Climate Catastrophe: Graphs and Commentary
Ongoing essay: updated regularly, last updated December 5, 2019
Climate data from NOAA unless otherwise stated.
Disclaimer: I am NOT a climate scientist!
A note on the name change
It seems that the names, “Global Warming” and “Climate Change” have recently been superseded by names like “Climate Crisis,” “Climate Emergency” and “Global Heating.” I don't think any of these names really express the gravity of the situation; so as long as we are changing names, let's go with the far more descriptive “Climate Catastrophe.”
See below for discussion of Crisis and Catastrophe
Recent Climate Highlights
NOAA released Version V of its climate dataset in May, 2019 and updated historical data accordingly. The main difference that I have noticed is that the new version shows more warming over the last few years than the previous version. Unless otherwise stated, data is from NOAA Version V
Some November 2019 Highlights (in progress)
Copernicus Programme rates November 2019 as tied with 2016 for the world's warmest November on record, only slightly ahead of third place November 2015. NOAA has not published November global climate data yet.
Average concentration of carbon dioxide in the atmosphere in November 2019 increased by 2.25 ppm over November 2018 as measured at the Mauna Loa site.
Neutral El Niño / La Niña conditions continued into the September through November three month period. El Niño conditions tend to bring warmer temperatures, while La Niña conditions tend to bring cooler temperatures.
Australia is experiencing its worst fire season ever. Drought, flood and fire have caused Australian agriculture to collapse leading to a decrease in emissions of greenhouse gases.
England and Southern Europe experienced catastrophic flooding. The City of Venice was hit particularly hard.
Parts of Africa including Kenya, Somalia and the Central African Republic also experienced catastrophic floods.
Over 2 million people were forced by Cyclone Bulbul to evacuate in Bangladesh and India.
California was hit again by high winds and dry conditions. The fires were bad, but not so bad as in the past two years, probably due to the increased preparedness of the California Fire Service.
Some October 2019 Highlights
October 2019 was the second warmest October on record. June, July, August and September 2019 were all either the warmest or second warmest months with that same name on record.
The last five 12-month periods ending in October were the five warmest on record.
Average concentration of carbon dioxide in the atmosphere in October 2019 increased by about 2.53 ppm over October 2018 as measured at the Mauna Loa site.
Neutral El Niño / La Niña conditions continued into the August through October three month period. El Niño conditions tend to bring warmer temperatures, while La Niña conditions tend to bring cooler temperatures.
Igor Semiletov and colleagues found that the ocean off Siberia is literally boiling methane as the permafrost beneath thaws. Methane is 25 times more potent than carbon dioxide as a greenhouse gas.
Hurricane Lorenzo became the easternmost North Atlantic Category V hurricane on record.
For the third year in a row, California experienced devastating Fall wildfires.
Category V Typhoon Hagibis caused extensive damage to Japan killing 89. Fukushima Prefecture was particularly hard hit, where Hagibis stirred up radioactive particles from the 2011 triple nuclear meltdown.
“But if the watchman see the sword come, and blow not the trumpet, and the people be not warned: if the sword come and take any person from among them, he is taken away in his iniquity: but his blood will I require at the watchman's hand.*” —Ezekiel 33:6 (KJV)
* I will hold the watchman accountable for his death.
How to read this graph:
Some points to note:
This graph compares each month separately to the 20th Century average (for months of that same name only) and ranks them separately. In other words: The month of March is compared only to other Marches. The month of September is compared only to other Septembers.
For example: The warmest March, June and October are all colored red. The second warmest January, May and December are all colored orange. The February colored light blue (2013) is between the 11th and 15th warmest Februaries inclusive. The December colored yellow (2017) is the third warmest December and is 0.87° C. warmer than the average of all Decembers in the 20th Century. Etc.
When there is a tie, both months are given the higher of the two ranks. For example, September 2016 and 2019 are both colored orange (second). No September is colored yellow (third)
1. The data for this graph come from the National Oceanic and Atmospheric Administration (NOAA)'s climate at a glance section.
