At todays 420 ppm CO2 level, the sea level is already set to rise by +10m or more, as it was 4 mio years ago

You wonder if we should regulate the burning of fossil fuels? The CO2 level of 420 ppm in the year 2021 is a problem – the last time it was that high was 4 million years ago. Geologic record shows the sea was 10 to 20 meters higher than today, in 2021. It just takes time for the ice to melt and the water to warm up and expand. All coastal towns and countries are already doomed.

How high was the ocean the last time there was a CO2 level of 420ppm in the atmosphere? Compared to the 280ppm CO2 that was in te atmosphere 200 years ago?

As far as the currently available measures and estimations say: with this much CO2 in the atmosphere, the normal sea levels to expect are +10 to +40 meters higher than today. We can already say goodbye to all coastal cities, say farewell to much of the fertile land in the world.

Note that the CO2 level is still rising, because we keep burning fossil fules, and the unstoppable chain reactions we currently trigger will push the climate crisis even further.

We need to stop burning fussil fuels now.

Article: Carbon dioxide hits new high / NASA

  • Imagine a planet where the sea level is about five to 40 meters (16 to 131 feet) higher than normal.
  • Imagine a planet that is hotter and wetter. Imagine, worldwide, it’s roughly 3 to 4 degrees Celsius (5.4 to 7.2 degrees Fahrenheit) warmer than today.
  • And the North and South poles are even warmer still – as much as 10 degrees Celsius (18 degrees Fahrenheit) hotter than today.

Article: Last time CO2 levels were this high, there were trees at the South Pole / The Guardian


  • Trees growing near the South Pole, sea levels 20 metres higher than now, and global temperatures 3C-4C warmer. That is the world scientists are uncovering as they look back in time to when the planet last had as much carbon dioxide in the atmosphere as it does today.
  • Fossil fuel burning was pumping CO2 into the atmosphere extremely rapidly, he said, though it took time for the atmosphere and oceans to respond fully.
  • Temperature had already risen by 1C since the industrial revolution, when CO2 levels were 280 parts per million (ppm).
  • CO2 was now at 412ppm and rising, suggesting the planet would be locked into rises of 3C-4C in the next few centuries.
  • Ice melting, he said, took even longer and the huge sea level rises indicated by the Pliocene evidence would probably take a few millennia to come about.
  • If we keep carbon emissions going at the current rate, by the end of the century we will have 1,000ppm
  • it’s crazy.
  • We’ve killed it.

Article: Climate explained: what the world was like the last time carbon dioxide levels were at 400ppm / The Conversation


  • The last time global carbon dioxide levels were consistently at or above 400 parts per million (ppm) was around four million years ago during a geological period known as the Pliocene Era (between 5.3 million and 2.6 million years ago).
  • For the Pliocene Era, research shows the sea-level change between cooler and warmer periods was around 30-40 metres and sea level was higher than today.
  • Also during the Pliocene, we know the West Antarctic Ice Sheet was significantly smaller and global average temperatures were about 3℃ warmer than today. Summer temperatures in high northern latitudes were up to 14℃ warmer.
  • a 1℃ increase at the equator may raise temperatures at the poles by 6-7℃. It is one of the reasons why Arctic sea ice is disappearing.
  • Sea-level rise from a partial melting of West Antarctica could easily exceed a metre or more by 2100. In fact, if the whole of the West Antarctic melted it could raise sea levels by about 3.5 metres.
  • In the recent geological past, during the most recent ice age about 20,000 years ago, sea levels were at least 120 metres lower than they are today.

Article: Climate Milestone: Earth’s CO2 Level Passes 400 ppm / National Geographic


  • Greenhouse gas highest since the Pliocene, when sea levels were higher and the Earth was warmer.
  • the amount of carbon dioxide in the atmosphere there has exceeded 400 parts per million (ppm) for the first time in 55 years of measurement—and probably more than 3 million years of Earth history.
  • The last time the concentration of Earth’s main greenhouse gas reached this mark, horses and camels lived in the high Arctic. Seas were at least 30 feet higher—at a level that today would inundate major cities around the world.