Posts Tagged ‘carbon dioxide’

Other Climate Change Indicators

Saturday, June 26th, 2010

Other than temperature, there are a few more indicators of climate change that are studied, which I will cover in overview here as promised in one of my earlier blogs.

Firstly, there is sea level rise.  The first thing to say about sea level rise is that the melting of the Arctic Ice Sheet does not increase the sea levels as you are simply replacing the volume of ice with the same of water.  Sea level rise comes mainly from the expansion of the water volume as the temperature of the oceans rises, plus just under half from the melting of land based ice such as on Antarctica or Greenland’s glaciers or over North America.  However, while there is definitely sea level rise, it is not that scary being of the order of centimetres rather than metres.  So we have historic sea level rises of 1.7mm to 3mm (after 1993) per annum  during the 20th century, or 20cm over 1900 to 2000, with forecast sea level rises of about 4mm every year reaching a total rise of 22cm to 44cm by 2090 from a base date of 1990. 

There is the remote possibility of a massive ice sheet melt from the Antarctic but this is viewed by the IPCC as a millenium scale event, i.e. really, really unlikely; in fact, increased precipitation is expected to continue with extra snowfall falling onto the Antarctic and so thickening the ice cap on the South Pole!  For a more detailed and easy to understand slide show go to this one on Slideshare.

Next, there is the increasing acidity of the oceans.  As carbon dioxide in the atmosphere increases, so more of this in dissolved in the oceans and waters of the world; other gases like nitrous oxide and sulphur dioxide also dissolve in water creating further acids, but here I am focussing on carbon dioxide.  The oceans act as an important sink or buffer for human activity, having absorbed over 80% of the heat added to the climate system and 30% of the human-derived carbon emissions over the last 200 years.  This point which has passed me by probably goes some way to explaining my earlier query as to why the link between greenhouse gas emissions and global warming is not so direct, i.e. because the water in the oceans, rivers and lakes dampens the impact [pun unitended but I like it] and takes up much of the initial heat and some of the increase in carbon dioxide and other gases. 

The ocean pH is about 0.1 pH units below the pre-industrial averages at around 8.1 and is forecast to fall another 0.4 to 0.4 pH units by 2100.  The impact directly on humans is minimal, however there is concern as to the impact on calcifying organisms that require carbonates to build their shells; a falling pH reduces the availability of carbonate in the water for corals, bivalves, crustaceans and plankton, which would then have implications on marine food webs and ecosystems.  These are simply explained at the following link and then there’s more detail on the oceans and coral reefs at the great web site Climate Shifts and on the BBC.

So we have further climate indicators that are showing that man is shaping the earth’s climate through his/her agricultural and industrial activity.

How Do Global Warming, Greenhouse Gases And The Earth’s Orbit All Link Together?

Thursday, June 17th, 2010

I’ve written a number of blogs now where I try to get to grips with some of the numbers underlying global warming.  So far, I agree that the historic figures do demonstrate global warming over the last 100+ years within a relatively wide band of possible growth rates, and that the evidence shows that the levels of carbon dioxide have increased since about 1950.  Furthermore, the science behind the link between carbon dioxide, methane and the greenhouse effect (and so global warming) is simple science that has been known for many years; in fact, global warming/the greenhouse effect is science that enables life on earth as without it our planet would have an inhospitable temperature closer to -18oC, i.e. it heats up the earth by about 33oC already to 15oC.

What interests me next is how have temperatures and greenhouse gases moved in the past? I will try and analyse this by looking at some neat science that analyses climate data over a longer period.  This will get to the nub of the issue, i.e. what is driving global warming, plus may answer my two current quandaries: (i) why isn’t global warming being driven exponentially by the very obvious and definite growth in CO2 per the Mauna Loa graphs? (ii) why do the predictive models of climate scientists suggest that we should be preparing for increases of 2 – 4oC for the next 100 years, while history shows global warming is more like 1oC over the last 100 or so years?

