Is the current climate change simply a natural variation like others that have occurred throughout geologic time. Some people still believe it, but more and more evidence points to human beings being (at the very least partly) responsible. The current global warming is in other words not natural. There is an abbreviation for the phenomenon - AGW (anthropogenic global warming).
In a paper, titled "Recent Changes in a Remote Arctic Lake are Unique Within the Past 200,000 Years", sediments retrieved by University at Buffalo geologists from a remote Arctic lake show that recent variations are unlike those that have been seen during previous warming episodes. The environmental transformations going on in the Arctic are dramatic.
The 20th century is the only period during the past 200,000 years in which aquatic indicators reflect increased warming, despite the declining effect of slow changes in the tilt of the Earth's axis which, under natural conditions, would lead to climatic cooling.
Reference: Recent Changes in a Remote Arctic Lake are Unique Within the Past 200,000 Years by Axford et al. Proceedings of the National Academy of Sciences Published online before print October 19, 2009 doi: 10.1073/pnas.0907094106 (requires a subscription or payment of US$10.00)
The arctic could potentially alter the Earth’s climate by becoming a possible source of global atmospheric carbon dioxide. The arctic now traps or absorbs up to 25 percent of this gas but climate change could alter that amount, according to a study published in the November issue of Ecological Monographs.
Carbon generally enters the oceans and land masses of the Arctic from the atmosphere and largely accumulates in permafrost. Unlike active soils, permafrost does not decompose its carbon; thus, the carbon becomes trapped in the frozen soil. Cold conditions at the surface have also slowed the rate of organic matter decomposition, allowing Arctic carbon accumulation to exceed its release. But recent warming trends could change this balance. Warmer temperatures can accelerate the rate of surface organic matter decomposition, releasing more carbon dioxide into the atmosphere. Of greater concern is that the permafrost has begun to thaw, exposing previously frozen soil to decomposition and erosion. These changes could reverse the historical role of the Arctic as a sink for carbon dioxide.
Within a few decades, the thawing permafrost could also result in a more waterlogged Arctic, a situation that could encourage the activity of methane-producing organisms. Currently, the Arctic is a substantial source of methane to the atmosphere: as much as 50 million tons of methane are released per year, in comparison to the 400 million tons of carbon dioxide the Arctic stores yearly. But methane is a very potent greenhouse gas – about 23 times more effective at trapping heat than carbon dioxide on a 100-year time scale. If the release of Arctic methane accelerates, global warming could increase at much faster rates.
Capture: This figure shows the mean extent of permafrost in the Arctic, estimated for (a) the years 1990-2000 and (b) the years 2090-2100. In (c), the estimation of loss of permafrost by 2100 is overlaid on estimations for the year 2000. Credit: A. David McGuire
Reference: McGuire et al. 2009. Sensitivity of the carbon cycle in the Arctic to climate change. November 2009, Ecological Monographs. (Vol. 79, No. 4, pp. 523-555) doi: 10.1890/08-2025.1 Open Access
Actually I Do think that we should do something to fight global warming, but not especially for the polar bears, I am too egoistic for that. The situation for the polar bear is just a symptom. The polar bear is a victim, just like we are. You and I thus. And as a victim the polar bear has my sympathy - now and loss of biodiversity is of course always bad (for everybody). Here are a few lines from the media in recent years:
Climate change is the number one threat to the 22,000 polar bears that remain in the world. (2002) Polar bears are drowning because climate change is melting the Arctic ice shelf. (2005) A U.S. Geological Survey study in 2007 concluded the projected decline in sea ice would mean the loss of two-thirds of the world's polar bear population by the mid-21st century. Do the bears deserve special protection? (2008) Should the endangered polar pear prompt action on climate change? (2009)
In fact it started with hunting. 40 years ago, widespread hunting had reduced polar bear populations in many parts of the Arctic. Thus, the polar bear range states, Canada, Denmark/Greenland, Norway, Russia and USA, entered into an agreement in 1973 to protect polar bears and their habitat. Well, hunting of polar bears has of course been important for the Inuits, and polar bears are essential to the livelihood for indigenous people in some areas, but hunting is no more what it has been. It must be based on sustainability. Polar bear hunters see their culture melt away. Less sea ice means fewer bears, less income and questions about the future. In March 2009, Norway invited the five nations with polar bears in their territory to a meeting under the Polar Bear Agreement from 1973. The final report of this meeting is now available.
In this document, the parties agreed that impacts of climate change and the continued and increasing loss and fragmentation of sea ice - the key habitat for both polar bears and their main prey species - constitutes the most important threat to polar bear conservation.
