The met office's global surface map which illustrates temperature anomalies clearly illustrates which parts of the world were colder or warmer in the recent month. The met office also allows people in the UK to dig deeper presenting a wealth of information including case studies of past weather events together with extremes. This data is an excellent springboard into investigating whether an extreme weather event is the result of climate change or just merely an extreme weather event.
For example, in 2013 the UK experienced the coldest March and May since 1962 and 1966. Investigating this I found out about the Arctic Oscillation which is an index of the dominant pattern of non-seasonal sea level pressures and that March 2013 was most negative since records began, When the AO is negative there tends to be high pressure in the polar region causing greater movement to middle latitudes. Associating this with climate change appears to be quite a complex activity although the climate anomaly maps are compelling.
I, also learned more about the impact of the jet stream. In 2012 the UK was the wettest on record according to the met office the jet stream was persistent remaining in the South of the UK therefore it did not drag the weather system away. As I mentioned in week 1 after undertaking some initial research on the UK climate some scientists have predicted more extremes in wet and dry weather in the UK because of there is a 4-5 percent increase in atmospheric moisture, as a result of changes in sea temperature and reductions in the amount of ice. Again it appears to be a challenge to look at rainfall patterns and to associate them with climate change because of natural variability.
I also found that ice is not just ice! According The National Snow and Data Centre the Antarctica and the Arctic are reacting differently to climate change partly because of their geographic differences, Antarctica is a continent surrounded by water and wind and ocean currents appear to isolate the continent from global weather patterns, keeping it cold. The Arctic, however, is an ocean surrounded by land, linked to the climate systems around it making it more sensitive to climate change.
I was surprised to see that the US still has the highest carbon emissions per capita, after looking at some of the climate maps, as I thought this may have changed because of the increase in industrial production in places like China, as 90% of carbon emission comes from burning fossil fuel.
The most difficult aspect of the course for me to understand this week was that the majority of CO2 is being absorbed by land and the ocean not the atmosphere. They act as a carbon sinks, draining CO2 back out of the atmosphere, absorbing and storing it away, the deep ocean being largest reservoir. About 80 percent of CO2 in the atmosphere is from the burning of fossil fuels, a reduction in the burning would help to reduce the amount of CO2 emissions, however carbon sinks can also help to address the balance. Deforestation and the warming of oceans (consequence of global warming) could change the amount of carbon dioxide absorbed and sinks may not be able to keep pace with the amount of global carbon emissions. The carbon brief sates that researchers have found that less organic carbon sinks to the deep ocean in warmer water, leaving more carbon dissolved in the surface ocean, which can then return to the atmosphere as carbon dioxide, However ,there is still considerable debate on best way to manage forests see this article in Nature Carbon Sequestration managing forests in uncertain times.
So I suppose the take away message this week is that although we can see that the climate is changing it is more difficult to predict whether extreme weather patterns are a result of climate change, although there is much research into this and the data sets can assist with this. Also, we should not underestimate the importance of nature in helping to control CO2, in particular carbon sinks, although it will be challenging for these sinks to keep a natural balance if the amount of CO2 increases - especially if oceans warm decreasing the amount of CO2 oceans can hold, which will release more CO2 into atomosphere, which will raise global temperatures - a positive feedback loop.
Useful references
Forests as a Carbon Sink
What are Climate Change Feedback Loops
