What’s the hottest the Earth’s ever been?

What’s the hottest the Earth’s ever been?(climate.gov)

58 points by throwaway2474 4 years ago | 64 comments

gorpovitch 4 years ago |

It is interesting to keep these numbers in mind, but these facts are not sufficient to think correctly about climate.

The earth is a dynamic system, and the rate of temperature growth is as much, if not more, important than temperature average here. A car going from 100 to 0 kmph in 15 seconds is definitely not the same as a car going from 100 to 0 kmph in 0.1 seconds in terms of damage.

the temperature rises described in the article (e.g. during the eocene) are about a few degrees every few hundreds of thousands of years. Flore and fauna had time to evolve.

Today we are talking about 4 degrees in less than a hundred years. That's more than thousand times faster.

dalmo3 4 years ago | |

Without any knowledge in the field I wonder if the timescale difference could be attributed to the measurement methods used for the last centuries vs literal ages ago.

I.e. if we (or someone a million years from now) tried to estimate the 21th century's temperatures using the same techniques used to estimate temperatures a million years ago, would we be able to detect that 4 degree change?

Conversely, can scientists today detect or rule out that there was an outlier century a million years ago in which temps varied as much as today?

pjc50 4 years ago | | |

I think they'd be able to spot the change, because the "step" would persist, but not tell you which century it happened in precisely.

Future archaeologists and ice core samplers would definitely find a "wtf" layer in all their ice cores: higher radioactivity! If they attempt carbon-dating there will be a huge discontinuity in the results.

Probably also a microplastics layer.

have_faith 4 years ago | | |

> would we be able to detect that 4 degree change?

I'm far from an expert on this. Assumedly the damage we are seeing currently and expecting in the near future due to our current warming would be detecteble over a a very large time scale. We seem to be able to detect much more subtle changes going very far back with our current techniques.

WithinReason 4 years ago | | |

This is a great question, and it seems that our methods can't detect temperature variation in past data that's similar to the recent rise. See the bottom answer:

https://earthscience.stackexchange.com/questions/8746/is-thi...

Helmut10001 4 years ago |

It is strange why many politicians and countries (Germany included) appear to close their eyes and still promote or work on the 1.5 °C goal, which seems pretty unrealistic at this stage. Maybe it is to calm the public, besides knowing better.

Instead, there is a need for more realistic plans to model and prepare for 3°C or 5°C increase of average temperature by 2060 (or 2100). Looking at these bigger swings in temperature, it is more likely that we're seeing temperature peaking beyond our expectations than below.

samwillis 4 years ago | |

Trouble is most politicians are incentivised to think in the short term and are increasing just in a perpetual campaigning mode. They are thinking about their careers and re-election. They cannot except and talk about bad news, and a 3-5degC increase is bad news.

On top of that you have had climate activists pushing for very large change to happen incredibly quickly (arguably needed). But it’s an incredibly hard sell to the public who won’t except a negative impact on their quality of life.

Basically:

1. People are unwilling to make changes that they perceive as being a net negative to their quality of life.

2. Businesses are unwilling to make changes that they expect to have a net negative to their bottom line.

3. Politicians are unwilling to ask for either of the above to happen because they want to be re-elected.

dav_Oz 4 years ago | | |

Update after 2 years of 'crisis management':

The social fabric of the western societies had been severely damaged.

Trust in science is at an all time low. The absurdly rich are absurdly richer. Not few people are now flirting openly with the idea to simply abandon those bulky civil liberties of the 20th century (2nd half) in order to save the world in the long run. So, in order to satisfy 2. ("green washing") and 3. ("emergency state") 1. (civil liberties) is the obvious pawn "sacrifice".

throwaway3b03 4 years ago | | |

> 1. People are unwilling to make changes that they perceive as being a net negative to their quality of life.

I don't think that's the case. It's a coordination problem. People don't want to reduce their quality of life if they don't know for sure that others won't do that as well. Most things in life and in human psychology are relative, in constant comparison to our peers.