To work this out, some scientists look at what happened at the end of earlier ice ages as this hints at the mechanics of atmospheric and other climatic changes.  There are several pieces of research that suggest how temperature and greenhouse gases interact – one strand looks at climate data in stalagmites in caves in China and the other is a series of classic pieces of climate change science around ice core data from the Antarctic.  I’ll deal with the Antarctic first.

The first one is pretty neat.  It is based on the fact that when snow falls it traps air in small bubbles within its structure.  Then as more snow falls the next year, this new layer not only brings its own store of information about air quality, snowfall, temperature and levels of greenhouse gases, but it permanently seals off the information stored in the previous year’s snowfall.  Over time, we get left with an annual layering of data that goes back for ages and ages in the Antarctic, as well as in the Arctic especially on Greenland.  Scientists have now dug vertical small circular shafts into the ice and then, after chopping up these ice cores, have analysed the information from them – there’s a video on Youtube that shows you what the scientists do.  Data collated from other similar projects basically corroborates information found in this much earlier paper, which was published back in 1999 by Petit et al (detailed reference at end).

In essence, Petit et al were able to drill down 3,130m, covering 420,000 years and providing a climate record through four climate cycles.  They found that temperatures are constantly changing, but always within given maximum and minimum levels.  They found that when concentrations of greenhouse gases (specifically CO2 and CH4) in the atmosphere went up, global temperatures, also, went up and vice versa.  They concluded “[f]inally, CO2 and CH4 concentrations are strongly correlated with Antarctic temperatures; this is because, overall, our results support the idea that greenhouse gases have contributed significantly to glacial-interglacial change.  This correlation, together with the uniquely elevated concentrations of these gases today, is of relevance with respect to the continuing debate on the future of earth’s climate.” (Petit et al, 1999).

However, they also stated earlier that “[t]hese results suggest that the same sequence of climate forcing operated during each termination [of a glacial period]: orbital forcing (with a possible contribution of local insolation changes) followed by two strong amplifiers, greenhouse gases acting first, then deglaciation and ice-albedo feedback.” (Petit et al, 1999).  This suggests to me that greenhouse gases, the melting of the ice caps and the positive feedback caused by white ice turning to dark seas usually act as amplifiers of changes in temperatures caused by other factors such as changes in solar energy caused by changes to the earth’s orbit, which gets me back to one of my original quandaries – what is driving climate change and so what happens when you have the amplifiers without necessarily the increased temperatures resulting from either a more active sun or a change in the earth’s orbit?

The next paper I read was in New Scientist only a couple of weeks ago and is also pretty cool.  This work is trying to understand the end of glacial periods by analysing stalagmites in caves in China and interlink this with known changes in the shape of the earth’s orbit – now how amazing is that?  Since then, I have been reading the original scientific papers, hence the time delay in writing this blog.

Firstly, we need to start with the concept of Milankovitch’s theories on the earth’s orbits.  Milutin Milankovitch undertook detailed calculations on the earth’s three main orbital cycles.  So, for example, every 41,000 years the tilt of the earth’s axis increases and decreases, making summers hotter and colder respectively.  It’s summer temperatures that are important as this is what drives the potential for ice packs to melt over time, rather than winter temperatures which just create more ice.  So from 2.5 million years ago to about 1 million years ago the ice ages occurred based on these cycles.  However, around 1 million years ago to the end of the last ice age, glacial periods started occurring every 100,000ish years.  This links in potentially with another orbital cycle of 95,000 – 125,000 years, but here the science is less strong and debate still rages as to what is actually happenning. 

Liu et al have measured oxygen-18 in stalagmites in several caves in China.  Water containing oxygen-18 is heavier than normal oxygen-16 and so condenses more easily, so heavy monsoonal air loses much of its oxygen-18 as it moves inland and each year a record is left on the stalagmites.  As each glacial period ends, the summer monsoons became much weaker than normally and so the oxygen-18 levels in stalagmites increased.  Their evidence showed that monsoons failed in the last four glacial terminations, or as they write “[t]his climate pattern, broadly resembling other cave records from China, appears to correlate with multi-decadal to millennial changes in Greenland temperature and the general pattern of the wind-borne calcium ion record in the ice.”  In fact, work on a stalagmite from the Dongge Cave in China agrees exactly (within error) with the Vostok ice core records of Petit et al, showing methane rise in the atmosphere at 129,000BP.

