The MICRO Lab

New Ice Core Improves Information on Low-Latitude Paleoclimate

David Vohra — Tue, 09 Apr 2013 22:59:13 +0000

Last week, an interesting article appeared on phys.org. In 2003, researchers from Ohio State University extracted a set of especially high-quality ice cores from the Quelccaya ice cap in the Peruvian Andes, and have preserved it to protect important data from loss due to regional melting. Recently, these scientists have produced a reconstruction of the regional climate dating back to about 1800 years BP. The enhanced resolution of the samples have allowed for more a detailed analysis using δ¹⁸O, along with other methods (ammonium, nitrate, and dust composition, and net accumulation), which is a rarity when investigating low-latitude glacial samples. The analysis of the cores also provide more finely tuned data on climate variability over time, which can be used to derive the position of the Intertropical Convergence Zone, and the weather patterns driven by El Niño. The analysis also provides valuable information on the low-latitude paleoclimate during climatic anomalies such as the Medieval Climatic Anomaly and the Little Ice Age, which is particularly helpful since most other sources of high resolution low-latitude glacial data are located around the region of the Tibetan Plateau. While improving our understanding of low-latitude climates is of academic interest, it is something that could prove to be important, due to the fact that the majority of the human population lives within relatively low latitudes.

The original article can be found here.

The two papers that were viewed can be found here and here.

Melting Glaciers in Canada Pose a Threat to Sea Level Rise

Adam Polis — Sun, 31 Mar 2013 20:48:10 +0000

On March 22nd, 2013, an article was posted in Climate Central about the melting of Canada’s glaciers. Author Alex Kirby explains that a group of European scientists have developed a model that accurately “predicted” the melting that has occurred in the last ten years, leading confidence to its future predictions. These future predictions indicate that Canada’s glaciers will melt at an accelerating pace, mostly as an effect of a positive feedback loop. As glaciers melt, they reveal dark colored land underneath, which absorbs more heat than the previously overlying glaciers did, warming the area further and melting more glaciers. Dr. Lenaerts explains that even if global temperatures rise only 3°C, temperatures over the ice caps will rise 8°C.

Interestingly, Dr. Lenaerts reports that the melting of the glaciers may be irreversible. The glaciers will likely continue to melt at a fairly fast pace, and the sea ice loss will contribute to more warming. In addition, the albedo, or reflectivity, will greatly decrease, causing the region to warm even more. Normally the ice and snow will reflect the sun rays back into the atmosphere, but when the snow and ice melt, these rays will not be reflected back, thus causing more warming.

The effect of glaciers in Canada melting poses a significant problem. Even though continental glaciers in Greenland and Antarctica dwarf glaciers elsewhere, Canadian glaciers are capable of raising the sea level significantly, especially with the addition of glaciers in Alaska, the Russian Arctic, and Patagonia. These glaciers are not as stable as the much larger continental glaciers, and are far more likely to melt quickly and completely.

http://www.climatecentral.org/news/canadian-glaciers-are-melting-fast-15709

http://onlinelibrary.wiley.com/doi/10.1002/grl.50214/abstract

http://igitur-archive.library.uu.nl/phys/2006-1019-200506/oerlemans_92_sensitivity_of_glaciers.pdf

Rising Temperatures Possibly Causing More Severe Storms

Marc Palmer — Wed, 27 Mar 2013 18:35:31 +0000

Last week in science news, an article was posted about how rising global sea temperatures are expected to cause more severe hurricanes in the Atlantic Ocean. The amount of hurricanes that occur and their severity depends upon the heat of the water and how much water vapor is evaporated that add fuels to the storms. Researches have concluded that for every 1.8˚F increase in water temperatures there will be a associated increase of hurricane severity by twofold to sevenfold. From 1970 to 2004 the total number of hurricanes has decreased, however the number of severe Category 4 or 5 hurricanes has almost doubled. The rise in sea level and increase in water vapor has been related to greenhouse gas emissions warming the Earths atmosphere. This has been a topic of controversy for years now and more research is needed to arrive at a middle ground.

Volcano Emitted Aerosol Could Affect Atmospheric Temperature

Xinyu Deng — Sat, 09 Mar 2013 04:05:27 +0000

This week, Ryan Neely III and his colleagues concluded in their new study that volcano erupted aerosol that went into the stratosphere had slowed down the increase in global temperature by about 25 %. The cooling effect of aerosol particles is primarily due to their light-scattering capability. According to the article published on Arizona Daily Star, the amount of stratospheric particles had been rising 4 to 7 percent from 2000 to 2010. Neely also argued that their computer model showed that human contribution on the increase in atmospheric aerosol was minimal.

