It is hard to avoid the topic of climate change. The ramifications of our warming climate are becoming increasingly apparent. In fact, changes in climate have already begun to impact biodiversity in Australia. The 2019-2020 bushfires here were exacerbated by our changing climate. And we all know that these fires have had a devastating impact on biodiversity. For us concerned about wildlife conservation, the climate change situation is extremely concerning.
The need to bring down and eliminate carbon emissions is urgent and, sadly, looking increasingly difficult. But what if there is more to the story? What if the focus on climate has been too narrow and there are ways, relevant to wildlife conservationists, that may well be very effective at dealing with the situation. Yes fossil fuel emissions must still come right down, but what if other human activities play a far more important role than reported in the media. There are a growing group of scientists arguing that we need to comprehend the climate change situation more broadly. They maintain that we can naturally cool the climate through addressing the water cycle, the health of our soils, and restoring vegetation to our landscapes. Judith Schwartz, who disseminates the work of these scientists in her books and reporting, writing in The Guardian puts it this way:
Let me now introduce an alternate definition of climate change: “manifestations of distorted carbon, water and energy cycles”. That doesn’t negate the single story of fossil fuel-borne carbon but broadens it in a way that creates opportunities beyond fighting fossil fuel interests. At this moment of reckless distraction and denial, it is crucial to find meaningful paths forward.
The essence of what these scientists are saying is that if we restore the water cycle and our soils through appropriate land use practices, including re-establishment of vegetation, then weather patterns will be normalised with resulting cooling effects on climate. Judith Schwartz, in her article, There’s another story to tell about climate change. And it starts with water, provides a wonderful basic summary of this work.
The practices mentioned above can be grouped under the label of 'regenerative land management'. A deeper appreciation of the water cycle, soils and their significance in ecological restoration work, can inform how we think and act on our own properties. With this in mind, there are a variety of resources on this page that explain the science in more detail, if you wish to understand this work more thoroughly.
The Half and Full Hydrological Cycles
The central idea behind restoring landscapes and cooling the climate is re-establishing the hydrological cycle through getting water back into the soil and reducing runoff. In the case where soils lack vegetation and are compacted, water runs off and does not enter the soil. This also occurs in urban areas where large amounts of land are totally impermeable to water. The lack of water in the soil and corresponding lack of transpiration by plants sets up what is referred to as the 'half hydrological cycle'. In contrast, soils well covered with appropriate perennial vegetation tend to be permeable to rainwater and hence soils in these instances store water. There is less runoff during rain events. This vegetation then recycles that water back into the atmosphere through transpiration. This is what is known as the 'full hydrological cycle'.
Thus in the full hyrological cycle instead of so much water being lost to the oceans the water is recycled on land through soils and vegetation. This is what is referred to as 'water retention landscapes'. For further information go here. There is a close relationship between retaining water in the landscape and soil health.
To further elaborate on the critical point made above, where water and soil meet is perhaps the most important factor for the proper functioning of the water cycle. Vegetation that covers the soil is an essential requirement for the water to infiltrate and be stored in the soil. This plant cover is especially important in climates where there are dry seasons. Most of Australia is in this category. As Peter Donovan of the Soil Carbon Coalition notes, "Soil cover, root mass, organic matter, and aeration - these are synonyms for an effective water cycle, where water is absorbed and retained as much as possible in the ground, and the surplus goes through plants (transpiration) and down into the water table". The implications of this, he suggests, is that in situations where vegetative cover is lacking then most rain runs off and does not enter the soil. Furthermore, because "what moisture is able to penetrate the soil is quickly sucked back out through the drying of the bare soil surface, there is little moisture available to nourish soil organisms plants or recharge the water table" (Water Cycle Post 2015). Soils, in these scenarios, tend to be very dry, lack biodiversity in organisms such as worms, bacteria and fungi, and are impaired in their ability to supply nutrients to plants.
Peter Donovan is essentially describing the desertification process where the soil becomes gradually less capable of storing water and supporting plant life. As mentioned above, this is exacerbated in climates where there are pronounced dry stretches with little rainfall with dire consequences for the biodiversity of the soil organisms, the ability of soil to store carbon and, ultimately, the fertility of the land. In addition, the land becomes susceptible to more wildfires as it gets increasingly dry. In short, the land becomes increasingly less capable of supporting life and above ground biodiversity declines.
Regenerative Land Management
Regenerative land management offers solutions to reverse the process outlined above. These methods range from physical strategies to slow and retain water on the land (e.g. swales. keyline ploughing etc) to planting or regenerating appropriate plant cover. These improve the capacity of soils to absorb moisture and store it. The full array of benefits are illustrated in the diagram below.