Lithosphere

Volcanoes and climate change

What happens to the atmosphere when volcanoes erupt? Can volcanic eruptions lead to climate change? In 2010 the eruption of Eyjafjallajökull in south Iceland brought air traffic in northern Europe to a standstill for almost seven days. Now, the Bárðarbunga volcano, which has erupted beneath the Dyngjujökull glacier in central Iceland, is being intensively studied by scientists. On average, there are around 50-60 volcanic eruptions around the world each year. When volcanoes erupt, they can emit huge volumes of gases, aerosols, and volcanic ash into the stratosphere (part of the atmosphere at around 10-45 km altitude http://climatica.org.uk/climate-science-information/earth-system). With all of this material, we might expect...

Desertification: land degradation under a changing climate

Today, 17th June, is the World Day to Combat Desertification, with an event being held by the United Nations Convention to Combat Desertification (UNCCD), and hosted at the World Bank in partnership with the Global Environment Facility (GEF), TerrAfrica and Connect4Climate. The UNCCD have recently published a comprehensive report on the impacts of desertification. Here we look at what desertification is, how it is affected by climate change, and what this means for global populations. What is desertification? Desertification is a form of land degradation by which land becomes more arid.  It’s definition is debated, but it generally refers to “the process of fertile land transforming into desert typically as a result...

Climate history from lakes

Lakes are distributed widely across the globe, and depending on their location, they can be particularly sensitive to changing climate.  For example, global warming is having a significant impact on lakes in polar and alpine environments, while variation in rainfall patterns impacts on lakes in semi-arid regions.  In order to understand the climate history that can be obtained from lakes, we need to briefly consider how temperature and precipitation affect different types of lakes.   In cold, polar-regions, lakes are normally covered by ice for many months of the year.  During spring, the ice melts and winds help mix the water up, which also ensures...

Challenged by carbon: rocks and climate change

You can’t argue with a rock.  So ideally we would now be on a field trip.  Instead, I offer you a short film made in the field by the Science Museum to accompany a lump of Hertfordshire Puddingstone that is featured in the Atmosphere Gallery, first opened in 2010.   Thanks to geology, the scientific case for human-induced climate change has recently become significantly more plausible.  New observational science based on cores taken from deep beneath the floor of the oceans offers crucial support and control for the computer-based forecasts of those creating models of future climate change.  Thanks to the work of the late...

Cave deposits (speleothems) as archives of environmental change

Speleothems, from the Greek words for cave and deposit, include the familiar descending stalactites, upward-growing stalagmites and more continuous sheets called flowstones.  They grow slowly, at rates of between 1 mm a year to 0.001 mm a year.   This growth can persist for many thousands of years before being interrupted.  As with trees, speleothems commonly display annual layers which may be visible when a sample is polished, or recognised through chemical analyses.  Ideally, a sample will accumulate regular, parallel layers,  allowing the investigator to study its growth through time, and see changes in environmental conditions. These speleothems grow in caves within limestone rock.  Typically the...