2. This graph gives the Earth's approximate average surface temperature for each month. Needless to say, distilling the world's climate into one number per month is a gross over-simplification. Further, surface temperature is only part of the story. Temperatures in the upper atmosphere and ocean depths contribute to surface anomalies through convection and heat exchange.
3. Temperature anomalies are not necessarily distributed equally around the globe. For example, while summer 2017 was third warmest globally, it was the warmest summer on record in California, which, preceded by a wet winter, contributed to devastating Summer and Fall wildfires and the mudslides which followed.
The maps in this article from the Washington Post show global cool and warm spots. The Arctic has warmed to a far greater degree then average. The North Atlantic where the Gulf Stream used to terminate has actually cooled.
4. Some historic data changed significantly in May as NOAA transitioned to using its Version V dataset. June brought many small changes, probably due to NOAA fine-tuning its new dataset. Generally, data change only slightly (at most one or two hundredths of a degree) month to month, as NOAA refines its models and data-crunching techniques.
5. Every month since February 2008 has an anomaly (distance from the 20th Century average) above 0.4° C. The last month with a negative anomaly was Dec. 1984. The highest anomaly was 1.31° C. in March 2016 (up from 1.23 in Version IV and roughly equivalent to 1.50°C. above the 1850-1900 average which the IPCC refers to as “pre-industrial” levels).
6. This graph shows a short term rising trend from 2008 to the present with a bump during the 2014-2016 El Niño episode. It also shows wide variation from month to month; but the rising trend is still discernible at a glance. 2005 (not shown) was the warmest year to date before this graph. It has since been surpassed by 2010, 2014, 2015 and 2016 (in that order) as the warmest year to date.
7. June and July (tie), 2019 were the warmest months with that same name on record. The second warmest March (tie), April, August (tie), September (tie), October and December, all lie within the latest 12 months.
8. All but one of the three highest ranking months of each name lie within the latest 60 months. The exception is November 2013 which was the second warmest November. All but one of the latest 60 months are within the top ten warmest with that name and have an anomaly greater than or equal to 0.75°C. above the 20th Century average. The exception is November 2014 which is the 13th warmest November and has an anomaly of 0.65°C.
9. Other models, such as ERA5 which is now used at the Copernicus Programme give somewhat different results. Copernicus gives a rough comparison of several popular climate models.
Which model is correct? All and none. Models are simply simplifications of the real world. No model of a complex system is exact (otherwise it wouldn't be a model).
9. The last five 12-month periods ending in October (2015-2019) have been the five warmest on record, significantly warmer then the 12-month periods ending in August 2010 and 2014, which tied for the sixth warmest. Seven of the ten warmest 12-month periods ending in October lie within the last ten years. (See table below.)
Why is this graph important?
10. Temperatures appear to have risen about 0.27° C. over the last ten years (difference between average anomaly of 36 months ending October 2019 and average anomaly of 36 months ending October 2009).
A longer term temperature graph — 50+ years
1. This is a “you can't see the forest for the trees” graph. Forests are important; but so are individual trees. Indeed, there is no forest without trees.
2. This graph allows you to see the present in detail. (present here meaning the approximate average monthly surface temperature over the latest 142 months or 11+ years.)
3. You can get a similar graph from NOAA's Climate at a Glance section; but I like the way this graph presents the data. I think the white spaces and the color coding increase readability.
4. Why 11+ years? Why not some other period like 7 or 15 years? No particular reason. With a longer period the lines get squished together and are harder to read. Shorter periods show less data. This started out as a ten year graph but has grown longer as I add months.
5. I intend to update this graph around the 20th of each month when NOAA comes out with a new month of global climate data.
6. How did I get into this? In 2016 my favorite website for news, Common Dreams, used to report the NOAA data month after month as they set new records. They stopped when September 2016 fell to second place. Being curious, I went to the NOAA site and wondered why it wasn't reported as news that the three warmest Septembers on record were in 2015, 2016 and 2014 respectively. After a few months of silence, I decided to start reporting this data myself.
