This article is about the Mid-Miocene Climate Optimum, which was a period of 5 degrees C of warming about 15 million years ago. Another similar event is the Paleocene-Eocene Thermal Maximum, which was a period of warming (6 degrees C in 20,000 years) about 55 million years ago. The PETM was in response to a massive increase in atmospheric CO2 (several times more than humans have added), though what caused the injection of CO2 is currently unknown. Interestingly, although during the PETM the Earth had no polar ice caps to begin with there was still a rise in sea levels simply due to the thermal expansion of the ocean. There was a great deep dive into the event on the podcast In Our Time by three climatologists: https://www.bbc.co.uk/programmes/b08hpmmf
What happened last time it was as warm as it’s going to get later this century?
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Re: What happened last time it was as warm as it’s going to get later this century?
#42Global warming is real and humans contribute to it. Just stating that so I am not called a 'denier' as I have been before. That being said, the computer models predicting what the consequences of global warming will be, have greatly over estimated (at least the timeline of) real world impacts. Since I was a kid I've heard in the news that in the next 5 years or 10 years there will be all these catastrophes linked to…
Since everyone is arguing their beliefs without evidence, and throwing out random storms and climate events as counter-evidence, here are some actual facts:
1. Recent studies on current climate models show they consistently over-predict carbon impact on global warming (source: Nature, Nov 2017: Emission budgets and pathways consistent with limiting warming to 1.5 °C). The article shows that the previous carbon budget was off by a factor of 4 for the next few years, and always predicted higher temps. In other words, the models over-fit the data and thus lose predictive capabilities.
2. Increase/decrease in drought occurrence is inconclusive (Trenberth et al in Nature, 2013): "Two recent papers looked at the question of whether large-scale drought has been increasing under climate change. A study in Nature by Sheffield et al entitled ‘Little change in global drought over the past 60 years’ was published at almost the same time that ‘Increasing drought under global warming in observations and models’ by Dai appeared in Nature Climate Change (published online in August 2012)."
3. On storms, SREX p. 159: The present assessment regarding observed trends in tropical cyclone activity is essentially identical to the WMO assessment (Knutson et al., 2010): there is low confidence that any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity are robust, after accounting for past changes in observing capabilities.
4. The greatest two-year cooling event of the last 100 years just occurred in Feb, per GISTEMP Team, 2018: GISS Surface Temperature Analysis data. Global avg temp dropped 0.56 deg C.
Re: What happened last time it was as warm as it’s going to get later this century?
#43This article is about the Mid-Miocene Climate Optimum, which was a period of 5 degrees C of warming about 15 million years ago. Another similar event is the Paleocene-Eocene Thermal Maximum, which was a period of warming (6 degrees C in 20,000 years) about 55 million years ago. The PETM was in response to a massive increase in atmospheric CO2 (several times more than humans have added), though what caused the injecti…
You should note that the PETM CO2 increase was over multiple orders of magnitude (appr. 20,000 year vs 100) and theoretical rate of emission was 1-2 orders of magnitude less than the current rate.
Re: What happened last time it was as warm as it’s going to get later this century?
#44Global warming is real and humans contribute to it. Just stating that so I am not called a 'denier' as I have been before. That being said, the computer models predicting what the consequences of global warming will be, have greatly over estimated (at least the timeline of) real world impacts. Since I was a kid I've heard in the news that in the next 5 years or 10 years there will be all these catastrophes linked to…
What I'm hearing from scientists is that we're already seeing unusual weather patterns that are due to global warming. For the past decade or so nearly every year has been warmer than the year before, and nearly every year is a record-breaking warm temperature. We're seeing more and more "exceptional" or 1000-year events happening every year. This is what you'd expect from global warming. Global warming is a slow-mov…
Per my comment above, we actually just experienced the largest 2-year drop in temp in the last 100 years. The danger with a hugely complex system like "global warming" (i.e. world climate) is that it can be attributed to be the cause of anything.
Re: What happened last time it was as warm as it’s going to get later this century?
