3.2.1. Climate

We’ve discussed climate from different angles and will do more when we discuss buildings, so let’s look at some highlights as a review and put it all together. As designers, why do we care about what climate we’re in?

Climate is the context for a huge part of what we do as designers

• It helps us determine which types and cultivars of plants and breeds of animals will adapt the best
• It helps us determine our seasonal rhythms for more effectiveness and efficiency
• It helps determine what building materials will be most effective and locally available
• It helps us determine what strategies to use for water and soils
• It is also what we’re spending a lot of time in, and understanding it can increase our enjoyment of it

Before we get into the next section, let’s clarify something about climate categories. There are dozens of climate maps out there with different opinions about which is what! One reason there are differences of opinion is that some maps put more emphasis on one element over another (like rainfall vs temperature).

There are also many factors that can create microclimates or gradients of climates - for instance, drylands can get gradiently wetter as we move into wetter areas. There is often not a clear delineation between climates, and there can be a completely different microclimate within a climate zone (like a wet forest near an ocean in a drylands climate).

So take these classifications with a grain of salt, and use them to the degree they’re useful to you.

We’re going to go over some basic points about these larger patterns because there are concepts that we use as designers to understand what we’re dealing with and make design decisions.

Your own observation of your land, and study of your local microclimate is central to understanding how to design your site and always will be, regardless of what any map says.

We earlier discussed different climate types around the world, called the Koppen climate categories.

Koppen is widely accepted and used. Others have created maps they feel improve on it, but for our purposes Koppen works. The first column is the general category. The second gives rainfall and other patterns. The third focuses on temperature. All of these factors affect what plants and animals will thrive in that climate. There are gradient changes within each climate as well depending on microclimates, which we discuss in the next lesson. Those include altitude, water bodies and other specific landscape factors.

By comparing your climate zone to others around the world, you can get an idea of what you can grow to some degree. For instance, his warm temperate category means that summers are hot and humid. But winters vary widely on his map - they can be cold and wet, or warmer and dry.

Here is one way this map can be useful if you take that into account. We’re in Florida, the lower end of the warm temperate category. I can go to S China, SE Australia, Central South America or other areas at a similar latitude in the same category to find examples of edible crops that I can grow in Florida, and many permaculturists have done just that.

There are plants that grow in the southern range of the warm temperate category, and different plants that grow in the northern range. Some plants can handle the entire range of temperature differences in winter in this category, like some types of pine trees. Any climate category can become confusing without the concept of microclimates. Koppen focused on broad areas, which can give us predictions about what pattern languages we can use as designers.

Let’s look at the major climate types in the US, and what opportunities and challenges they bring.

Desert / Drylands

Opportunities

• Fungus and disease are usually less present
• Pests are sometimes less present than in more humid situations
• If you grow plants adapted to drylands, little care or inputs are needed
• Large selection of edible and useful plants (including grazing)
• Opportunity for high end specialty crops, like pistachios or mesquite flour
• This category can include the Mediterranean climate which can get a fair amount of rain in winter, and is one of the most productive climates in the world
• Can be very productive with the right water catchment techniques

Challenges (the drier the climate, the greater the challenge, usually)

• Water can be a major design challenge - store more water than you think you need
• Evapotranspiration - you must protect plants, water supply and soil
• Temperature extremes, both heat and cold - protect plants with shade, slow gain heat sources (like large rock)
• Soil is usually poor in nutrition
• Organic matter to build soil is sometimes scarce
• Pests can sometimes be more concentrated when you add a permaculture garden, because you have created a gourmet restaurant
• Flash flooding
• Dust storms
• Fire potential
• Prone to desertification

Humid Tropics or Wet/Dry Tropics

Note, Koppen puts subtropics (including most of Florida) in the “Warm Temperate” category - hot, humid summers, colder winters. For most of Florida, our pattern language for design is closer to wet/dry tropics than to temperate regions, and this is true of some other warm temperate/subtropical regions as well with a winter dry season. The "edge" between these categories is a gradient scale - it has qualities of both types of systems.

