Towards a Baltic Sea Region Strategy in Critical ... - Helsinki.fi

CHAPTER VI: WATER
strategies. The awareness that adaptation strategies evolve from regional
experience and that their integration is better feasible and judge able at the
regional rather than at the global level, was a further motivation for ASTRA. Much
the same subject matter was discussed in the FINADAPT-project (Silander et al.
2006). The results of these previous projects are here applied on a new case study
area, including a wider scope, i.e. risks.
Concerning the associated hazards of climate change, the major endeavour
for humankind is to provide safe limits for both nature and humanity. The global
population and economy will grow further. Most energy and industrial production,
as well as transportation, will rely on fossil fuels also in the near future, and
climate change scenarios indicate an increase in the average global temperature of
up to 6.4 °C by 2100 (IPCC 2007). Therefore regional consequences, in particular
with respect to future planning strategies, must be evaluated carefully.
Climate change in the BSR
The SEAREG project developed three scenarios ranging from ‘low case’ to ‘high
case’ for winter mean sea surface height for 2071-2100 using a reference data from
1961-1990. In the Hanko area, the low case scenario indicates a drop of the 1990
sea level by -35 cm, the ensemble average scenario 15 cm and the high case
scenario of 64 cm sea level rise, respectively (Meier et al. 2004 and Meier et al.
2006). Although mean annual sea surface height is an important figure, storm
surges pose a greater acute risk in the Baltic Sea Region (BSR). For example, the
westerly winds of 9 January 2005 caused the sea level to rise 151 cm in Helsinki
and 130 cm in Hanko. The storm surges that push the water masses towards the
south coast of Finland are reckoned to become more common in late 21st century
(Marttila et al. 2005).
Scenario simulations have shown that for the BSR some serious
consequences of climate change can be anticipated by 2100. This holds for
warming and changes in precipitation patterns, as well as for sea-level increases.
Recent state of the art knowledge implies that effects like temperature increase and
sea-level rise have been underestimated over recent decades. If the prognosis of
the IPCC (2007) comes true, and if humankind does not take appropriate action to
reduce atmospheric carbon dioxide concentration radically, this would lead to the
warmest period on Earth in 1,000 years, and probably even the last 100,000 years.
This large-scale warming is expected to be accompanied by increased frequency
and/or intensity of extreme events, such as heat waves, heavy rainfall, storms and
coastal flooding. Model results and examination of measured data in several
regions show that there might be strong variations in precipitation patterns.
Changes in temperature extremes have already been observed, for example during
the summer of 2003, with maximum heat record of 33.3 °C in the Mietoinen
province, southwestern Finland. Model outputs show changes in extreme events
for future climates, including increases in extreme high temperatures, decreases in
extreme low temperatures, and increases in intense precipitation events.
An important threat for BSR is the rise in sea level. Although the SEAREG
project has already attempted to estimate future risks, new results imply that the
rise in sea level is accelerating. For example, neither the rapid melting of the
Greenland glaciers over the last 20 years, nor the measured and simulated gauge
levels, was considered adequately. Also, it is highly likely that an increase in
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