions continue to accumulate under the IPCC’s “business as usual” scenario, says John Williams, who studies plant dynamics at the University of Wisconsin at Madison. If that happens, up to 48 percent of Earth’s land surface will lose existing climate zones, he and two colleagues recently calculated.

That loss is at the cold ends of the spectrum – largely toward the poles and at high altitudes in the tropics. At the same time, some 12 to 39 percent of the planet will see hotter – or what the team calls “novel” – climate zones.

How novel? The prolonged drought the US Southwest has experienced is probably not temporary, says an international team of scientists. Instead, it’s likely to be a manifestation of the northward expansion of a belt of subtropical, dry climate conditions. If the team’s projections are correct, the Southwest’s average climate conditions will be just as dry as the drought or the Dust Bowl. The team’s results appear in Friday’s issue of the journal Science’s online service.

Not all effects will be harmful, many experts agree. High latitudes would experience a longer growing season. And increased carbon-dioxide concentrations in the atmosphere have stimulated plant growth worldwide – at least for now.

But such effects have their limits. Researchers have found that if water and soil nutrients available to trees, shrubs, and grasses don’t keep pace with rising CO2, plant growth will stall as plants get too much of a usually good thing.

Even when plants take up lots of CO2 in the spring, they throttle back in the summer if conditions heat up and dry out. Such conditions are expected to cover broad swaths of Earth’s landscape. This essentially cancels the effects of the spring uptake.

There may be other, more subtle effects. Researchers at the University of New Hampshire, for example, have found that trees, which emit hydrocarbons naturally, give off more hydrocarbons as CO2 levels rise. Scientists already have shown that these hydrocarbons, when mixed with nitrogen-based gases from coal-fired power plants, can contribute smog and tiny aerosol particles to already polluted urban air. The New Hampshire group is now trying to see what impact these additional hydrocarbons may have on air quality.

In general, “With the small climate change we’ve already had, 59 percent of the world’s species have shown a response – on all continents, in all major oceans, and across taxonomic groups,” says Dr. Parmesan. Some 70 species have become extinct, largely at the poles or on mountaintops, where cold-adapted organisms have no place left to go as warmth creeps into higher latitudes and altitudes. Others, such as polar bears, are threatened. In other cases, rising CO2 levels are forcing organisms into a new regime where they have to compete for resources. In California, for example, researchers have found that higher CO2 levels have delayed flowering in some wild grasses but accelerated it in wild herbs that share the same turf. This is forcing the plants to compete directly for nutrients – ultimately changing the character of the ecosystem.

In the oceans, researchers are noting shifts in fish migration patterns. Coral-reef bleaching remains a concern, but its connection to global warming is still somewhat contentious, notes Chris Langdon, a marine scientist at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science. Measurements don’t go back far enough in time to see if bleaching events are any more frequent than in the past.

But ocean acidification, a byproduct of rising CO2 levels in the air, is far more straightforward. It threatens a range of organisms – from tiny shell-forming plankton to reefs themselves. Some researchers say the changes in ocean chemistry from human CO2 emissions are expected to last from tens of thousands to hundreds of thousands of years, until natural buffering can take hold.

With some care and feeding, however, some ecosystems may be able to retain their resilience in the face of changes expected from global warming. Researchers at Duke University have found, for example, that if rates of sea-level rise remain relatively low, tidal marshes build themselves to keep pace, continuing to provide a buffer against storm surge and serving as a nursery for marine life.

“Marshes are not necessarily doomed,” says Matt Kirwan, who led the study.

 

Arctic sea ice narrowly missed record low in winter 2007, says University of Colorado team

The Arctic sea-ice extent, which is the area of ocean covered by at least 15 percent ice, was 5.7 million square miles in March 2007, slightly higher than the record low of 5.6 million square miles measured in March 2006. The declining sea ice has been blamed on higher winter temperatures in the Arctic, a result of rising greenhouse gases in the atmosphere and strong natural variability in the ice, said researcher Walt Meier of CU-Boulder’s National Snow and Ice Data Center.
“This year’s wintertime low extent is another milestone in a strong downward trend,” said Meier. “We’re still seeing near-record lows (in sea ice) and higher-than-normal temperatures, and we expect this downward trend to continue in future years.”
While researchers monitor Arctic sea ice year round, they pay special attention to the months of March and September because they generally mark the annual maximum and minimum sea-ice extents respectively for the year, Meier said. Sea ice usually stops growing, or recovering, from the summer melt each March.

A review study led by CU-Boulder research scientist Mark Serreze of NSIDC and published in Science last month indicated Arctic sea-ice extent trends have been negative for every month since 1979, when reliable satellite record-keeping efforts began. The September minimum measurements indicate the Arctic has been losing about 38,000 square miles of ice annually.

Source: University of Colorado at Boulder