Dangerous climate change?


I am certain you have heard the phrase "there is 97% consensus on climate change among scientists."


Is this statement true?


Well yes, it could be. It depends a lot on how the statement is phrased. If the question is, ”has our climate changed or is climate changing,” there is sure to be at least 97% consensus that it has and is. Has our climate warmed in the last 50, 300, or 1500 years, most would still agree that it has. State that it is warmer than it was 950, 2500 or 3000 years ago and most would not agree with you. So, is the climate getting warmer? Well, it depends on where your starting point is.



Ask If there is an anthropogenic influence on current climate change and you 97% or better agreement that there is. Ask what percentage of warming is caused by human activity and you are likely to get a fairly wide range of answers. Then ask how dangerous is a warmer climate to civilization. The answers will probably range from not worth worrying about to catastrophic.


The fact is that there is really no consensus except on the most basic of questions.


So, is climate change dangerous? Of course, it can be. Another ice age, for example, would wreak havoc on civilization with most of the huge land masses of the Northern hemisphere covered with ice or suffering much colder temperatures. Most of the planet would become dryer with much of the world's water locked up in ice and with colder air unable to carry as much moisture. With much of the world's landmass unavailable for agriculture, starvation would be a real threat, and can you imagine the chaos from the resulting mass migrations.


Even some things like major volcanic eruptions often cool the earth enough to put considerable stress on agriculture. Krakatau erupted in 1883, in one of the largest eruptions in recent time. Krakatau is an island volcano along the Indonesian arc, between the much larger islands of Sumatra and Java (each of which has many volcanoes also along the arc). The volcanic dust veil acted as a solar radiation filter, lowering global temperatures as much as 1.2 degrees C in the year after the eruption. Temperatures did not return to normal until 1888. It is fortunate that major volcanic eruptions are reasonably far apart in recent history and it will likely be many generations before the next ice age.


You may have noticed that proponents of anthropogenic climate change like to start with 1880 as the beginning of significant human effect. It is easier to make your case for a warming planet if you start from a low point.


'Whether from small or large eruptions, volcanic aerosols reflect sunlight back into space, cooling global climate. The 1815 eruption of Mount Tambora produced enough ash and aerosols to cancel summer in Europe and North America in 1816." NOAA Climate.gov.


Should we make an effort to prevent another ice age from happening? The threat, at this moment, does not seem to be immediate enough for us to worry. We may have, inadvertently, set events in motion that will delay the next ice age. That would be anthropological global warming.


Is a warming climate dangerous? There are dangers associated with a warmer climate, as well, although it is hard to imagine anything as frightening as 2 or 3 kilometers thick ice over your home (yes, judging from past events, that could be possible sometimes in the future.) The most threatening is likely sea level rise. Many cities and large parts of some nations are near sea level. Some are already below sea level and saved from inundation only by human-built mega projects. You will be able to easily outrun the rising waters. Sea levels only rose an estimated 6 to 7 inches in the 20th century. Estimated because the data is hard to sort out from land subsistence and other variables. In another context, If you had stood in the same spot at sea level for a very long lifetime the water would have risen a little above your ankles.



How much will sea level rise in the next 100 years? Well, the more credible sources estimate any place from  less than in the past to a total of about 300mm (12 inches.) Of course, some say, that if all the worlds ice was to melt sea levels could rise as much as 70 meters (275 feet) through ice melt and thermal expansion. This, however, is virtually impossible on any timescale relevant to human civilization. In most cases, we simply have to quit building stuff so close to the water. Most current infrastructure will be obsolete before it is seriously threatened. The other solution is more mega projects to hold back the waters, though these may have a limited lifespan and be doomed to eventual failure.


Widespread drought is often quoted as a possible consequence of a warming climate. Drought (sometimes severe and long-term) has always been a threat to agriculture. Why would they be more common or more severe in a warming world? After all, evaporation should increase from warmer water and the larger surface area of rising seas. Transpiration from plants should increase. Warmer air can carry more moisture. Should not all these changes lead to more precipitation? As an aside, wouldn't more moisture in the atmosphere mean less in the oceans?


Floods could become more common and severe. That is actually quite likely. Building on flood plains may have to be curtailed (that’s always been a good idea.) Infrastructure projects will have to take this into consideration and costs will probably increase.


Severe weather may become more common and more damaging. There is really no conclusive evidence linking most types of severe weather to warming. Just to be safe, though, we should build smarter and stronger.


