- Email: [email protected]
UK statistical indifference to its military casualties in Iraq
Comment
6 7
8
9
10
Moreno C, Gustot T, Nicaise C, et al. CCR5 deficiency exacerbates T-cell-mediated hepatitis in mice. Hepatology 2005; 42: 854–62. Gallant JE, Staszewski S, Pozniak AL, et al. Efficacy and safety of tenofovir DF vs stavudine in combination therapy in antiretroviral-naive patients: a 3-year randomized trial. JAMA 2004; 292: 191–201. European AIDS Treatment Group. Press release: European activists require regulatory agencies to halt unethical trial. April 11, 2005: http://www. eatg.org/modules.php?op=modload&name=News&file=article&sid=463&m ode=thread&order=0&thold=0 (accessed Nov 8 2005). Mocroft A, Ledergerber B, Viard JP, et al. Time to virological failure of 3 classes of antiretrovirals after initiation of highly active antiretroviral therapy: results from the EuroSIDA study group. J Infect Dis 2004; 190: 1947–56. Deeks SG. Treatment of antiretroviral-drug-resistant HIV-1 infection. Lancet 2003; 362: 2002–11.
11
12
13
14
15
Gulick RM, Ribaudo HJ, Shikuma CM, et al. Triple-nucleoside regimens versus efavirenz-containing regimens for the initial treatment of HIV-1 infection. N Engl J Med 2004; 350: 1850–61. Greaves W, Landovitz R, Fatkenheuer G, et al. Late virologic breakthrough in treatment naive patients on a regimen of Combivirvicriviroc. 13th Conference on Retroviruses and Opportunisitic Infections, Denver, Colorado, USA, Feb 5–8, 2006; 161LB (abstr). Spudich SS, Huang W, Nilsson AC, et al. HIV-1 chemokine coreceptor utilization in paired cerebrospinal fluid and plasma samples: a survey of subjects with viremia. J Infect Dis 2005; 191: 890–98. Wolinsky SM, Veazey RS, Kunstman KJ, et al. Effect of a CCR5 inhibitor on viral loads in macaques dual-infected with R5 and X4 primate immunodeficiency viruses. Virology 2004; 328: 19–29. Koot M, Keet IP, Vos AH, et al. Prognostic value of HIV-1 syncytium-inducing phenotype for rate of CD4 cell depletion and progression to AIDS. Ann Intern Med 1993; 118: 681–88.
UK statistical indifference to its military casualties in Iraq “The brave poor sodger ne’er despise, Nor count him as a stranger . . . Remember, he’s his country’s stay, In day and hour of danger.” When wild war’s deadly blast was blawn (Robert Burns)
Neither the UK nor US Governments properly counted, or even seriously sought to count, civilian casualties in Iraq.1–3 In January, The Scotsman4 exposed the Ministry of Defence’s failure properly to count UK military casualties in Iraq. By contrast, US military casualties, as well as fatalities, are accounted for.5 First, what can we learn from the US casualty data? The reported ratio of US military casualties to deaths in Iraq5 was 2409 to 486 in 2003 (ie, 5:1), but it was much higher in 2004 at 7989 to 848 (9:1) and in 2005 at 5939 to 846 (7:1). Other things being equal, the UK—which had 53 military deaths in Iraq in 2003, 22 in 2004, and 23 in 2005—could thus have sustained over 600 military casualties (estimated at 263207161, based on the reported US ratios). This calculation might not be apposite for three reasons: because UK and US forces have different areas of operation in Iraq, because US troops have a significantly higher proportion of deaths from hostile fire (1767/2252 [78·5%] up to Feb 3, 2006) than do other coalition forces (147/204 [72%], p=0·05),5 and because no account has been taken of statistical uncertainty. Nevertheless, the US data clearly signal that the ratio of casualties to fatalities might not be constant over time, which means that both values should be reported. Second, because casualties are five to nine times more numerous than fatalities, the monitoring of casualties on a quarterly basis has at least as much statistical power as the monitoring of fatalities on a yearly basis. www.thelancet.com Vol 367 March 4, 2006