The parties noted with deep concern the escalating rates and extent of changes in the Arctic induced by climate change to date and that future changes are projected to be even larger. The parties agreed that long term conservation of polar bears depends upon successful mitigation of climate change.
In light of the growing concern over polar bear conservation in relation to climate change and a number of other emerging issues, such as oil- and gas activities, shipping and tourism, I am happy to say that the parties agreed to initiate a process that would lead to a coordinated approach to conservation and management strategies between the parties.
The most pronounced climate changes to the Arctic are likely to include increased temperatures and changes in precipitation patterns: both which will affect sea ice patterns and ultimately, polar bears. Polar bears will likely be shifted pole-ward if the sea ice retreats. According to new scenarios the polar ice cap will disappear almost entirely during summer in the next 100 years.
Because polar bears feed almost exclusively on ice-associated seals, changes in the sea ice that affect access to prey will have a negative effect on the bears. In particular, if more snow falls, polar bears are less successful at breaking into the birth lairs of ringed seals. If too little snow falls, ringed seal pups are born on the sea ice without a lair and this makes them very vulnerable to predation by polar bears and arctic fox. With less food, polar bears will fail to reproduce more often and give birth to smaller young cubs that have higher mortality rates.
Polar bears are totally reliant on the sea ice as their primary habitat. If climate change alters the period of ice cover, bears may be forced on shore for extended periods and forced to rely on stored fat. If these periods become excessively long, mortality will increase. If the ice changes in character such that there is more open water, young cubs which are unable to swim long distances may suffer greater mortality. Sea ice is also used for access to den areas and if ice patterns change, existing den areas may be unreachable. Another factor is that in some areas, warmer temperatures and higher winds may reduce ice thickness and increase ice drift. Because polar bears must walk against the moving ice (like walking the wrong way on an escalator) increased ice movements will increase energy use and reduce growth and reproduction.
Another problem is unusual warm spells during the period that females are on land in dens. If severe rain events occur during the den period, it is possible that snow banks slump and can kill mothers and their cubs.
Polar bears are a keystone species in ice-covered Arctic marine ecosystems and alterations to the distribution, density or abundance of this top predator will likely have impacts throughout the arctic ecosystem. There is little doubt that polar bears and other ice-inhabiting marine mammals in the Arctic, are being, or will be, negatively affected by the effects of climate change via changes to their habitats.
Prediction is very difficult, especially if it's about the future, Niels Bohr once said. This is certainly true for predictions about climate change. Climate models are important tools for climatologists. They are based upon what we know (and assumptions) about to-days climate and climate change in the past. They rely on the input, which means that climate models don't tell the full story.
To date, climate models ignored the nutrient requirements for new vegetation growth, assuming that all plants on earth had access to as much 'plant food' as they needed. But now climate scientists have successfully incorporated the nitrogen cycle into global simulations for climate change, questioning previous assumptions regarding carbon feedback and potentially helping to refine model forecasts about global warming.
By taking the natural demand for nutrients into account, the authors of a new study have shown that the stimulation of plant growth over the coming century may be two to three times smaller than previously predicted. Since less growth implies less CO2 absorbed by vegetation, the CO2 concentrations in the atmosphere are expected to increase. However, this reduction in growth is partially offset by another effect on the nitrogen cycle: an increase in the availability of nutrients resulting from an accelerated rate of decomposition – the rotting of dead plants and other organic matter – that occurs with a rise in temperature. Combining these two effects, the authors discovered that the increased availability of nutrients from more rapid decomposition did not counterbalance the reduced level of plant growth calculated by natural nutrient limitations; therefore less new growth and higher atmospheric CO¬2 concentrations are expected.
Capture: Schematic illustrating feedback pathways coupling terrestrial carbon and nitrogen cycles. Blue arrows show, in general, the processes represented in previous carbon-only land model components: plant carbon uptake by photosynthesis draws down atmospheric carbon dioxide (Atm CO2); litterfall and plant mortality pass biomass from plant to litter and coarse woody debris (CWD); decomposition of fresh litter generates soil organic matter; respiration by both plants and heterotrophic organisms returns CO2 to the atmosphere. Orange arrows show the additional processes represented in our coupled carbon-nitrogen land model, differentiated here between rapid internal cycling (solid arrows), and slower fluxes between land pools, the atmosphere, and ground water (dashed arrows). The critical feedback pathway connecting heterotrophic respiration with plant growth is highlighted as a thick orange arrow: decomposition of soil organic matter not only releases CO2 to the atmosphere, it also releases nitrogen from the organic matter (mineralization) in forms that can then be taken up by plants (assimilation). Plant nitrogen uptake competes with the demand for mineral nitrogen from heterotrophic organisms decomposing fresh litter (immobilization, abbreviated (i) in the figure.