Further work has shown that CO2 and CH4 levels increase at the same time as the ice packs at the poles decrease, suggesting that the reduction in ice is actually causing the rise in CO2 and CH4.  It is suggested that as the tilt of the earth’s axis changes this increases the temperature of the earth and the ice sheet over North America flows into the Antarctic, which interferes with and then stops the circulation of water around the oceans, which normally keeps the southern hemisphere warmer and the northern cooler (the so-called Atlantic Meridional Overturning Circulation).  As the southern seas warm up, CO2 is released into the atmosphere as CO2 is less soluble in warm water than cold and so further increasing the impact of the higher temperatures from the sun.  In effect, over the last 400,000 years, whenever the tilt of the earth’s axis reached a maximum, the intensity of sunshine increased (based on insolation in July at 60o north), CO2 levels increased to a maximum, relative sea levels also increased to maxima, all correlating with the strength of the Asian monsoon.

All of this comes from ice core data, analysis of stalagmites and other stores of climate data like coral reefs.  That in itself is amazing.  Then there is agreement in climate records going back many hundreds of thousands of years that correlate with each other across the world and using different techniques and types of ancient, geological record.

Finally, I would like briefly mention another set of amazing work by Zachos et al in the US which tries to get to grips with temperature and atmospheric gases in deeper time in the order of millions of years ago.  They have analysed various types of proxy data in deep sea cores of rocks to determine temperature and carbon in earth’s history and have tried to relate this to events in the geology of the earth and evolution, so developing a framework for the development of the earth’s climate over a much longer timescale.  What I like about these pieces of research is not just how clever they are, but also because Bjørn Lomborg uses them in a section trying to refute the science within climate change work in his book “Cool it – the skeptical environmentalist’s guide to global warming” – he has a tendency to misquote, or at least to quote out of context, as well as jumble up numbers and data to make his own points, which are often at odds with what the original scientists actually have stated.  Just like Nigel Lawson, Bjørn Lomborg has authority when it comes to economic and political discussions around climate change, but they sometimes get it wrong when they try and refute the science; most of their errors stem from two simple problems: (i) they don’t understand the scientific process; and (ii) they mistake/confuse weather for climate.  I will try and get back to Lomborg’s book “Cool It” some time and show how he shoots himself in the foot at times by blatantly altering the available research to suit his arguments.

The research by Zachos et al shows that carbon and temperature are correlated at least to about 34 million years ago at the edge of the Eocene and Oligocene Ages, which is when the Antarctic Ice-sheets became fairly permanent, and that there is correlation with the orbit of the earth around the sun even if the impact is sometimes relatively weak over millions of years.  Prior to then, getting clarity in the temperature and carbon dioxide levels gets ever harder and we find that the linkage between carbon levels and temperature is much less clear and even perhaps non-existent, however later research by Zachos et al indicates that this lack of correlation may not be as extreme as some researchers have indicated and is perhaps simply a result of lack of experimental data.  The other interesting occurrence is that whenever there has been a sudden change in temperature this has also been accompanied by a similarly sudden change in carbon; these occurred at 23, 34 and 55 million years ago.  Later research at the 34 million years ago tipping point suggests that carbon dioxide is a key factor in climate transition; Pagani et al (2005) showed that “[i]n detail, a trend toward lower CO2 concentrations during the middle to late Eocene, reaching levels at the E[ocene]/O[ligocene] boundary that could have triggered the rapid expansion of ice on east Antarctica; and work by Pearson et al (2009) indicates that there was a fall in atmospheric carbon dioxide at 34 million years ago that triggered climate transition to an ice-house world and “[t]his study reaffirms the links between cryosphere development and atmospheric carbon dioxide levels at the largest and most important climatic tipping point of the last 65 million years.”

However, when you look at research into climate over such a long time period, you realise pretty quickly that long term climate progression is the sum of many different processes and that it is far more complex than any of the commentators and scientists would have everyone believe, plus that correlation does not necessarily mean causation.