Against such statistical imperatives for improved accountability, who or what thwarts the UK’s competent compilation and dissemination of statistics by which to monitor death rates and casualty rates for UK military personnel deployed to Iraq?6,7 The calculation of such rates needs period-specific numerators (fatalities, casualties) and denominators (military personnel deployed to Iraq). Monthly denominators were revealed in Hansard as a written answer on Feb 13, 2006 to Jeremy Corbyn, a Member of Parliament who had asked the Secretary of State for Defence what the total strength of UK forces in Iraq had been every month since May, 2003,8 which was the very question that I had posed to the Defence Analytical Services Agency (DASA) on Feb 6, 2006. DASA could not immediately provide me with monthly or quarterly numbers (to the nearest 100) of military personnel deployed to Iraq, because these data are not held electronically. However, subsequent press reports, which sought to put alleged abuse by UK soldiers in context suggested that, overall, some 80 000 military personnel had been deployed,9 with 8500 currently in Iraq. Time-consuming effort, I was told, would be entailed in backtracking to find relevant denominators from answers to parliamentary questions since March, 2003. DASA was willing to do this, but only after imminent national statistics deadlines had been met. Meanwhile, staff at the House of Commons Library pointed me to a website,10 which indicated that some 45 000 personnel had been deployed to Iraq initially, including amphibious, land, and air forces of some 4000, 26 000, and 7000 personnel, respectively (specified components totalled 37 000 personnel). Various adjustments to UK troop numbers have been announced since; for example, on May 27, 2004, and 713
Comment
Number of days
UK military deployed to Iraq
UK military fatalities (rate per 1000 person-years)
Mean military deployment* Inferred M values (95% CI)†
UK military fatality rate (per 1000 personnel-years [95% CI])
Actual numbers, Hansard (to nearest 50)
Mar 20 to May 1, 2003 (end of major combat) 43 45 000 33 (6·2)‡ .. 46 000 6·1 (4·0–8·2) May 2, 2003, to June 28, 2004 (sovereignty to Iraq) 424 M2‡ 27 18 700 (11 700–25 800) 10 150 2·3 (1·4–3·2) June 29, 2004, to Jan 30, 2005 (Iraqi elections) 216 M3‡ 25 34 000 (20 700–47 400) 9800 4·3 (2·6–6·0) Jan 31 to Dec 14, 2005 (Iraqi general election) 318 M4‡ 13 12 400 (6300–18 500) 9850 1·6 (0·8–2·3) Dec 15, 2005, to Feb 12, 2006 60 M5‡ 3 Total 1061 .. 101 .. .. .. *Includes the 15% of troops on Operation Telic who will be stationed outside Iraq and who support the operation from aboard ships, airfields, or other bases outside the country. †As per fatality rate after major combat of 6·2 divided by 5. ‡Initially unknown denominators.
Table: UK military deployment to Iraq and fatality rates per 1000 person-years, during specific periods
later, the first Battalion of the Royal Highland Fusiliers was deployed for a limited time to support security during the Iraqi election in January, 2005. The Iraq Coalition Casualty Count5 reports military fatalities in five periods, the first of which is the initial 43 days of major combat (March 20 to May 1, 2003, inclusive; the table shows UK military fatalities during these five periods up to Feb 12, 2006). Initially without the denominators M2 to M5 in the table, I turned statistical detective and presumed that the death rate of military personnel was substantially lower— by a factor of five, for example—after the end of major combat. I then inferred how many personnel, relative to an initially deployed 45 000, would have to have been in Iraq if the military death rate between May 2, 2003, and Feb 12, 2006, had been a fifth only of the rate during major combat. The extent to which inferred totals differed from actual totals would give a measure of period-specific risk increases after major combat ended. Period 3 stands out because it is unlikely that UK deployment at that time would have actually been two and a half times its typical level in 2005 (period 4)—Parliament and the press would surely have been aware. The table also includes M2 to M5 derived from the newly released monthly denominators, and therefore provides estimates of the UK’s period-specific military death rate per 1000 personnel deployed to Iraq. Fatality rates ranged from 6·1 during major combat (95% CI 4·0–8·2) to 1·6 (0·8–2·3) in the most recent period (both per 1000 personnel years). For comparison, the yearly death rate is 1 per 1000 men in the general population at age 20–39 years. However, military personnel are fitnessselected: for example, the mortality of 53 409 UK Gulf War 714
