Australia is burning, coral reefs are dying. What next?

As we watch in horror at a continent in flames and hear repeated stories of dying coral reefs, it is important to ask what comes next? I am no expert on Australian vegetation, but ecological science can offer some theoretical considerations, and suggest the significance of the climate crisis to what we are observing around the world. I do know about coral reefs, and see striking parallels with what is happening on land.

Many ecosystems are adapted to major disruptions. Forest fires are a natural occurrence. Coral reefs are smashed by cyclones. Resilience is one sign of successful ecosystems. They are knocked down and bounce back. The result is often a mosaic of parts of ecosystems at various stages of regeneration, some mature and fully developed, others going through stages of succession towards maturity. On land, some species regenerate from rootstocks after a fire, or seeds buried in the soil sprout in the new sunlight. Some conifers only release their seeds after a fire has opened their cones. Fires are a natural occurrence in areas with dry seasons like Australia and California. A damaged coral reef can be repopulated by larvae and immigrants coming from elsewhere, assuming there is a healthy reef as a source.

What has changed is the scale of human impacts, especially linked to climate change. In a landscape of burned and unburned areas, seeds are carried into the burned area by birds or the wind, wildlife moves in from adjacent habitats, and the forest regenerates. When climate change increases the frequency of fires or storms so that there is insufficient time for the ecosystem to recover, the ecosystem is degraded and may lose essential species or components. With the massive burns in Australia, such large areas are affected that there are not longer adjacent forests to support regeneration. Coral bleaching over large areas from high water temperatures has the same effect; the ecosystem loses the capacity to recover. Instead, the degraded area is occupied by weeds or invasive species, or algae on the reef, and this can prevent the return of the original communities.

An additional factor on land has been the natural desire to protect forests from fire, either because of human occupation of the area with houses, tourism or other activities, or simply because burned areas are unattractive. Where fires were a natural part of the ecosystem cycle, returning nutrients to the soil, clearing out an excessive accumulation of biomass and preventing really destructive fires, the result has been devastation when a fire does finally occur. The sequoias of California have fire-resistant bark, so occasional fires would clear out fast-growing competitors and allow young sequoias to establish themselves. Controlled burning is necessary to maintain the sequoia ecosystem. The many houses burned in Australia suggest that some forests where fire is a necessary part of the ecosystem are inappropriate for human habitation.

In the light of these significant impacts of the climate crisis, what is required to compensate for the damage we have caused? Where we have destroyed natural resilience, we must replace it with compensating human actions. First would be to save and protect any remaining fragments of the natural ecosystems that have survived and might contribute to recovery. Then we shall have to replant native species before invasives take over, and artificially rebuild the key elements of the original ecosystem. As the forest or reef regenerates, then missing elements of wildlife can be reintroduced. As we acknowledge the environmental havoc we have wrought, and cut back our damaging activities, environmental restoration will become a priority to rebuild the carrying capacity of our planet so that it can support an ever-advancing, sustainable human civilisation.