The inclusion of the nitrogen cycle marks one more step toward a more realistic prediction for the future of the earth’s climate.
Reference: Thornton et al. (2009) Carbon-nitrogen interactions regulate climate-carbon cycle feedbacks: results from an atmosphere-ocean general circulation model. Biogeosciences, 6, 2099-2120 (Open Acces, and thus freely available for download)
Tomorrow is “Blog Action Day ‘09 Climate Change”. It is expected that more than 6000 bloggers from more than 100 different countries will blog about climate change - posts that will be read by more than 10 million readers.
Blog Action Day is an annual event that unites the world's bloggers in posting about the same issue on the same day on their own blogs with the aim of sparking discussion around an issue of global importance - such as “climate change”. Blog Action Day 2009 will be the largest-ever social change event on the web. One day. One issue. Thousands of voices.
Sea butterflies, also known as flapping snails, are small swimming sea snails. Their wing-like foot allows them to swim. Some species of sea butterfly have shells composed of aragonite, a form of calcium carbonate with the same chemical formula as calcite, CaCO3, but with another crystal shape. These snails play a key role in the cycling of carbon and carbonate, and are considered sentinels for environmental change, even though they can survive for a couple of days in water depleted of calcium carbonate, their shells already begin to show dissolution marks.
Since they have an aragonitic shell, they could be very sensitive to ocean acidification driven by the increase of man made carbon dioxide (CO2) emissions. (The oceans have absorbed about one third of total man made CO2 emissions since 1800. Although this uptake of greenhouse gases limits global warming, it also causes profound changes in the chemistry of sea-water such as a decrease of pH referred to as “ocean acidification”.) The only shelled sea butterfly in Arctic waters is Limacina helicina, a species that can occur in high densities in both the Arctic and the Southern Ocean. Comeau et al. have collected Limacina helicina from Kongsfjorden, Svalbard, to study their response to the acidification of polar waters that has been predicted will occur as atmospheric CO2 increases, carbonate declines, and ice melt.
Kongsfjorden
The impact of changes in the carbonate chemistry was investigated on Limacina helicina. The snails were kept in culture under controlled pH conditions corresponding to pCO2 levels of 350 and 760 μatm. Calcification was estimated using a fluorochrome (a fluorescent substances used in fluorescence microscopy to stain specimens) and the radioisotope 45Ca. It exhibits a 28% decrease at the pH value expected for 2100 compared to the present pH value. This result supports the concern for the future of sea butterflies in a high-CO2 world, as well as of those species dependent upon them as a food resource. A decline of their populations would likely cause dramatic changes to the structure, function and services of polar ecosystems.
The results of this study support the concern for the future of sea butterflies in a high-CO2 world, as well as of those species dependent upon them as a food resource. A decline of their populations would likely cause dramatic changes to the structure, function and services of polar ecosystems. In fact it has been said that sea butterflies might be at risk to climate change and their demise would be “catastrophic” to the ocean food chain.
The study was published in Biogeosciences. Biogeosciences is an Open Access Journal (with Peer-Review) under a Creative Commons License. This means that you can download the full article as pdf-file for free. Thank you!.
Reference: Comeau et al. Impact of ocean acidification on a key Arctic pelagic mollusc (Limacina helicina), Biogeosciences, 6, 1877-1882, 2009.
Arctic and Greenland ice is often in the news. With good reason. Some years from now on it may be history, as the ice is melting extremely fast. The news brought by redOrbit on 2 and 3 September 2009 was bad news.
On 2 September: “Arctic sea ice thickness down 53 percent”. U.S. scientists using satellite data and records from cold war submarine missions have found Arctic Ocean ice thickness has declined 53 percent since 1980.
On 3 September: “Greenland Glaciers Melting At Shocking Speed”.
Can it be repeated too often - or often enough - that the fate of the world’s ice sheets remains one of the biggest concerns in the field of climate prediction?
“Predictions of regional climate change for the next few decades are characterised by high uncertainty, but this uncertainty is potentially reducible through investments in climate science.”
This conclusion may not be new, but I find it nice to see it backed up by new research published by scientists from the UK's National Centre for Atmospheric Science (NCAS) in the scientific journal, the Bulletin of the American Meteorological Society. The study shows that investments made now, can lead to as much as 10-20% improvement in climate predictions for the UK and Europe in the coming decades, and up to 20% across the rest of the globe.
