There’s no need to worry about global warming, argues Dennis Avery. History shows it will lead to great benefits
`Climate extremes would trigger meteorological chaos – raging hurricanes such as we have never seen, capable of killing millions of people; uncommonly long, record-breaking heat waves; and profound drought that could drive Africa and the entire Indian subcontinent over the edge into mass starvation.”
That was the alarming scenario presented by United States senate majority leader George Mitchell in 1991. And as the Kyoto treaty on global warming, setting targets for the reduction of “greenhouse gases”, remains stalled, we face strident predictions of climatological catastrophe.
But there is no cause for alarm. Mitchell’s scenario was implausible when he presented it eight years ago – when crude computer models were predicting three times as much warming as they currently do – and is clearly untenable today.
Climate researchers still do not agree on whether the Earth will become warmer during the next century. More importantly, none of them expects the planet to get much warmer in the foreseeable future. They say the Earth is likely to warm by no more than 2C during the next century.
The world has experienced that much warming fairly recently. And we loved it. Between 900AD and 1 300AD, the Earth warmed by 3C to 4C. Historians call it the Little Climate Optimum. This warming created one of the most favourable periods in human history. Crops were plentiful, death rates diminished, and trade and industry, art and architecture flourished.
Food production surged because winters were milder and growing seasons longer. Growing regions had fewer floods and droughts. Human death rates declined, partly because people spent less of their time huddled in the damp, smoke-filled hovels that encouraged the spread of infectious diseases.
The Vikings discovered and settled Greenland around 950AD. Greenland was then so warm that thousands of colonists supported themselves by pasturing cattle on what is now frozen tundra. Europe built looming castles and soaring cathedrals. These colossal buildings required the investment of millions of man hours, which could be spared from farming because of the higher crop yields.
Europe’s population expanded from 40-million to 60-million. Trade flourished because there were fewer storms and muddy roads. (There was more rainfall, but it evaporated more quickly.)
England was warm enough to support a wine industry. The Mediterranean basin was wetter than today. Farming moved further north in Scandinavia, Russia, Manchuria, northern Japan and North America. Iceland grew oats and barley.
Technology flourished. The water mill, the windmill, coal, the spinning wheel and soap entered daily life. Sailors developed the lateen sail, the rudder and the compass. New iron-casting techniques led to better tools and weapons.
Real earnings in China reached their highest point in 3 000 years. The Indian subcontinent prospered, producing temples, sculptures and elaborate art. The Khmer people built the huge temple complex at Angkor Wat. The Burmese built 13 000 temples at their capital, Pagan.
In North America the Mississippi valley and the south-west received more rainfall than they do now. The Anasazi civilisation of the south-west grew abundant irrigated crops and then vanished when the Little Optimum ended. The Toltecs and Aztecs built marvellous civilisations in Mexico.
Far from causing more drought and expanding deserts, global warming brings more clouds and more rainfall, especially near the equator. During the Little Optimum, North Africa received more rain than today, and the Sahara shrank in response.
Later in the 15th century, however, the good weather ended. The world dropped into the Little Ice Age, with harsher cold, fiercer storms, severe droughts, crop failures and famines. In China there were twice as many floods and four times as many droughts as in the Little Optimum. The cold persisted until the 18th century.
Predictions that we face a new global warming should be greeted with enthusiasm: the medieval experience should reassure us, and the latest scientific evidence supports such optimism. It is clear, for example, that a planet earth with longer growing seasons, more rainfall and higher carbon dioxide levels would be a “plant heaven”.
Modest warming would help crops, not hinder them. There is virtually no place on Earth too hot or humid to grow rice, cassava, sweet potatoes or plantains, for example, and corn can be grown in a wider variety of climates than any other crop.
The expected increase in carbon dioxide will be an additional blessing. Carbon dioxide acts like fertiliser for plants. Dutch greenhouses, for example, routinely triple their carbon dioxide levels deliberately and the crops respond with 20% to 40% increases in yield. It also helps plants use their water more efficiently. The “pores” on plant leaves partially close, and less water vapour escapes from inside the plants. More than a thousand experiments with 475 crop plant varieties in 29 countries show that doubling the world’s carbon dioxide would raise crop yields an average of 52%.
The amount of carbon dioxide in the atmosphere does seem to be rising, but current levels are very low compared to past periods. In fact, most of the Earth’s species of plants and animals evolved in much higher levels of carbon dioxide than we have today – up to 20 times the recent pre-industrial level of 280 parts per million.
Scientists examining the impact of global warming on wildlife in the two most at-risk environments (tropical forests and the Arctic) say that they would expect a modest global warming to produce little or no species loss. Dr Gary S Hartshorn, in Global Warming and Biodiversity, notes that the tropical forests already undergo enormous variability in rainfall. He writes: “It is unlikely that higher temperature per se will be directly deleterious to tropical forest [wildlife] communities.”
In the same book, Dr Vera Alexander notes that Arctic marine systems would be threatened if the sea ice melted. The Arctic, however, has already survived major temperature changes without shrinking appreciably. Even with worldwide temperatures 6C to 9C warmer than today’s, Alexander notes, the sea ice would re-form in the winter.
Most of the trillion-dollar estimates of global warming “costs” headlined in the 1980s were based on forecasts that cities such as New York and Bangladesh would be drowned by a rising sea. Frightening scenarios, but completely untrue.
The Little Climate Optimum did not produce devastating floods. Nor will a new global warming. It may seem paradoxical, but a modest warming in the polar regions will actually mean more arctic ice, not less. The polar ice caps depend on snowfall. If polar temperatures warm a few degrees, there will be more moisture in the air and more snowfall, and more polar ice.
The world’s ocean levels have been rising at approximately the same rate – 18cm per century – for at least 1 000 years. No one knows why. In 1992, Science magazine published a paper based on ice core studies suggesting the projected warming would actually reduce the sea level by 0,3m.
Forging onward intrepidly, some alarmists have claimed that a warmer world would suffer huge increases in deaths from malaria, yellow fever and other warm-climate diseases. Fortunately, these claims ignore some fundamental realities. Global warming would be very slight near the equator and thus would only slightly expand the range of the malarial mosquitoes, for instance.
Far from creating a plague of pestilences, the Little Optimum engendered a worldwide population surge and set the stage for several historic invasions such as the Viking incursions into Normandy and England, and the movement of German peoples into Eastern Europe.
History and the emerging science of climatology tell us we need not fear a return of the Little Climate Optimum. If there is global warming in the 21st century, it will produce a milder, more pleasant and fertile climate with the added benefit of more carbon dioxide in the atmosphere and a more luxuriant natural environment. We have nothing to fear but the fearmongers themselves.
Dennis T Avery is a former senior agricultural adviser to the US Department of State. He is the author of Saving the Planet with Pesticides and Plastic. A longer version of this article appeared in American Outlook. Visit their website at