Opportunities

• Year round explosive growth - fast food supply
• Can replace failed crops quickly
• Large selection of edible and useful crops
• Lots of organic matter for “chop and drop” (used to enrich soil)
• Lots of pest predators
• Dry season (in wet/dry systems) reduces fungal pressures

Challenges

• Overgrowth and weeds
• Fertility eaten up fast, must regularly replace
• Disease
• Pest pressures year around
• Heat
• Flooding and hurricanes/cyclones
• Drought potential during dry season (wet/dry)
• Fire
• In subtropics, freezes can cause crop failure

We’ve found that the edge of warm temperate climates closest to the equator sometimes behaves more like a wet/dry tropics than temperate systems, except that they can freeze in winter. During some winters in Central and S Florida, there are no freezes at all. Even when it freezes, it is rarely a hard freeze, allowing many tropical plants to survive. Tropicals like papaya or banana may die to the ground in a harder freeze, but come back in the spring from the roots and continue to fruit. In N Central Florida, freezes may happen every year, and hard freezes (meaning the ground freezes to some degree) occur more often. True tropical plants like coffee suffer anywhere under 45 F. They can't grow without protection above USDA zone 9A. Only cold tolerant varieties of avocado and banana can grow in these regions, and the only temperate fruit trees that will grow well are specially bred to handle the heat and fungal pressures. But with those adaptions, a wide range of food can be grown in these zones.

Many tropical foods can be grown, and water catchment, cooling, and other design tools used in the tropics are useful here too. But we also find strategies for preventing frost damage to early budding fruit, a strategy used in warm temperate climates, to apply as well, for instance.

Temperate

• Soils are often fertile and deep
• Winter allows soil to rest and rebuild
• Rain patterns tend to be evenly distributed
• Large selection of edible and useful crops
• Lots of chop and drop
• Supports tree growth well
• Not a brittle climate, can recover from stress

• Late and early freezes can destroy crops
• Overgrowth and weeds
• Periodic drought and flooding
• Short growing season, trees are not so quickly replaced
• Disease and pests
• Temperature extremes, sometimes rapid
• Tornado, hail, straight wind (derecho) damage

Subpolar

Opportunities

• Usually lots of game available (most indigenous people in these regions hunt or ranch for a large part of their food)
• Low population, more land access
• Areas with sufficient moisture are stable and productive forest, not brittle
• Maybe will get warmer in climate change
• Greenhouses make a huge difference here

Challenges

• Late and early freezes can destroy crops
• Very short growing season
• Sunlight access can be a problem
• Violent winds and storms
• Year around snow/ice with frozen ground in some locations
• Small selection of edible and useful plants - in tundra, this selection becomes almost nonexistent
• These are very harsh environments to survive in

Remember, there are some climates that are on the edge of one or more of these and can have a mixture of opportunities and challenges from both types of climate, and there are subcategories for these that have varying degrees of these factors or maybe new ones. But these are the major patterns.

Rapid Climate Assessment

Let’s review which aspects of climate are most important to know about (Note: most of these can be found on https://weatherspark.com. See the Site Assessment section for more info.)

If you research the below points, you will have a good feel for the microclimate you are in, within the larger climate pattern. And you will have a lot of predictions about what to expect from your land, year round. Weatherspark is a good source to quickly determine what overall climate and microclimate you’re in.

Temperature - monthly averages and high and low records
USDA zone.
Temperature records.
Temperature averages by month.

Rainfall - monthly distribution, and extremes (how long between rains during dry season?)
Rainfall averages by month.
Average length of drought.
Extreme length of drought.
Record rainfalls and frequency (hurricanes, monsoons, mega rain storms).

Marine or Large Lake Microclimate Influence (buffers highs and lows)
Compare inland temperatures.

Humidity (buffers highs and lows)
Monthly humidity averages.

Altitude - every 100m (328ft) is approximately equivalent to 1 degree of latitude or 69 miles

Wind speeds & Frequency - check tree flagging, other signs of wind stress (see microclimates section)
Average wind speed per month.

Local microclimates
See section on microclimates in this course.
Placing temperature gauges in different microclimates on your land and recording results over time can be very revealing and helpful.

Evapotranspiration
This is the rate in which water evaporates. In deserts and in dry seasons, this can be extreme and must be designed for. The drier the air, the faster the rate. This rate changes according to temperature and humidity. It is not important for you to know the exact numbers on this. If you’re in a dry area, or have a dry season, understand you need to protect against evapotranspiration. Go overboard on it, and you’ll be ok. See soils and water sections for strategies on doing this.

Climate Change

We are in the midst of changing climate patterns, which is obvious to those of us who have lived close to the land for many years.

What this means is that the challenges for each climate above may increase, and we may experience new challenges yet to be seen.

There are two ways to approach this and both are necessary.
1. Do what you can to reduce fossil fuel use for yourself and as many others as possible.
2. Design for resilience. Design every point of resilience for more than your climate demands.

We will cover specific strategies for this throughout the course.