As some (climate) science bloggers have pointed out adaptation to climate change may be a smarter way forward than climate engineering (also known as geoengineering). Anyway a certain amount of climate change is inevitable, and we will certainly need to adapt. Policy-makers currently need better predictions to aid planning for adaptation to climate change in the coming years, and such improvements could present enormous economic savings: uncertainty in climate forecasts means that adaptation measures have to be designed with greater resilience, making them more expensive.
“Because the costs of adaptation are expected to be very large, the clear implication is that reducing uncertainty in climate predictions is potentially of enormous economic value.”
Invest more in climate science - NOW!
Reference: Hawkins and Sutton The potential to narrow uncertainty in regional climate predictions 2009 Bulletin of the American Meteorological Society doi: 10.1175/2009BAMS2607.1 (So far only preliminary version)
Pollution knows no frontiers and has also reached the (former pristine) Arctic. Pollution, global warming and acidification of the ocean is threatening the vulnerable environment of the Kongsfjorden in Svalbard. Kongsfjorden on the west coast of Spitsbergen is a perfect laborarory for watching how pollution and climate change affects fauna and flora.
First a few words about Kongsfjorden (I have been told that this fjord was originally named Kings Bay, later translated into Norwegian). Kongsfjorden leads to Ny-Ålesund, one of the four permanent settlements on the island of Spitsbergen in the Svalbard archipelago. Ny-Ålesund is one of the world's northernmost settlements at 78°55′N 11°56′E, and is the world's northernmost functional public settlement. At the bottom of the fjord you see three spectacular mountain peaks, known as “Tre Kronor” which means three crowns. They were named by a Swedish expedition after the three Royal Crowns in the Swedish coat of arms. The peaks are individually called Svea, Nora and Dana (symbolising the royal crowns or kingdoms of respectively Sweden, Norway and Denmark).
Kongsfjorden is situated far from any pollution source and where Atlantic waters via the West Spitsbergen Current meet the Arctic waters. A project called the Alkekonge Project has been set up to study the impact of climate warming on Arctic zooplankton communities, Little Auks (Alle alle) and their physical environment. The goal is to obtain data on water circulation, heat and salt transport by the West Spitsbergen Current, fjords hydrology and fjords - deep sea exchanges, optical parameters concerning the phyto- and zooplankton living conditions, plankton communities and local Little Auk population parameters, breeding and feeding ecology and behaviour. Little auks breeding in Spitsbergen, feed mainly on the large copepod Calanus glacialis, so tend to restrict their foraging activity to Arctic Water and avoid Atlantic Water, which contains mainly smaller copepod, Calanus finmarchicus. Parallel to the changes in zooplankton community structure a change in vital population dynamical rates of Little Auks is expected. In the areas where the Little Auks can reliably forage, the reproductive output, corrected for predation, should be higher than in colonies where Little Auks have to either fly far or utilize scattered patches of large zooplankton. Clear, natural system environment-zooplankton-seabirds seems to be a perfect tool for envisaging into future climate changes.
Alkekonge means in fact Little Aulk. As the bird is on the top of the food chain it is an excellent indicator of what happens further down the chain. Sign of a changing situation is also that until 2002 the fjord was filled with cold water and ice. In 2006, however, warm atlantic water flew into the fjord. Since then we have seen three consecutive practically ice free winters in the fjord, while the ice used to be a metre thick in the winter months.
Flotsam is another indicator. This year saw a new record in flotsam (delivered by the Gulf Stream) on the Svalbard coasts. You may not be able to read Norwegian, but the view alone of the image on top of this (Norwegian) page should be enough to tell you that the situation is grave.
Well, as you know temperatures change. 5000- 8000 years ago the water temperature here was 2°C warmer than until 2005, so a comparison with past climates is also possible. In another project sediments from the bottom of the Kongsfjorden is being sampled and studied.
In my latest post I wrote about snow-lines. I suppose you would expect tree-lines to respond to global warming in a similar way to snowlines in their way upwards.
The tree line or timberline is the line below which trees are capable of growing. Above the tree line, they are unable to grow because of inappropriate environmental conditions like cold temperatures, insufficient air pressure, or lack of moisture. This limit can be the elevation (above sea level) or the latitude (pole-wards), and it is in fact more like a transition zone.
Tree-lines are considered to be early indicators of climate warming because they are constrained primarily by cold temperatures. Summer temperature is widely considered to be the primary control of treeline formation and maintenance, whereas winter temperatures have previously been considered less critical because of the insulative effects of snow.
