In the news this week...

7 billion and counting…

The main news hitting the headlines this week is the world’s population surpassing the 7 billion mark. Today is meant to be the big day, and significant attention has been paid on what this could mean for our planet.  National Geographic have released a special issue covering how the growing global population is affecting our ecosystems worldwide, from rainforests to mountain glaciers and the the socio-economic consequences of long-term climate change. Accompanying a short video on population growth there is also an Ipod App highlighting the key points with photos taken from around the world and a quiz  (the answers are at the bottom and make an interesting read) on demographic statistics.

To calculate how your birth fits into current population growth, the BBC have released an interactive program online. By entering your date of birth, gender, and country of origin you can see how you relate to trends in population expansion.

Have a go yourself.

New Scientist: ‘Climate change what we do and don’t know’.

New Scientist have released a collection of articles stating what we currently know and don’t know about climate change.  These articles highlight that substantial improvements have been made in understanding the earth’s climate, but there are still significant uncertainties surrounding the scale and the rate of changes for example in glacial extent and sea level rise.

Climate change and glaciers in southwestern China

An article has been released this week in Environmental Research Letters by Li et al., (2011) studying the long-term change in climate and glaciers around southwestern China. Daily temperature and precipitation measurements were taken between 1961-2008 at 111 stations throughout the region and conclusions indicate temperature patterns over this period are consistent ‘with warming at a statistically significant level’. This increase was more apparent at higher altitudes (>3500m) than at lower altitudes (<1500m) (Table 1, Figure 1), which may account for the rapid glacial retreat observed in mountain regions.

Table 1. Correlation coefficients between trend magnitudes for temperature ( ◦C/a) and precipitation (mm/a) and altitudes (n = 48, when r = ±0.29, P = 0.05). (Note: values for trends significant at the 5% level are set in bold.)

Altitude (m)	Annual	Spring	Summer	Autumn	Winter
Temperature	0.36	0.25	0.46	0.36	0.33
Precipitation	0.41	0.31	0.02	0.51	0.08

(Source Lei et al., 2011: 6).

Lei et al., (2011) attributes this greater magnitude of temperature rise in higher altitudes to three main factors:

1.   Change in cloud cover;

An increase in low cloud cover at night and a decrease in the total cloud cover and daytime cover had resulted in an increase in temperature as higher levels of insolation are reaching  the surface.

2.   A positive feedback from snow/ice albedo;

An acceleration in melting would decrease albedo under warming at higher altitudes as the darker ground surface underneath is uncovered. This results in an increased absorption by the surface, causing the temperature to rise causing a further acceleration in melting.

3.   Black carbon present in snow.

The ‘darkening’ of the snow increases the absorption of radiation at the surface, causing surface temperature to rise and accelerating glacial melt.

 

Figure 1. Variation of temperature and precipitation with elevation (Source Lei et al., 2011: 9).

Observations of precipitation variations were less marked, but generally exhibited a weak negative trend between 1961-2008. Lei et al., (2011) attributed this decrease to a strengthening of the Western Pacific Subtropical High and a weakening of the East Asian Monsoon which has become more unreliable and unstable in recent years. This is further supported by ice-cores which in the region which show a decreasing trend in accumulation, especially after 1980.

The article suggests that temperature is a dominant factor controlling glacial extent in southwestern China but also notes significant spatial variability in the response of glaciers to climate change in the region. Potential factors that may account for some of these variations were summarised by Yasunami (2011), of which a few will be discussed in the following weeks:

1.   Debris-covered effect (heats the surface when it is thin, but insulates when it is relatively thick, though there is no uniform response.

2.   The interaction between glacial lakes and exposed ice parts of glaciers.

3.   Atmospheric heating effect over the foothills of the Himalayas due to atmospheric brown clouds (include black carbon, dust and organic matter), resulting in the so called Elevated-Heat Pump (EHP).