1 veterans (755 deaths up to Dec 31, 2005) is only 63% of the mortality that would be expected in a similar-sized cohort taken from the general population with the same age and sex profile.11 Thus the fatality rate of military personnel in Iraq after the end of major combat should probably be compared with an out-of-theatre fatality rate, which is between 0·4 and 0·6 per 1000 personnel-years. After major combat had ceased, the fatality rate was significantly higher for UK forces in period 3 (in the run-up to first elections in Iraq) than in periods 2 (p=0·05) or 4 and 5 (p=0·01). Indeed, during period 3, UK military deaths in Iraq were not significantly lower than the deaths during major combat itself, a fact that is now revealed for the first time. Deployment was not greatly increased during period 3—save for a changeover at the end of October, 2004 (ie, July, 9400; August, 9200; September, 9200; October, 11 200; November, 10 300; December, 9700; January, 9700). What made period 3 so fatally dangerous? Insurgents’ devastating use of more sophisticatedly triggered roadside bombs and shaped charges, which penetrated armoured vehicles more easily, may have contributed to the high fatality rate in period 3. The increased rate could also be indicated in a high ratio of unreported casualties to deaths. Thereafter, counter-measures could have been developed which improved hazard detection or preservation of UK lives. Alternatively, just one large air accident, could by itself account for a major increase in fatalities. Indeed, an RAF Hercules—which took off on Jan 30, 2005—was hit by ground-to-air fire and crashed in Iraq, killing ten UK servicemen.12 Their deaths would account for 40% of fatalities in period 3, and are sufficient to explain its excess mortality. www.thelancet.com Vol 367 March 4, 2006
Comment
The monitoring of UK casualty rates as well as fatality rates should give improved insight into the dangers faced by our forces in their defence of democracy for Iraq. Parliamentarians should therefore ensure that the Ministry of Defence puts in order its statistics on UK military casualties, as well as deaths, in Iraq—both retrospectively and prospectively—and that corresponding numerators and denominators are made available about the fates of UK personnel in Afghanistan. The least that we owe our soldiers is to care about their morbidity and mortality, and be seen to do so.
7
Sheila M Bird
8
MRC Biostatistics Unit, Cambridge CB2 2SR, UK [email protected]
9
SMB chaired the Royal Statistical Society’s Working Party on Performance Monitoring in the Public Services, and recently tendered her resignation from the Advisory Group on the use of National Statistics data for Medical Research. Her reasons were that scientific method, public interest, and public-health importance seemed not to be sufficiently weighed in the balance when considering “without consent” follow-up for morbidity and mortality. One
such example concerned military personnel. I thank Col Clive Fairweather, Edinburgh, UK, for giving military insight into this Comment. 1
2 3 4 5 6
10 11
12
Roberts L, Lafta R, Garfield R, Khudhairi J, Burnham G. Mortality before and after the 2003 invasion of Iraq: cluster sample survey. Lancet 2004; 364: 1857–64. Horton R. The war in Iraq: civilian casualties, political responsibilities. Lancet 2004; 364: 1831. Bird SM. Military and public-health sciences need to ally. Lancet 2004; 364: 1831–33. Chamberlain G. MOD accused of hiding real cost of Iraq war. Scotsman Jan 31, 2006: 1. Iraq Coalition Casualty Count. Military fatalities: by time period. http://icasualties.org (accessed Feb 6, 2006). Bird SM. Keeping a proper record of our war dead is the least we owe them. Scotsman Feb 4, 2006: 24. Royal Statistical Society working party on performance monitoring in the public services. Performance indicators: good, bad, and ugly. J R Stat Soc Series A 2005; 168: 1–27. House of Commons. Written answers. Hansard Feb 13, 2006: column 1584–85. Norton-Taylor N, Howard M, Jones S. Army’s image in Iraq under the spotlight. Guardian Feb 13, 2006: 3. Ministry of Defence. Operation Telic—British Forces. http://www. operations.mod.uk/telic/forces_archive2.htm (accessed Feb 10, 2006). Defence Analytical Services Agency (DASA). 1990/1991 Gulf conflict—UK Gulf veterans mortality data: causes of death. Jan 16, 2006. http://www. dasa.mod.uk/natstats/gulf/intro.html (accessed Feb 6, 2006). BBC news. RAF Hercules was shot down—Reid. Dec 8, 2005. http://news. bbc.co.uk/1/hi/uk_politics/4510324.stm (accessed Feb 15, 2006).
