Review

Climate change, dermatology and ecosystem services; trends

and trade-offs

Scott A. Muller, BSE

Director, CODESTA, Panama, Republic

of Panama

Correspondence

Scott A. Muller, BSE

Aptdo. 0843-00372

Republic of Panama

E-mail: s.muller@mac.com

Abstract

Climate change is one of the defining issues for human well-being in the 21st century.

As several dermatological diseases have a high sensitivity to climate and ecologic

change, dermatologists will have an increasingly important role in public health affairs.

The International Society of Dermatology’s (ISD) establishment of a task force to track

the impact of climate change on the incidence of dermatologic conditions is an example

of scientific monitoring critical to future interdisciplinary adaptation and decision making to

improve human well-being.

Climate change

At continental, regional, and ocean basin scales, severallong-term changes in climate have been documented.These include significant changes in polar ice, tropicalglaciers, widespread changes in precipitation, ocean pHand salinity, and wind patterns as well as extremeweather events, including droughts, heavy precipitation,heat waves, and the intensity of tropical cyclones.1 Thedecade 2000–2009 is the warmest recorded, and compar-ing this anomaly with that of the average of 1951–1980shows dramatic increases (Fig. 1). In 2009, the largestand most studied tropical glacier in the world wasrecorded retreating at a rate of 46 cm/d.2

The Keeling curve (named after Dr. Charles DavidKeeling of the Scripps Institution of Oceanography)

shows the climbing measurements of atmospheric CO2

measured continuously since 1958.4 The June 7, 2010measurement was 392.3 p.p.m. (Fig. 2).

Ice is an excellent recorder of environmental history.Reconstructions from tropical and polar ice cores allowthe technical analysis of atmospheric CO2 concentrationsto be put into an 800,000 year historical context. Thisanalysis shows that during ice ages, CO2 levels wereabout 200 p.p.m. and during the warmer interglacial peri-ods near 280 p.p.m. (Fig. 3).

With modern isotope ratio mass spectrometers,researchers are able to separate out the different isotopesof carbon in atmospheric CO2. Because plants prefer 12C,the CO2 from fossil fuels is depleted in 13C relative to12C when compared with CO2 that comes from othersources (breathing, volcanoes, ocean, etc.). Isotopic ratios

504 Figure 1 This map shows the 10 year average (2000–2009) temperature anomaly relative to the 1951–1980 mean3

International Journal of Dermatology 2011, 50, 504–507 ª 2011 The International Society of Dermatology

of 13C/12C in CO2 allow researchers to distinguishanthropogenic CO2 from natural baseline CO2.7,8

Increasing CO2 concentrations can be directly tied to thewidespread burning of fossil fuels starting in the indus-trial revolution. The changing ratio of carbon-13 to car-bon-12 in the atmosphere is a signature of anthropogenicglobal warming.

Biological adaptations

While glaciers have advanced and retreated several timesover the past millions of years, these climate forcings wererelatively gradual. Well established in species’ genetic codeis the ability to adapt to changes in their environment.Biological diversity can be considered the ‘‘criticalresource of an adaptive system.’’9 Also, without 6.9 billion

people on the planet, species could migrate with relativeease in response to changing climate patterns.

Comparatively, the current changes in climate andatmospheric CO2 concentrations are extremely abrupt.When the stresses on biological systems are so dramati-cally increased, the ability to adapt to changes is exceededand results in mass extinctions.

The 3rd United Nations Global Biodiversity Outlookestimates the current pace of biological extinctions at1000 times faster than historical rates.10 The reportwarns, ‘‘the world’s ecosystems are at risk of rapid degra-dation and collapse.’’

In fact, the last mass extinction near the current levelof species loss was the Cretaceous Tertiary extinction, 63million years ago.11 This was precipitated with an abruptchange in atmospheric gas concentrations and climatewhen a meteor struck the earth. This caused the extinc-tion of non-avian dinosaurs and allowed for the prolifera-tion of mammals.

Between 1970 and 2006 the total population of verte-brate species on earth fell by 31%.10 Since the year 2000,60 breeds of livestock have become extinct.10 Today,48% of the world’s 634 primate species are classified asthreatened with extinction.12 The 2009 IUCN Red List ofspecies under threat of extinction, includes 21% of allknown mammals, 30% of known amphibians, 12% ofknown birds, 28% of reptiles, 37% of freshwater fishes,70% of plants, and 35% of invertebrates assessed. (http://www.iucnredlist.org/documents/summarystatistics/2010_1RL_Stats_Table_1.pdf)

