Global heating
The earth has a blanket of gases around it - atmosphere. Some of these glasses absorb heat radiation from the sun and re-emit it into the atmosphere, causing heat to be ‘trapped’. These are called Greenhouse Gasses (GHG). GHGs include Carbon Dioxide, Nitrous Oxide, Methane and Chlorofluorocarbons. The level of GHG in the atmosphere has been rapidly rising since western industrialisation, resulting in global average temperature rise of 1.1C.
Whilst there have been fluctuations of carbon dioxide concentrations (measured in parts per million, ppm) over the earths history (measured using deep ice cap analysis), levels have never risen above a certain pont, until the year 1950. They have risen consistently and intensively since then.
Carbon dioxide stays in the atmosphere for 1000’s years, until it is absorbed by plants, oceans or soils; a process part of the earth’s carbon cycle. Carbon dioxide currently accounts for approx. 75% GHGs. Methane lasts for approx 12 years, but has a warming potential 30x that of CO2. It accounts for approx 16% GHG. Nitrous Oxide declines over 120 years, with a warming potential of 280x CO2. It accounts for approx 6% GHG. CFCs have various lifespans and warming powers, the highest of which is 28,000x CO2.
Projections
The IPCC has estimated 5 main emissions scenarios, from ‘High emissions’ (our current pathway), Medium emissions scenarios, and low emissions scenarios. Complying with pledges made at the Paris and Glasgow COPs would take us to 1.8-2.7C by 2100. Low emissions scenario would take us to 1.5C by 2100, and would require an immediate ceasing of all GHG emissions, combined with significant sequestration (carbon absoarbing) efforts such as afforestation.
The UK is likely to experience around an additional 0.5°C increase in annual average temperature by 2050, even under ambitious global scenarios for cutting greenhouse gas emissions. (Climate Change Comittee UK Risks report 2021)
Resources
Climate Action Tracker has excellent, simple analysis of countries and industrys emissions, pledges, targets and progress towards their targets.
Climate interactive have made a fun simulation tool that looks at different national emissions reductions strategies and energy use and shows how these would impact global temperatures.