4.   Snow darkening over non debris-covered regions decreasing snow albedo and accelerating snow melt.

5.   Feedbacks.

Reference:

Li, Z., Y. He, W. An, L. Song, W. Zhang, N. Catto, Y. Wang, S. Wang, H. Lui, W. Cao, W. H. Theakstone, S. Wang and J. Du (2011) ‘Climate change and glacier changes in southwestern China during the past several decades’, Environmental Research, 6,4: 1-25.

Yasunami, T.J. (2011) ‘What influences climate and glacier change in southwestern China’, Environmental Research Letters, 6,4: 1-4.

In the news this week...

Okay so maybe its not quite this week but its still worth a read. An article in The Guardian published on the 11th October 2011 highlights one of the potential impacts that glacial retreat may have on communities in the lowland valleys of the Himalayas. The article focuses on the pro-glacial Imja lake near Mount Everest which formed in the 1960s. Unlike normal floods, outbursts from pro-glacial lakes can occur repeatedly as glacial meltwater breaches the moraine dam on the leeward (downward) side of the valley. Goldenberg (2011) states that the lake is growing by around 47m a year, nearly three times faster than any other glacial lake in Nepal. This claim is partially supported by Bolch et al., (2011) study which estimated that the lake area had grown since 1960 to ~0.9km squared in 2003.

Due to its situation (5100m a.s.l), mobilising engineering equipment and expertise to attempt to mitigate against a glacial outburst is not an easy task. There is also the issue of predicting when the pro-glacial lake might flood compared to other lakes to assess how soon action needs to be taken to reduce the flood risk. Whilst the Nepali government ranks Imja as among the six most dangerous glacial lakes in the country, John Reynolds, a British engineer and supposed expert on glaciers argues that the gradual relief of the glaciers feeding the lake mean that it is a lower risk than other lakes in the region as ice is less likely to break off and cause a tsunami.

Nevertheless, there is the prospect that lake Imja, like many of the other 20,000 lakes in the Himalayas may flood at some point in the future. A prospect only increased as the glaciers continue to retreat. As the article concludes 'the question is how to decide which are hazardous now and which are going to become hazardous in the future'. (The Guardian, 2011).

Click here for a link to the video that accompanies this report.



Figure 1: Growth in Imja pro-glacial lake between 1992 and 2007 (Source: University of Maryland, 2008).

Reference:
Bolch, T., T. Pieczonka and D. I. Benn (2011) 'Mulit-decadal mass loss of glaciers in the Everest area (Nepal Himalaya) derived from stereo imagery', The Cryosphere, 5: 349-358.


The Guardian, ' Glacier lakes: growing danger zones in the Himalayas', Tuesday 11th October 2011.

Fact vs Fiction: Is it all a fairy tale?

Throughout this blog I hope to look at some of the major factors that affect the distribution of glaciers and their contribution in causing oscillations in glacial extent over time. Palaeoclimatic evidence indicated substantial fluctuations in global glacial extent throughout the late quaternary (Lehmkuhl and Owen, 2005). It is generally accepted that last global peak in ice extent occurred during the Last Glacial Maximum around 18ka BP in radio-carbon dating (or marine isotope stage II) (Lowe and Walker, 1997). Since then, repeated advances and retreats have occurred responding to exogenous (solar insolation, volcanoes), and endogenous forcings (atmospheric GHG concentration, dust cover and atmospheric circulation patterns) with the last glacial advance occurring during the neoglacial or 'Little Ice Age' between 1550 to 1850 AD (Junglclaus, 2000).  

It is this period after 1850AD, the period classed by some as the 'anthropocene' (Crutzen, 2000) that has gained particular attention from glaciologists and other scientists studying changes to the global environment. Ice core-analyses show rises in carbon dioxide concentrations from the mid-18th century corresponding with the start of the Industrial Revolution (Steffen et al., 2011). Since then, atmospheric carbon dioxide concentrations have risen (see previous blog), surpassing natural Holocene variability and are at their highest concentration at any time point during the Holocene. Alongside this increase global mean annual temperature has risen by approximately 0.55 ºC since 1860 (see Figure 1), and it is anticipated to continue in the 21st century (IPCC, 2007).