CO2 and trees: that sinking feeling Air travellers with an environmental conscience can seek to assuage their guilt by visiting the Climate Care website,1 entering their flight details, finding out how much carbon they have helped to release into the atmosphere, and then paying a financial penalty. The money goes to support various projects that help limit output of greenhouse gases, or sequester them in some less troublesome form. One of the options in this second carbon-sink category is tree planting. Although deforestation contributes to the rising level of atmospheric carbon dioxide (CO2), our understanding of the relation between trees, CO2, and climate change remains less than precise. Nothing shows this more dramatically than the claim that, under certain conditions, tree planting might even promote warming. This seemingly improbable claim was first mooted by Richard Betts, when he brought albedo into the equation.2 The amount of the sun’s heat absorbed by the earth’s surface depends on the earth’s albedo—its capacity to reflect radiant energy back into space. Regions of the planet covered by ice and snow have a high albedo. Although every extra tree locks up more carbon, what would happen if open land in northern latitudes were to be forested, particularly with conifers? Much of the snow www.thelancet.com Vol 367 March 4, 2006
on the trees would slide off and drop to the ground, leaving much of the forest canopy exposed. What had been a region of uniform white would now be mottled with darker patches. The overall albedo of the area would fall, and less heat would be reflected. Questions of location aside, environmental optimists have long hoped that all trees, whether newly planted or already established, will respond to extra atmospheric CO2 much as they do to fertiliser: by growing faster and, more to the point, larger. This would serve to mop up at least some of the extra CO2. So how to test this experimentally? One way is to grow trees under controlled conditions in a laboratory; but this hardly replicates the reality of nature. A more extravagant approach would be to enclose part of a real forest in a plastic bubble, and artificially manipulate the make-up of its atmosphere. But this too would be no more than an approximation of the real world. Back in the mid-1990s, researchers at Duke University devised a more ambitious experiment. FACE, the Free-Air CO2 Enrichment project,3 relies on raising the atmospheric level of the gas in a small region of open loblolly pine forest. 30-m diameter plots of trees have been surrounded by 16 towers, each releasing CO2 sufficient to maintain the air within the plot at a concentration 715
6 7
8
9
10
Moreno C, Gustot T, Nicaise C, et al. CCR5 deficiency exacerbates T-cell-mediated hepatitis in mice. Hepatology 2005; 42: 854–62. Gallant JE, Staszewski S, Pozniak AL, et al. Efficacy and safety of tenofovir DF vs stavudine in combination therapy in antiretroviral-naive patients: a 3-year randomized trial. JAMA 2004; 292: 191–201. European AIDS Treatment Group. Press release: European activists require regulatory agencies to halt unethical trial. April 11, 2005: http://www. eatg.org/modules.php?op=modload&name=News&file=article&sid=463&m ode=thread&order=0&thold=0 (accessed Nov 8 2005). Mocroft A, Ledergerber B, Viard JP, et al. Time to virological failure of 3 classes of antiretrovirals after initiation of highly active antiretroviral therapy: results from the EuroSIDA study group. J Infect Dis 2004; 190: 1947–56. Deeks SG. Treatment of antiretroviral-drug-resistant HIV-1 infection. Lancet 2003; 362: 2002–11.
11
12
13
14
15
Gulick RM, Ribaudo HJ, Shikuma CM, et al. Triple-nucleoside regimens versus efavirenz-containing regimens for the initial treatment of HIV-1 infection. N Engl J Med 2004; 350: 1850–61. Greaves W, Landovitz R, Fatkenheuer G, et al. Late virologic breakthrough in treatment naive patients on a regimen of Combivirvicriviroc. 13th Conference on Retroviruses and Opportunisitic Infections, Denver, Colorado, USA, Feb 5–8, 2006; 161LB (abstr). Spudich SS, Huang W, Nilsson AC, et al. HIV-1 chemokine coreceptor utilization in paired cerebrospinal fluid and plasma samples: a survey of subjects with viremia. J Infect Dis 2005; 191: 890–98. Wolinsky SM, Veazey RS, Kunstman KJ, et al. Effect of a CCR5 inhibitor on viral loads in macaques dual-infected with R5 and X4 primate immunodeficiency viruses. Virology 2004; 328: 19–29. Koot M, Keet IP, Vos AH, et al. Prognostic value of HIV-1 syncytium-inducing phenotype for rate of CD4 cell depletion and progression to AIDS. Ann Intern Med 1993; 118: 681–88.
