Cold environments - Distribution



The Distribution of cold environments Climate variations The last ice age Reasons for changing climate Find out more
A huge proportion of our globe could be classified as a cold environment. Cold environments cover over 25% of the World's land surface and are incredibly varied in their nature. Defining cold environments is therefore difficult because of the variety of cold environments. In Britain, parts of Northern and upland Scotland are cold environments for at least part of the year and there is regular snow cover in winter in Aviemore. Indeed, one of the main controlling factors of how cold a place is and what cold features an area has is LATITUDE. At extreme latitudes there are Ice sheets in areas of extreme cold such as Antarctica, which can be over 2000m in depth and which cover almost the entire continent. In the Northern Hemisphere no such large continental land mass exists at the North Pole, so the Arctic is composed of sea ice which changes in thickness and extent from month to month and year to year. Away from these icy areas we can sea that seasonal sea ice dominates within the ocean realm, or areas of PERMAFROST of varying degrees exist on land. All of these environments can be seen on the map below. This distribution of cold environments is not static and changes from place to place and time to time. The Earth has gone through a series of warm and cold periods within its history and climate cannot be said to be static by any means. Times when the temperature has dropped significantly are known as GLACIAL periods, and are marked by advances of the World's ice masses to lower latitudes and lower altitudes. Times when temperatures are warmer for extended periods of time are known as INTERGLACIALS and these periods are marked by the retreat of ice to higher altitudes or Latitudes.		Think about it! 1) Research the possible causes of climate change below - consider the validity of each cause. 2) Watch the video below - what happens to the extent and distribution of Arctic sea ice over time? What are the possible causes of this?

Glacial periods can be punctuated by short climatic events known as INTERSTADIALS, where there are short term retreats in the extent of ice. Interglacials can similarly by interrupted by STADIALS, where for a short period of time temperatures drop and ice masses can advance. The way to remember this is using the football analogy "there is only one INTER in Milan" - that is - stadials occur in Interglacials AND Interstadials occur in Glacials!
Climate variations Over the past 1 million years it can be seen on the graph opposite that glacial periods have lasted longer that interglacial periods and that the temperatures of glacials have dropped lower than the rises of the interglacials. It should also be noted that the world is nearing the end of our current warming pattern, and what happens next to global temperature is still the subject of much debate. You should also note that the difference in temperature between the mean global air temperature and a glacial period is as little as 2°C colder than the global mean, and that the difference from the mean to today's warm period is only 2-3°C warmer. It therefore takes only small changes in temperature to switch global climate from hothouse to ice house!
The last Ice Age The last ice age to occur in the Quaternary period (which began 2 million years ago) started around 30,000 years ago, peaked 18,000 years ago when ice in Britain reached as far south as Bristol and London and ended between 12,000 and 10,000 years ago. The impact of this ice age was marked in the British landscape and evidence can be seen in the landforms that make up many of our much loved countryside areas.	From the Scripps Institution of Oceanography
Reasons for changing climate There are several possible causes of these fluctuations in temperature, including; Milankovitch cycles - theories about the variations in the way that the Earth rotates around the sun and changes in the Earths tilt. Video below. Note - the word equinox on Dec21st and Jun 21st should read Solstice - sorry! Changes in Ocean Currents Changes in the amount and composition of volcanic dust and aerosols following major eruptions. Changes in the location of the Earth's land masses. Variations in sunspot activity. Carbon and methane trapping in various sources, including peat bogs, tundra and the oceans.
Study these flash cards \| Study glaciers flash cards

Video Resources

2. the global distribution of cold environments

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