In overview, we know that the earth’s general temperature, hence climate, has gone up and down over time dependent on the earth’s tilt and orbital shape, i.e. effectively how close the earth gets to the sun during its orbit and so how much solar energy gets to the earth.  These changes in temperatures are then further affected by the earth’s environment, especially the levels of greenhouse gases in the earth’s atmosphere, the ice sheets and the ice-albedo effect.  In addition, climate gets impacted by a whole raft of other factors ranging from geological through to biological, which is a point that I will get back to in a later blog.

The science, therefore, does show that the basic greenhouse effect has impacted climate in the earth’s past and present and so will affect it in the future, but that it is not the only factor that impacts climate nor perhaps the most important climate factor over longer time periods.  Furthermore, while the research does indicate that sudden changes in carbon dioxide often occur with quick moves in climate, it doesn’t explain the consequences of these amplification or forcing impacts on our future climate, so that’s my next journey and is where I will need to start investigating the computer models devised by climate scientists to predict the climate in the future.

Before I go there, however, I would like to round off this section of my journey around global warming /climate change with a look at some of the other indicators of current global warming, such as sea levels and sea acidity just to round off the historical and current status of climate indicators.

References

Battersby, S. (2010) Meltdown: Why ice ages don’t last forever, New Scientist, issue 2761, 24 May 2010, Available on the Internet at http://www.newscientist.com/article/mg20627610.900-meltdown-why-ice-ages-dont-last-forever.html (Accessed 25 May 2010)

Kelly, M. J., Edwards, R.L., Cheng, H., Yuan, D., Cai, Y., Zhang, M., Lin, Y., An, Z. (2005) High resolution characterization of the Asian Monsoon between 146,000 and 99,000 B.P. from Dongge Cave, China and global correlation of events surrounding Termination II, Palaeogeography, Palaeoclimatology, Palaeoecology 236 (2006), 20 -38, Available from the Internet at http://www.sciencedirect.com.libezproxy.open.ac.uk/science?_ob=MImg&_imagekey=B6V6R-4JX38YR-1-R&_cdi=5821&_user=126980&_pii=S0031018206001301&_orig=search&_coverDate=06%2F23%2F2006&_sk=997639998&view=c&wchp=dGLzVlb-zSkzV&md5=a8ffdf76ab6ec0bde843ad331aeaa780&ie=/sdarticle.pdf (Accessed 2 June 2010)

Liu, D., Wang, Y., Cheng, H., Edwards, R.L., Kong, X., Wang, X., Hardt, B., Wu, J., Chen, S., Jiang, X., He, Y., Dong, J., Zhao, K. (2010) Sun-millennial variability of Asian monsoon intensity during the early MIS 3 and its analogue to the ice age terminations, Quaternary Science Reviews 29 2010, 1107 – 1115, Available on the Internet at http://www.sciencedirect.com.libezproxy.open.ac.uk/science?_ob=MImg&_imagekey=B6VBC-4YHSCPG-1-B&_cdi=5923&_user=126980&_pii=S0277379110000107&_orig=search&_coverDate=05%2F31%2F2010&_sk=999709990&view=c&wchp=dGLzVlz-zSkWb&md5=2e3a05cdb40b477b6a09872b4120f444&ie=/sdarticle.pdf (Accessed 25 May 2010)

Pagani, M., Zachos, J.C., Freeman, K.H., Tipple, B., Boahty, S. (2005) Marked Decline in Atmospheric Carbon Dioxide Concentrations During the Paleogene, Science 309, 600,  22 July 2005, Available on the Internet from www.sciencemag.org (Accessed 7 June 2010)

Pearson, P.N., Foster, G.L., Wade, B.S. (2009) Atmospheric carbon dioxide through the Eocene-Ologocene climate transition, Nature 461, 1110- 1114, 22 October 2009 Available on the Internet from www.nature.com (Accessed 7 June 2010)