Figure 1: Global temperature change from a) 1860-2007, b) 1000 AD to present. In the top panel the global mean surfac temperature is shown year-by-year (red bars with very likely ranges as thin black whiskers) and approximately decade-by-decade (continuous red line). Analyses take into account data gaps, random instrumental errors and uncertainties, uncertainties in bias corrections in the ocean surface temperature data, and also in adjustments for urbanization over the land. The lower panel merges proxy data (year-by-year blue line with very likely ranges as grey band, 50-year-average purple line) and the direct temperature measurements (red line) for the Northern Hemisphere. The proxy data consist of tree rings, corals, ice cores, and historical records that have been calibrated against thermometer data. Insufficient data are available to assess such changes in the Southern Hemisphere. (Source: IPCC, 2007).

 
The literature disputes the amount that natural variability and anthropogenic forcing contributes to the observed warming in the atmosphere. Lean et al., (1995) state that the contribution of natural and anthropogenic forcing to global warming has a temporal element, with solar forcing accounting for about 50% of the observed warming since 1860, which falls to a third post-1970. However, Crowley (2000) argues that the contribution of natural forcings (volcanism and solar forcing) only accounts for 25% of the 20th century warming. The key observation to be drawn from these studies is that not all of the warming since 1850 AD can be explained by natural variability alone. This is an essential point to consider in order to understand the potential impacts that global warming and other climate changes may have on glaciers and other ecosystems, the former of which I shall discuss in the oncoming weeks.

BACK TO BASICS: What is a glacier?

Glaciers are a mass of snow and ice which, if it accumulates to sufficient thickness deforms under its own weight and flows. There are three main types of glacier: ice sheet/ice cap; ice shelf; and mountain glaciers (Thomas and Goudie, 2000). Mountain glaciers, which are constrained by the underlying topography of the mountains will be the focus of this blog, with particular attention to the Himalayan glaciers in central Asia.

GLACIERS AND CLIMATE CHANGE

Understanding how glaciers could be affected by climate change is of substantial socio-economic relevance. Significant retreat of glaciers could have wide-ranging impacts causing sea-level rise, an increased risk of glacial lake outburst floods (GLOF) and alterations to runoff affecting the discharge of rivers sourced by glacial meltwater.
This is of greatest concern in the Himalayas. The Himalayas are one of the largest bodies of ice outside of the polar regions covering approximately a 33,000 square km area (Space Application Centre, 2010: 7). Meltwater and rainfall from this region feed major rivers such as the Indes, Ganges and Brahmaputra, supporting over one-sixth of the world's population that inhabit the Indio-Gangetic Plain (Prasad et al., 2009).

In recent years there have been mixed reviews over the rate that these glaciers are declining compared to other regions of the world. Bolch et al., (2011) study using a combination of stereo and aerial images and satellite data, concluded that all of the ten Himalayan glaciers studies had lost an average mass of 0.32±0.08 m w.e.a^-1, despite of their thick debris cover. Though this was statistically greater that earlier time periods (though this may have been partially due to improvements in the resolution of the data), this value was not found to be higher than the global average (0.32m w.e.a^-1) estimated by Zemp et al., (2009) using 30 reference glaciers from around the world. In contrast, Prasad et al., (2009) suggest Himalayan glaciers to be among the fastest receding glaciers in the world. Despite these mixed conclusions, it was the fourth IPCC report published in 2007 that brought this debate to the centre stage, encouraged by extensive coverage by the global media (Barley, 2010; Pearce, 2010).

THE IPCC FOURTH REPORT: When facts are not always facts.

The claim:

'Himalayan glaciers are receding at a faster rate than in any other part of the world and if the present rate continues, the likelihood of them disappearing by the year 2035 and perhaps sooner is very high if the Earth keeps warming at its current rate' (IPCC, 2007)

This controversial and alarmist statement was later withdrawn after it was found it had been founded on grey literature published by WWF in 2005 (Pearce, 2010).

