EMECO

Climate Change

What is Climate Change? 

Climate change is any long-term significant change in the "average weather" of a region or the Earth as a whole. Average weather may include average temperature, precipitation and wind patterns. It involves changes in the variability or average state of the atmosphere over durations ranging from decades to millions of years. These changes can be caused by natural climate variability.

More recently, natural climate variability appears to have been intensified by human activities, such as increased greenhouse gas emissions. Climate change influences the physical, chemical, and biological components of the Earth's ecosystems.

Impacts of Climate Change on Marine Ecosystems

The combined natural and human-induced climate change has changed the oceans physical, chemical, and biological properties.  These changes appear to be having a detrimental impact on the ability of the world's oceans to provide sufficient resources to support the industries and societies that depend upon them.

Impacts of Increased Atmospheric Carbon Dioxide

Most carbon dioxide (CO₂₎ released into the atmosphere as a result of human activities, such as burning fossil fuel and farming live stock, will eventually be absorbed into the ocean. This results in increased acidity (deceased pH) of the seawater.

As the amount of CO₂ in the atmosphere rises, more of the gas is absorbed by the oceans, thereby increasing the acidity of the seawater. 

Ocean pH was around 8.2 in the pre-industrial era and is now 8.1.  The projected increase in atmospheric CO₂ could result in a pH reduction at the ocean surface to 7.4 by 2300.

The absorption of excess carbon dioxide from the atmosphere affords some protection against global warming. The question is:

How much atmospheric CO₂ is the ocean able to absorb?

Impacts of Climate Change on Ocean Currents

Ocean currents are driven by two engines: wind and the thermohaline circulation (THC). 

The term thermohaline circulation (THC) (or global ocean conveyor) refers to the part of the large-scale ocean circulation that is thought to be driven by global density gradients created by surface heat and freshwater fluxes. The adjective thermohaline derives from thermo- referring to temperature and -haline referring to salt content, factors which together determine the density of sea water.

The wind driven Gulf Stream, together with the THC driven North Atlantic Current carry warm water northwards into the Atlantic and along the coast of Western Europe. This system is known as the Atlantic Heat Conveyor and has a considerable warming influence on the North-west Europe's climate.  For example, UK temperatures between 3-5°C higher than elsewhere at similar latitudes. 

However, melting ice and increased precipitation associated with climate change are causing the Atlantic waters to become less 'salty'. This is believed to be slowing the Atlantic THC. Observations suggest that this circulation system has reduced in strength by up to 30% since the early 1990s. These changes will have a significant impact on European climate.

Impacts of Climate Change on Marine Life

Marine organisms are sensitive to temperature, salinity, ocean circulation, and exchange of heat water and gases (including CO₂) with the atmosphere. 

Climate induced changes in these factors have corresponded to changes in the abundance and distribution of commercial fish stocks, plankton, and other marine life that has had severe adverse effects of Europe's fishing industries. 

Impacts of Climate Change on Infrastructure 

Increased storm frequency and intensity, coupled with rising sea-levels continues to pose growing threats to coastal communities, shipping, and oil and gas industries.