The climate has changed: The physics

The scientific consensus on the physics of climate change is that
  • the world has warmed on average by 1.1°C
  • there are more extreme weather events
  • this is caused principally by mankind's emissions of CO2
  • global warming is causing increased droughts, heatwaves, storms and floods
  • future emissions will cause additional warming
  • the larger the total emissions, the greater the warming.
This is the scientific consensus based on the IPCC AR6 WG1 report of 2021.

Average temperatures have increased

Source: IPCC [1]

There are more extreme weather events


(Source: IPCC [1])

The oceans are changing

Oceans are warming, acidifying, and losing oxygen (Source: IPCC [1])

Global warming is caused principally by mankind's emissions of CO2

As the CO2 builds up in the atmosphere, the average temperature rises - see document 52.

Future emissions will cause additional warming

As more CO2 is added to the atmosphere, the temperature will rise further; every tonne of CO2 emissions adds to global warming - see document 52.

Unless there are immediate, rapid, and large-scale reductions in greenhouse gas emissions, limiting warming to 1.5°C will be beyond reach [3].

Sources

The information presented here is the scientific consensus, i.e. the conclusions of people who have engaged in rational collaborative discussions.

The main source for this scientific consensus is the IPCC AR6 WG1 report of August 2021.

Alternative views

Not everyone accepts the scientific consensus given above. Some common objections are scrutinised and countered at the website https://skepticalscience.com.

References

[1]IPCC press conference slides (Aug 2021): https://www.ipcc.ch/report/ar6/wg1/downloads/outreach/IPCC_AR6_WGI_Press_Conference_Slides.pdf
[2]Nasa https://climate.nasa.gov/vital-signs/global-temperature/ (viewed 6.4.2019)
[3]Abdalah Mokssit (Secretary of the IPCC) (Aug 2021) IPCC press conference https://un-spbf.org/event/ipcc-press-release-climate-action-cannot-wait/
[4]IPCC press release (Aug 2021): https://www.ipcc.ch/site/assets/uploads/2021/08/IPCC_WGI-AR6-Press-Release_en.pdf

For copyright information on the chart and images shown, see document 2.

First published: Feb 2019
Last updated: 8 Dec 2023