As Earth.Org’s data visualization editor, I’ve delved  into environmental reports for the better part of the last two years. Here is a short list of some of the most interesting climate change facts I find most people aren’t aware of – enjoy, and share with your friends! 

1. We are certain we’ve caused it

The IPCC kicks off its latest report with the following statement: “It is unequivocal that human influence has warmed the atmosphere, ocean and land.” 

How are we so certain? It took a while, but climate modelling is now refined enough to predict how things would go without human influence, within a margin of error. What we are observing today is beyond that margin of error, therefore proving that we have driven the change. 

2. The last decade was the hottest in 125,000 years

Most straightforward of our climate change facts: according to the recent IPCC report on the state of our climate, the past decade is likely to have been the hottest period in the last 125,000 years. We’ve been oscillating between glacial (ice ages) and warmer interglacial periods like ours for about 100,000 years, yet we;ve now reached temperatures similar to those before glacial periods became a thing. 

climate change facts temperature at its highest in 125,000 years

Source: IPCC, 2021.

The vertical bar on the left shows the estimated temperature (very likely range) during the warmest multi-century period in at least the last 100,000 years, which occurred around 6500 years ago during our current era called the Holocene. Prior to the last ice age, around 125,000 years ago, is the next most recent candidate for a period of higher temperature. Each of these past warm periods were caused by slow (multi-millennial) orbital variations that are not in play today. 

3. The ocean absorbs most of the heat we produce

A 2019 study found that it had sucked up 90% of the heat gained by the planet between 1971 and 2010. Another found that it absorbed 20 sextillion joules of heat in 2020 – or 2 Hiroshima bombs per second. 

ocean absorbing heat climate change facts

The ocean obviously has tremendous volume and heat-storage capacity, which is why some organisms are used to temperatures being quite stable. Of these, coral reefs are particularly sensitive to temperature levels which is why many are dying off. 


4. CO2 is at its highest in 2 million years

Pre-industrial CO2 levels were around 280  parts per million (ppm). Today, we stand near 420 ppm. 

CO2 over the past 800,000 yearas, NASA climate change facts

Source: NASA.

The most distant period in time for which we have estimated CO2 levels is around the Ordovician period, 500 million years ago.

historic CO2 levels

Source: Descent into the Icehouse.

Once again, the ocean comes to our rescue by absorbing about a third of the carbon in the atmosphere. Before the industrial revolution, it was actually a source of carbon, and not a sink, but the massive amount of CO2 now in the atmosphere has forced it to start absorbing the gas. 


5. We are losing 1.2 trillion tons of ice each year

This item on our list of climate change facts can be hard to comprehend because we are dealing with volume beyond our comprehension.

Since the mid-1990s, we’ve lost around 28 trillion tons of ice, with today’s melt rate standing at 1.2 trilliono tons a year. 

To help you put that into perspective, the combined weight of all human-made things is 1.1 trillion tons. That’s about the same weight as all living things on earth


6. Air pollution is both good and bad

We recently found out that air pollution kills more than 10 million people per year, far more than the estimated 4.4 million that have died from COVID at the time of writing. Developing hotspots in south Asia and Africa will be dealing with poor air quality for years to come, but there is a silver lining.

outdoor air pollution air pollution vs covid-19 covid

Polluting particles, such as PM10 or PM2.5, which cause adverse health effects similar to those of cigarettes, actually reflect the sun’s heat rather than trap it. We’ve pumped enough greenhouse gases into the atmosphere to warm it by 1.5°C already, but fine particles have kept it around 1.1°C so far. 

Some have proposed intentionally disseminating particles into the atmosphere to help reflect more sunlight, but potential unforeseen consequences have kept us from doing so. 


7. Attribution is now possible (extreme weather)

We can now attribute natural disasters to human-driven climate change with certainty. This hasn’t always been the case – a lack of data and refined techniques for detecting attribution made it hard to tell how much we had to do with each extreme weather event. 

We can tell with precision how much likelier we made things like the North American summer 2021 heatwave, which the World Weather Attribution says was “virtually impossible” without climate change.


8. Global warming is (partially) reversible

If global net emissions were entirely ceased, the warming we’ve caused would gradually reverse but other climate changes would continue for at least decades. For example, sea level rise would take several centuries to millennia to reverse its course. 

if we stopped using fossil fuels and other scenarios

Source: Carbon Brief.

9. We lost 302.4 billion work hours to excessive heat in 2019

If you’ve ever been in humid south east Asia on a hot August day, you’ll know that working outdoors with shade is barely feasible, and without, simply dangerous. A report from The Lancet found that the number of work hours lost to heat increased from 199 billion in 2000 to 302.4 billion in 2019. That is equivalent to 436,969 average human lifetimes in 2019 alone. 

workk hours lost to heat climate change facts

Of course, daytime outdoor labor is most exposed, which often targets lower-income areas and professions, especially agriculture.

work hours lost to heat by sector

Source: The Lancet Countdown Report 2019.


10. It could become to hot to live in many places by the end of the century

This may the most catastrophic of our climate change facts. As of now, only 0.8% of the planet’s land surface has mean annual temperatures above 29°C, mostly in the Sahara desert and Saudi Arabia (solid black in the map below).

A study by Xu et al. (2020) called “Future of the Human Niche” found that by 2070, under a high emissions scenario, these unbearable temperatures could expand to affect up to 3 billion people (black hashes).

too hot to live climate change facts

Source: Xu et al. 2020, Future of the Human Niche.

Lost work hours are only one example of the impacts of extreme heat, especially  when sustained over long periods. Others include agriculture yield losses, the spread of disease-carrying mosquitoes, and the increased need for air conditioning with its accompanying energy consumption.


11. The cost of inaction is higher than the opposite

On the current path, climate change could end up costing us 11 to 14% of the global GDP by mid-century. Regression into a high emissions scenario would mean an 18% loss, while staying below 2°C would reduce the damage to only 4%. 

It has been proposed that ending climate change would take between $300 billion and $50 trillion over the next two decades. Even if $50 trillion is the price tag, that comes down to $2.5 trillion a year, or just over 3% of the global GDP. 


Climate change is an incredibly complex phenomenon, and there are many other things happening that weren’t covered above. If you want to learn more, please visit our data visualization page!


This article was written by Owen Mulhern.

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