Ecosystem services

Completed in 2005, the Millennium Ecosystem Assess-ment (MA) is a 4-year international scientific assessmentof the consequences of ecosystem change for human well-being.13 The MA defined ecosystem services as simply thebenefits obtained by people from ecosystems. They areproduced by interactions within the ecosystem. Theyinclude:• provisioning services; such as food, clean water, timber,

fiber, and genetic resources;• regulating services; such as the regulation of climate,

disease, floods, water quality, and pollination;• cultural services; such as recreational, aesthetic, and

spiritual benefits;• supporting services; such as soil formation and nutrient

cycling.The comprehensive, scientific analysis by more than

1360 experts worldwide revealed that humans havealtered ecosystems more rapidly and extensively inthe past 50 years than in any comparable period in his-tory. Indeed global economic activity increased nearly

Figure 2 Monthly average carbon dioxide concentration,Mauna Loa Observatory, Hawaii5

Figure 3 Variation in atmospheric carbon dioxideconcentrations6

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sevenfold between 1950 and 2000.14 However, whilethese changes in ecosystems contributed to net gains inhuman well-being and economic development, the MAconcludes that they have come at a growing cost and ifnot altered will substantially diminish the benefits futuregenerations will obtain from ecosystems.

The MA discovered that 60% of the ecosystem servicesexamined were being used unsustainably, including 70%of provisioning and regulating services. The MA also con-cluded that the harmful consequences of ecosystem changewould increase during the first half of this century.13

An assessment by the World Health Organization, tak-ing into account only a subset of the possible healthimpacts from climate change, concluded that the moder-ate warming that has occurred since the 1970s wasalready causing over 140,000 excess deaths annually bythe year 2004.15

The changes being made to ecosystems increase theprobability of potentially high-impact and abrupt changesin biological systems. This includes disease emergence, aswell as dead zones in water bodies and fishery collapses.The increased likelihood of sudden, nonlinear changecomes from the interaction of a variety of factors, includ-ing climate change, the loss of biodiversity, increasednumbers of invasive alien species, overharvesting, andnutrient loading. Comprehension of nonlinear change isimproving, but for most ecosystems and their services,science cannot yet determine tipping points and thresh-olds where nonlinear change will occur.

Disease emergence

Changes in climate can alter the transmission seasons ofimportant dermatological vector-borne diseases andexpand their geographic range. For example, climatechange is expected to significantly widen the area ofChina where schistosomiasis occurs.16 Other dermatologi-cal diseases that react to climate and ecologic changesinclude: filariasis and onchocerciasis in cultivated andinland water systems in the tropics; leishmaniasis andChagas disease in forest and dry land systems; and WestNile virus and Lyme disease in urban and suburban sys-tems of Europe and North America.

Cryptococcal disease was thought to be an exclusivelytropical disease. Before 1999, human cases were limitedto Australia and other tropical and subtropical regions.However, during January 1, 2004–July 2010, a total of60 people with Cryptococcus gattii infection in the PacificNorthwest of the USA had been reported to the US Cen-ter for Disease Control (CDC), prompting them to issuean alert for patients showing signs of a cryptococcalinfection17 (Fig. 4). Some health experts believe that cli-mate change is partially to blame and that the emergence

fits with the redistribution of infectious diseases predictedby various climate models. The CDC report noted thatepidemiologists have ruled out increased disease aware-ness and improved reporting, but emphasized that otherfactors apart from climate change could affect the dis-ease’s spread; such as adaptation to a new climate nicheby C. gattii or that environmental conditions favorable tothe fungus might be broader than previously observed.More research is needed in these emergent trends tounderstand potential impacts.

Monitoring and decision making

Thanks to tracking by the ISD Climate Change TaskForce, dermatology will play an increasingly importantrole as an indirect generator of change, utilizing dermato-logic sciences to monitor disease trends, impacts, andcosts. This will not only improve patient care but it willalso strengthen the ability of public officials and decisionmakers to manage the increasing and unevenly distributedburdens of climate change.

A good example of emergent disease monitoring toimprove decision making is the recent study in theAmazon by scientists from the University of Wisconsin-Madison, linking an increased incidence of malaria toland-use practices.18

Malaria infected an estimated 500,000 Brazilians annu-ally across the Amazon basin from 1997 to 2006. Usingcross-cutting technologies to combine detailed informa-tion on the incidence of malaria in 54 Brazilian healthdistricts and high-resolution satellite imagery of the extentof logging in the Amazon forest, researchers were able todetermine that a 4% change in forest cover was associ-ated with a 48% increase in malaria incidence in theseareas. Now the government comprehends how land

Figure 4 Cases of Cryptococcus gatti infection (n = 51) withknown illness onset date, by quarter – California, Idaho,Oregon and Washington, 2004–201017 (Cryptococcus gattii

Public Health Working Group)

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management is a useful and cost-effective intervention toreduce malaria risk factors. They are better informed tomake their trade-off decisions.

In the very difficult decisions that our society will makein the coming 40 years, there will be many trade-offs.With cross-cutting research and a risk-based approach,dermatologists indeed have an increasingly importantcontribution to make towards our collective futures.

References

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