The last time carbon dioxide levels on our planet were as high as today was more than 4 million years ago. Here are 8 interesting climate change facts you should know about.
1. We Are Certain We Caused It
The UN’s Intergovernmental Panel on Climate Change (IPCC) kicked off its 2021 report with the following statement: “It is unequivocal that human influence has warmed the atmosphere, ocean and land.”
How is that possible? 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, however, 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 IPCC’s sixth assessment report on the state of our climate, the past decade is likely to have been the hottest period in the last 125,000 years. For about 100,000 years, we have been oscillating between glacial (ice ages) and warmer interglacial periods like the one we currently live in. Yet, this is also the warmest multi-century period we have had in this timespan.
3. The Ocean Absorbs Most of the Heat We Produce
A 2019 study found that oceans 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 – equivalent to two Hiroshima bombs per second.
The ocean 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, reason for which many are now 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 close to 420 ppm.
The most distant period in time for which we have estimated CO2 levels is around the Ordovician period, 500 million years ago.
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 trillion 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
It was recently found that air pollution kills more than 9 million people per year. Developing hotspots in south Asia and Africa will be dealing with poor air quality for years to come, but there is a silver lining.
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 1.5C already, but fine particles have kept it around 1.1C so far.
Some have proposed intentionally disseminating particles into the atmosphere to help reflect more sunlight, but potential unforeseen consequences have prevented us from doing so.
7. Global Warming Is (Partially) Reversible
If global net emissions were entirely ceased, the warming we’ve caused would gradually reverse but other climate-induced changes would continue for decades if not centuries. For example, sea level rise would probably take millennia to reverse its course.
8. It Could Become Too 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.
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.
Source: earth.org
