Climate Change 2021 - The Physical Science Basis
The Intergovernmental Panel on Climate Change (IPCC) has released the most comprehensive and conclusive “state of the science” on the climate crisis. Why it is happening, how it impacts every region of the planet, how much worse things will get, and what we must do to avoid the worst consequences.
Some devastating impacts of global warming are now unavoidable. We are now at “Code Red for Humanity.”
More than 200 scientists from over 60 countries contributed to the Report - Climate Change 2021: The Physical Science Basis.
Humans have already heated the planet by roughly 1.1°Celsius, since the 19th century. The warming is happening even faster than scientists previously thought. The latest projections have us reaching or exceeding the 1.5°C threshold scientists say is critical to stay below – within the next decade or two.
So, what’s happening?
Extreme heatwaves are already about five times more likely to occur with our current warming of just over 1°C. At 2° warming, this frequency increases to 14 times as likely to occur. Heatwaves are getting hotter, and with 2° of warming, the hottest temperatures would reach nearly 3°C higher than previous heatwaves.
Climate change is increasing the frequency and severity of droughts. Severe droughts that used to occur an average of once per decade are now surfacing about 70% more frequently. If warming continues to 2°, these droughts will occur between two and three times as often.
Climate change is intensifying the water cycle on both sides. While more intense evaporation will lead to more droughts, warmer air can hold more water vapor to produce extreme rainfall. On average, the frequency of heavy downpours has already increased by about 30%, and they contain about 7% more water.
Hurricanes are growing stronger and producing more rain as global temperatures increase. It has already been observed that, globally, a higher percentage of storms are reaching the highest categories in recent decades. This is expected to continue as temperatures climb.
Sea level rise
Sea level is rising worldwide, and the rate is increasing, worsening high tide flooding and storm surge. By 2100, once-in-a-century coastal flood events will occur at least once per year at more than half of coastlines worldwide.
Climate change is not just increasing the severity of extreme weather; it is interrupting the natural patterns, leading to “weather whiplash” – wild swings between dry and wet extremes.
- Read the Full Report - AR6 Climate Change 2021: The Physical Science Basis (pdf).
- IPCC reports coming next year will go into more detail on specific impacts and ways to mitigate them.