Heat waves? It is claimed that cold kills 20 times as many people as heat. I know it is much nicer sitting in the shade of a palm tree at 30C than it is sitting in a snowdrift at -30C.


Wildfires? Well, they can be harder to control in hotter weather, but the incidence of them depends more on moisture conditions.


Reduced food production? I don’t think there is any credible evidence to support that. In fact, the opposite might be true. Carbon dioxide increases have been shown to contribute to a much greener earth.


Mass migrations? Certainly, some areas could become inhospitable (mostly due to seawater inundation), but the pace would be very slow. Definitely not lemming like crowds trampling everything in their wake. Other areas, such as the large land masses of the north, could become more hospitable to human habitation.


Let's not forget the effect on nature. It will be there and in some cases obvious. The sad part is that human activity has already had such a massive and profound effect on the natural world. Existing plant and animal life have been extremely stretched to find niches or to adapt. Adapting to a warmer climate will probably be much easier than to the other changes we have wroth. It is long past the time when we should be starting to repair past damage. Global warming is likely the least important and the least repairable, even if we only focus on the future anthropological share of climate change.


There is a fine essay about our adaptability to a warming climate at this link.




Before we decide to panic, or to enforce destructive public policy, in order to combat Climate change (global warming,) we really should study what the earth was like during a previous warm period.


The obvious candidate would be the Eocene epoch. This was a period from about 55.8 million years ago (MYA) to about 33.9 MYA or a period of about 22 million years. Our current cycle of ice ages is believed to have started near the end of the Eocene.


The early part of the Eocene is thought to have been the warmest portion of the Cenozoic era, which is the era in which we live.  At times global temperatures may have averaged as much as 27ºC or more. Today’s global mean is someplace less than 20ºC, likely around 16ºC.


In that period, the earth’s land masses were moving towards their current positions but were still in a different configuration than today. As a result, the major Ocean currents circulated differently. This probably allowed for part of the extra warmth and distributed the warmth more evenly around the globe. Temperature gradients between the equator and the poles are believed to have been smaller. That would seem to indicate that temperature cannot get as high today, or that the south polar area in particular, will not warm as much.


Many scientists attribute the beginning of this warm period to an increase in atmospheric CO2 from a major increase in volcanic activity. Perhaps, but haven’t recent volcanic eruptions resulted in global cooling? Speculation is that some of this CO2may have resulted from lava sheets heating carbon-rich sediments. Possible, but have any scientists attempted to verify this? There should be some evidence beneath the great lava sheets of the world that exist in Russia, India, the U.S. and elsewhere.


There is also speculation that a warming deep ocean may have released methane clathrates, but it seems to me the warming would have to occur first, particularly under the higher pressures from a higher sea level. This could, however, work to reinforce a warming trend. CO2 levels may have been as high as 3000 ppm for relatively short durations during the Eocene.


Whatever the cause of the warm climate, my main topic of discussion is, what was the environment like under those conditions, and what the world will face if they should occur again.Most of the following comes from my imagination with as much scientific support as I could find. Try your own imagination on this.


It is likely that, since the temperature gradient between the poles and the equator was much smaller, there would have been less severe wind events. More precipitation and higher humidity seems likely over most of the globe. Cloudy skies may have been the norm. The difference between the seasons may have been much less, with only a variation of about 3 or 4 degrees Celsius. Snow would be rare at lower elevations. I wonder about the variations between different elevations, and the difference between the center of large land areas and the coasts. I assume the differences would be as substantial as they are today.



There was more water and less ice than today, but what that means for the relationship between land and seas is difficult to reconstruct. It is possible that more area was covered by shallow seas and shorelines were longer but we can only guess.


The landscape was probably dominated by large trees and plants, rainforests and jungle, with less open grasslands. Fast growth, encouraged by moisture, warm temperatures and high levels of CO2 may have been tempered somewhat by limited sunlight.


Many of the land animals would have seemed somewhat familiar if smaller than what we are accustomed to today. Most of today's mammals evolved from ancestors of this period. There were larger animals as well, some evolving as the climate cooled towards the end of the Eocene. The dinosaurs were gone but reptiles and amphibians existed, many very similar to those of today as were fish. Birds and sea life were continuing to evolve and the first whales left the land for permanent residence in the seas.