Another 50+ year graph — CO2 in the atmosphere
1. This 50+ year graph of 12 month overlapping periods measures the temperature anomaly from the 20th Century average. The colors refer to the El Niño / La Niña condition during the three month interval centered on the final month of the 12 month period.
2. El Niño / La Niña refer to cyclical changes in atmospheric and oceanic circulation patterns over the tropical Pacific Ocean. El Niño episodes usually bring warmer global surface temperatures; La Niña episodes usually bring cooler surface temperatures. There is a brief explanation of El Niño and La Niña here.
An ONI (Oceanic Niño Index) is computed for each overlapping period of three consecutive months based of conditions in the tropical Pacific Ocean. If the ONI index is at least 0.5 (at most -0.5) the three-month period is considered an El Niño (La Niña) period. Five or more consecutive El Niño (La Niña) periods are considered an El Niño (La Niña) episode. An El Niño episode is very strong (strong, moderate, weak) if it contains three El Niño periods with index at least 2.0 (1.5, 1.0, 0.5). A La Niña episode is strong (moderate, weak) if it contains three La Niña periods with index at most -1.5 (-1.0, -0.5). These classifications are somewhat arbitrary.
3. This graph is surprisingly smooth in spite of all the crests and troughs.
4. Exceptionally high temperature crests have followed the two very strong El Niño episodes of 1997-98 and 2014-16. Surface temperatures have fallen after the end of these El Niño episodes but remained much higher than before the El Niño episode began. This happened to a lesser extent after the moderate El Niño episode of 2009-2010.
6. We experienced nine consecutive overlapping three-month periods with ONI indices between 0.5 and 0.9 in 2018 and 2019. Not surprisingly, global surface temperatures appear to have risen over this period. Although the three month period, June-August 2019, brought a return to neutral conditions, temperatures have continued to rise.
7. This graph consists of a progression of waves (heat waves) with increasingly high crests and troughs. Crests and troughs are marked with black dots and connected with black lines.
Crests are local maxima which are greater than or equal to all readings to the left. Troughs are local minima that are lower than or equal to all readings to the right. If more than one crest lies between two troughs only the rightmost crest is marked. If more than one trough lies between two crests only the leftmost trough is marked.
8. Crests have increased from a height of 0.22° C. (above the 20th Century average) in 1973 to 1.06° C. in 2016. Troughs increased from a height of -0.10° C. in 1976 to 0.82° C. in 2018. Temperature increases do not appear linear; they appear to be accelerating at a super-linear rate.
9. Climate-wise, extrapolation and longterm prediction are a very risky endeavor. However, looking at the two graphs above, I would not be surprised to see us exceed 1.31° C. above the 20th Century average (roughly equivalent to what the IPCC refers to as 1.5° C. above pre-industrial levels) within a decade.
10. In short: We're in terrible trouble. We better do something quick.
The missing graphs
1. The data for this graph come from the average monthly readings for CO2 in the atmosphere, taken at the Mauna Loa site in Hawaii. Each line in the graph is a weighted average of the current month and the 11 consecutive previous months. (E.g.: The line for March 2018 is the weighted average of April 2017 through March 2018.)
2. CO2 (and other greenhouse gases like methane) in the atmosphere act like a one way glass allowing incoming electromagnetic radiation from the sun to pass through the atmosphere, but trapping outgoing radiation from the Earth, thereby warming the planet.
3. For each month since the end of 1974, the change in the 12 month running average from month to month has been positive. The monthly change since 1968 ranges from -29 to 342 ppb (parts per billion). The average yearly increase over the period covered by this graph (since 1968) is 1.73 ppm (parts per million).
4. The increase in CO2 from the 12 months ending in
November 2018 to the 12 months ending in November 2019 is 2.88 ppm, 66% above the average annual increase since 1968. (We have a lot of work to do if we are to meet the goal of the December 2015 Paris Climate Agreement.)
5. The monthly record for the year for CO2 in the atmosphere is typically set in May, when northern hemisphere trees come out of dormancy and begin to sequester CO2 in earnest. CO2 concentrations in the atmosphere typically fall from June through September and then rise again from October through May as northern hemisphere trees go into winter dormancy.
