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Rapid Responses: Rapid Responses published:
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Changing climate
- colin bannon (28 January 2008)
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Re: Changing climate
- Örjan Hallberg (31 January 2008)
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Economics of tackling climate change
- William D Jeans (3 February 2008)
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colin bannon, GP The mannamead surgery, 22 eggbuckland road, Pltmouth PL3 5HE
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The editorial, leader, and analysis in last weeks BMJ (BMJ 336) correctly highlight the dominant determinant of health during what geologist are now calling the Anthropocene, (the era of mankind) which is climate change. However, I believe that doctors can do more than they suggest. The IPCC ‘s fourth report and the Stern Review define with unprecedented clarity the diagnosis, treatment and prognosis for our ailing climate and our life support systems. While we may be committed to an increase of 2 Deg C due to our emissions to date, this is not the whole story. Carbon dioxide has a very long atmospheric half-life, its effects of emissions are cumulative and there are some potent positive feedbacks lurking in the wings. This means that global temperature rise, unless some pretty drastic changes are made and made soon, could go way beyond the 2degree C rise discussed and continue beyond. If that happens, our prognosis will be poor. While the developing nations will suffer earliest, no one will be exempt. Climate change will be very difficult to adapt to, even for us in the west. The effects on health of collapsing agricultural systems, shortages of water and fuel as well as the potential for disorder go beyond anything that global health services would be capable of mitigating as they too feel the brunt of change. I can imagine a world when primary care does what it can long after the energy hungry, centralised and unsustainable secondary care sector has shrunk to vanishing. However, to have a chance of success we have to be honest about what needs doing. To prevent the worst of climate change we must design zero carbon local communities which could become increasingly self sufficient for food, energy and water and which could provide work and a good quality of life for its citizens. The days of air travel must largely be brought to an end through increasingly stringent carbon rationing and which would also see buses, coaches and taxis replace private transport and local renewable sources of energy replace fossil and nuclear fuels. Such communities could be correctly termed villages, either rural or urban and they may be resilient enough to survive the harsher times ahead. Indeed they could improve the local environment and have a balance sheet with nature in the black though massive tree planting, restocking of fisheries and development of local food production in gardens, allotments, smallholdings and farms. The health benefits brought by such communities would be vast and are well described by Roberts. This could serve as a template for development around the world which could reverse the climate crisis, avert the climate crisis and offer hope for a sustainable future. I hope the next generation of doctors will be able to ply their trade for the benefit of their patients, however, with the worlds population climbing, consumption rising, the skies full of planes, the roads full of cars, the natural world shrinking and the developing nations emulating the most unsustainable aspects of the west only a fool or a politician would say the prognosis, at the moment, looks good. Yours sincerely, Dr Colin Bannon Competing interests: member of the green party |
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Örjan Hallberg, MSEE Hallberg Independent Research, Polkavägen 14B, 142 65 Trångsund, Sweden
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Changing climate This letter gives references to climate projections done by the Intergovernmental Panel on Climate Change (IPCC). Of special interest are the models used for the thermal response to increasing levels of atmospheric content of carbon dioxide. The projections done by IPCC were used together with measured and reported data on temperature increase and CO2 contents to extract the basic response function to a stepwise increase of carbon dioxide in the atmosphere. IPCC data Projected temperature increase after 70 years of 1% annual increases of CO2 in the atmosphere gives a doubled CO2 content after 70 years. Note that the temperature levels off very fast after a stabilization of the CO2 -level. The time to 50% of the remaining temperature increase is according to this graph around 40 years. Figure 1: http://www.grida.no/climate/ipcc_tar/wg1/345.htm#fig91 According to this graph IPCC assumes around 3,5 degrees C increase after a doubling of the CO2 contents from today's 380 to 760 ppm. Before that we have had close to one degree C increase after 100 ppm increase from 280 to 380 ppm. Thus, IPCC assumes that in total an increase of 480 ppm will result in a temperature increase of 4,5 degrees C or around 1 degree C per 100 ppm CO2. Figure 2 shows the thermal response to a peak (not a step function, though) according to the same organization: Although the increase in CO2 is not a step function but a ramp the time to 50% of temperature increase looks to be around 50 years, quite in line with the projections made in Figure 1. Calculated thermal response to a somewhat slower reduction of annual CO2 outlet than assumed in Figure 1. Figure 2: http://www.grida.no/climate/ipcc_tar/vol4/english/fig5-2.htm It is clear that IPCC here assumes a very fast response to increasing levels of carbon dioxide in the atmosphere. The temperature starts immediately to level off once the increasing levels of CO2 also slows down. However, in Figure 3 a quite different picture is given from another IPCC report. Here the thermal response is assumed to need 120-150 years to reach half of the final temperature level after a step increase of CO2. Time to 50% increase of different climate characteristics after a stepwise increase in