The word biome was invented well under a hundred years ago and was unknown to me in my schooldays, but I believe it is familiar to students of geography these days. However, biome’s classification words go back a long way and are mostly familiar rather than technical. I like the Wikipedia sentence “Biomes are distinct biological communities that have formed in response to a shared physical climate.” The key word is “response”. It suggests that climate determines biology, which does not sound unreasonable. (Classifications of physical climate tend to be more technical and go back until at least 1884.) When it comes to climate change, some biological responses may be fast. Drought may cause desertification pretty fast. However, an evolutionary response may be reckoned a gradual process requiring many generations. Human intervention may make a difference. A problem with biomes is that the world is a more complicated place than seventeen biomes -- or whatever number the preferred classification stipulates. In what follows, I shall be referring to tundra; and to taiga and boreal forest as separate classifications -- not merely as Russian and American terms for the same thing. I take forest in it usual sense to mean an extensive wooded area of some density. By taiga I am referring to the areas of patchy, scrubby and sometimes stunted growth found between the boreal forest and the tundra. However, there is much more vegetation in the taiga than the thin “reindeer food” of the tundra. Taiga deserves its Russian name because it is a much greater feature of the Asian continent than of the North American continent. Siberia tends to have the more extreme low temperatures and less precipitation. At present, there is much concern over the warming of the tundra, the melting of the permafrost, and the belching of methane into the atmosphere. This warming does not turn the tundra biome into taiga. The warming of the taiga does not turn it into boreal forest. But with time -- and human intervention, particularly in the form of afforestation -- this “response to physical climate” can take place; may even be expected to take place. But speed is a vital necessity. Global warming brings the chance for the greening of not less than a million square kilometers in Northern Asia -- possibly much more; the total area would depend on climatic changes in precipitation. The creation of this massive lung would suck carbon dioxide from the atmosphere and prevent runaway global warming. Whether or not I am right, whether or not I have explained it well, this aspect of global warming needs an airing and does not seem to be getting one -- or have I missed it?