Climate change is the greatest threat facing humanity, causing noticeable effects on the life cycles and distributions of the world’s vegetation. Although it may actually benefit some plants by lengthening growing seasons and increasing carbon dioxide, the effects of a warmer world, such as more pests, droughts, and flooding, will be less benign. Therefore, as gardeners, we need to adapt to the changing climate. At the end of this guide we suggest some actions you can take and have listed Jekka's top herbs that will best tolerate either dry, damp, sunny or shady conditions.
Understanding climate change
We have understood our impact on the world for a long time. The role of carbon in the climate system was first modelled in the 1960s but the greenhouse effect, which underpins the science of climate change, was discovered much earlier, in the 19th Century. In the 1970s, the Keeling Curve, revealed for the first time that the observed increase of the atmospheric CO2 was the result of the combustion of carbon, petroleum and natural gas.
Numerous frameworks, conferences, panels and targets have been implemented in order to reduce emissions and reduce or mitigate our impact on the world. The most notable being, the Intergovernmental Panel on Climate Change (IPCC) that was established in 1988 to provide policymakers with regular scientific assessments on the current state of knowledge about climate change. This was followed by the United Nations first Earth Summit in 1992, which was created for Member States to cooperate together internationally on development issues and, in 1995, the Kyoto Protocol was adopted that legally binds developed country to emission reduction targets. More recently, in 2015, the Paris Agreement brought all nations into a common cause to undertake ambitious efforts to combat climate change and adapt to its effects, with enhanced support to assist developing countries to do so.
Underpinning this has been an increasing body of scientific evidence, that was summarised in the IPCC's fifth assessment as:
- From 1880 to 2012, the average global temperature increased by 0.85°C.
- Oceans have warmed, the amounts of snow and ice have diminished and the sea level has risen.
- Most aspects of climate change will persist for many centuries, even if emissions are stopped.
From shifting weather patterns that threaten food production, to rising sea levels that increase the risk of catastrophic flooding, the impacts of climate change are global in scope and unprecedented in scale.
Fast forward to today, and we are on course to have the hottest year since records began. The Met Office projects the average global temperature to be between 1.15°C and 1.46°C above pre-industrial conditions. The IPCC 2018 Special Report showed that many of the adverse impacts of climate change will come at the 1.5°C mark, with the negative impacts of climate change becoming much more intense and frequent in the future.
Even though the influence of humans on the climate system has been known for a long time it can be argued that not enough has been done to combat climate change. Even if we stopped emitting greenhouse gases today, global warming would continue to happen for at least several more decades, if not centuries. How much the climate will change is what we can hopefully mitigate. Although the coronavirus lockdown has temporarily cleared the skies, it has done nothing to cool the climate, which, the scientists say, needs deeper, longer-term measures.
What can gardeners & horticulturists do?
Climate change is the defining issue of our time and we are at a defining moment. Without drastic action today, adapting to these impacts in the future will be more difficult and costly. The role of the gardener is increasingly important as a means to support biodiversity, grow food (and thereby reduce carbon miles) and improve the health and well-being of yourself and those around you.
Jekka's climate action list
Even if your actions seem small and ineffectual, the cumulation of everyone working towards a sustainable and environmentally conscious world will have great far reaching impacts.
- Grow your own herbs and vegetables.
- Grow and eat with the seasons.
- Collect and recycle water and compost.
- Use sustainable and organic feeds and pesticides.
- Support your local biodiversity by planting a range of pollinating plants and allow plants to go to flower and set seed without harvesting.
- Buy plants and herbs from local, often specialised, nurseries.
- Educate and teach non-gardeners.
How will we overcome the challenge of climate change?
Climate change poses new challenges to the horticulturist or gardener. One predicted response to climate change is the variation in a plant’s phenology (the timing of life cycle events in plants and animals, especially in relation to climate). This includes the timing of spring emergence that has generally been occurring progressively earlier since the 1960s, which impacts, for example, when a plant will flower. Furthermore, in the UK, Met Office data suggests the growing season in Central England is about a month longer on average since the period between 1961 and 1990. The growing season refers to the extended period of time in which average daily temperatures are sustained at five degrees or higher. In addition to lengthening growing seasons, we are also seeing fewer frosts, which are important in the growing cycle of herbs and plants. Therefore, herbs and plants are adapting how, where and when they will grow under climate change.
This means that we will also need to adapt how we garden and grow herbs and other plants. For example, changing the time we sow seeds and how we sow seeds. If the winter is mild, we might need to trick the seeds into breaking their dormancy by putting them in the fridge. In general, milder winters and hotter summers are changing how native plants grow, with gardens being pushed towards hardier species capable of withstanding weather extremes, such as floods, droughts and heat waves.
Below Jekka lists her favourite herbs that will best tolerate either sun, shade, drought or damp conditions. However, this is written now, who knows what will happen in years to come.