UK statistical indifference to its military casualties in Iraq “The brave poor sodger ne’er despise, Nor count him as a stranger . . . Remember, he’s his country’s stay, In day and hour of danger.” When wild war’s deadly blast was blawn (Robert Burns)
Neither the UK nor US Governments properly counted, or even seriously sought to count, civilian casualties in Iraq.1–3 In January, The Scotsman4 exposed the Ministry of Defence’s failure properly to count UK military casualties in Iraq. By contrast, US military casualties, as well as fatalities, are accounted for.5 First, what can we learn from the US casualty data? The reported ratio of US military casualties to deaths in Iraq5 was 2409 to 486 in 2003 (ie, 5:1), but it was much higher in 2004 at 7989 to 848 (9:1) and in 2005 at 5939 to 846 (7:1). Other things being equal, the UK—which had 53 military deaths in Iraq in 2003, 22 in 2004, and 23 in 2005—could thus have sustained over 600 military casualties (estimated at 263207161, based on the reported US ratios). This calculation might not be apposite for three reasons: because UK and US forces have different areas of operation in Iraq, because US troops have a significantly higher proportion of deaths from hostile fire (1767/2252 [78·5%] up to Feb 3, 2006) than do other coalition forces (147/204 [72%], p=0·05),5 and because no account has been taken of statistical uncertainty. Nevertheless, the US data clearly signal that the ratio of casualties to fatalities might not be constant over time, which means that both values should be reported. Second, because casualties are five to nine times more numerous than fatalities, the monitoring of casualties on a quarterly basis has at least as much statistical power as the monitoring of fatalities on a yearly basis. www.thelancet.com Vol 367 March 4, 2006
Against such statistical imperatives for improved accountability, who or what thwarts the UK’s competent compilation and dissemination of statistics by which to monitor death rates and casualty rates for UK military personnel deployed to Iraq?6,7 The calculation of such rates needs period-specific numerators (fatalities, casualties) and denominators (military personnel deployed to Iraq). Monthly denominators were revealed in Hansard as a written answer on Feb 13, 2006 to Jeremy Corbyn, a Member of Parliament who had asked the Secretary of State for Defence what the total strength of UK forces in Iraq had been every month since May, 2003,8 which was the very question that I had posed to the Defence Analytical Services Agency (DASA) on Feb 6, 2006. DASA could not immediately provide me with monthly or quarterly numbers (to the nearest 100) of military personnel deployed to Iraq, because these data are not held electronically. However, subsequent press reports, which sought to put alleged abuse by UK soldiers in context suggested that, overall, some 80 000 military personnel had been deployed,9 with 8500 currently in Iraq. Time-consuming effort, I was told, would be entailed in backtracking to find relevant denominators from answers to parliamentary questions since March, 2003. DASA was willing to do this, but only after imminent national statistics deadlines had been met. Meanwhile, staff at the House of Commons Library pointed me to a website,10 which indicated that some 45 000 personnel had been deployed to Iraq initially, including amphibious, land, and air forces of some 4000, 26 000, and 7000 personnel, respectively (specified components totalled 37 000 personnel). Various adjustments to UK troop numbers have been announced since; for example, on May 27, 2004, and 713
Comment
Number of days
UK military deployed to Iraq
UK military fatalities (rate per 1000 person-years)
Mean military deployment* Inferred M values (95% CI)†
UK military fatality rate (per 1000 personnel-years [95% CI])
Actual numbers, Hansard (to nearest 50)
Mar 20 to May 1, 2003 (end of major combat) 43 45 000 33 (6·2)‡ .. 46 000 6·1 (4·0–8·2) May 2, 2003, to June 28, 2004 (sovereignty to Iraq) 424 M2‡ 27 18 700 (11 700–25 800) 10 150 2·3 (1·4–3·2) June 29, 2004, to Jan 30, 2005 (Iraqi elections) 216 M3‡ 25 34 000 (20 700–47 400) 9800 4·3 (2·6–6·0) Jan 31 to Dec 14, 2005 (Iraqi general election) 318 M4‡ 13 12 400 (6300–18 500) 9850 1·6 (0·8–2·3) Dec 15, 2005, to Feb 12, 2006 60 M5‡ 3 Total 1061 .. 101 .. .. .. *Includes the 15% of troops on Operation Telic who will be stationed outside Iraq and who support the operation from aboard ships, airfields, or other bases outside the country. †As per fatality rate after major combat of 6·2 divided by 5. ‡Initially unknown denominators.