Life seems to have rebounded quite well with many new forms after the K-T extinction.


The emergence of the first humans was still a very long time in the future, but had they existed they would probably have had a fairly easy time of it. Elaborate shelter or clothing would not have been needed. There should have been good hunting and fishing. There would have been some types of nuts and fruits, but very little grains as grasses were not far along in their evolutionary story.


Is this a time capsule that gives us an idea of what the planet may be like if current warming continues.


There are some differences. Current warming has proceeded quite rapidly, with what may be unprecedented speed. The placement of land masses is not quite the same, and ocean currents were different.


Some of the end results may be similar. If warming continues some future generations will probably be facing a warmer, rainier climate with considerably less seasonality in higher or lower latitudes. The earth will probably be a lot greener as a result of warmth and CO2 levels if we don’t pave over too much. Extreme weather events should be less common and less severe with the exception of precipitation events. Changes in precipitation likely will not be consistent.


Sea levels will likely be higher, and in the future, more humans may opt to live in or on the seas. 


If the change is too rapid many species may not be able to adapt fast enough and extinctions could occur. However, like in the past, this will leave niches for newer species to evolve into. The progression is the same, with constant change.


Will human beings be able to adapt? It would certainly seem so. Humans have survived vast changes in the couple of million years of their evolution. And they only seem to have gotten better at it. Instead of simply filling niches as they appear, humans have spread over the entire earth and into all but the most extreme environments. Humans even live, for short periods, in environments as extreme as space, outside of our atmosphere. 


There is no doubt that rising sea levels will make some migrations of population necessary. I doubt if there will be a great hurry, though. Not likely nearly as fast as people will be forced to move from resource-based industry towns, or even nations if their sources of income disappear because of a rapid abandonment of fossil fuels.


How quickly could this happen? At the very least it would take 1000 years to approach conditions similar to the Eocene. Probably, it would take much longer. Plenty of time for humans to adapt and prepare, but perhaps a little short for the natural world.


In much of the world, our biggest concern is still going to be how to stay warm during our winters. In most cases, this still requires a reliance on fossil fuels. 


This morning the temperature outside my door was -28ºC. Wind chill added to make an effective temperature of minus 40, about the same in either Celsius or Fahrenheit. If you are caught unprepared in these temperatures, you can survive only a very short time.


I have experienced temperatures of 40ºC (105ºF.) All I needed was a slight breeze, some shade, and a cool drink to be very comfortable.


What if the opposite to warming occurs, and the earth falls into a rapid cooling trend with a return to ice age conditions. The maximum glaciation of this ice age (that we are still emerging from) occurred less than 25,000 years ago. This is just the last in a continuing cycle including several glaciations. We could possibly start descending into a new ice age at any time but it is more likely it will be in 10,000 years or so and take another 70,000 years to reach it’s maximum. It is, however, an almost certain consequence of climate change. It is possible that human-induced warming may delay the onset for a 1,000 years or so.


What would our environment be like? Well, at the height of the last glaciation about 27% of the earth's land surface was covered with ice, often several kilometers thick. Most areas were much cooler and much drier and there was a lot of dust in the air. Drought was a dominant climatic feature.


Most of Canada, the northern states, northern Europe and large chunks of Asia were icebound. All the higher elevations carried glaciers. About the only northern areas not glaciated, like Eastern Asia, were bare because there was too little precipitation to build ice. In the southern hemisphere, southern Chile and Argentina carried ice sheets. Australia was mostly shifting sand dunes. Even some volcanic peaks of Hawaii carried glaciers.


The cold and drought would have made agriculture impossible or severely limited over most of the globe. With those conditions today, most of us would starve, even if we did have a place to live.


Could humans adapt to ice age conditions? To some degree we could, after all, humans have survived these conditions before, but there is no way the earth could support our current population or, even less so, our expected future population. Luckily, the worst of these conditions are not likely for hundreds of generations.



We have compared our environment, under a several degrees of warming, to past environments that were much warmer. I think it is fair to make some comparisons that are a little closer to home.


What would Canada be like if it were to warm considerably?


 The source of much of the information is here.


Let us compare to Mexico. The average temperature of Mexico is currently about 21ºC, while Canada is about 0ºC. Because of the large land mass of Canada, it is not very practical to use that large a difference in temperatures. I think we could assume that the difference that could apply to the most populated and to the productive agricultural areas would be at least 10 degrees. