In the news this week...

ADVANCING GLACIERS IN THE KARAKORAM HIMALAYAS

Following on from an earlier study in 2005 that indicated glaciers in the Karakoram Himalaya have not followed the general trend of glacier retreat observed in other parts of the Himalayas, Hewitt (2011) undertook a review of the literature to investigate the later Little Ice Age in the Karakoram and the recent 'expansion'  of the glaciers in the region. From a review of the literature, Hewitt (2011) observed that on average, Karakoram glaciers only declined by 5% between 1920 and 1960, becoming almost static in the 1970s, with some glaciers advancing during this period. From the studies, generally rates of retreat were resumed in the 1980s and into the early 1990s but were largely insignificant and since the 1990s a stabilisation of the glacial balance and advances in the High Karakoram (coinciding with increases in snow cover) were observed.

Hewitt (2011) attributes the relatively static response to global warming of the Karakoram glaciers to their relatively high-elevation 'buffering' against rising atmospheric carbon dioxide levels. Due to the higher altitude, precipitation in the region mainly falls as snow throughout the year, and Hewitt (2011) states that the warmer ocean temperatures may also contribute to greater moisture systems reaching the region. In addition to this, local studies have observed a recent cooling in summer temperatures coinciding with increased cloudiness and greater snow cover, an observation that Hewitt (2011) suggests could be due to the albedo feedback.

Thus, this article suggests that whilst glaciers are retreating across the Himalayas, this cannot be generalised to all glaciers in the region and highlights the complex interaction of feedback mechanisms that control an individual glacier's response to global warming.

OUTLOOK ON CLIMATE CHANGE: MUCH OF THE SAME OR EVEN WORSE!

In preparation for the fifth IPCC report due for 2013 a meeting was held this week by climate scientists to assess any advancements in our knowledge of our changing climate since the last report almost five years ago. Overall, although there has been substantial improvements in modelling, with larger, more sophisticated and integrated models than five years ago, the simulations being produced have remained relatively similar (Science, 2011). Results from one-third of the thirty models expected to be used in AR5, were only slightly more sensitive to greenhouse gas emissions than the past AR4 model and predict similar regional patterns of temperature and precipitation changes throughout the world.

However, some of the simulated responses to global warming in the most recent models did diverge from past estimations. For example the AR4 (2007) report estimated ice sheet melt would contribute to around a 25cm rise in sea levels by 2100. The increased sensitivity of the latest models has increased this value to 32cm, which is higher than the IPCC last conservative estimate but substantially lower than earlier estimates of one metre (Science, 2011). Incorporation of this new value produces a range of cumulative sea level rise from ocean thermal expansion, ice and glacial melt between 63 to 71cm by 2100, a sufficient level to inundate a substantial area of Bangladesh.

Although the meeting did not review all of the models or studies that will be included in the final report, conclusions from the meeting confirm our current understanding of the rate of global warming and the regional impacts that it could have around the world. Despite minimal changes in the observations of the models, this still supports the claim that global warming is occurring and should be seen as evidence for action to be taken to attempt to minimise or reverse this rising trend. Due to the complexity of the Earth's systems, uncertainty can never be removed from models of climate change. However, the consistency between the models analysed in this meeting and models from the last report suggest that the observed warming trend is not anomalous and the simulated regional responses to global warming are likely, within their observed ranges, to occur.

Reference 
Hewitt, K. 2011. Glacier change, concentration, and elevation effects in the Karakoram Himalaya, upper Indus Basin. Mountain Research and Development , 31: 188-200.

Science, 2011 'Climate outlook looking much the same, or worse', Science, 334, 1616

BBC News: Hocus pocus:the disappearing and reappearing Ngozumpa glacial lake

Figure 1: Time lapse video of the Ngozumpa glacial lake filling and draining over a fifteen day period (Source: Live Science, 7th December 2011).