6. One usually sees these graphs of CO2 in the atmosphere as a
succession of waves rising higher each year; but I like this graph of 12 month running averages, because it shows the steady month to month increases of CO2 in the atmosphere.
7. The month of February, 2019 set a new record for CO2 in the atmosphere, 411.75 ppm, surpassing the record set in May 2018 by 0.52 ppm. Over the period covered by this graph, rarely has the record set in the previous Spring been surpassed as early as February and never by an amount even close to 0.52 ppm. This could reflect an increase in CO2 produced by human activity, a failure of forests, oceans or other carbon sinks to absorb CO2, and/or other factors. CO2 in the atmosphere in February 2019 has been surpassed in March, April and May 2019, each month setting a new record.
8. For six consecutive days in May, 2019, the daily average at Mauna Loa measured above 415 ppm, the first time the daily average broke 415 since record keeping began. There was a great brouhaha in the news media over this. But its not single days or weeks that are the problem, it is the consistent month to month increase in the 12-month running average as detailed in the graph above. As should have been expected, the monthly average fell below 414 ppm in June and below 409 ppm in September and October, although if this was reported as news in the media, I am not aware of it.
9. The average reading for CO2 in the atmosphere between July 2018 and June 2019 inclusive was 410.05 ppm, the first time the 12-month average exceeded 410 ppm. Although it received little attention, this was a much more important milestone then the 415 ppm daily reading, because unlike the daily readings it is extremely unlikely to come down in future months. Indeed, it rose to 411.21 ppm by November, 2019.
Here should go historic graphs on global land use, droughts, desertification, floods, cyclones, wildfires, etc. Sadly, I have no such graphs, and not even the data to make them. Maybe later.
1. The problem seems to be that weather is by nature extremely variable and extreme events are by nature rare. So how is a changing climate affecting the occurrence and intensity of individual weather events? Statistical methods seems to be of little help here. This article from realclimate.org might give you a feeling for the difficulty and also the advances that have been made in attributing extreme weather to climate change.
2. Two examples: If Hurricane Harvey had come ashore in a sparsely populated stretch of the Gulf Coast, it might not even be considered a significant event. If Hurricane Barry had come ashore 100 miles to the East and lingered offshore a little longer, it could have caused Katrina-style devastation in New Orleans.
3. It's pretty clear to me that extreme weather events are becoming both more extreme and more likely. Consider: three years in a row of devastating fires in California; heat, drought, floods and fires during Australia's 2018-19 summer; record-breaking summer 2019 heatwaves in Europe and the Arctic; and much much more. Climate models can explain these events. I've yet to see any other reasonable explanation.
4. I think what is needed to deal mathematically with extreme weather events is an entirely new branch of statistics. Any of you mathematicians out there care to work on this?
5. I think that no one has understood the relationship between climate and weather better than Joseph Conrad, who wrote in Typhoon (1902):
Conrad's Captain MacWhirr sailed his ship into the eye of a typhoon, and then brought her battered and bruised into port. Would that the captains of our Ships of State could show such dedication and tenacity.
“Had he been informed by an indisputable authority that the end of the world was to be finally accomplished by a catastrophic disturbance of the atmosphere, he would have assimilated the information under the simple idea of dirty weather, and no other, because he had no experience of cataclysms, and belief does not necessarily imply comprehension.”
Some notes on the IPCC, 1.5° C. and Science
1. This graph (also from NOAA data) of 36 month overlapping averages (each 36 month period ending in month with same name as latest month for which data is available) from 1880 to the present shows a longer term rising trend, with an increasing rate of warming in recent years.
2. I like 36 month overlapping graphs. I think they smooth the data, but not too much. You can view 12 month or 60 month overlapping graphs at NOAA's Climate at a Glance section too.
3. There have been various pronouncements that global warming stopped in 1998 (or some other recent year) and global cooling began. This graph demonstrates clearly, without the need for any statistical analysis, that no such thing has happened.
4. Data previous to the 1960s are from surface-based measurements and probably not as accurate as data from later years which include satellite-based measurements.