Petit, J.R., Jouzel, J., Raynaud, D., Barkov, N.I., Barnola, J-M., Basile, I., Bender, M., Chappellaz, J., Davis, M., Delaygue, G., Delmotte, M., Kotlyakov, V.M., Legrand, M., Lipenkov, V.Y., Lorius, C., Pepin, L., Ritz, C., Saltzman, E., Stievenard, M. (1999) Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica, Nature, Vol 399, 3 June 1999, Available on the Internet from http://www.daycreek.com/dc/images/1999.pdf (Accessed 25 May 2010)

Zachos, J., Pagani, M., Sloan, L., Thomas, E., Billups, K. (2001) Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present, Science 292, 686, 27 April 2001, Available on the Internet from www.sciencemag.org (Accessed 7 June 2010)

Global Warming And Greenhouse Gases

Saturday, April 24th, 2010

We’ve looked at whether there is global warming and there does appear to be global warming albeit not at such a dramatic level as we read about in the press – perhaps more like 1oC rather than 4oC or 5oC. 

I will need to understand how the UK Met Office gets from these historic numbers to a future rise that’s much higher as I worry that it’s because of the computer model, which is a human-based interpretation of long-term weather patterns; as humans, we cannot predict economic performance and have been trying for many years so I remain to be convinced that we will be able to get it right for the weather – UK weather forecasters cannot get it right over a 24 hour period!

The first stage of this is to assess the drivers for global warming.  The key culprit is stated as man and particularly industrial and agricultural pollution.  Of these, the finger is pointed at greenhouse gases where carbon dioxide – or CO2 – is used as the proxy for all the other pollutive gases like methane and nitrous oxide etc.

It is clear that these gases especially carbon dioxide and methane have increased and much of this is due to energy generation from fossil fuels like coal and petrol and diesel and gasoline – but not nuclear or wind or water driven power.  It is also driven by the burning of the rainforests and other natural features like heather and grasslands, while chopping down trees takes away the trees that pull carbon dioxide out of the atmosphere and fix this into carbohydrates and other natural substances.

Great work has been done on this by the Keeling family at the Mauna Loa Observatory in Hawaii and graphs from their website clearly show how carbon dioxide has grown and links this back to fossil fuels.  I’ll let their pictures tell the story below.

The Classic Mauna Loa Graph

The Classic Mauna Loa Graph

More Globalised Look At Carbon Dioxide

Carbon Dioxide Over Hawaii and South Pole

Carbon Dioxide Growth Over Time And Fossil Fuel Trend

Carbon Dioxide Growth Over Time And Fossil Fuel Trend

Impact Of Fossil Fuel Growth And Carbon Time Over Long Time

Impact Of Fossil Fuel Growth And Carbon Time Over Long Time

Now how greenhouse gases work is simple.  Solar energy enters the earth’s atmosphere and is either absorbed by plants or objects on the earth or bounces off the earth back into the atmosphere.  Some of this goes out into space but a proportion is reflected back onto earth by water vapour – ie clouds – or greenhouse gases, so the more greenhouse gases and water vapour the more solar energy stays in the atmosphere and the warmer the earth gets (all things being equal).  This can be understood much better in a picture so here’s one I got from Google:

The Greenhouse Effect

The Greenhouse Effect

I don’t doubt that mankind has driven up the level of greenhouse gases in the atmosphere and that these will have had an impact on the temperature.  But the big question is how much warmer the earth gets and are all things equal and (I suppose) does everything need to stay the same and why cannot man adapt or change…

How We Are Reducing Our Family Environmental Impact – Insulating the Loft

Sunday, February 21st, 2010

One of the major users of energy in a house is for heating the building.  Space and water heating in homes gives off about 20% of the UK’s carbon dioxide emissions, which is about 5 tonnes CO2 per home every year.

However, one of the key issues for old houses, and in our case very old house, is that they have not been built with the benefit of modern technology that has invested much time, effort and legislation to make housing more heat efficient and so retain much of the heat within the building rather than to radiate it out into North Yorkshire – it’s a godforsaken task to heat up Northern England.

So as a start, you need to keep as much heat in as possible.

