To date, human activities are estimated to have caused approximately 1.0°C of global warming above pre-industrial levels. Global warming is likely to reach 1.5°C between 2030 and 2052 if the warming continues to increase at the current rate.

Warming from the pre-industrial period to the present will persist for centuries to millennia and will continue to cause further long-term changes in the climate system, such as sea level rise, but these emissions alone are unlikely to cause global warming of 1.5°C. Emissions from today onward will be responsible for that.

Climate-related risks are higher for global warming of 1.5°C than at present, but lower than at 2°C. As the average global temperature makes small increases from 1° to 1.5° or even 2°C, there will increases in average temperatures on land, more hot extremes, more heavy rainfalls, and high probabilities of droughts a low rainfall in some areas. The extinction of species is also expected to increase.
[Read more about extreme heat, flooding, droughts.]

To achieve a future where we do not go over (or only briefly go over) 1.5°C, the total, global CO2 emissions must decrease by about 50% of 2017 levels by 2030 and reach net zero by 2050. Emissions of other greenhouse gases must also rapidly decline.  We have to cut our emissions in half by 2030 and net zero by 2050.

Such cuts in emissions will require rapid and far-reaching transitions in energy, land, urban and infrastructure (including transportation and buildings), and industrial systems. These systems transitions are unprecedented in terms of scale, but not necessarily in terms of speed, and imply deep emissions reductions in all sectors, a wide portfolio of mitigation options and a significant upscaling of investments in those options.

Emissions targets of the Paris Agreement would not limit global warming to 1.5°C, even if supplemented by very challenging increases in the scale and ambition of emissions reductions after 2030.