Although it doesn’t sound much we are already seeing significant impacts. The 1°C is the average temperature increase across the surface of the globe meaning some parts of the globe get much hotter causing impacts on things like the water cycle, resulting in more frequent flood events. What we are seeing now is huge changes in winter conditions, with more temperature volatility, significant glacial retreat, significant coral reef death (due to the fact that most of the warming has gone into the sea) and many more extreme weather events, heatwaves such as Lucifer in Southern Europe in 2017 and so called ‘500 year’ storms like Hurricane Harvey. The heatwaves are causing huge forest fires – the summer of 2017 saw extensive wildfires in Canada, Greenland (!!), Southern Europe and Russia.
Another risk is sea level rise. This takes longer to happen though as things like ice caps need to melt and nobody is really sure how quickly that might happen. Scientists estimate current levels of global warming, that’s the 1°C, are consistent with sea level rises of 6m to 9m, which would put large parts of many major coastal cities underwater.