White_Wolf 4 years ago | | |

Quality of life is one thing but what happens with the bottom 20%-30% earners? Would they be able to afford living after a sudden change like this? Everyone pushed for a change but I've never seen one(so far) that talk about those that can barely survive as it is.

adriand 4 years ago | | |

> But it’s an incredibly hard sell to the public who won’t except a negative impact on their quality of life.

The idea that solving the climate crisis would have a negative impact on people's quality of life is one that has been successfully promoted by the fossil fuel industry. But it's not true. We could get to a net zero economy AND deliver improvements to (most) people's quality of life.

A few quick thoughts:

* I read that the richest 1% of Americans are responsible for 30% of American carbon emissions, although I'm struggling to find the source of that. It was easy, however, to find stats that indicate the richest 1% of people across the globe are responsible for 15% of global carbon emissions, which is nearly twice as much as the poorest 50%. The vast majority of us can keep on living our lives as normal. The 1% need to stop jet-setting and ripping around in lambos. That's not going to harm my quality of life. [1]

* Investments in green energy and related technologies are creating a job boom and plenty of wealth for the people participating in the green revolution. There are lots of direct economic benefits. [2]

* Air pollution from burning fossil fuels is responsible for ~1 in 5 deaths worldwide. Imagine the increase in quality of life for everyone with far cleaner air. [3]

* Millions of people, myself included, suffer from (entirely rational) feelings of anxiety, worry and depression related to climate change. The knowledge that we are destroying the planet, killing off animal and plant species by the thousands, and ruining the future of my children and grandchildren is a daily drag on my happiness and sense of well-being. I would feel so much better knowing that we were actually doing what we needed to do to solve this crisis. That would be a huge benefit to my quality of life! [4]

1: https://www.bbc.com/future/article/20211025-climate-how-to-m...

2: https://www.globalcitizen.org/en/content/renewable-energy-jo...

3: https://www.hsph.harvard.edu/c-change/news/fossil-fuel-air-p...

4: https://www.nytimes.com/2022/02/06/health/climate-anxiety-th...

moralestapia 4 years ago | |

The thing is that, for businesses and governments, complying with the 1.5ºC goals/projections is already a monumental task. If it does happen, even though it won't be enough, we should at least get an A for effort ... too bad nature is not forgiving.

Anyway, what is still nice is that it should be easier to adapt to 3-5ºC once we're all doing something for 1.5ºC than if we were doing nothing at all, i.e. static friction is always higher than kinetic friction. I think the true covert goal at the moment is to at least get things moving and have everyone jump on it asap.

Source: I build/code software related to sustainability.

ahevia 4 years ago | | |

Youre right about the difficulty of the task, but should we even be considering 3 degrees of warming as acceptable? That’s a nightmare scenario for most of the global south

5 degrees is a nightmare scenario for the whole world. Albeit I think it’s far more likely if we have to finally admit we’re on the pathway to 3 degrees, many countries might independently deploy solar geoengineering projects to save their skin (especially island nations)

vixen99 4 years ago | |

Which data sources have persuaded you that the realistic and likely increases of 3 or 5 degrees are more probable?

"In 1979, the Charney Report from the US National Academy of Sciences suggested that ECS was likely somewhere between 1.5C and 4.5C per doubling of CO2. Nearly 40 years later, the best estimate of sensitivity is largely the same. This has led some to question why there has been so little progress on estimating climate sensitivity."

Is this quote above now no longer true? If not, please provide a link.

Helmut10001 4 years ago | | |

I could cite individual observations and reports, but the field is difficult to summarize in a single HN comment. There are many factors that we cannot completely oversee, primarily tipping points (disappearing reflective polar caps) and feedback loops (melt of permafrost with methane release).

More concretely, have a look at the latest IPCC report [1], page SPM-16. Three of the five scenarios include temperature rises from 3 to 5 °C. Based on the last decade, the world has not reduced total CO2 emissions at all (not even slowed), despite its knowledge about climate change. Therefore, I have reason to believe that the three bad scenarios (intermediate to high CO2 emission), are more likely to happen than scenarios covering halted or little CO2 emission.

