Hydrosphere

Mangroves and mud: Investigating past sea level

Dawn had already broken when our plane touched down on Mahé island, lighting up the cloudy shifting sky and the turquoise waters lapping at the runway’s edge. From my plane window I could already see sheer cliffs of pinky-grey granite rising up from the narrow coastal plain, covered in lush tropical vegetation. I was sleepy, but excited to be here. Mahé is the largest island of the small island nation of Seychelles – a tropical archipelago in the western Indian Ocean. I was visiting for three weeks to begin the field work component of my PhD research. My destination: the mangroves that fringe the western...

Coastal flooding around the UK coastline

Coastal floods, driven by extreme sea levels, are a major hazard both nationally and globally, with wide-ranging social, economic and environmental impacts. Nationally, it is estimate that £150 billion of assets and 4 million people are currently at risk from coastal flooding in the UK [1]. Coastal flooding is rated as the second highest risk for causing civil emergency in the UK, after pandemic influenza [2]. Combined with fluvial flooding, it is responsible for at least £0.25bn in annual economic damages [3]. Coastal flooding is a growing threat due to accelerating average sea-level rise and possible changes in storminess associated with climate change [4] as well...

Oxygen Isotopes in Speleothems

Stalactites and stalagmites (also called speleothems) are found in cave environments across the planet (see Figure 1). They form as water from the surface percolates into the ground and drips into the cave. Speleothems can be extremely sensitive to changes in climate and environmental conditions and they record these changes as variations in their chemistry. An excellent review of speleothem formation and their use for palaeoclimate reconstruction by Prof. Ian Fairchild can be found here, so this article focuses on the way that oxygen is stored in speleothems and how we can use this as a record of past climate conditions.   Why and how do we use oxygen isotopes? Oxygen...

Oceans and climate change: ecosystems

As the final part of our oceans and climate change series, this article explores marine ecosystems, looking at primary productivity, microorganisms, and changes in species composition and biodiversity.  Have a look at the previous parts of the oceans series.  Part 1 includes the key facts on the global ocean. Part 2 explores physical ocean processes and Part 3 explores ocean chemistry and the impacts climate change may have on the marine environment.  Written in collaboration with Sir Alister Hardy Foundation for Ocean Science, their original reports and outreach materials can be accessed here.   Primary productivity, phytoplankton and microorganisms   Primary productivity Primary productivity is the rate at which living...

Understanding past sea-level change

Sea-level change is an important consequence of climate change, whether natural or anthropogenic.  Global mean sea level has been rising. For the 20th century, the average rate was 1.7 ± 0.5 mm yr–1 (IPCC AR5), and in some locations (such as the east coast of the USA) there is some evidence that the rate of sea-level change appears to have increased from the 19th to 20th centuries.  However, sea-level change is not a global process but in fact the sea level at any location and at any time is result of a complex combination of a range of factors.  Changes in sea level are a result of any...