Posts tagged "climate"
The Anthropocene: our place in Earth’s history
The Anthropocene – the concept that the Earth’s surface geological processes are now human-dominated – is often considered to be more or less synonymous with climate change. Today, however, climate change is only one component – relatively minor, still – of the changes to the Earth system invoked to justify the Anthropocene. However, the last couple of centuries have seen large and accelerating changes in some of the key factors that drive global climate, and it is widely agreed among scientists that climate change has begun. In future decades, centuries and millennia, climate change seems likely to emerge as a central driver of changing geological process on Earth. The...
Wildfire: recycled sunlight or fuel for climate change?
The rainforest is burning in Sumatra, Indonesia. A majestic Meranti tree is close to the fire line. As flames from the surrounding canopy rage closer to this ancient tree, water quickly evaporates from its leaves, transforming the foliage into dry fuel for the fire. When turbulent, convective winds within the canopy bring hot air to the immediate surroundings of our tree, long-chain cellulose molecules in the desiccated foliage begin to crack, producing hydrocarbon gases and solid char deposits; with a flash, the gases ignite, forming the flames of the fire. This brief, catastrophic episode at the end of this tree’s life quickly re-balances a century...
Extinction: the changing face of the biosphere
In the Earth’s 4.6 billion year history, over 99% of all the species that have ever existed have become extinct. In the majority of cases, these extinctions are due to competition between species for space, food, or other resources; or that a species did not adapt sufficiently or quickly enough to changes in the environment. Extinction is a natural and on-going part of the biosphere’s engineering that continues at a background rate. This constant cycle of extinction, adaptation, and evolution means that as one species meets its demise, another will take its ecological niche. Over long time periods (thousands or millions of years), this can...
Alpine plants and recent climate change
Alpine plants grow above the altitudinal tree-line in mountains around the world. Because alpine plants grow in areas with low summer and winter temperatures, very low night temperatures, frost, short growing-season, high winds, or extended snow-lie, and grow very slowly, it is widely accepted that alpines grow in such extreme habitats because of their physiological tolerance or requirement for cold conditions and/or their intolerance to competition from taller, more rapidly growing lowland or montane plants. Some, but certainly not all, alpines can, with care, be successfully grown in lowland gardens in the absence of competition from tall plants. Alpine plants are thus potentially sensitive to climate...
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...
