Either Way, It’s the End of the World as We Know It
Dr Nathan Tamblyn
Worst case scenario is that global warming continues to rise. This will lead to the collapse of human civilisation, including billions of deaths, perhaps even as soon as 2050.
This is because of the effects of global warming; droughts, floods, wildfires, acidification of the ocean, extreme weather events, rising sea levels threatening coastal communities, land degradation, increased pests and diseases and more besides. This combines with habitat destruction and biodiversity loss in a mutually reinforcing cycle. In human terms, this ultimately means food and water shortages, mass displacement, conflict and death.
Best case scenario is that we halt global warming at 1.5 degrees (which is above 1850 pre-industrial levels). This is possible, and survivable, but only with urgent action and with what scientific bodies call ‘deep adaptation’. 
The causes of global warming are largely attributable to greenhouse gases which in turn are generated by various human activities including animal farming and most notably the use of fossil fuels. A halt to global warming within a very short timeframe, requires zero net emissions from fossil fuels. This is where adaptation comes in. Think of the things we currently have which are dependent on fossil fuels; cars, planes, factories – to name just three. If we get rid of fossil fuels, we need to integrate major changes to how we live.
It is not simply a case of taking all our current practices and making them run on green electricity. There are not enough raw materials in the world to do so. Therefore, it means giving up some of the things we once enjoyed, but which we now know are killing us.
Between these two extremes, of best and worst case scenarios, higher temperatures mean worse consequences. Each 0.5 degree increase in global warming equates to hundreds of millions of lives suffering. Hence the urgency.
A new way of living will be different. It must be different. Indeed, it will likely need to be radically different. This is not the same as saying it will be worse. The period of transition will pose emotional and practical challenges. However, once we have settled into a new way of living we will still fall in love as often as before, still argue, still tell stories and bad jokes. A new way of living, whilst starting from a position of great advancement, will still be full of opportunity for the expression of our humanity.
Some science fiction writers, and even some public figures, have talked about quitting the Earth and starting again. But we can start again here! Not only this but we do not have to give up our friends and families, culture, or the beauty and wonder of this astonishing planet. Indeed, it is in order to save these things, to keep them vital, that we must change how we live.
What can we do as individuals? Avoid single use anything. Go vegan. Avoid flying. Drive less. Consume less. Switch to renewable energy. Re-wild. Finally and most importantly, tell our leaders to provide the structural support needed for us to make these changes.
The facts underlying this article can be read here:
United Nations Intergovernmental Panel on Climate Change: https://www.ipcc.ch/
(UK) Committee on Climate Change: https://www.theccc.org.uk/
Natural History Museum: scarce metals and electric cars