5. This graph begins about a century after the start of the “industrial revolution” and well into the 1850-1900 period that the IPCC refers to as “pre-industrial.” It details the sharp and increasing rise in global temperatures with the development of technology from around 1910 to the present.
6. This graph also details the sharp and unprecedented rise in global temperatures beginning around mid-2014 and continuing through mid-2016; and then the slight fall in global temperatures to the period from mid-2016 through mid 2019.
Discussion of Climate Crisis and Climate Catastrophe
the Intergovernmental Panel on Climate Change (IPCC)
1. Thousands of scientists contribute to the assessments of the Intergovernmental Panel on Climate Change (IPCC). Good science is not done by committee — never has and likely never will be. If Albert Einstein had to work with a committee like the IPCC, we might still be struggling without a theory of general relativity.
2. The “IPCC Special Report on Global Warming of 1.5°C” (2018) notes that there are few direct temperature measurements from before the industrial revolution, so they declare that they will use 1850-1900, the earliest period from which there exist near-global observations to represent the “pre-industrial” period which ended a century earlier. I don't get it. Why don't they just drop the “pre-industrial” and say they are measuring warming from the latter half of the 19th Century? And just how do they know that 1850-1900 is a good representation of pre-industrial temperatures when there are so few direct measurements?
3. I think “pre-industrial” should mean before the start of the industrial revolution which is generally considered to have begun sometime between 1750 and 1800. I find this conflating of the second half of the 19th Century with pre-industrial times confusing at best and perhaps even a deliberate obfuscation. (Sorry folks. Consider this as coming from an unrepentant paranoid conspiracy theorist.)
How do you convert anomaly from the 20th Century average to anomaly from the 1850-1900 average?
1. It ain't easy.
2. Copernicus Programme estimates its base period, 1981-2010 as 0.63° C. warmer than the 1850-1900 average. With NOAA's data, I computed Copernicus's base period at 0.44° C. above the 20th Century average. Subtracting, I get 0.19° C., so I add 0.19° C. to NOAA's anomaly from the 20th Century to get a rough estimate of anomaly from the 1850-1900 average. (Sorry folks, but that's the best I can do.)
3. I'm still no closer to an anomaly from real pre-industrial times (before 1750 more or less).
4. Whereas the temperature differences between pre-industrial times and 1850-1900 are thought to be negligible and we estimate the 20th Century average at 0.19° C. above the 1850-1900 period, the latest ten years (2009-2018) measure an average 0.77° C. above the 20th Century average. Who says global warming is a hoax?
Why 1.5° C.?
1. Based on the recommendations of the IPCC, the Paris Climate Agreement seeks to limit global warming to 1.5°C. above pre-industial (later redefined as 1850-1900) levels. So what's the big deal about 1.5° C. anyway?
2. If (unlike yours truly) you are a normal human being, your body temperature is probably around 37° C. (98.6° F.) Now raise your body temperature 1.5° C. At 38.5° C. (101.3° F.) you are probably feeling sick and better go to bed and drink plenty of fluids. Now raise your temperature another 0.5° C. At 39° C. (102.2° F.) you are feeling terribly weak, dizzy and disoriented. Suppose your temperature goes up yet another 2° C. At 41° C. (105.8° F.) you will die, if your body temperature does not come down very quickly.
3. The analogy is not exact. Gaia (The Living Earth) is much more resilient than we puny humans. She has weathered wilder swings in temperature than this. The climate at 4° C. above pre-industrial levels would be very inhospitable to human “civilization,” with monster hurricanes, floods, droughts, and other extreme weather events which would dwarf anything on Earth today. A 4° C. rise in temperature would cause crop failures, famine, disease, and likely, wars over Earth's dwindling resources. It's very unlikely that many of us would survive a 4° C. rise in the Earth's temperature.