A study published in the journal Ecology Letters reveals, however, that tree-lines are not universally responding to climate warming by advancing, as expected, The study does however demonstrate the importance of temperature on tree-line advance over other factors such as disturbance, latitude, scale, elevation and distance to the ocean. A surprising result was, however, an association with winter, rather than summer, warming. The results provide no evidence of the prevailing view that high altitude and latitude tree-lines are controlled only by summer temperatures. Instead they show that tree-lines are more likely to advance at sites that had warmed during the winter months. It is known, at least in northern latitudes that climate-associated changes in winter conditions are on average more extreme than changes in summer conditions.
Reference: Harsch.M, Hulme.P, McGlone.M, Duncan.R Are Treelines Advancing? A global meta-analysis of treeline response to climate warming Ecology Letters, 2009 DOI:10.1111/j.1461-0248.2009.01355.x
The question of whether clouds act as a positive or negative feedback to climate change has been an issue for decades, and the uncertain effect of feedback between climate and clouds is one of the largest obstacles to producing more confident projections of global climate. As the earth warms under increasing greenhouse gases, it is not known whether clouds will dissipate, letting in more of the sun’s heat energy and making the earth warm even faster, or whether cloud cover will increase, blocking the Sun’s rays and actually slowing down global warming.
In a study published in the 24 July 2009 issue of Science researchers try to unravel this mystery. Using observational data collected over the last 50 years and complex climate models, the team has established that low-level stratiform clouds appear to dissipate as the ocean warms, indicating that changes in these clouds may enhance the warming of the planet. In other words the analysis indicate that clouds act as a positive feedback - at least in the studied region.
What are “low-level stratiform clouds”? Clouds can be sheetlike (stratiform) or vertical, and stratiform clouds are usually classified by level - low, medium or high. Low stratiform clouds are known as stratus.
The examined clouds were in particular marine stratiform clouds (comprising ordinary stratocumulus, cumulus under stratocumulus, fair-weather stratus, and badweather stratus) over the Pacific Ocean.
One key finding in the study is that it is not the warming of the ocean alone that reduces cloudiness - a weakening of the trade winds also appears to play a critical role. All models predict a warming ocean, but if they don't have the correct relationship between clouds and atmospheric circulation, they won't produce a realistic cloud response.
Reference: Clement et al. Observational and Model Evidence for Positive Low-Level Cloud Feedback Science 24 July 2009: Vol. 325. no. 5939, pp. 460 - 464 DOI: 10.1126/science.1171255
Some friends of mine got it into their heads that they wanted to visit an ophiolite. As a reader of John McPhee's geology books, I thought "of course, what could be more distinctively Californian?" But as I researched and visited likely field sites and did some reading, the subject grew more and mor ...
Yesterday I visited the Del Puerto Ophiolite, in preparation for a small field trip I'm planning later this month. Every time I go in the field I return amazed at the energy and insight of geologic mappers. Even though I followed a good field-trip guide, I found it difficult to discern everything on ...
The classroom treatment of aftershocks is fairly simple: An earthquake hits, and then a series of aftershocks occurs that is well summarized by three mathematical expressions called the Gutenberg-Richter relation, Bath's law and Omori's law. The first two relate the aftershocks to the mainshock in t ...
After a slow drive last month through the eastern Klamath Mountains, with many stops to take pictures and examine rocks, I now consider myself well acquainted with peridotite. That can be hard to do, because peridotite is almost all deep in the mantle and lower oceanic crust. And most of the peridot ...
I've cared about geoparks for several years, so I made sure to attend a session on geoparks at the Geological Society of America meeting, on 19 October. The most important news to me was that the National Park Service is collaborating with the GSA on a formal proposal for establishing geoparks in th ...
Leaf ghosts in the Vancouver morning rain
I was in Portland, Oregon earlier this week, presenting a paper at the Coastal and Estuarine Research Federation meeting. This big conference attracted people who study all aspects of modern coasts, with a particular focus on human-caused environmental chang ...
With static google maps geotagging now has become possible on this blog, where I cannot use JavaScript. So far it seems to work OK, but I still have to experiment a bit. Any helpful suggestions are of course welcome :idea:
We got confirmation that I'm scheduled to make a presentation to the Arizona Legislature's Ad Hoc Committee on Mining Regulations at their next meeting on Monday, Nov 16. The agenda should be released this coming Tuesday. The Committee is looking at ways to increase investment in mining in Ariz ...
Arizona State Parks is celebrating the 10th anniversary of the opening of Kartchner Caverns to the public. Tours and lectures and going on all day yesterday and today. [ right, construction of the main entrance to the cave a decade ago. Credit, Arizona State Parks ]
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