We then explored a paper published in 1992 by Labitzke and McCormick, that studied the eruption of Pinatubo in 1991. The study concluded that the 1991 Pinatubo eruption ejected significant amount of aerosol into the stratosphere, and resulted in an increase of about 2.5oC in stratospheric temperature. This finding seems to be contradicting the perviously discussed study, but we think that this stratospheric warming may be the co-product of the tropospheric cooling.

To test this, we found a study published in 2002 by Melissa Free and James K. Angell, that studied the effect of volcano eruptions on the vertical temperature gradient across latitudes. They studied three eruptions from Pinatubo (1991), El Chichon (1982), and Agung (1963). According to their study, they concluded that volcano eruptions generally cause cooling in the troposphere, but warming in the stratosphere. However, the vertical change in temperature gradient and the latitudinal variation in temperature change vary among different eruptions. The temperature change after eruptions merged into background noice after two to three years, but they argued that given the high heat content of the ocean, the actual surface effect might extent up to four to five years. The understanding on this temperature change can help us better understand the mechanisms controlling global temperature, and enable better modelling regarding the temperature budget.

One thing notable about the uncertainty associated with this study is that the three eruptions they studied all occurred before the emergence of advanced remote sensing technique. Consequently, the data they obtained from the Hadley Center in UK were probably associated with high error and uncertainty.

http://azstarnet.com/news/science/volcanoes-curb-global-warming/article_7ba76ae3-92b0-5494-bacc-fad9097845d6.html

http://www.arl.noaa.gov/documents/JournalPDFs/Free&Angell.JGR2002.pdf

http://media.cigionline.org/geoeng/1992%20-%20Labitzke,%20McCormick%20-%20Statospheric%20Temp%20increase%20due%20to%20Pinatubo%20Aerosols.pdf

China in danger of drastic Sea-level Rise

Hannah Davis — Wed, 06 Mar 2013 15:54:59 +0000

According to a recent article in China Daily, titled “China’s sea level continues to rise,” many Chinese citizens living along the coast are in extreme danger due to relative sea level rise. With a coastline of more than 32,000 kilometers, many of these already low-lying areas are also being forced into the sea by the enormous weight of fluvial sediment, exacerbating the issue of a rising sea due to global warming. This escalating situation is foreboding for coastal China as a State Oceanic Administration report stated that sea level rose 53 mm higher last year than in 2011. Additionally, air and sea temperatures rose 0.4 and 0.3 °C, respectively. This situation may worsen in the coming years, potentially submerging 87,000 km² of the Chinese coast by 2050, and could make town re-planning a necessity for many coastal Chinese communities.

In the article Potential Impacts of Sea-Level Rise on China’s Coastal Environment and Cities: A National Assessment (Han, Hou, Wu, 1995) sea-level rise is not the only factor affecting China’s coastline, but tectonic factors, salt-water intrusion, groundwater depletion, and erosion all play large roles. Dikes and consolidation of coastal cities are two of the few solutions China has come up with to help solve the impacts of sea-level rise.

Another article, by Li et al. 2004, contributes this issue of relative sea level rise to the environmental setting of China. Specifically, China is located on a tectonic plate that is both high in elevation and still actively uplifting and also has abundant precipitation thanks to active monsoons. While this geographical location is ideal for hydroelectric dams, it is also ideal for erosion and fluvial sediment transport into the sea, forming many deltas. The weight of these deltas driving the coast down, combined with the global rise in sea level, makes China particularly susceptible to rising relative sea level.

However, these deltas may be the only thing keeping Chinas coast intact. Hydroelectric dams block sediment from being deposited in the deltas, aggravating coastal erosion and shoreline retreat. Although this situation may seem insurmountable, much faith may soon be placed in the ability of protection structures, such as sea walls, to withstand the onslaught of a rising sea.

Han, Mukang, Hou, J., and Wu, L. 1995. Potential Impacts of Sea-Level Rise on China’s Coastal Environment and Cities: A National Assessment. Journal Of Coastal Research. 14: 79-95.

http://www.chinadaily.com.cn/cndy/2013-02/27/content_16258964.htm

Li, Congxian, Fan, D., Deng, B., and Korotaev, V. 2004. The Coasts of China and Issues of Sea Level Rise. J. Coast. Res. 43: 36-49.