atmospheric CO2 contents. Figure 3: http://carto.eu.org/article2515.html Figure 4 shows the variation in atmospheric contents of CO2 and temperature since 420 000 years back. Here we can see that 10 degrees C always correspond to 100 ppm increase in CO2 level. This is far away from the one degree C that IPCC expects to be the response to an increase of 100 ppm CO2. Figure 4: http://carto.eu.org/article2481.html Analysis of data The data in Figures 1 and 2 can be used to extract the thermal response function to a stepwise increase in atmospheric contents of carbon dioxide. Likewise it is also possible to analyze already reported temperature/CO2 data to see what history already has taught us about the thermal response. An analysis of the data actually reported since 1850 was done to get the response pattern that best fits to reported data. The best fit between calculated and reported data was obtained when the final thermal response to an increase of 100 ppm was 5,45 degrees C. According to IPCC (Figures 1 and 2) the time to 50% of final temperature is 37 years while our analysis of real reported data says 113 years, quite in line with Figure 3. A sensitivity analysis of our model using minimum and maximum temperature bands gave a response time varying from 97 years (max temp line), 113 years (mean temp line) and 127 years for a low temperature line. Thus, there is no doubt that reported data actually supports the estimate made by IPCC in Figure 3 but certainly not in Fiures 1 and 2. When using the fast response model by IPCC we were unable to get a good match between calculated and reported temperatures based on reported CO2 contents since 1850. According to Figure 4 a temperature increase of 10 degrees C has always been related to an increased level of atmospheric CO2 of 100 ppm. Now, when we add another 400 ppm IPCC believe that this will cause the temperature to increase by only 4,3 degrees or 1,1 degrees per 100 ppm. In our analysis the best fit to reported data was obtained when the final temperature increase for 100 ppm was 5,45 degrees C. Source Temp increase related to 100 ppm Historic data, 420 000 y 10 Our model 5,45 IPCC model 1,1 Table I. Temperature increase related to 100 ppm increase of atmospheric contents of CO2. If we manage to completely stop the increasing level of CO2 by year 2010 then the projected temperature according to our model will still increase by around another 2,8 degrees C from today to year 2100 and still continue increasing for another century. Note that the IPCC model, as extracted from Figure 1, predicts only 0.6 degrees C of increase from 2010 up to 2100. 50% of that, i.e. 0.3 degrees C is expected to happen within the first 20-30 years. In the latest IPCC report there is a graph showing what temperature increase is expected if the GHG was held constant from year 2000. Also here the increase is plotted as 0.6 degrees up to year 2100. See Figure 5. And here the time to 50% increase is 20-30 years. This means that our method is useful, and we also saw that the IPCC model did not correctly depict what really has happened since 1850. Figure 5. The temperature increase for different scenarios. Source: http://www.ipcc.ch/SPM2feb07.pdf Conclusions The authorities need to assure that the most correct model is being used as a base for climate policy and corrective actions. The official picture looks too optimistic and may have been influenced by strong economic interests from the car and oil industry. The fast increase in atmospheric CO2 contents since 1970 up till now has not yet had the time to manifest itself in corresponding temperature increases. There is more to come - like it or not! The authorities also think that if large companies and organizations apply carbon trading, the problem will be solved. Nothing could be more wrong. If all customers have unlimited carbon release rights (millionaires in CO2 if you wish) why should the companies try to limit the GHG pollution from their products? The customers would not care, anyway! It is only when we all have a limited amount of CO2 to release every month that we will see the beginning of a competitive carbon trading market. The company providing the best CO2-specification will win the market. And a real change will happen very fast. We know since World War 2 that ration cards worked well for sugar and coffee, so why not for CO2? Especially since we today can manage ration cards just as easy as any other credit card. As a thermal run-away may not stop until we reach 480 degrees C, we will most certainly need the assistance of many doctors in the future! Competing interests: None declared |
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William D Jeans, Retired doctor Sultan Qaboos University Oman
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Ian Roberts’ editorial relating health benefits to tackling climate change is interesting.1 However, outside public health concerns, for most doctors his advice in summary comes down to “Eat less meat and take more exercise”. There is more to their possible input and to the equation than that.
Consider the following statements:
1. CO2 levels in the upper atmosphere are increasing.
2. Human activity produces CO2 (by food production, cooking and heating, industry, transport, as outlined by Roberts).
3. Growth of human activity increases CO2 production.
4. World population doubled from 1960 to 1999 (from 3 to 6 billion)
It seems likely that the increase in CO2 levels is related to the growth in world population.
Perhaps doctors can give more advice to their patients than “Eat less meat and take more exercise”?
Perhaps economists and businesses could find a better goal than ‘Increase growth’?
Perhaps aid givers could fund education for women in developing countries since that
reduces both fertility and infant mortality?
I fear that we are ignoring the elephant in the room, and swatting at the flies that came in with him.
W.D. Jeans
PO Box 552 PC116 Oman
Retired doctor
wdjeans@yahoo.co.uk
Competing Interests: None known (but currently lives in a developing country).
1. Roberts, I. The economics of tackling climate change. BMJ 2008;336:165-6. (26 January)
Competing interests: None declared |
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