There have been many ice ages in the history of the Earth; but the last, which covered vast tracks of the Northern Hemisphere, came to an end some nine to ten thousand years ago – when the temperature (and sea level) rose. It has always been assumed that no trees survived in the regions covered by the thick ice sheet, and that trees (like other plants) have returned to areas like Scandinavia by the gradual northern migration of species that had taken ‘sanctuary’ in warmer latitudes.
Throughout the twentieth century, stations like that at Manua Loa have monitored the level of carbon dioxide in the air. It is clear that atmospheric concentrations of carbon dioxide have risen from about from about 300 ppm in the 1960’s to nearly 400 ppm by 2010.
However, if we look back some 480 million years (to the Ordivician Period) the level of carbon dioxide was some sixteen times higher than the present level and the average global temperature was about 25 oC, that is, about 10 oC higher than today’s average. So how and why has global temperature fallen ? Read more...
Butterfly Conservation UK and the Centre for Ecology and Hydrology have been involved in the monitoring the status of butterflies through various citizen science schemes*. UK butterflies (and indeed, birds) are probably the best-studied wildlife groups thanks to the dedication of an enormous workforce of highly skilled and committed volunteer recorders. Butterflies and birds have been observed and recorded in detail for many, many years and these detailed records and counts yield an invaluable resource of information for the analysis of population change(s).
We have experienced an extended and warm autumn, and now true to Pliny's words -
"A fair and dry autumn brings in always a windy winter" - winter weather has now firmly settled upon us. The temperature is down to "more representative" seasonal values for December, and cold, high winds have recently lashed Scotland and other parts of the U.K.
The warmest Autumn (for some 300 + years) was in 2006, when the temperature was some 2.4 / 3 oC above the seasonal average ; places like Kinlochewe recording a daytime temperature of 22.5 oC. The recent mild weather * was due to an unusual pattern of high altitude winds over the Continent. The course of the jet stream meant that there were southerly winds and relatively settled conditions over the United Kingdom.
The trend in the weather since the 1980’s has been for a general increase in temperature. Perhaps, in consequence, new species of dragonfly and damselfly have arrived in Britain from the warmer climates of Southern Europe.
The following species have been recorded to date
- the Willow Emerald
- the Southern Migrant Hawker
- the Southern Emerald Damselfly
- the Vagrant Emperor
- the Small red-eyed Damselfly and
- the Dainty Damselfly.
Books often describe our climate as being ‘mild for the latitude’. It might be difficult to believe this given the actual weather over these last few weeks. Newfoundland is similar in latitude to the British Isles, but the average temperature is some 10oC colder in winter. We are the beneficiaries of the warming effect of the North Atlantic Drift – a current that develops in the Gulf of Mexico and then flows north-east across the Atlantic. It is a part or continuation of the Gulf Stream but we are also at the mercy of the jet stream. Read more...
Generally speaking, the sight of butterflies marks the return of spring sunshine and the warmth associated with long summer days. However, after three wet summers in a row, some of our rarest butterflies are under threat. The summers of 2007 and 2008 were characterised by very wet weather, and July and August last year were marked by above average rainfall. Butterflies that have been particularly affected by the wet weather are the :- Read more...
It will not be long before the signs of autumn are apparent to all of us, especially after such a hot and dry summer. Once again the BBC, the Woodland Trust and the UK Phenology Network are inviting people to help chart the advance of autumn – by recording 6 key species – blackberry, hawthorn, swifts, conkers, ivy and oak.
The collated information will help the UK Phenology Network build up a picture of Read more...