Hydrosphere
Microbes on ice: Climate amplifiers?
Lifeless ice? At first glance, the cryosphere – including all frozen water on Earth – appears to comprise vast, cold expanses devoid of biology. However, even the most remote, hostile and unlikely icy locations in both hemispheres have been found to harbour diverse and active microbial life. It is hard to imagine ice offering many viable places for microbes to exploit; but liquid water and energy sources exist beneath, within, and especially on the surfaces of glaciers and ice sheets. Research has shown us that not only are ice-dwelling microbial communities crucial stores of biodiversity, they might be important amplifiers of global climate change. The area...
Changing glaciers in Antarctica
Glaciers are the ‘canary in the coal mine’. Shrinking glaciers are the world’s most visual, most impressive evidence of globally warming temperatures. This is particularly evident around the Antarctic Peninsula, which is currently warming at around six times the global average. This warming is driving dramatic changes in snow and ice cover; glaciers are thinning, accelerating and receding, and their buttressing ice shelves are collapsing. The Antarctic Peninsula The ~400 glaciers around the Antarctic Peninsula are particularly sensitive to climate change because they are relatively small and are located on a high mountainous spine, projecting northwards from the Antarctic continent towards warmer latitudes....
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...
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...