4. In truth, I think it misguided to focus on 1.5°, 2.0° or any other number. I think it misguided to focus on the late 19th Century, pre-industrial times, or any other period. It is distracting. We already know what needs to be done; and we know that it needs to be done now. It is quite clear and simple. We must all work together now to stop warming the Earth. We must focus on drastically reducing our carbon footprint immediately. That means giving up our addictions to fighting wars, burning fossil fuels, eating meat, building with concrete, wearing fashion clothing, having lots of babies, traveling by air, etc. etc. etc. It means planting trees, nurturing forests, walking and riding bicycles, eating locally raised foods, etc. etc. etc. Are we ready to do all that? Nothing less will do. It's hard to give up so many addictions all at once; but it may save us from extinction.
An Exercise: Especially for Climate Skeptics
1. Estimate from the graphs and commentary above the probability that if we continue with business as usual, the result will be the collapse of our “global civilization.” 1%? 5%? 10%? 20%? 50%? 90%? 99%?
2. Think about at what percentage value you would recommend that the world take action to reduce global warming. 1%? 5%? 10%? 20%? 50%? 90%? 99%?
3. Think about your answers to the two questions above.
Can Science save us?
1. Well, uh, Science got us into this mess. Scientists taught us how (in the words of Joseph Conrad) “To tear treasure out of the bowels of the land ..., with no more moral purpose at the back of it than there is in burglars breaking into a safe.” But they taught us much more than that. They taught us how to make lots of money by burning the treasure and fouling the air. They also taught us how to make bombs which would render the Earth uninhabitable by humans for years to come, and oh so much more.
2. So can Science save us? When someone tells you they can clean up the mess they made, but you have to pay them to do it, beware. Now we're told that scientists can geo-engineer the planet to keep it cool. Lots of money to be made on geo-engineering, which, judging by past experiences, will create even bigger problems, that scientists will be very happy to solve for an ever-increasing price.
Global Warming and Climate Change are objective criteria. We can measure temperature today and compare it with measurements taken 50 years ago. Likewise with rainfall, wind velocity, cloud cover, chemical makeup of the atmosphere and other factors, all of which influence climate. The terms Global Warming and Climate Change have served us well. I suggest we stick with them. There is a consensus, not only among scientists, but among all people, particularly young people, that the world is warming and the climate changing.
Crisis is a different matter. Crisis is subjective. Crisis implies a turning point. How do you measure degrees of Crisis? Likewise with Catastrophe. A Catastrophe is a terrible event. How do you measure degrees of terribleness? If one doesn't take advantage of a Crisis to turn in the proper direction, one can easily create a Catastrophe.
Indeed, that is exactly what has happened with our climate. I've been hearing for some 20 years that the Earth is warming and we must take action now. I'm still hearing it 20 years later. I think we are well past the Crisis stage and into Catastrophe. So what is to be done?
Let's revisit Joseph Conrad's Captain MacWhirr. Sitting in the chart room with his ship in the eye of the typhoon, he finally realizes the folly of what he has done. He understands that the worst is to come and his ship is likely to go down with all hands on board. He says to himself, half aloud, “I shouldn't like to lose her.” And indeed, he does not. Against all odds, he sails his ship safely to port, battered and bruised.
Like Captain MacWhirr, I, too, “shouldn't like to lose her.” And Captain MacWhirr has sound advice for us: “Don't you be put out by anything. ... Keep her facing it ... Facing it — always facing it — that's the way to get through. ... Face it. ... Keep a cool head.”
It is difficult to tell people that we are in the proverbial eye of the typhoon and the worst is to come; yet, tell them we must. How are we to face the looming Catastrophe, if we ignore its true nature?
Panic would not be helpful. We must face the looming catastrophe with a cool head. “Facing it — always facing it — that's the way to get through.”
Many have wondered what will happen to mankind as the climate continues to warm. Some say we will continue with business as usual; others say we will join the dodos and the dinosaurs. I suspect somewhere in between. Our current “civilization” is certainly unsustainable; but I see no reason why, with the grace of God, a few of us can't continue to live on Earth in much the same way as our ancestors did during the Pleistocene, which ended about 11,300 years ago.
