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Imaggeo on Mondays: America’s dead sea

Imaggeo on Mondays: America’s dead sea

On the blog today, Jennifer Ziesch, a researcher at the Leibniz Institute for Applied Geophysics, takes us on a tour of the Great Salt Lake, located in the north of Salt Lake City (Utah). Did you know it is one of the largest salt water lakes in the world?

The large salt lake and Salt Lake City, named after the lake, lie on a flat plain about 1300 m above sea level. The salt lake is bordered to the east by the beautiful high Uinta Mountains (3700 – 4100 m) – part of the Rocky Mountains – and to the west by a huge salt desert, which developed towards the end of the last Ice Age due to dehydration. A semi-arid climate characterizes the landscape of the lake and surrounding area.

Like the Dead Sea, the Great Salt Lake is shrinking rapidly. In the middle of the 19th Century, the lake was almost twice as large as it is today. Mankind diverts the inflow of freshwater from the rivers for agriculture and industry. Local people have reported problems with saline groundwater.

The Great Salt Lake is becoming more salty (up to 27%). How high the salinity is shown in the close-up of a footprint. Salt crystals are formed in their full beauty.

Salt precipitation after a walk near the Great Salt Lake. Credit: Jennifer Ziesch (distributed via imaggeo.egu.eu)

The economy uses the salt and other minerals for fertilisers and wintering products. Unfortunately, the ecosystem is becoming more and more fragile: bird species, crabs and other creatures are losing their habitat.

By Jennifer Ziesch, geoscientist at the Leibniz Institute for Applied Geophysics.

Editor’s note: This text was modified on 14/02/2017 with the addition of an extra photograph to show salt precipitation in the lake. 

If you pre-register for the 2017 General Assembly (Vienna, 22 – 28 April), you can take part in our annual photo competition! From 1 February up until 1 March, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

Geosciences Column: Africa’s vulnerability to climate change

Climate change is set to hit the nations of the Global South the hardest.

Ravaged by armed conflicts, a deep struggle with poverty, poor governance and horizontal inequality, some parts of Africa and other Global South regions are arguably the most vulnerable to the impacts of climate change. Largely reliant on natural resources for sustenance, current and future changes in temperatures, precipitation and the intensity of some natural hazards threaten the food security, public health and agricultural output of low-income nations.

Climate change increases heat waves across Africa

Among other impacts, climate change boosts the likelihood of periods of prolonged and/or abnormally hot weather (heat waves). A new study, by researchers in Italy, reveals that in the future all African capital cities are expected to face more exceptionally hot days than the rest of the world.

The new research, published in the EGU open access journal Natural Hazards and Earth System Sciences, has found that extreme heat waves affected only about 37% of the African continent between 1981 to 2005 while in the last decade, the land area affected grew to about 60%. The frequency of heat waves also increased, from an average of 12.3 per year from 1981 to 2005 to 24.5 per year from 2006 to 2015.

By merging information about the duration and the intensity of the recorded heat waves, the authors of the study were able to quantify the heat waves using a single numerical index which they called the Heat Wave Magnitude daily (HWMId). The new measure allowed the team to compare heatwaves from different locations and times.

Geographically plotting the HWMId values for daily maximum temperatures over five-year periods from 1981 to 2015, clearly showed there has been an increase, not only in the number of heat waves and their distribution across the continent, but also an escalation in their intensity (see the figure below). The trend is particularly noticeable since 1996 and peaks between 2011 and 2015.

Heat Wave Magnitude Index daily of maximum temperature (HWMIdtx) for 5-year periods of Global Surface Summary of the Day (GSOD) gauge network records from 1981 to 2015. The bottom-right panes show the spatial distribution of the GSOD station employed in this study. From G. Ceccherini et al. 2016 (click to enlarge).

The figure also highlights that densely populated areas, particularly Northern and Southern Africa, as well as Madagascar, are most at risk.

The rise in occurrences of extreme temperature events will put pressure on already stretched local infrastructure. With the elderly and children most at risk from heat waves, the health care needs of the local population will increase, as will the demand for electricity for cooling. Therefore, further studies of this nature are required, to quantify the implications of African heat waves on health, crops and local economies and assist government officials in making informed decisions about climate change adaptation policies.