Reflecting the general trend across the region, melting of the debris-covered Ngozumpa glacier in Nepal is of growing concern for scientists due to the rapid growth of the glacial lake at the glacier's snout. Named the 'Spillway', the glacial lake is equivalent in size to 40 Olympic swimming pools contained behind a terminal moraine dam (BBC News, 26th December, 2011). Although it is claimed the threat of a glacial lake outburst flood (GLOF) is less imminent than other glacial lakes, scientists are still monitoring changes in the dynamics of the lake. Using timelapse cameras, research by the Cooperative Institiute for Environmental Sciences (CIRES) have demonstrated dynamic fluctuations in the lake volume reflecting complex interaction of factors controlling inflow and outflow to the lake (Figure 1). Observations from the time-lapse cameras showed a decrease in volume by over 100,000m³ in two days, followed by a recovery of around half of this volume in the five days following this event (BBC News, 26th December 2011).

Although assessments of the Spillway suggest this glacial lake is less of an imminent threat to outburst compared to other glaciers in the region, the results from the timelapse videos demonstrate the complex interaction of factors controlling the growth of glacial lakes in the Himalayas. Beyond a basic understanding of the relationships between glacial lake growth and glacier melt this research highlights our limited understanding of the mechanisms regulating volume within these glacial features. Coinciding increased rates of glacial melt due to climate change, the frequency of GLOFs are increasing. Thus understanding the dynamics behind the formation and regulation of lake volume, being undertaken in studies such as this is becoming increasing important.

Reference:

Amos, J. (2011) 'Taking the pulse of Ngozumpa', BBC News, 26th December 2011. 

National Geographic Special Issue: Water Is Life

Source: Hogshon, R. National Geographic 21st December 2011).

This week the National Geographic have released a special series dedicated to the importance of freshwater for humans and global biomes around the world. Specifically related to this blog, one of the articles summaries recent research presented at the American and Geophysical Union last month (National Geographic News, 20th December 2011). Findings from different mountain ranges around the world including the Andes, Himalayas and the Canadian Rockies indicate that rates of retreat are occurring faster than previously anticipated. For example, research by the University of British Columba, Vancouver suggest in the Saint Ellias region of the Canadian Rockies glaciers could decrease to 50% of their size by 2100, of which many may even disappear completely. The article also states that global changes in glacier melt will have severe consequences on local and regional river discharge, as discussed in my last post.

The national geographic provide a variety of interactive applications including: calculating your own water footprint and visual representations that put your water use into perspective compared to other regions of the world. As our population continues to increase, trying to use our freshwater as efficiently as possible has never been more important.

In the news this week...

PAPER COMPARING THE MEDIEVAL WARM PERIOD, LITTLE ICE AGE AND THE 20TH CENTURY WARMING RATES

Using the climate system model 'FGOAL', TianJun et al., (2011) compared the differences between the rates of global warming between the Medieval Warm Period (MWP), Little Ice Age (LIA) and twentieth century. Multiple proxies were used in the model obtained from tree rings, ice cores, pollen and other records from thirty areas around the world, resulting in forcing data on volcanic events, solar insolation, nirous oxide, carbon dioxide and methane (Figure 1). Simulating changes on a global scale, the model indicated a warming during the MWP in all regions except the North Pacific. The model also demonstrated that warming was not uniform, with rates greater in the Northern hemisphere, than in the Southern hemisphere, and greater warming at higher latitudes. However, the overall warming during the MWP was not as strong as observations during the 20th century (Figure 2). During the LIA overall a global cold anomaly was observed in surface temperature, although mean surface temperature remained around +0.5° C in North-east America (although this is comparitively lower than during the MWP and 20th century anomaly).

Figure 1: Time series of forcing data used in the FGOAL model (Source Tian et al., 2011: 3084)



Figure 2: Annual mean surface air temperature anomalies for top to bottom (Medieval Warm Period, Little Ice Age and the 20th century).

Observations from the model support the concept of accelerated warming during the 20th century due to increased inputs of greenhouse gases into the atmosphere. This is evident in Figure 1, where there are significant increases in carbon dioxide, methane and nitrous oxide concentrations in the atmosphere from the Industrial Revolution in the mid-18th century, and is claimed by some (Crutzen, 2002) as the start of the 'anthropocene'.  


