1.5°C vs 2°C Global Warming

What is the importance of rates of change vs one-off climate events?

The climate has always varied, however rapid climate change is always disruptive and we are seeing climate changes at unprecedented rates. It may be that climate locally changes to be one that is better, but it won’t stay that way as it keeps changing. 

One factor not adequately appreciated is that the evidence policy responses rely on may be muted or delayed given the massive inertia and time horizons of climate change. By the time the problems become visible and clear, it may be too late to do anything about it. 

The inertia and long time-horizons come about due to the centuries-long atmospheric life of carbon, the slow response of the climate system due to dlow warming of the oceans, land, ice etc, and the complexity of current infrastructure.

It is estimated that the current rates of change are a factor of 100 or greater more rapid than natural changes. It is the rates of change that are very disruptive, not only to natural ecosystems and biodiversity, but also society. 

What will the planet look like at 1.5°C vs 2°C warming?

The goal of the COP21 Paris agreement is to attempt to limit global warming to well below 2°C, preferably to 1.5°C compared to pre-industrial levels. The IPCC released a report outlining what the differences would be at the two temperatures. They found that even at 1.5°C the world will face severe climate impacts, but the effects will be much worse at 2°C warming.