If we compare the climates on the opposite coasts of the Northern Atlantic, we find a remarkable difference in favour of the Old World. The frozen regions of Labrador, lie under the same degree of latitude as Plymouth, where the myrtle and laurel remain perpetually verdant in the open air. In New York, which has a more southern situation than Rome, the winter is colder than at Bergen in Norway, which lies 20° farther to the north. While on the northern coasts of the old continent, the waters remain open a great part of the year, even beyond the latitude of 80°, the ice never completely thaws on the opposite shores of Greenland. What a contrast between the Feroë islands, where the harbours are never frozen, where fertile meadows afford pasturage to numerous flocks of sheep, and even crops of barley reward the labours of the husbandman, and the frightful wildernesses on the shores of Hudson's Straits!—and yet both are situated under the same latitude of 62°.
The milder winter and earlier spring which characterise the north-west coast of Europe, are due, in some measure, to the prevailing westerly winds; but there can be no doubt that they are mainly owing to the influence of the Gulf-stream, which, as we have seen, conveys the heated waters of the Mexican Gulf far to the north-east, and thus imparts warmth to the climate of our native isle. In both seas, on the contrary, which bound the peninsula or island of Greenland, icy currents descend, and continue their course to the south, along the coasts of North America. Near Newfoundland their temperature, in May, is found to be 14° lower than that of the air, and even in spring and the early summer they carry along with them immense ice-blocks, which are frequently drifted as far south as the latitude of New York, and finally disappear in the Gulf-stream.
It is evident that the cold of winter must be increased, and the spring retarded along the North American coasts by these cold streams, just as the coasts of Europe are favoured by streams of a contrary nature; and thus the ocean-currents go a great way to explain the remarkable differences of climate between the opposite shores of the Northern Atlantic.
On this occasion I cannot omit directing the reader's attention to the influence which the far-distant barrier of Central America has upon the climate of Great Britain. Supposing yon narrow belt of land to be suddenly whelmed under the ocean, then instead of circuitously winding round the Gulf of Mexico, the heated waters of the equatorial current would naturally flow into the Pacific, and the Gulf-stream no longer exist. We should not only lose the benefit of its warm current, but cold polar streams, descending farther to the south would take its place, and be ultimately driven by the westerly winds against our coasts. Our climate would then resemble that of Newfoundland, and our ports be blocked up during many months, by enormous masses of ice. Under these altered circumstances, England would no longer be the grand emporium of trade and industry, and would finally dwindle down from her imperial station to an insignificant dependency of some other country more favoured by Nature.
On examining other coast-lands, in different parts of the globe, we shall everywhere find the influence of the reigning currents producing analogous effects to those I have already mentioned.
The Southern Atlantic is not warmed like the European seas by tepid streams, it is exposed on all sides to the free afflux of the cold waters of the Antarctic Ocean, and during the summer months to the influence of drift ice. Thus, the southern extremity of America, Terra del Fuego, the Falkland Islands, South Georgia, Sandwich Land, and other isles of the southern ocean, have a much colder climate than the European coasts and islands situated under the same latitude.
Let us for instance compare the temperature of the Falkland Islands and of Port Famine in the Straits of Magellan, with that of Dublin, which is situated at an equal distance from the line.
| Mean Temperature. | |||||||
| Latitude. | Winter. | Summer. | Annual. | ||||
| Dublin | 53° 21′ N. | +4· | 0° R. | 15· | 3° | 9· | 6° |
| Port Famine | 53° 38′ S. | +0· | 6 | 10· | 0 | 5· | 3 |
| Falkland Islands | 52° 0′ S. | 4· | 36 | 11· | 8 | 8· | 24 |
| Feroë Islands | 62° 2′ N. | 3· | 9 | 11· | 6 | 7· | 1 |
Thus the climate of the Falkland Islands is, as we see, not very different from that of the Feroë Islands, although the latter lie ten degrees farther from the equator.