[1]: https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6...

CJefferson 4 years ago | |

I can't imagine anything most countries could reasonably do to prepare for 5c, what type of things would you suggest?

eloff 4 years ago | | |

If you're Bangladesh, give up on being a country and join India so your people at least have somewhere to migrate to.

If you're New Orleans, time to give up on being a city. Start preventing new construction. Incentivize people to leave.

Things like that really if we're going to get honest with ourselves about where things are headed.

parkingrift 4 years ago | | |

Blast sulfur into the stratosphere. No, I’m not joking.

goodguyamericun 4 years ago | |

Except Biden has stationed troops halfway across the world and if the MIC gets its way, we might get to pre 1800 levels of temperature, so, thanks Biden I guess. Let's go Biden

matkoniecz 4 years ago |

During Hadean geologic eon, when Earth surface was molten and cooled to form the first rocks.

https://en.wikipedia.org/wiki/Hadean

bcraven 4 years ago | |

Yes, the article acknowledges that but also makes the point that it's not interesting from a human perspective.

"None of these techniques help with the very early Earth. During the time known as the Hadean (yes, because it was like Hades), Earth’s collisions with other large planetesimals in our young solar system—including a Mars-sized one whose impact with Earth likely created the Moon—would have melted and vaporized most rock at the surface. Because no rocks on Earth have survived from so long ago, scientists have estimated early Earth conditions based on observations of the Moon and on astronomical models. Following the collision that spawned the Moon, the planet was estimated to have been around 2,300 Kelvin (3,680°F)."

"Even after collisions stopped, and the planet had tens of millions of years to cool, surface temperatures were likely more than 400° Fahrenheit. Zircon crystals from Australia, only about 150 million years younger than the Earth itself, hint that our planet may have cooled faster than scientists previously thought. Still, in its infancy, Earth would have experienced temperatures far higher than we humans could possibly survive."

"But suppose we exclude the violent and scorching years when Earth first formed. When else has Earth’s surface sweltered?"

melling 4 years ago |

“For most of the time, global temperatures appear to have been too warm (red portions of line) for persistent polar ice caps. The most recent 50 million years are an exception”

egberts1 4 years ago | |

Our Sun probably ate a planet thereby disrupting the solar cycle.

mrlonglong 4 years ago |

Interesting article, but one thing let it down, it didn't give the Celsius equivalent for the temperatures quoted in Fahrenheit, I think it would have been nice to have those in brackets for those who can't quite make the mental contortions converting from one to the other. Apart from that quite fascinating to see that life did find a way to exist in temperatures higher then today or in the past.

egberts1 4 years ago |

I often wonder about terraforming (on places like Mars planet).

Earth obviously had the leg up on water accumulation during its accretation stage (Hadean period).

Perhaps we can start generating oxygen early over there on Mars using a one-step CO2->O2+C catalyst.

This comes to mind: https://www.pnas.org/content/109/39/15606

MichaelZuo 4 years ago |

On the positive side of things, northern cities of the world will likely not be buried under an ice sheet anytime soon.

tim333 4 years ago | |

That's a relief. I'm old enough to have gone through the 1970s global cooling scare stories https://en.wikipedia.org/wiki/Global_cooling

tim333 4 years ago |

I like to see stuff like this published that gives some hope that a bit of warming in the next century or two is probably not going to lead to a "we're all going to die" situation.

cable2600 4 years ago |

During the age of dinosaurs it was hotter than it is now.

beowulfey 4 years ago | |

Yes, we live in a relatively cold era in the history of our earth. It’s a great, very informative article.

tamaharbor 4 years ago |

Instead of trying to stop the changes (which is probably impossible), why don’t we focus on adapting to what will inevitably become the new normals.

Tagbert 4 years ago | |

The efforts are to reduce the degree of change. Full on stop is not likely at point. Adaptation will be even more expensive, but we still get people complaining that efforts to head off climate change are too expensive.