Week 3 - We are changing the climate!

So this is what we want to know. I know that we changing the climate but I want to know how we know we are changing the climate. If I have to go out in my day job and explain the negative impact peoples activities have on the climate then I want to have the ammunition to explain why, I suppose this is why I am doing the course. So lets crack on with it...

(Please note that this week is super busy so my notes and findings from the course are less comprehensive than usual)

Signs of Climate Change

Key indicators

Taking data from weather stations all over the world and working out the global average temperature, over the last century the temperature of the earth has significantly gone up in the last century and the last decade was the warmest. if you also look at the temperature of the ocean this follows the same trend.
year to year and decade to decase

Since 1880 there has been a steady rise in sea levels which is down to thermal expansion and melting of land ice (greenland ice sheet and glaciers. The melting of sea ice does not contribute to sea level rise, only the melting of land ice does.

The MET office scientists develop observational datasets which are used to monitor climate change. they create month climate bulletins to explain what's been happening in the worlds climate. The September 2014 monthly bulletin shows the temperature anomolies in comparison with the average temperatures between 1961-90, see below. 

The global temperature anomalies from the different months can be collated together to see how the climate is changing, such as in the graph below. This shows the best estimate of the global surface temperature but they are only estimates and the reality may slightly differ from these readings. The readings will fall in the shaded areas in 19 out of 20 cases.

Global surface temperatures have increased and the IPCC state "most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations."

There are issues with the causes at the beginning of the century as these may have been likely to be due to solar, volcanic and green house gas factors and the natural variability in the climate system. Other factors include El Niño, La Niña and volcanos eruptions such as like Mount Agung in 1963 and Mount Pinatubo in 1991.

El Niño, La Niña and ENSO (El Niño-Southern Oscillation) are terms that refer to a cycle that occurs naturally in the climate system in the Pacific ocean region of the world near the equator. The cycle involves both the ocean and the atmosphere and has wide-ranging effects. For example it can cause drought and famine in some of the areas that are affected. El Niño and La Niña are opposite states of the cycle. It is possible to see which state the cycle is in by looking at whether the water in the eastern Pacific is warmer or cooler than normal (which identifies El Niño or La Niña states respectively).

Extreme events

Scientists also keep careful records of all the extreme events and anomalies to see what areas of the world are sensitive to and if these events are increasing.The Climate.gov website tracks these events - below is a segment of the map of the extreme events around the globe.

There are very different activities happening in the Arctic and the Antarctic. In the Arctic (up the top) the sea ice extent is getting lower, each year the ice is becoming thinner, there are more gaps between the ice sheets and there is less older ice which can all be attributed to the warmer temperatures through climate change. The Antarctic sea ice on the other hand has reached record highs but this is because the warmer temperatures in the winter do not take the ice over zero but there are really strong winds, the 'westerlies,' which have gotten stronger in response to a stubbornly cold continent, and the warming ocean and land to the north.

Urgent Action report

American Geophysical Union is a union of scientists dedicated to enhance the understanding of geophysical science. The put a report together called Human-induced climate change requires urgent action. It came out in 2003 and has since been revised and re-affirmed with the latest update being 2013. The crux of the report explains that since the industrial revolution the level of carbon dioxide and other trapped greenhouse gases has increased, mainly through fossil fuel burning. Human-caused green house gases are responsible for the observed global average surface warming of almost 0.8 degrees celsius over the last 140 years. Natural process in the earths climatic systems cannot remove this level of green house gases quick enough so our past, present and future emissions will affect the climate for millennia.

They identify in the report that observations show large‐scale increases in air and sea temperatures, sea level, and atmospheric water vapor; they document decreases in the extent of mountain glaciers, snow cover, permafrost, and Arctic sea ice. With greater warming there will be risks to ecosystems and society such as increased extremes of heat, precipitation, and coastal high water, threats to public health, water availability, agricultural productivity, and coastal infrastructure. Biodiversity loss is expected to accelerate due to both climate change and acidification of the oceans, which is a direct result of increasing carbon dioxide levels.

 

Carbon cycles changes

Since 1750 when the steam engine was designed, economic development has been centred on the burning of fossil fuels. 10 petagrams of carbon (10 to the power of 16 gram of carbon) are released to the atmosphere every year due to human activities. 90% of the emission of CO2 comes from the burning of fossil fuel. The remaining 10% comes from deforestation.

 
Whilst the 10 petagrams are emitted each year, the atmospheric levels are only increasing by 4.5 pentagrams and this is because the ocean and land are absorbing them like a sink. If we didn't have  them there to absorb the CO2 then things would be a lot worse.

 

The current level of CO2 is 400ppm. USA has the highest carbon emissions per capita.

 

1. What are the most important themes you have learned this week? - the importance of observations and measurements and looking at the bigger picture and not just current events.
2. What aspect of this week did you find difficult? - How we work out what is happening with so many variations going on in the world and throughout time.
3. What did you find most interesting? And why? - The maps of the extreme events and how different each country is and the effects from climate change.
4. Was there something that you learned this week that prompted you to do your own research? - Yes, looked into rainfall around the world which spurred a question about rainfall differing in different parts of the world.
5. Are there any web sites or other online resource that you found particularly useful in furthering your knowledge and understanding?

LINKS
http://www.metoffice.gov.uk/research/monitoring/climate
http://www.climate.gov/news-features/featured-images/state-climate-extreme-events
http://nsidc.org/news/newsroom/20121002_MinimumPR.html
http://sciencepolicy.agu.org/files/2013/07/AGU-Climate-Change-Position-Statement_August-2013.pdf