#45Earlier quoted context omitted.
What I'm hearing from scientists is that we're already seeing unusual weather patterns that are due to global warming. For the past decade or so nearly every year has been warmer than the year before, and nearly every year is a record-breaking warm temperature. We're seeing more and more "exceptional" or 1000-year events happening every year. This is what you'd expect from global warming. Global warming is a slow-mov…
Per my comment above, we actually just experienced the largest 2-year drop in temp in the last 100 years. The danger with a hugely complex system like "global warming" (i.e. world climate) is that it can be attributed to be the cause of anything.
Here's what seems to be a chart of the last hundred and thirty-six years of global land-ocean temperature.
https://climate.nasa.gov/vital-signs/global-temperature/
It seems some years are cooler than others, but the general trend is upwards.
I don't see where the last two years indicate much of a temperature drop. Do you have a source of information for your statement?
Re: What happened last time it was as warm as it’s going to get later this century?
#46A better and much more recent proxy observation for the effect of a warming climate is the Eemian [1] aka the last interglacial. Peak temperature 125k years ago was at least 2 C higher than today, and global sea-level was 8-9 m higher (of which less than 0.5 m is attributable to thermal expansion of ocean water). Scandinavia was an island.
Re: What happened last time it was as warm as it’s going to get later this century?
#47Earlier quoted context omitted.
Per my comment above, we actually just experienced the largest 2-year drop in temp in the last 100 years. The danger with a hugely complex system like "global warming" (i.e. world climate) is that it can be attributed to be the cause of anything.
Here's what seems to be a chart of the last hundred and thirty-six years of global land-ocean temperature. https://climate.nasa.gov/vital-signs/global-temperature/ It seems some years are cooler than others, but the general trend is upwards. I don't see where the last two years indicate much of a temperature drop. Do you have a source of information for your statement?
NASA GISS surface temp data [0]. Feb 2016 to Feb 2018. It's a noteworthy occurrence (and not something the news cycle would pick up) since the focus is always on warming. It certainly doesn't refute the short-term trends present.
Re: What happened last time it was as warm as it’s going to get later this century?
#48Does anyone know if there is any party or even organization anywhere right now pushing proper utilization of the free market to at least internalize the current cost of CO2 emissions (though that by itself could not solve the historical lack). It seems like this would actually be one of the few places where a free market should work extremely well: simply set the price of emitting a ton of CO2 at the ratcheted price…
So far the free market has failed spectacularly at addressing global warming.
The free market cannot suitably address the "tragedy of the commons".
If all companies currently follow expensive but environment-friendly processes, a rouge company can undercut them by following a cheaper but environment-harmful process. This will either force other companies to follow the rogue company, or they go out of business.
Re: What happened last time it was as warm as it’s going to get later this century?
#49This article is about the Mid-Miocene Climate Optimum, which was a period of 5 degrees C of warming about 15 million years ago. Another similar event is the Paleocene-Eocene Thermal Maximum, which was a period of warming (6 degrees C in 20,000 years) about 55 million years ago. The PETM was in response to a massive increase in atmospheric CO2 (several times more than humans have added), though what caused the injecti…
You should note that the PETM CO2 increase was over multiple orders of magnitude (appr. 20,000 year vs 100) and theoretical rate of emission was 1-2 orders of magnitude less than the current rate.
While that's probably true, it's not known for certain what the rate of emission was. 20,000 years is only an upper bound. It's possible that the process that led to the CO2 emissions happened over very short timescales (e.g., a comet impact or volcanic activity). Until we know the process, we can't constrain the rate.
Re: What happened last time it was as warm as it’s going to get later this century?
#50The one big problem I don't see talked about as much for some reason is ocean acidification. Given more of the surface of the planet is covered in ocean than in land, and the influence the oceans have on everything, it's pretty hard not to get worried about it. One consequence that is already happening (partly due to ocean acidification, and partly due to water getting warmer) is coral reef die-offs/bleaching.