Table: UK military deployment to Iraq and fatality rates per 1000 person-years, during specific periods
later, the first Battalion of the Royal Highland Fusiliers was deployed for a limited time to support security during the Iraqi election in January, 2005. The Iraq Coalition Casualty Count5 reports military fatalities in five periods, the first of which is the initial 43 days of major combat (March 20 to May 1, 2003, inclusive; the table shows UK military fatalities during these five periods up to Feb 12, 2006). Initially without the denominators M2 to M5 in the table, I turned statistical detective and presumed that the death rate of military personnel was substantially lower— by a factor of five, for example—after the end of major combat. I then inferred how many personnel, relative to an initially deployed 45 000, would have to have been in Iraq if the military death rate between May 2, 2003, and Feb 12, 2006, had been a fifth only of the rate during major combat. The extent to which inferred totals differed from actual totals would give a measure of period-specific risk increases after major combat ended. Period 3 stands out because it is unlikely that UK deployment at that time would have actually been two and a half times its typical level in 2005 (period 4)—Parliament and the press would surely have been aware. The table also includes M2 to M5 derived from the newly released monthly denominators, and therefore provides estimates of the UK’s period-specific military death rate per 1000 personnel deployed to Iraq. Fatality rates ranged from 6·1 during major combat (95% CI 4·0–8·2) to 1·6 (0·8–2·3) in the most recent period (both per 1000 personnel years). For comparison, the yearly death rate is 1 per 1000 men in the general population at age 20–39 years. However, military personnel are fitnessselected: for example, the mortality of 53 409 UK Gulf War 714
1 veterans (755 deaths up to Dec 31, 2005) is only 63% of the mortality that would be expected in a similar-sized cohort taken from the general population with the same age and sex profile.11 Thus the fatality rate of military personnel in Iraq after the end of major combat should probably be compared with an out-of-theatre fatality rate, which is between 0·4 and 0·6 per 1000 personnel-years. After major combat had ceased, the fatality rate was significantly higher for UK forces in period 3 (in the run-up to first elections in Iraq) than in periods 2 (p=0·05) or 4 and 5 (p=0·01). Indeed, during period 3, UK military deaths in Iraq were not significantly lower than the deaths during major combat itself, a fact that is now revealed for the first time. Deployment was not greatly increased during period 3—save for a changeover at the end of October, 2004 (ie, July, 9400; August, 9200; September, 9200; October, 11 200; November, 10 300; December, 9700; January, 9700). What made period 3 so fatally dangerous? Insurgents’ devastating use of more sophisticatedly triggered roadside bombs and shaped charges, which penetrated armoured vehicles more easily, may have contributed to the high fatality rate in period 3. The increased rate could also be indicated in a high ratio of unreported casualties to deaths. Thereafter, counter-measures could have been developed which improved hazard detection or preservation of UK lives. Alternatively, just one large air accident, could by itself account for a major increase in fatalities. Indeed, an RAF Hercules—which took off on Jan 30, 2005—was hit by ground-to-air fire and crashed in Iraq, killing ten UK servicemen.12 Their deaths would account for 40% of fatalities in period 3, and are sufficient to explain its excess mortality. www.thelancet.com Vol 367 March 4, 2006
Comment
The monitoring of UK casualty rates as well as fatality rates should give improved insight into the dangers faced by our forces in their defence of democracy for Iraq. Parliamentarians should therefore ensure that the Ministry of Defence puts in order its statistics on UK military casualties, as well as deaths, in Iraq—both retrospectively and prospectively—and that corresponding numerators and denominators are made available about the fates of UK personnel in Afghanistan. The least that we owe our soldiers is to care about their morbidity and mortality, and be seen to do so.
