Updated: Oct 26
Biodiversity or 'biological diversity' encompasses all living organisms (animals, plants, fungi, and microorganisms plus the diversity within species, between species, and within ecosystems) on our planet. We need biodiversity in order to maintain healthy ecosystems that provide food, medicine, clean air and water, as well as a stable climate.
We're losing biodiversity at an alarming rate
Species are disappearing 1,000 times faster than at any other time in recorded human history.  This is due to the way we produce food, dispose of waste and consume energy and resources.
Even though we represent 0.01% of all wild animals, we're responsible for 83% of the loss of all wild mammals, and half of plants, in the last century.  Devastatingly, we've wiped out 69% of all wildlife in the last 50 years, prompting scientists to conclude that we're now living through the 6th mass extinction – the largest loss of life on Earth since the time of the dinosaurs.  (Infographic from Pinterest )
Without biodiversity, the entire support system for life on Earth will collapse
Without pollinators, who are responsible for an estimated third of the world’s crop production,  invertebrates and microbes (which maintain the health of the soil crops grow in), we won't be able to feed ourselves. Likewise, the loss of healthy forest-, wetland-, grassland-, soil organism- and ocean-ecosystems (which lock away atmospheric carbon) will result in more frequent climate disasters.
With increasing floods, fires and droughts we'll experience further losses in biodiversity, significantly reducing our access to clean water, air and food, plus significantly impacting our flood defences, health and soil. Catastrophic economic loses, as a result of this, will force low income countries to sink deeper into poverty.  And by 2050, an estimated 1.2 billion people around the globe could be displaced. 
Nature-based solutions can reverse the effects of biodiversity loss on the climate
For governments and big business, the costs of nature restoration (through practises like regenerative farming, marine protection, low impact silviculture and nature tourism) are outweighed by the benefits to communities.  Restoring coastal mangroves, for example, could protect land from storm surges and erosion. Likewise, the restoration of wetlands, mangroves and coral reefs could protect areas vulnerable to flooding, while ecological forestry practices could safeguard regions prone to wildfires.
Connectivity is also important, to avoid creating islands of biodiversity that species struggle to move between.  In Britain, for example, native woodlands cover just 2.5% of our land,  and our seafloor has been damaged by trawling. Connecting our remaining biodiverse regions, through a mosaic of species-rich habitats, would allow wildlife to move and ecosystems to adapt as climate zones alter.  And an easy way to do this is to increase biodiversity in our gardens. Working together we can create 'wildlife corridors' with undisturbed patches of garden (left to grow wild), wildlife-friendly installations (ponds, bug hotels, bird- and bat boxes plus log piles) and the planting of hedges in place of fencing and walls. Together these small acts could save a significant number of species from extinction. 
If we take the right steps now, biodiversity will return on land, in seas, rivers and lakes, but the window of opportunity is closing. Conservation is urgently needed to save our struggling wildlife, and damaged ecosystems need to be repaired. This is crucial to mitigating the worst effects of biodiversity loss on the climate.
To help restore nature in the U.K., please consider donating to Green Up Britain.