PALEOCLIMATIC RECORD SUGGESTS TIBETAN PLATEAU TEMPERATURES WILL DECREASE UNTIL 2068

A paper released by Lui et al., (2011) using palaeorecords from tree rings in the central-eastern Tibetan Plateau suggests that temperatures in the region will decrease until AD 2068 and will then begin to increase. Based on a 2485 year record, the tree ring record observes changes in temperature coincising with the MWP, LIA and 20th century warming, and cycles in temperature related to sunspot activity. Six cold and six warm events (half a standard deviation,±0.4°C, from the mean) were observed during the 2485-year period. Several significant cycles at 1324 year, 800 year, 190 year and 110 year were noted in the temperature series, and the cold events observed in the time-series coincided with periods of sunspot minimum. From the reconstructed temperature record, Lui et al., (2011) projects a decrease in temperature until 2068 reflecting as the earth enters a sunspot minimumn, followed by an increase in temperatures to 2088 (Figure 1).

However Lui et al.,'s (2011) study does not consider other forcings that influence global temperatures. Studies in previous posts have suggested that anthropogenic emissions of GHG's have accounted for a greater amount of the variability in global temperatures during the 20th century relative to insolation and volcanic activity. Therefore further research using multiple proxies covering a larger area is required to validate these findings. 

Figure 1: Reconstructed temperature record from a tree ring proxy in the central-eastern Tibetan Plateau over the last 2485years, and future changes projected due to sunspot variability.

Reference:

Liu, Y., Q. Cai, H. Song, Z. An and H. W. Linderholm (2011) 'Amplitudes, rates, periodicities and causes of temperature variation in the past 2485 years and future trends over the central-eastern Tibetan Plateau', Chinese Science Bulletin, 56: 2986-2994.

TianShun, Z., B. Lou, W. Man, L. Zhang and J. Zhang (2011) ' A comparison of the Medival Warm Period, Little Ice Age and 20th century warming simulated by the FGOALs climate systems model', China Science Bulletin, 56: 3028-3041.

Christmas Number One? Not quite 'I saw mummy kissing santa'!

Now here's a challenge. Making a song about glaciation. Now call me a scrudge but current Christmas songs don't seem to have any relation to Christmas or snow in them at all. So here's my contribution. I can't say I wrote it myself, and it is based on glaciation rather than Christmas so no relation to Santa, but its got snow in it so why could this not be number one? Then we could have education and festivities at the same time. Okay, so maybe I'm taking it too far, but I believe this song produced by Dan Bull on 'glaciation' provides a unique way of explaining scientific topics to a wide variety of people. Coming from someone who cannot think of a word to rhyme with glaciers, I was impressed and thought this song was worth sharing. Let me know what you think…

BBC report: Melting glaciers and changes to the River Ganges (1st November 2009)

I found this clip of a BBC report explaining how the melting Gangotri glacier (the source of the headwaters of the River Ganges) is affecting the the flow of the River Ganges and the communities that rely on the river (Figure 1). Although rather basic, it provides a brief review of the points made in my post last week about the link between melting glaciers and changes in the dynamics of rivers in the Himalayas. However, there are some overlooked generalities made in the report that are worth highlighting:

1) States that all glaciers in the Himalayas are retreating, but at different rates.

Work by Hewitt (2005) has demonstrated this statement cannot be applied to all glaciers in the Himalayas. Hewitt (2005) shows that glaciers in the Karakoram region are largely remaining static and some are advancing. This highlights the spatial complexity of glaciers within the Himalaya, and emphasises the importance of local research, as general patterns cannot be generalised across the entire region.

2) The retreat of the Gangotri glacier by 15m in 6 months.

The period of retreat described in the clip occurred during the summer months between May to October when the rates of glacier melt are at that greatest in most parts of the Himalayas. Although it visually provides a persuasive argument for the retreat of glaciers, in order to assess the significance of this rate of retreat can only be evaluated by comparison of long-term changes in the extent of the Gangotri snout.

Figure 1: Video of a BBC report on the melting Gangotri glacier and potential impacts on the River Ganges. First aired on the 1st of November in 2009 this report occurred in the weeks before the 2009 Copenhagen Summit and the release of the ClimateGate scandal where the IPCC were forced to retract their statement that all Himalayan glaciers potentially all vanishing by 2035.


Reference:
Hewitt, K. (2005) 'The Karakoram anomaly? Glacier expansion and the 'elevation effect', Karakoram Himalayas', Mountain Research and Development, 24, 4: 332-340.

In the news this week...

