CLIMATE CHANGE REPORT: Key findings from the UN’s new climate science report
A new UN report sets out the impact of human activity on the climate – and possible futures facing the planet.
Here are some of its key findings.
– It is “unequivocal” that human activity has warmed the atmosphere, ocean and land – with widespread and rapid changes across the world.
– Many of the changes are unprecedented over many centuries to many thousands of years, with the world warming at a rate unprecedented in at least 2,000 years.
– Carbon dioxide levels in the atmosphere are higher than they have been for three million years and methane concentrations are higher than they have been for 800,000 years, with rises in both greenhouse gases well above natural changes seen for hundreds of thousands of years.
– Global average temperatures were nearly 1.1C higher in the last decade than in pre-industrial times, or the period 1850-1900, driven by emissions caused by human activities such as burning fossil fuels and deforestation.
– Human-caused climate change is already affecting many weather and climate extremes in every region around the world, with stronger evidence of more frequent or intense heatwaves, heavy rain, droughts and tropical cyclones and the role humans play in driving the changes.
– Humans are very likely the main driver of the global retreat of glaciers, decline in sea ice, warming oceans and rising sea levels. The rate of sea level rise is speeding up.
– Global surface temperatures will continue to increase until at least mid-century, and the world will reach or exceed 1.5C of warming over the next 20 years.
– Global warming of 1.5C and 2C – limits countries have committed to in order to avoid the most dangerous impacts of climate change – will be exceeded in the 21st century unless deep reductions in carbon dioxide and other greenhouse gas emissions occur in the coming decades.
– Continued warming will drive increases in the frequency and intensity of hot extremes, marine heatwaves, heavy rain, droughts in some regions, the proportion of intense tropical cyclones, and reductions in Arctic sea ice, snow cover and permafrost.
– Every additional increment of warming causes larger changes in extremes, with every extra 0.5C temperature rises leading to clear increases in the intensity of heatwaves, heavy rain that can cause flooding, and droughts.
– Under scenarios for the future with increasing carbon dioxide emissions, the ocean and land carbon sinks such as forests are projected to be less effective at slowing the accumulation of the greenhouse gas in the atmosphere.
– Changes to oceans, sea levels and melting permafrost and glaciers are irreversible for decades, centuries or even millennia as a result of past and future warming.
– Strong, rapid and sustained reductions in emissions of methane would help curb warming, and would also improve air quality.
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