THE REALITY CHECK!

Though it is highly unlikely that the Himalayas will have completely disappeared by 2035, the long term outlook still is not good.
Taking rainfall predictions into account Immerzel ( cited in Barley, 2010) found that by 2050, 60 million fewer people (4.5% of the world's population) will be able to support themselves on the main rivers supplied by the Himalayas. Therefore, although the loss of these 'water towers' may not occur within the next few decades, in general, most Himalayan glaciers are in a state of retreat (Scherler et al., 2011). In the short-term, glacial melt may result in an increase in meltwater discharge to rivers such as the Indes, Ganges and Brahmaputra, but in the long-term the water security in these regions is likely to come under threat (Bolch et al., 2011).

With the IPCC projecting potential global temperature rises of 1.1-6.4 ºC by the end of the 21st century, it seems Himalayan glaciers will only continue to retreat. The key question now is at what rate and how is this impacted by other forcings such as dust cover and monsoon-rainfall? Conclusions from the Snow and Glacial Studies Report (2010) show spatial disparities in the number of glaciers in retreat, advance or observed as no change (2184, 435, 148 of the 2767 glaciers studied respectively). This suggests local climatic variations and glacial characteristics may also affect their resilience to changes in climate, some of which will be discussed in the oncoming weeks. Case studies will also give an insight to regional disparities caused by variations in glacial characteristics which add to the complex picture of estimating changes in the mass balance of these ice giants.

Reference:
Barley, S. (2010) 'Himalayan glaciers good for a while yet', New Scientist, 206, 2765: 1.

Bolch, T., T. Pieczonka and D.I. Benn (2011) 'Multi-decadal mass loss of glaciers in the Everest area (Nepal Himalaya) derived from stereo imagery' The Cryosphere, 5: 349-358.

Crowley, T. J. (2000) 'Causes of climate change over the past 1000 years', Science, 289: 270-277.

Crutzen, P.J. (2002) 'Geology of mankind' Nature, 415, 1:23.

IPCC (2007) Climate Change 2007: Impacts, Adaptation and Vulnerability, in M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson (Eds) Contributions of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press: Cambridge.

Jungclaus, J. H. (2009) 'Lessens from the past Millennium', Nature Geoscience, 2: 468-488.

Lean, J. J. Beer and R. Bradley (1995) 'Reconstructions of solar irradiance since 1610: Implications for climate change', Geophysical Research Letters, 22: 3195-3198.

Lehmkuhl, F. and L.A. Owen (2005) 'Late quaternary glaciation of Tibet and the bordering mountains: a review', Boreas, 34: 87-100.

Mayewski, P.A. and P.A. Jeschike (1979) 'Himalayan and trans-himalayan glacier fluctuations since AD1812', Arctic and Alpine Research, 11, 3: 267-287.Pearce, F (2010) 'Debate heats up over IPCC melting glaciers claim. How did a 10 year old speculative comment over disappearing Himalayan glaciers come to be included in an IPCC report?', NewScientist, 11th January 2010.
Prasad, A.K., K.-H.S. Yang, H.M. El-Askary and M. Kafatos (2009) 'Melting of major glaciers in the western Himalayas: evidence of climatic changes from long ter, MSU derived tropospheric temperature trend (1978-2008)', Annuals of Geophysics, 27: 4505-4519.

Scherler, D., B. Bookhagen and M.R. Strecker (2011) 'Spatially variable response of Himalayan glaciers to climate change affected by debris cover', Nature Geoscience, 4,3: 156-159.Space Application Centre (2010) Snow and Glacier Studies Report, Ministry of Environment and Forests Department of Space of India.
Steffen, W., J. Grinewald, P. Crutzen and J. McNeill (2002) 'The Anthropocene: conceptual and historical perspectives', Philosophical Transactions of the Royal Society of London A, 369: 842-867.Thomas, D.S.G., and A. Goudie (2000) The Dictionary of Physical Geography (Eds) Blackwell Publishers: Oxford.