7
Sheila M Bird
8
MRC Biostatistics Unit, Cambridge CB2 2SR, UK [email protected]
9
SMB chaired the Royal Statistical Society’s Working Party on Performance Monitoring in the Public Services, and recently tendered her resignation from the Advisory Group on the use of National Statistics data for Medical Research. Her reasons were that scientific method, public interest, and public-health importance seemed not to be sufficiently weighed in the balance when considering “without consent” follow-up for morbidity and mortality. One
such example concerned military personnel. I thank Col Clive Fairweather, Edinburgh, UK, for giving military insight into this Comment. 1
2 3 4 5 6
10 11
12
Roberts L, Lafta R, Garfield R, Khudhairi J, Burnham G. Mortality before and after the 2003 invasion of Iraq: cluster sample survey. Lancet 2004; 364: 1857–64. Horton R. The war in Iraq: civilian casualties, political responsibilities. Lancet 2004; 364: 1831. Bird SM. Military and public-health sciences need to ally. Lancet 2004; 364: 1831–33. Chamberlain G. MOD accused of hiding real cost of Iraq war. Scotsman Jan 31, 2006: 1. Iraq Coalition Casualty Count. Military fatalities: by time period. http://icasualties.org (accessed Feb 6, 2006). Bird SM. Keeping a proper record of our war dead is the least we owe them. Scotsman Feb 4, 2006: 24. Royal Statistical Society working party on performance monitoring in the public services. Performance indicators: good, bad, and ugly. J R Stat Soc Series A 2005; 168: 1–27. House of Commons. Written answers. Hansard Feb 13, 2006: column 1584–85. Norton-Taylor N, Howard M, Jones S. Army’s image in Iraq under the spotlight. Guardian Feb 13, 2006: 3. Ministry of Defence. Operation Telic—British Forces. http://www. operations.mod.uk/telic/forces_archive2.htm (accessed Feb 10, 2006). Defence Analytical Services Agency (DASA). 1990/1991 Gulf conflict—UK Gulf veterans mortality data: causes of death. Jan 16, 2006. http://www. dasa.mod.uk/natstats/gulf/intro.html (accessed Feb 6, 2006). BBC news. RAF Hercules was shot down—Reid. Dec 8, 2005. http://news. bbc.co.uk/1/hi/uk_politics/4510324.stm (accessed Feb 15, 2006).
CO2 and trees: that sinking feeling Air travellers with an environmental conscience can seek to assuage their guilt by visiting the Climate Care website,1 entering their flight details, finding out how much carbon they have helped to release into the atmosphere, and then paying a financial penalty. The money goes to support various projects that help limit output of greenhouse gases, or sequester them in some less troublesome form. One of the options in this second carbon-sink category is tree planting. Although deforestation contributes to the rising level of atmospheric carbon dioxide (CO2), our understanding of the relation between trees, CO2, and climate change remains less than precise. Nothing shows this more dramatically than the claim that, under certain conditions, tree planting might even promote warming. This seemingly improbable claim was first mooted by Richard Betts, when he brought albedo into the equation.2 The amount of the sun’s heat absorbed by the earth’s surface depends on the earth’s albedo—its capacity to reflect radiant energy back into space. Regions of the planet covered by ice and snow have a high albedo. Although every extra tree locks up more carbon, what would happen if open land in northern latitudes were to be forested, particularly with conifers? Much of the snow www.thelancet.com Vol 367 March 4, 2006
on the trees would slide off and drop to the ground, leaving much of the forest canopy exposed. What had been a region of uniform white would now be mottled with darker patches. The overall albedo of the area would fall, and less heat would be reflected. Questions of location aside, environmental optimists have long hoped that all trees, whether newly planted or already established, will respond to extra atmospheric CO2 much as they do to fertiliser: by growing faster and, more to the point, larger. This would serve to mop up at least some of the extra CO2. So how to test this experimentally? One way is to grow trees under controlled conditions in a laboratory; but this hardly replicates the reality of nature. A more extravagant approach would be to enclose part of a real forest in a plastic bubble, and artificially manipulate the make-up of its atmosphere. But this too would be no more than an approximation of the real world. Back in the mid-1990s, researchers at Duke University devised a more ambitious experiment. FACE, the Free-Air CO2 Enrichment project,3 relies on raising the atmospheric level of the gas in a small region of open loblolly pine forest. 30-m diameter plots of trees have been surrounded by 16 towers, each releasing CO2 sufficient to maintain the air within the plot at a concentration 715