So my theory has been simple work down from the roof to the ground floor slowly but surely insulating the house.  We will work from the top downwards, as hot air rises so you want to capture it as it tries to escape upwards first rather than worrying about the ground levels at the outset.

The first thing, we felt, was to get insulation laid in the roof between the joists.  This had been done using old fashioned roof insulation over 10 years ago, insulating to 100mm in depth.  But we decided to insulate again with a cross layer of 200mm recycled glass mineral wool blankets.  For the first attempt at this, we bought recycled mineral wool – each pack of this Knauf Insulation Space Blanket contains 2.4 wine bottles (it was a 200mm thick roll of 1.48m2) and has a R value of 4.50m2K/W.   Government advice is to get insulation to about 300mm.

I liked this because it comes in a roll and encased in fire retardant polyethylene film, so does not need all that cutting and special equipment that normal loft insulation needs, and even more important it’s currently subsidised by e.on under some Government scheme to mitigate climate change so it was half price at Homebase, costing just £5.74 per roll.

It has got a metallic coating which Knauf Insulation claims reflects heat and so keeps more heat in – I think this sounds a bit spurious!

That means that the 35 rolls that I bought cost £143.50; this should mean that we recoup the energy savings within 2 – 3 years (assuming that we will save 10% of our fuel bills and that we had covered the whole roof void with the same insulation, i.e. multiply cost by 3/2; 25% of heat loss in total is through the loft and we already had 100mm in place, so I reckon 10% would be a good estimate for additional savings).

It was pretty easy to lay it and took me about 5 hours over the other weekend to buy the kit and lay it over two-thirds of the roof void.

Typically, however, when I got into the roof, I discovered that the heating engineers (or plumbers as I would have known them) never completed the lagging of the pipes nor the insulation of the water tanks, which was okay as they never relaid the insulation so the heat from the house kept the area around the tank warm – so muggins here had to finish that off as well.

Now feeling a bit good about myself, I bought something last week that’s a bit less simple to lay but definitely a greener alternative.

There are two main alternatives: one from newspapers (Warmcel) and the other from British sheep’s wool and recycled polyester (Thermafleece).  These both have the same levels of insulation capability as mineral wool, but I chose Warmcel and bought 15 bags of this from £165.27, costing £11.02 per bag inclusive of transport to us.  The Thermafleece is roughly double Warmcel again for the same price per m2 for the same depth, i.e. four times as expensive roughly as the recycled mineral wool insulation and so tripling the payback period.

So going back to my payback calculations – Warmcel has a payback of 4 – 6 years, which I am happy about, but Thermafleece has a payback of 8 – 12 years, which is too long for me.  Basically, I think for the cost-reward, it’s probably best to go with either the Space Blanket or (to give you a greener feeling about life) go with the Warmcel.  I cannot see the point with going for Thermafleece unless you feel romantically attached to lining your house in a woolly jumper.

But you do need to put the insulation down yourself as it’s pretty simple, and if you get a builder to do the work, you will blow any meaningful chance at getting a payback.

To buy these greener insulation materials, try these to web sites:

New Information About Global Warming

Thursday, February 11th, 2010

I’ve been reading New Scientist this week (6/2/2010) and there were 2 interesting articles on climate change this week:

  1. Water vapour fingered in climate change:  this reported that a rise in water vapour in the atmosphere fuelled 30% of global warming in the 1990s, while a 10% fall in 2001 has slowed down global warming in last decade by 25%;
  2. Imports mean UK emissions are up not down: this is a report commisioned by defra that they are now sitting on that shows that while national carbon dioxide emissions are down by 148 megatonnes between 1992 and 2004, this was outweighed by a 217 megatonne rise in embedded carbon dioxide emissions from imported products over the same period. 

A fuller report is found at Environmental Science and Technology but in essence all this says is that the fall in greenhouse gas emissions in the UK is mainly due to the fact that we have exported our greenhouse gasses to India and China, together with all our manufacturing capability and much of our social and health and safety issues.

What do you reckon – is the UK Government seeking to hide an embarassment that actually undermines its supposed adherence to the Kyoto process?