“Yet will I leave a remnant, that ye may have some that shall escape the sword among the nations, ... and they shall lothe themselves for the evils which they have committed in all their abominations.” —Ezekiel 6:8-9 (KJV)
Unlike the graphs above, the graphs below are based on “proxy data.” That is: global temperatures are inferred from things like tree rings, ice cores, the makeup of the shells of sea critters, type of flora and fauna in the fossil record, etc.
Needless to say the graphs below may not be all that accurate; and the further back in time we go, the less accurate they are likely to be. Nevertheless they seem to be the best we have; so let's go with them.
1. This graph is derived from research by Michael Mann published in 2008.
2. The baseline, 1961 to 1990 average, is approximately 0.14° C. higher than the Twentieth Century average used in the first three temperature graphs above. The scale is Fahrenheit instead of Celsius (1.8° F. = 1.0° C.). The dark gray band represents probable uncertainty.
1. This graph is from research by Shaun Marcott et al. published in 2013 and represents a probable reconstruction of temperatures over the last 11,300 years (Holocene).
2. During the Holocene, mankind learned to domesticate animals, build cities, develop written languages, cut down forests, burn fossil fuels, fight wars etc.
3. The baseline, 1961 to 1990 average, is the same as the previous graph and is approximately 0.14° C. higher than the Twentieth Century average used in the first three temperature graphs above.
4. The gray squiggly lines at the right represent the previous graph superimposed on Marcott's findings.
5. The wide band represents probable uncertainty.
6. This graph shows global temperatures rising 0.5 to 1.0° C. until 7000 years ago and then falling back to a low close to the start of the Holocene. This low is generally called the “Little Ice Age” which lasted, roughly, from around 1500 to around 1900. From the Little Ice Age onward temperatures have risen sharply.
7. One problem with this graph is that the right end of the x-axis (labeled 0) is “the present.” Which year is the present? This is important with temperatures rising by perhaps 0.27° C. in the last decade.
8. It appears from this graph and the temperature graphs presented above that we surpassed the previous Holocene maximum temperature in 2015 and remain above it.
1. This graph represents a possible reconstruction of temperatures during the ice ages and the interglacial periods. (Pleistocene)
2. The scale is Fahrenheit instead of Celsius (1.8° F. = 1.0° C.) and the baseline is the average over the past millennium.
3. The Pleistocene was a succession of wide swings in temperature between ice ages and interglacials, according to this graph by as much as 16° C.
4. I have found it difficult to reconcile this graph with the previous graphs. Since the data come from ice cores, likely they do not reflect global temperatures as a whole.
5. Modern man evolved during this period, probable around 250,000 years ago. Around 50,000 years ago he began to develop more advanced technology and migrated throughout Eurasia, Africa and then Australia and even later, the Americas.
7. Since modern man has been able to survive in almost every ecosystem on the planet, it appears very likely that he will be able to survive in at least some future ecosystem.
8. The same can not be said about “civilization.” “Civilization” developed under some very specific climatic conditions that are unlikely to exist on Earth in the near future.
9. I suspect, if we have not already done so, we will surpass the highest interglacial temperatures soon. (Keep in mind that the temperature has probably risen about 0.27° C. (0.49° F.) over the past decade. (See graphs above.)
1. I don't know where this graph comes from originally. It is all over the internet.
2. 65 million years ago marks the probable demise of the dinosaurs.
3. Temperatures in the Eocene, some 50 million years ago were likely considerably higher than they are today.
4. There are no known “great extinctions” during the Eocene. Indeed, life seems to have thrived during the warm period in the early Eocene.
5. Atmospheric carbon dioxide is thought to have also been much higher during the Eocene than today.
6. The Eocene might give us some clues as to what might happen on Earth in the near future.
More discussion of these and other temperature graphs to be added later
1. I don't know where this graph comes from either. It is also all over the internet.
2. The combination of linear and logarithmic scales on the x-axis are somewhat confusing, but allow for extra detail to be shown in more recent times.
3. 542 million years, back to the Cambrian, is a long time. Planet Earth has weathered a lot of changes. May she also weather this one.
4. Looking at these graphs, one should realize how hard it is to predict the future. Science talks in probabilities. There are few certainties in Science.