Future Developments of Sea Level Rise and Its Unequal Distribution

Catrice Rice — Tue, 26 Feb 2013 04:55:09 +0000

On February 18th, an article was posted on eurekalert.org about new projections on sea level rise. Paul B. Holland reports the latest analysis developed by a team of scientists who further examined the proven fact that the sea does not rise uniformly and formulates a new model that gives greater insight into the details of the distribution. The model takes into account several factors, such as the varying amounts of isostatic rebound of continental crust around the globe, thermal expansion, and gravitational pull of ice sheets. It indicates that ice melting from two glaciers the Greenland and Antarctic ice sheets, will likely play a crucial role in regional sea-level change in the Equatorial Pacific Ocean. The melting of these massive ice sheets will cause a reduced pull of water towards the poles, causing more sea level rise around the equator. This readjustment of water can translate into particularly high levels of relative sea level rise for Australia, Oceania, and small islands scattered across the Equatorial Pacific, such as Hawaii. These areas are predicted to experience about 3mm/yr of sea level rise from ice melt alone by the end of the century, with approximately 25 cm of sea level rise by then. The model also predicts that heavily populated low-lying coastal areas can expect 50% to 150% of the global mean sea level change. Church et al. 2004 provides a solid interpretation of regional patterns in relative sea level rise based on regional patterns. The results produced from this study also found that“ lower rates of sea level rise can observed at European Gauges could be reconciled by the fingerprint of Greenland melting” (Church et al. 2004). This emphasizes the importance of the information gleaned from the model presented by Spada et al. 2012 and its significance for the development of sea level science. By identifying regional patterns, sea level scientists have the ability to develop precise estimates of sea level rise in different regions.

Sandy, Katrina, and Sea Level Rise

Adam Polis — Sat, 16 Feb 2013 21:28:41 +0000

On February 13, 2013, an article was posted in Scientific American about Hurricane Sandy. Author Jeff Tollefson illustrates the effects of the hurricane in the New York area, and how it relates to sea level rise. During the storm, sea level rose “2.75 meters above the mean high-water level.” There has been a great deal of contention within the science world about how human contributions to global warming can lead to more intense and more frequent “super storms”. It may be too soon to tell, but there are some interesting discoveries that have been made.

Comparing Hurricane Sandy to Hurricane Katrina, the relief for Katrina came surprisingly faster than Sandy. On December 27th, Senator Robert Menendez said that just within 10 days of Katrina, Congress had approved over $60 billion for relief efforts. This is fairly shocking because it took about 2 months to get $60 billion approved for Sandy. This is an extremely large lag for relief funds; the wait for Katrina relief was bad enough, and it turns out that relief for Sandy took even longer.

Recently (Jan 27, 2013), an article called “Modeling the influence of changing storm patterns on the ability of a salt marsh to keep pace with sea level rise” was posted in the Journal of Geophysical Research: Earth Surface. This article made the case that more frequent (and to a lesser extent, more intense) storms actually help marsh survival by providing additional sediment that marshes can use to grow upon and outrace sea level rise. Since New York is considering increasing its wetlands and marshes in the wake of Hurricane Sandy, this news is especially interesting. While increasing storms may be a bad thing for humans who have to deal with economic damage, those same storms may be the saving grace of marshes being threatened by the rising sea.

http://www.scientificamerican.com/article.cfm?id=natural-hazards-new-york-city-vs-the-sea

http://onlinelibrary.wiley.com/doi/10.1029/2012JF002471/full

http://www.politifact.com/new-jersey/statements/2013/jan/03/robert-menendez/hurricane-sandy-aid-still-pending-us-sen-robert-me/

Demand for Energy Increases Demand for Fresh Water

Lydia Olson — Mon, 11 Feb 2013 19:36:52 +0000

Two weeks ago in the news, an article was published in National Geographic News that predicted the global energy industry would double their demand for fresh water by 2035. Written by Marianne Lavelle and Thomas Grose as part of a special series on energy issues, the article outlined how biofuels and coal plants use around 75% of fresh water consumed in energy production today: with the population increasing, the demand for energy and therefore for water is expected to increase dramatically in this field. The article concludes that the only sure way to preserve water resources and successfully generate energy is to move towards alternative energies that do not require water, such as wind and solar power.

The use of water by humans, not just necessarily in energy production, is discussed in an article titled “Peak Water Limits to Freshwater Withdrawal and Use”, by Peter Gleick and Meena Palaniappan. They present the concept of “peak water”, a point where water production will hit a peak and then start to decline, similar to the concept of peak oil. They define three components of peak water: peak renewable water, peak nonrenewable water, and peak ecological water. Much of the water used for energy production falls under the peak nonrenewable water and the peak ecological water category, where the water is being pulled from sources that when used are damaged environmentally and also cannot be easily recharged: sources such as wetlands or underground aquifers. Using nonrenewable water sources poses a problem for our future: as with oil, the sources will run out eventually, so conservation and sustainability must be directed towards water use. Also the depletion of underground aquifers causes sea level to rise with the subsidence of the ground, as was stated in last week’s blog post.

