| A region's climate may alter over time | | | | |
| becoming hotter, cooler, drier or wetter. | | | | In warm climates organisms need to cool off. |
| Natural selection will determine the | | | | Animals' strategies include heat avoidance |
| organisms with characteristics appropriate to | | | | (by going underground, or into water), |
| the new climate. Over hundreds and thousands | | | | or sweating and panting to induce evaporative |
| of generations constant minute changes will | | | | temperature reduction. Plants must adapt to |
| eventually lead to a new species that can | | | | heat and drought by using leaves to minimise |
| survive and thrive in the altered climate. | | | | heat stress and water loss. |
| | | | |
| The success or failure of an organism is | | | | In cold climates, some endothermic animals |
| reliant upon its ability to reproduce young | | | | continue to be active at night and during the |
| that mature to produce more young. Only the | | | | winter, but eat constantly to keep |
| young with the greatest survival traits for | | | | their core temperature steady. Some other |
| any given habitat will endure. These | | | | approaches adopted by endotherms include |
| surviving young will transfer their adaptive | | | | minimising heat loss with body insulation |
| characteristics to the subsequent | | | | such as fat, feathers or hair, or avoidance |
| generations. This process is known as natural | | | | of adverse temperatures by migration to a |
| selection. | | | | cooler environment or burrowing underground, |
| | | | or reducing body temperature by hibernating. |
| If climatic or environmental changes occur | | | | |
| too abruptly some species may not be able to | | | | But even man, so often adaptable to the |
| adapt quickly enough and can become extinct. | | | | conditions we find ourselves, can be |
| This has become a large problem in recent | | | | vulnerable to rapid climatic change. The |
| times with human altered environments | | | | Icelandic Vikings that settled on the south |
| changing so rapidly that there has been an | | | | western coast of Greenland in the 10th |
| ominous rise in the extinction rate. | | | | Century eventually died out within 500 years |
| | | | as they were caught by the grip of the Little |
| Birds and mammals are warm-blooded | | | | Ice Age. This was a period of cooling after a |
| (endothermic). This means they can keep their | | | | warmer period, known as the Medieval Warm |
| body at a fairly constant, warm temperature | | | | Period. The Little Ice Age brought bitterly |
| by processing body fat and carbohydrates. All | | | | cold winters to the Northern Hemisphere and |
| other groups of animals are termed | | | | the Greenland Viking colonies died out simply |
| ectothermic as their body temperature is | | | | because they could no longer grow enough food |
| dictated by the temperature of the | | | | there to support themselves. They had arrived |
| environment around them. The term | | | | on Greenland in much more favourable climatic |
| cold-blooded is used to describe ectotherms, | | | | times. |
| but this is something of a misnomer, | | | | |
| particularly in hot, arid climates. As an | | | | So whether endothermic or ectothermic life |
| example a "cold-blooded" lizard basking in | | | | has a way of surviving, and although our |
| the hot midday sun can easily increase its | | | | current global warming trend is a serious |
| body temperature to over 100 degrees F, | | | | cause for concern, the earth has seen it all |
| giving it warm blood. | | | | before, and I am sure life will endure. |