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increased insolation. In the same way as land cover change enhanced the greening of the
Sahara in North Africa, the studies from the arctic regions show a feedback between changing
insolation and land cover, which magnified the warming that was already initiated by orbital
effects (Wohlfahrt et al. 2004, Gallimore et al. 2005, Braconnot et al. 2006, 2007).
In the 'greenhouse climate' of 2100, the models suggest even larger changes to Arctic
biomes than those that occurred in the mid-Holocene, because raised CO 2 is expected to
cause a year-round warming, whereas the effects of orbital forcing were mainly concentrated
in the northern hemisphere summer. This would move the tree line even further north, with
more reduction in tundra (Bigelow 2003, Kaplan et al. 2003). There is already evidence for the
widespread, northward advance of boreal forests into tundra in Alaska, north-west Canada,
and the polar Urals (MacDonald et al. 1998, Chapin et al. 2004, Lloyd 2005). However, future
responses of boreal forest to climate change may be complex because of regional variations in
climatic warming, as well as differences in resilience, which depends on substrate, water bal-
ance, topography, and permafrost, as well as interactions with fire (Oswald et al. 2003, Lloyd
2005, Lloyd and Bunn 2007, Williams and Jackson 2007, Payette et al. 2008, Tinner et al. 2008).
In addition, it is not clear how much the release of carbon from melting permafrost will be
offset by uptake from expanding forest cover (Lloyd and Bunn 2007). Recent simulations sug-
gest that as the forest-tundra boundary advances poleward, there will be an expansion of tall
shrub tundra and a shift from deciduous to boreal forest over northern Eurasia (Zhang et al.
2013). While longer growing seasons and CO 2 fertilization will enhance carbon sequestration
over the coming decades, it is likely that the net effect will be carbon emission, due to changes
in snow-season albedo, increased soil respiration, and wildfire disturbances by the end of the
twenty-first century (Zhang et al. 2013).
Studying distribution changes during past warm periods like the MHA can help to identify
vulnerable species, such as those with narrow climatic tolerances and poor dispersal abili-
ties, thereby helping to improve the prediction of changes in the distribution of plants at the
levels of species, communities, and ecotones. This information can help in the design of
reserve configurations and networks that conserve genetic diversity, evolutionary potential,
connectivity, and future climate space (Hannah et al. 2007, Sgrò et al. 2011, Weeks et al. 2011,
Seddon et al. 2014).
Planning reserve configurations and networks that accommodate future
climate space
Protecting the climate space and habitat of species that are sensitive to climate change, con-
figuring reserves with a range of microclimates, and providing connected networks of all rep-
resentative habitats, are all essential elements of conservation in a changing climate. Current
strategic conservation planning includes representivity of future as well as present distribu-
tions, and aims to enhance evolutionary potential and resilience through conservation
of genetic diversity and connectivity (Hannah et  al. 2007, Dawson et  al. 2011, Gillson et  al.
2013). There is vast potential to incorporate palaeo-information into regional conservation
planning tools that maximize adaptive capacity, conserve genetic diversity, and develop
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