Climate change is probably the most widely discussed global environmental issue of our day. When I carried out a small survey for a project with my friend and asked people on the street to list the global environmental issues they are aware of, nearly everyone mentioned climate change on the first place and only a few noted pollution, biodiversity loss, deforestation or any other issues. Things are no different in the media: if one looks at Richard Black’s Environment blog on BBC, they will find that a great proportion of entries are on climate change and less attention is payed to other environmental problems. Therefore I will start the blog by discussing the biological effect of climate change.
In 2006 the Annual Review of Ecology Evolution and Systematics published Camille Parmesans outstanding review on ‘Ecological and Evolutionary Responses to Recent Climate Change’. The paper outlines the possible species level responses to climate change: species either shift their range, evolve, or go extinct. I discuss range shift below, and the rest of possible responses will be explored in tomorrow's post.
Range shifts
As the climate warms, species are expected to move to colder ares, that is shift their ranges either polewards, or to higher altitudes. However, not all species are capable of doing so: many either encounter geographic boundaries, or have very limited dispersal ability which makes them extremely vulnerable to climate change.
Many cases of range shifts have been documented in both marine and terrestrial ecosystems and in all major taxonomic groups. In polar ecosystems, these shifts occur mostly in response to changes in sea-ice extent: in the Antarctic, open-ocean feeding penguins invades southwards to occupy previously ice-covered areas, whereas sea ice dependent birds such as the emperor penguins have disappeared from their northernmost territories. Things are no different in the Arctic: some species, such as plants benefit from warming conditions and expand their ranges into the tundra, whereas others like polar bears whose ranges contracted significantly on both southern and northern boundaries, suffer the consequences of melting ice.
The Polar bear and the emperor penguins: two iconic species from the Arctic and the Antarctic respectively, which are seriously suffering the consequences of climate change and melting sea ice.
Amongst temperate and tropical species, birds, butterflies and other insects provide some of the neatest example of poleward shift: tropical butterflies invade northwards to Florida and the Mediterranean, whereas their temperate relatives were documented to shift their ranges as much as 420 miles northwards in just 35 years in USA and Europe.
The sooty copper ( Heodes tityrus ), an European butterfly species which shifted its southern range boundary 50 km northwards in Spain. Source: http://www.guypadfield.com/sootycopper.html
Amongst temperate and tropical species, birds, butterflies and other insects provide some of the neatest example of poleward shift: tropical butterflies invade northwards to Florida and the Mediterranean, whereas their temperate relatives were documented to shift their ranges as much as 420 miles northwards in just 35 years in USA and Europe.
Species may well move upwards as well in response to warming, which is often neatly demonstrated by upward shift of the tree line. It must be noted however, that response of tree line is somewhat more complex, since it is determined by both change in temperature and participation patterns. The problem with upward shift is that there is a danger of running out of space: from the very top of the mountain no further upward shift is possible, and the way back down is of course blocked by warmth. This phenomenon accounted for the extinction of populations of the cool adapted butterfly Parnasius apollo in southern is only one of the numerous examples.
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