How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Global Warming and Tick-Borne Encephalitis
Randolph, S.E. and Rogers, D.J.  2000.  Fragile transmission cycles of tick-borne encephalitis virus may be disrupted by predicted climate change.  Proceedings of the Royal Society of London Series B 267: 1741-1744.

Tick-borne encephalitis (TBE), according to Randolph and Rogers, "is the most significant vector-borne disease in Europe and Eurasia," with "a case morbidity rate of 10-30% and a case mortality rate of typically 1-2% but as high as 24% in the Far East."  The flavivirus (TBEV) that causes TBE is maintained in natural rodent-tick cycles; and humans may be infected if bitten by an infected tick or by drinking untreated milk from infected sheep or goats.

Early writings on the relationship of this disease to global warming predicted that TBE - like so many other vector-born diseases - would expand its range and become more of a threat to humans in a warmer world.  However, Randolph and Rogers draw our attention to the fact that "like many vector-borne pathogen cycles that depend on the interaction of so many biotic agents with each other and with their abiotic environment, enzootic cycles of TBEV have an inherent fragility," so that "their continuing survival or expansion cannot be predicted from simple univariate correlations," as, we might add, is commonly done by climate alarmists intent on scaring people into reducing CO2 emissions on the basis of false premises.  Hence, the two researchers decided to explore the subject in significantly greater detail than had ever been done before.

What was done
Confining their analysis to Europe, the authors first matched the present-day distribution of TBEV to the present-day distribution of five climatic variables: average monthly mean, maximum and minimum temperatures, plus rainfall and saturation vapor pressure, "to provide a multivariate description of present-day areas of disease risk."  They then applied this understanding to outputs of a general circulation model of the atmosphere that predicted how these five climatic variables may change in the future.

What was learned
It was determined that the distribution of TBEV may expand both north and west of Stockholm, Sweden in a warming world.  Elsewhere, however, the authors say that "fears for increased extent of risk from TBEV caused by global climate change appear to be unfounded."  In fact, they note that "the precise conditions required for enzootic cycles of TBEV are predicted to be disrupted" in response to global warming, while the new climatic state "appears to be lethal for TBEV."

What it means
This analysis, in the words of the authors, "gives the lie to the common perception that a warmer world will necessarily be a world under greater threat from vector-borne diseases."  In the case of TBEV, in fact, they note that the predicted change "appears to be to our advantage."

Reviewed 31 July 2002