Zemp, M., M. Hoelzle and W. Haeberli (2009) 'Six decades of glacier mass balance observations- a review of the worldwide monitoring system', Annuals of Glaciology, 50:501-511.  (see link to UNEP long-term monitoring of glaciers around the world).

Videos speak louder than words.

Heres a rather novel video I came across by the Extreme Ice Survey. It clearly demonstrates the rate that some of our glaciers around the world are retreating. This video shows the mass balance changes of of Mendenhall glacier near Juneau, Alaska between 2007 and 2008 (in only one year!!).

It should be noted with reference to this that rates of retreat and advance are highly complex and will vary between each individual glacier. Also, this rate would need to be compared to paleaoclimatic reconstructions at Mendenhall to assess the significant of this observed retreat. Still, I think it is a very novel way of showing the dynamics of glacial environments. 350 days in the life of a glacier...enjoy!

'Preventing dangerous climate change is a great investment. It will cost between one and two percent of GDP, and the benefits will be between 10 and 20 percent. That’s a return of 10 to 1—attractive even to a venture capitalist' (Geoffrey Heal)

So what's all the fuss about?

Most people have heard of climate change. It seems to be everywhere nowadays. In the newspaper, on the tv. Some might say its just some excuse weather reporters have made to use when they get the forecast wrong (as we all know how much we, me included, like to moan about that). Jokes, aside though there is a growing consensus that our global climate is changing (Crowley, 2000; Oldfield, 2005). Palaeoclimate research using proxies such ice core (GISP II, 1993) and pollen analysis (Seppa and Bennett, 2003; Birks and Birks, 2006) show the Earth's climate exhibits natural variability on both short (intra-annual, inter-annual) and long term (decadal, centinnal) timescales. So what's the problem? Fundamentally, it is the rate and scale of the change in climate compared to historical variability that is the cause of concern (Barry and Chorley, 2010) and this will be assessed further in the ongoing weeks. The IPCC in 2007 estimated that the global mean temperature has risen by approximately 0.74°C.  Estimates of the contribution of natural variability to the current warming trend vary, but tend to range between 25% (Crowley, 2000) and 50% (Lean et al., 1995) depending on the timescale and parameters used for the investigation. Therefore, whilst a significant proportion of the current rise in global temperatrures can be attributed to natural fluctuations, even after accounting for uncertainties and modelling errors, a substantial proportion is still unaccounted for.

And in this lies the main aims for this blog. By reviewing academic journals on climate change and issues being highlighted in the media, this blog firstly aims to evaluate the state of our current climate in the context of past variability during the Holocene period. The blog will then try to cover how these changes may impact our glacial environments and the communities that depend on them.

Why glaciers I here you ask? I'll just let the video speak for itself.

The photos taken by David Breashears are also on display at the Royal Geographical Society, so if you need any more persuading as to severity of this issue then go and have a look for yourself.

'As well all know, the Chinese expression for "crisis" consists of two characters side by side. The first is the symbol for "danger," the second the symbol for "opportunity."' (Al Gore, 2006)

References:
Barry, R.G. and R. J.Chorley (2010) Atmosphere, Weather and Climate, Routledge: London

Birks, H.H. and H.J.B Birks (2006) 'Multiproxy studies in palaeolimnology', Vegetation History and Archaeobotany, 15: 235-251.

Crowley, T. J. (2000) 'Causes of climate change over the past 1000years', Science, 289: 270-277.

IPCC (2007) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, (Eds) S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller, Cambridge University Press: Cambridge.

Lean, J., J. Beer and R. Bradley (1995) 'Reconstruction of solar irradiance since 1610: Implications for climate change, Geophysical Research Letters, 22: 3195-98.

Oldfield, F (2005) Environmental Change: Key Issues and Alternative Approaches, Cambridge University Press: Cambridge.

Seppa, H. and K.D. Bennett 92003) 'Quaternary pollen analysis: recent progress in palaeoecology and palaeoclimatology', Progress in Physical Geography, 27: 548-579.