The text of the article is shown below. I have added ‘screen tips’. Mouse over any of the bold blue terms and some notes will appear (but don’t click onto follow the link- it will just jump to the top of page one). I’ve also copied all these notes into a table on the second page in case you want to print them all out together.
Methane From the Arctic
Most scientists agree that global warming is due to greenhousegases, and that theconsequences of continued global warming will be severe. Concern about greenhouse gases has focused on carbon dioxide, which has been released in greater and greater amounts over the past two hundred years.However, methane also absorbsinfrared radiation, and so contributes to the greenhouse effect. The table shows how the levels of these gases in the atmosphere have changed over the past two hundred years.
Water vapour is also a powerful greenhouse gas, but it has been omitted from the table as the water cycle has kept the amount of water vapour in the atmosphere roughly constant since preindustrial times.
The carbon dioxide level has gone up by 107 ppm since pre-industrial times, an increase of nearly 40 %. In the same time, however, the amount of methane has gone up by 150 %. Further increases in methane could have a serious effect.
Methane is a much more powerful greenhouse gas than carbon dioxide. Although the methane level is 200 times less than the carbon dioxide level, the current contribution of methane to global warming is estimated to be about one-third that of carbon dioxide. Most methane is produced by bacteria decomposingdead tissues from plants or animals. These bacteria live in places where there is no oxygen, such as the mud at the bottom of stagnant ponds.
Bubbling lakes
Recently, scientists have discoveredan alarming new source of methanein the frozen north of the Arctic.Investigating bubbles coming outof lakes at Fairbanks in Alaska,Professor Katey Walter of theUniversity of Alaska found thatlarge quantities of methane werebeing released from the groundunderneath. Field work by otherscientists in Cherskiy in northernRussia produced similar results.
Thawing Permafrost
The top few centimetres of the ground in the Arctic thaws in the summer. Beneath this, the ground is frozen all the time. This is the permafrost (permanently frozen ground). Permafrost contains deadplant and animal matter that has been locked in cold storage for thousands of years.
As the climate warms, the melting snow and glaciers are producing more and more lakes. The water at the bottom of these lakes melts the permafrost, allowing microorganisms to break down the dead matter into methane.
Threat orOpportunity
As global warming continues, the problem of methane being released from the Arctic permafrost becomes more serious. The more thawing there is, the more lakes will be formed. These lakes will warm up the permafrost underneath them and release methane. This will increase global warming further.
One method suggested to deal with the methane is to collect it and burn it. Although this produces carbon dioxide, the carbon dioxide is far less powerful as a greenhouse gas than methane. Burning the methane can generate energy for the local inhabitants too, although there are problems with supplying this methane to a thinly-spread population in such a harsh environment.
Another possible method is to prevent the permafrost from thawing by introducing massive herds of plant-eating animals to the region. These animals will remove the insulating layer of snow when foraging for food. This allows the cold winter temperatures to penetrate deeper into the ground and keep the permafrost frozen. This is what used to happen when mammoths, which are now extinct, roamed around the Arctic.
The animals suggested for this are moose, reindeer and horses. This is currently being tried out in a village in northern Russia.
consequences of global warming
- flooding – as global temperatures rise, there is more melting of glacial ice, and the sea water expands (as it warms); this causes sea levels to rise and low lying land will be flooded; people living in these areas may lose their homes and their farmland (so they won’t be able to grow crops).
- changes to farming – farmers grow the crops that grow best in their climate; as climate changes, a farmer may change from growing oats to growing oranges (but trees take time to grow, so there are expected to be food shortages - so price rises, and some people may starve)
- more frequent hurricanes / violent storms – with more water vapour in the air and with more energy in the atmosphere, we expect more frequent violent storms – these damage buildings and crops at great cost.
global warming / worldwide increase in average temperature - global warming here is referring to global warming caused by human activities, but remember without any greenhouse effect the Earth would be too cold to support life.
greenhouse gases / you’ll need to know their names. Common greenhouse gases in the atmosphere are: carbon dioxide, methane and water vapour
consequences of global warming / flooding, changes to farming, more frequent hurricanes / violent storms – see the notes at the end for more details
carbon dioxide / given out when any carbon based fuel is burned - all fossil fuels are carbon based; also given out by respiration; all living things contain carbon too; revise the carbon cycle so you know more processes that release carbon dioxide into the atmosphere
past two hundred years / what's been different in the last two hundred years - we've burned lots of fossil fuels
absorb / revise key words to describe radiation journeys - emission, transmission, reflection, absorption; and source, journey, detector
infrared radiation / revise the names of all the parts of the electromagnetic spectrum: radio, microwave, infrared, visible, ultraviolet, X-ray, gamma
greenhouse effect / revise the greenhouse effect - page 55 in the text book
ppm / ppm = parts per million; 107 ppm is 107/1000000 x 100% = 0.0107%
40% / increase from 280 to 387 = 107; percentage increase is 107 / 280 x 100% = 38.2%
150% / percentage increase = 1.045 / 0.700 x 100% = 149.3%
decomposing / decomposing means rotting
plants or animals / remember all animals and plants contain carbon, so when they break down carbon dioxide or methane can be produced
dead plant and animal matter / dead organic matter is a store of carbon in the carbon cycle
glaciers / glaciers are large permanent bodies of ice, often covering mountains - if all the glacial ice covering Antarctica melted, global sea levels would rise by 65 metres!
microorganisms / such as bacteria
break down / decompose
increase global warming further / scientists might call this positive feedback - as the effect is bad, it's also called a vicious circle
produces carbon dioxide / it produces carbon dioxide as burning methane is the combustion of a carbon based fuel
foraging / when herbivores are looking for food, we sometimes call it foraging