Climate change: the defining issue of the twenty-first century
"Climate risks escalate over time: some of the changes we are seeing were not expected to occur so soon - or at all." Dr. Michael Oppenheimer
Carbon dioxide is the main anthropogenic greenhouse gas. It is responsible for about 66% of the anthropogenic greenhouse effect.
Since the pre-industrial era, the carbon dioxide concentration in the atmosphere has risen by 52%, from 280 ppm to 424 ppm.
Most of this growth has occurred since 1970 and has come directly from fossil fuel combustion. Indeed, fossil fuels account for 80% of the global energy mix.
This sharp increase has had a critical impact on the average global temperature on Earth, which has grown by 1.3°C since the pre-industrial era.
Methane is the second main anthropogenic greenhouse gas. It explains 30% of the global human-induced greenhouse effect. Over 20 years, it is 80 times more potent than CO₂ (28 times over 100 years).
Since 1880, methane concentration has risen from 837 ppb to 1929 ppb. That increase is directly due to the growth of human activities, which account for 60% of global methane emissions (fossil fuel use, agriculture, etc.).
Since 2021, 159 states have signed the "Global Methane Pledge", whose goal is to reduce CH4 emissions by 30% between 2020 and 2030. That goal seems nevertheless unattainable given the current levels of methane emissions.
Since 2000, global fossil CO2 emissions have sharply increased, mainly because of China's emissions, which have almost tripled in 20 years.
China's CO2 emissions account for 32% of global CO2 emissions, the United States' ones 13% and Europe's ones 10%.
Those numbers must naturally be weighted by the size of the populations and by the historical responsibility of developed countries for climate change.
Coal use is a defining issue of climate warming. According to the IEA, about 45% of global CO2 emissions come from coal. China's coal consumption account for almost 50% of the global coal consumption.
It is worth to be noted that the Covid-19 crisis has had a significant impact on emissions.
Hundreds of millions of people have been affected by climate warming. Its intensity is unprecedented in history and its effects (heatwaves, droughts, floods, storms, sea level rise, etc.) will increase within the next decades. But to what extent ?