Lessons learned from climate adaptation strategies

In the face of weather extremes across Africa including heat waves, droughts and floods, it is just as important to carefully assess the suitability of climate change adaptation policies, argues another recently published study in the EGU open access journal Earth System Dynamics.

Take Malawi, for instance, a severely poor nation: over 74% of the population live on less than a dollar ($) a day and 90% depend on rain-fed subsistence farming to survive. According to Malawi government figures, one-third of the country’s gross domestic product (GDP) comes from agriculture, forestry and fishing.  As a result, the country – and its population – is vulnerable to weather extremes, such as variability in the rainy season, prolonged dry spells and rise in the number of abnormally hot days.

A 2006 Action Aid report states that “increased droughts and floods may be exacerbating poverty levels, leaving many rural farmers trapped in a cycle of poverty and vulnerability. The situation in Malawi illustrates the drastic increases in hunger and food insecurity being caused by global warming worldwide.”

The Lake Chilwa Basin Climate Adaptation Programme (LCBCCAP) aims to enhance the resilience of rural communities surrounding Lake Chilwa to the impacts of droughts, floods and temperature extremes. The lake is a closed drainage lake (meaning it relies on rainfall to be replenished) in the south eastern corner of Malawi.

Perceptions of how climate change affects residents of the Lake Chilwa Basin. From H. Jørstad and C. Webersik, 2016 (click to enlarge).

The authors of the Earth System Dynamics study interviewed a group of 18 women (part of the LCBCCAP programme), back in early 2012, to understand how they perceived they were affected by climate change and whether the adaptation tools provided by the programme would meet their long-term needs.

The women agreed unanimously: climate in the Lake Chilwa Basin was changing. They reported that rainy seasons had become shorter and more unreliable, leading to droughts and dry spells. One of the women mentioned raising temperatures and fewer trees, due to overexploitation.

All those interviewed were part of the women fish-processing group, an initiative which sought to provide an alternative income for the women as traditional agricultural activities became unreliable due to erratic rainfall and prolonged dry seasons.

While the women’s new occupation did provide economic relief, the study authors highlight that the group’s new source of income was just as dependant on natural resources as agriculture.

Throughout the interviews, the women of the fish-processing group expressed concerns that the they thought Lake Chilwa might dry up completely by 2013.

“Yes, the lake will dry up and I will not have a business,” says Tadala, one of the women interviewed in the study. While another local woman said “Yes, lower water levels in the lake is threatening my business.”

Lake Chilwa has a long history of drying up: in the last century it has dried up nine times.  If the lake dried up completely, the women of the fish-processing group would be out of business for 2 to 4 years. Even small drops in the water level affect the abundance of fish stocks.

Lake Chilwa has a history of drying up. These Landsat images show the net reduction of lake area between October 1990 and November 2013. show changes to the extensive wetlands (bright green) that surround Lake Chilwa. These wetlands are internationally recognized as an important seasonal hosting location for migratory birds from the Northern Hemisphere. Credit: USGS

The interviews were carried out in early 2012. The previous two years had seen very limited rainfall. Not enough to sustain the lake, but the situation, at the time of the interviews wasn’t critical. However, throughout the summer of 2012 the lake water levels started falling rapidly prompting the relocation of large groups of lakeshore residents. Those dependant on fishing to support their families were most affected.

The women fish-processing group is a good demonstration of how local communities can adopt low-cost measures to adjust to climate change. At the same time, it highlights the need to assess climate adaptation strategies to take into consideration whether they too are dependent on climate-sensitive natural resources. The new research argues that diversifying people’s livelihoods might provide better long-term coping mechanisms.

By Laura Roberts Artal, EGU Communications Officer

References and resources

Ceccherini, G., Russo, S., Ameztoy, I., Marchese, A. F., and Carmona-Moreno, C.: Heat waves in Africa 1981–2015, observations and reanalysis, Nat. Hazards Earth Syst. Sci., 17, 115-125, doi:10.5194/nhess-17-115-2017, 2017

Jørstad, H. and Webersik, C.: Vulnerability to climate change and adaptation strategies of local communities in Malawi: experiences of women fish-processing groups in the Lake Chilwa Basin, Earth Syst. Dynam., 7, 977-989, doi:10.5194/esd-7-977-2016, 2016.