A report written by the EW3 Scientific Advisory Committee, entitled “Freshwater Use by U.S. Power Plants” lays out many of the same points made in the National Geographic Article. With the climate changing and weather patterns shifting, droughts have caused this committee to examine water usage in the energy industry and how we can assuage the related water stress caused by generating power. Their solutions include adding power plants that conserve water and refitting existing plants for water conservation, making policies for power plant water use, getting the public involved through shareholders, and reducing carbon emissions, which contribute to climate change and drought.

http://news.nationalgeographic.com/news/energy/2013/01/130130-water-demand-for-energy-to-double-by-2035/

http://www.pnas.org/content/107/25/11155.full.pdf

http://www.ucsusa.org/assets/ documents/clean_energy/ew3/ ew3-freshwater-use-by-us- power-plants.pdf

Groundwater Depletion Contributes to Rising Sea Level

Mackenzie Oettel — Sun, 03 Feb 2013 03:38:24 +0000

This week, Diana Allen, an Earth scientist at Simon Fraser University, stated in an interview that agriculture in many regions of the world is heavily dependent on groundwater for irrigation. In one of her articles, she said that climate change and several other human-driven factors would combine to further contribute to groundwater depletion. The growing population and extreme droughts are the major contributing factors discussed in her article. She believes that the depletion will also contribute to sea level rise, by transporting stored water on land into the ocean. She proposed that ground water usage would add “another half-a-centimetre-a-year rise” to the current models.

Two factors controlling groundwater level are the extraction rate and the recharging rate. A recent study by Yoshihide Wada and his colleagues argued that past groundwater depletion was primarily driven by the increased demand from the growing population. However, future depletion, they proposed, would be mostly likely due to “decreased surface water availability and groundwater recharge”. They estimated that, globally, “the contribution of groundwater depletion to sea-level increased from 0.035 (+/-0.009) mm/yr in 1900 to 0.57 (+/-0.09) mm/yr in 2000. “They projected future contribution of groundwater to sea level rise using three socio-economic models. Taking the mean value of the three models, the cumulative contributed sea level rise due to groundwater depletion would reach about 60 mm by 2050, offsetting the -31 mm contribution by the artificial dams. This type of sea level rise, as a result of increasing water volume in the ocean basin, is termed eustatic sea level rise. However, groundwater depletion can also contribute to local sea level rise by causing land subsidence.

One study by Gholamreza Khanlari and the colleagues in western Iran has shown that groundwater depletion, especially in karstic regions, can result in substantial amount of land subsidence. In the region they studied, they observed about 450 mm subsidence between 1993 and 2001. In some area, the annual subsidence rate can reach 60-80 mm. If the same rate of subsidence is also occurring in other karstic regions at sea level, the rate of relative sea level rise would be significantly increased.

http://www.sciencedaily.com/releases/2013/01/130128104747.htm

Finding Fossils for Pliocene Proxy

Evan Anway — Mon, 28 Jan 2013 03:23:30 +0000

This past week, Justin Gillis published an article in the New York Times titled “How High Could the Tide Go?” as part of Temperature Rising, a series that describes the controversy and science of global warming. This article highlights the exciting fieldwork of paleoclimatology and stresses the significance of this research for modeling and predicting future sea level rise.

To better understand how sea level may change today, Dr. Maureen E. Raymo of Columbia University is locating fossil beaches to determine the sea level during the Pliocene, an era about 3 million years ago that had higher levels of carbon dioxide than today. The current elevations of some Pliocene fossil beaches can illustrate the potential future sea level rise. However, the rates of current and historic sea level rise may not be comparable because humans didn’t burn fossil fuels during the Pliocene.

Previous research by Raymo et al., 2011, illustrated the importance of eustatic as well as isostatic changes in order to understand changes in sea level. As glaciers melted and the oceans rose (eustasy), the crust independently moved fossil beaches to very different elevations (isostacy).

Dr. Raymo has based many of her predictions for the future of sea level rise on geological records and sea level indicators of the past. Research provided by Kopp et al., 2009, has found that there is a 95% probability that the global sea level peaked 6.6m higher than modern sea level during the last interglacial period, the Eemian, which occurred nearly 125,000 years ago. This period has been used as reference due to the high amounts of carbon dioxide in the atmosphere. However, as mentioned above, our overuse of greenhouse gases and fossil fuels, which increases amounts of carbon dioxide, will push future sea level far above that of the Eemian period. This research, although unable to tell you how quickly the sea level will rise, indicates the level we should prepare and make adjustments for.

Kopp, R.E., F.J. Simons, J.X. Mitrovica, A.C. Maloof, M. Oppenheimer. Probabilistic assessment of sea level during the last interglacial stage. 2009. Nature 462: 863-868.

Raymo, M.E., J.X. Mitrovica, M.J. O’Leary, R.M. DeConto, P.J. Hearty. Departures from eustasy in Pliocene sea-level records. 2011. Nature Geoscience 4: 328-332.