The Gardeners Guide to Weather and Climate is a thorough explanation of the history of our planet’s climates and the behavior of our weather. As you know our planet has endured through both ice ages and warmer periods, with our flora and fauna evolving to meet these changes. This book is not a fast read, you will need to slow down to absorb the information presented. Charts, graphs, drawings and photographs are on almost every page to enhance understanding.
“The climate, which is weather averaged over many years, determines most of the physical parameters within which plants and animals must live.” [Pg. 253]. So how do we gardeners manage our landscapes in unpredictable weather, such as our New England climate? I found out that the our weather is very complicated.
First is the daily rotation of the earth around a tilted axis. This tilted axis defines the different zones of our planet: tropic, temperate, and polar. Next is the year-long solar orbit: first one hemisphere is turned toward the sun, then the other. When the northern hemisphere is tilted towards the sun, our days are longer, and the reverse when our hemisphere is slanted away from the sun. The earth’s orbit is also eccentric (not a perfect circle), so our distance from the sun varies through the year. We have named these different locations in our annual orbit ‘seasons’.
Our planet has an atmosphere of air and large bodies of water. The atmosphere has its movements and so do the oceans. The atmospheric movements have names such polar cell, polar front, Ferrel cell, horse latitudes. On top of the cells are jet streams that move into the direction of our planet’s orbit. The ocean currents have names such as the Gulf Stream, North Atlantic Current, and Canary Current that have their own circuits. It is these constant movements of the atmosphere and oceans that create our weather. Subtle changes in either can have a big impact on the weather we experience.
Solar radiation on the oceans and over the land cause evaporation (water vapor) which rises through the atmosphere where it condenses into clouds. Different types of clouds form in the different layers of the atmosphere. Atmospheric movements cause the clouds to move. The cloud movements are also influenced by the land masses and oceans over which they flow.
These are the basic factors that produce our weather. There are many more elements described in this book that can impact our weather patterns. What about our current weather patterns? Do you think it has changed from 10, 20 or even 50 years ago? How do we know if it is changing?
By phenological observations of daily weather and seasonal length (growing season) scientists and citizen scientists around the world have documented growing seasons for many years. “The growing season is defined as the period that begins on the first of five successive days when the average daily temperature is higher than 5C (41F) and ends on the last day prior to a series of five successive days when the average daily temperature is lower than 5C. The threshold of 5C is used because most plant growth ceases below this temperature.” [Pg. 90]. The lengthening of the growing season in the twentieth century is well documented in the world with the exception of one small part of the Russian north. In the east-central United Sates that growing season increase is about 7 days. While we experienced a slow, cool spring in 2017, delaying the planting of our vegetable gardens, a lingering warm autumn meant a longer growing season for fall crops, with an abrupt end due to a four-inch snow fall in early December here in Western Massachusetts.
Is this Climate Change? If so, what is causing this Climate Change, increasing CO2 in our atmosphere? Are we causing this rise in CO2 with our use of fossil fuels? Michael Allaby’s answer is that there may be more than one cause for the increase in global temperature. He does give in-depth explanations of several possibilities and combination of possibilities for the warming climate. Nothing concerning weather is simple or can stand alone as the only cause of the current warming climate.
I found all of this interesting but what I want to know was how a gardener in Western Massachusetts can work with the changing weather patterns. After all, our weather in the last 10 years has been different from the New England weather we are used to. What do we do in these changing times?
It begins with the soil. Michael Allaby gives us a chapter on the formation of soil. “Soil and Climate are intimately linked…The processes that converts bare rock into soil, function only under certain conditions of temperature and humidity. In other words, soil formation is driven by climate.” [Pg. 192]. All of the climatic periods and weather processes described in the first four chapters are used to explain the formation of soil and the continuing forces at work on our soils, even within our gardens. Good soil has decomposing organic material and humus for fertility but also to create a good balance of porosity and permeability for plant growth and survival under both good and difficult weather conditions. In addition to good soil, knowing your soil profile and pH is key to selecting the right plants for your garden site.
The last three chapters (Plants and Climate, Plants and the Environment, and Protecting Against Harsh Weather) contain in-depth information for understanding a plant’s life cycle needs not from a biologist’s perspective but from weather events; providing the best environment to work with unpredictable weather; and knowing what and how you can take steps to protect the garden against weather’s worst excesses. These chapters also discuss different environments with a selection of plants and their specific needs that can thrive in different world climates.
“Climates are the accumulation of weather and it is the combined effects on the atmosphere and oceans of energy from the Sun and the rotation of the Earth that generate our weather. The atmosphere behaves in very complicated ways and much of its behavior is inherently unpredictable….Of one thing we can be sure, however: there will be gardeners raising plants whatever the weather brings.” [Pg. 290]. It’s complicated, yes, but to understand weather and climate, the Gardeners Guide to Weather & Climate, is the book to read.
Michael Allaby is a prolific writer of books and articles about plants, animals, the countryside, and all aspects of the natural world. Some of his books include: 16 books on Weather and Climate; an eight book series on Dangerous Weather; eight dictionaries such as the Dictionary of Science for Gardeners; a seven book series on Discovering the Earth; a nine book series on Bromes and Ecosystems; eleven books on the Natural World; ten books on Countryside and Farming such as A Year in the Life of a Field; two books on World Food; four books on the Elements; seven Textbooks and References.; twelve books on Ideas and Speculations; and one Anthology on Essential Ecological Writing