ActionAid: Climate change and smallholder farmers in Malawi: Understanding poor people’s experience in climate change adaptation, ActionAid International, 2006.

NASA: The consequences of climate change

United States Environmental Protection Agency (EPA): Understanding the Link Between Climate Change and Extreme Weather

National Oceanographic and Atmospheric Administration (NOAA): Heat wave, a major summer killer

Imaggeo on Mondays: littoral rainforests

Littoral rainforests

Seagull lunch. Credit: Alicia Morugán (distributed via imaggeo.egu.eu).

Making room for growing populations, and the resources they demand, comes at the cost of precious natural environments. Rainforests, globally, are under threat from farming, logging and ever expanding cities. It is reported that if current rates of exploitation continue, the world’s rainforests could be lost within the next century.

Like almost anything else, rainforests come in all shapes and sizes. Typically, rainforests are depicted as lush, jungle-like concentrations of tall trees characterised by heavy rainfalls. But, perhaps unexpectedly, stretches of the coastline in eastern Australian are also peppered by rainforest. Because of their proximity to the ocean, these closed-canopy forests – where  approximately 70% of the sky obscured by tree leaves and limbs – are known as littoral rainforests.

Much like their equatorial cousins, Australian littoral rainforests are under threat. Large swathes of forest have been destroyed for/by agriculture, animal browsing/grazing, fire, mining or housing. Invasive species and weeds pose a particular danger to the forests too.

Today’s featured image was taken from “The Brunswick Heads Nature Reserve, a protected nature reserve located in the Northern Rivers region of New South Wales, Australia. The 221-hectare (550-acre) reserve is situated near Brunswick Heads and contains an intact segment of littoral rainforest,” writes Alicia Morugán, author of the photograph.

The reserve is home to many critically endangered rainforest plants that are either at the southern limit of their distribution or not found in many other places in New South Wales, as well as many threatened animal species. Current conservation efforts center around monitoring to identify key threats to the precious ecosystems, as well as protecting known sites.

 

If you pre-register for the 2017 General Assembly (Vienna, 22 – 28 April), you can take part in our annual photo competition! From 1 February up until 1 March, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

 

Imaggeo on Mondays: the remotest place on Earth?

Imaggeo on Mondays: the remotest place on Earth?

Perhaps a bold claim, but at over 4,000 km away from Australia and 4,200 km from South Africa, Heard Island is unquestionably hard to reach.

The faraway and little know place is part of a group of volcanic islands known as HIMI (comprised of the Heard Island and McDonald Islands), located in the southwest Indian Ocean. Shrouded in persistent bad weather and surrounded by the vast ocean, Heard Island, the largest of the group, was first sighted by the merchant vessel Oriental in 1853.

Its late discovery and inaccessibility mean Heard Island is largely undisturbed by human activity (some research, surveillance, fishing and shipping take place on the island and it’s surrounding waters). It boasts a rich fauna and flora: seals, invertebrates, birds and seals call it home, as do hardy species of vegetation which grow low to the ground to avoid the fierce winds which batter the island.

Geologically speaking the islands are pretty unique too. They are the surface exposure of the second largest submarine plateau in the world, the Kerguelen Plateau. Limestones deposited some 45–50 million years ago began the process which saw the emergence of the islands from the ocean floor. Ancient volcanic activity followed, accumulating volcanic materials,  such as pillow lavas and volcanic sediments, up to 350m thick. For the last million years (or less) Heard Island has been dominated by volcanism, giving rise to the 2745m tall Big Ben and 700m tall Mt. Dixon. Eruptions and volcanic events have been observed on the island since 1947. Much of the recent volcanism in the region has centered around McDonald island, which has grown 40 km in area and 100 m in height since the 1980s.   

As the group of islands provides a remarkable setting, where geological processes and evolution (given that large populations of marine birds and mammals numbering in the millions, but low species diversity) can be observed in in real time, UNESCO declared HIMI a World Heritage Site back in 1997.

If you pre-register for the 2017 General Assembly (Vienna, 22 – 28 April), you can take part in our annual photo competition! From 1 February up until 1 March, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

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