USAID STUDY TO ASSESS ASIAN WATER RESOURCES

United States Agency for International Development have teamed up with a University Boulder team to carry out a four year study investigating the contribution of snow and glacier melt to water resources supplied by the Himalayas. This report aims to increase our understanding of the snow and glacial input to river discharge which can then be used to predict future variability in river discharge under climate change.Due to the limited data available in the region, USAID will use a combination of remotely sensed data to produce time-series maps of intra-annual snowfall and glacial ice melt (NSIDC, 7th December, 2011). This will be combined with meterological and hydrological data in the region to estimate current relationships between snow and glacier contribution and river discharge that can then be extrapolated to predict future river discharge under differenet warming scenarios.

The findings of this study will be highly beneficial for scientists and policy makers within the regions, potentially highlighting the regions that will be at most risk under climate change allowing mitigation methods to be put in place to reduce water scarcity threat in these areas. The data could also be informed in further development schemes, such as avoiding the development of new irrigation plants in areas that are assessed at being at high risk of reductions in river discharge. As my last post has stated, changes to Himalayan glaciers is anticipated to have substantial intra-annual and longer term impacts on river discharge in the region, however, with studies like this being undertaken, our ability to understand the factors determining these changes and how they may change in the future may allow mitigation measures to be put in place to attempt to reduce their impacts.

Figure 1: Major rivers within the ten countries surrounding the Himalayas with headwaters in the mountain area (Source: NSIDC, 7th December 2011).

ICIMOD RELEASE NEW REPORTS SUGGESTING HIMALAYAN GLACIERS ARE MELTING

Following the retraction of a statement in the Fourth IPCC report that ‘all of the Himalayan glaciers would have melted by 2035’, the IPCC has announced that the most recent conclusions from three ICIMOD reports provide new evidence Himalayan glaciers are melting Compiling data from across the Hindu-Kush Himalaya (HKH) Region, these reports provide the most recent data regarding climate change for the region. However, although these reports are the most comprehensive studies yet, ICIMOD state that further research needs to be carried out (ICIMOD, 4th December, 2011)

The reports:

1) The Status of Glaciers in the Hindu-Kush Himalayan Region.

The first report used remotely sensed data to estimate the current extent and distribution of glaciers within the HKH region. Identifying approximately 54,000 glaciers within the region, the lack of data in the region is underlined as of these only ten have been continously monitored to assess changes in glacial mass. Conclusions from the remotely sensed data showed an overall reduction in glacial mass in the central and eastern Himalayas, with reductions over the last thirty years being 22% and 21% in Bhutan and Nepal respectively.

Although additional research will need to be carried out this comprehensive report provides a baseline that can be used to inform discussions over climate change within the Himalayas and can be used to direct further research in the area.

2) Snow Cover Mapping and Monitoring in the Hindu-Kush Himalayas

This report uses regional monitoring to observe changes in the HKH region over the last decade. It concludes that there has been regional disparities within the mountain chain with snow cover decreasing within the central part of the Himalayas, but monitoring indicating a slight increase within the eastern and western regions.

3) Climate Change in the Region: The State of Current Knowledge..

Reviewing the current literature available under the three broad headings: climate and hydrology; biodiversity and ecosystems; and atmospheric changes. The reports underlines the bias of the limited spatial data within the region, often restricted to areas of easier access at lower elevations. Despite this, the report identifies several conclusions within the region including:

•  More pronouced warming in the winter months than the summer months (A claim supported by Singh et al., (2006) report cited in my last post).
• The average overall warming in the region (around 0.74°C in the last 100years) is greaer than the global average, although the ICIMOD emphasis that this is not evenly distributed across the region.
• The report found that warming was most pronounced in the higher altitudinal regions such as the central Himalayas and the Tibetan Plateau, and related to the second report may partially account for the reduction in snow cover in these regions 

• Significant changes in mountain habitats are beginning to occur with the mountain treeline shifting to higher elevations, and the report suggests that some species at higher elevations may disappear as the ecosystems change.

Overall these three reports represent a significant step in bridging some of the major knowledge gaps present in this region, and highlights the benefits of using remotely sensed data when access is to the study area is limited. These reports also support the growing evidence that changes due to global warming may be exaccerbated in the Himalayan region, and therefore the continuation of studies such as this are highly important.