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## When did atmospheric CO2 reach 400 ppm?

May 9, 2013
On May 9, 2013, an instrument near the summit of Mauna Loa in Hawaii recorded a long-awaited climate milestone: the amount of carbon dioxide in the atmosphere there had 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.

### What does 400 ppm CO2 mean?

If all the carbon dioxide in the atmosphere were shared equally amongst every person on the planet (7 billion of us) this is how much we’d have each – 446 tonnes of it. A concentration of 400 ppm means that for every million air particles, 400 of them are carbon dioxide molecules (0.04%).

Passing the 400 ppm threshold will not trigger any devastating effect by itself, but it does provide one metric of just how fast humans are emitting carbon dioxide. It is the concentration of carbon in the atmosphere that actually intensifies the greenhouse effect, in turn warming the climate.

What percentage is 400 ppm?

ppm to percent conversion table

ppm Percent (%)
200 ppm 0.02%
300 ppm 0.03%
400 ppm 0.04%
500 ppm 0.05%

How many ppm CO2 now?

409.8 parts per million
The global average atmospheric carbon dioxide in 2019 was 409.8 parts per million (ppm for short), with a range of uncertainty of plus or minus 0.1 ppm. Carbon dioxide levels today are higher than at any point in at least the past 800,000 years.

## What happens when CO2 reaches 500 ppm?

At the current rate of growth in CO2, levels will hit 500 ppm within 50 years, putting us on track to reach temperature boosts of perhaps more than 3 degrees C (5.4°F) — a level that climate scientists say would cause bouts of extreme weather and sea level rise that would endanger global food supplies, cause disruptive …

### Is 400 ppm a lot?

In the big picture, 400 ppm is a low-to-middling concentration of CO2 for the planet Earth. Some 500 million years ago, when the number of living things in the oceans exploded and creatures first stepped on land, the ancient atmosphere happened to be rich with about 7,000 ppm of carbon dioxide.

#### What does born at 375 ppm mean?

slow climate change
When most of the youngest Portland State students were born, that level was 375 ppm, meaning efforts to stop or slow climate change since their birth have been completely unsuccessful. For these activists to succeed in their efforts at turning the rising tide of climate, they will need the support of prior generations.

What is normal CO2 ppm?

400 ppm: average outdoor air level. 400–1,000 ppm: typical level found in occupied spaces with good air exchange. 1,000–2,000 ppm: level associated with complaints of drowsiness and poor air. 2,000–5,000 ppm: level associated with headaches, sleepiness, and stagnant, stale, stuffy air.

What is the ppm level of CO2 in the atmosphere?

## What happens when CO2 reaches 1000 ppm?

The studies indicate that with 900 or 1,000 ppm CO2 levels, Earth’s water cycle becomes hyperactive in terms of extreme rainfall events, again in good agreement with the paleoclimate proxy data.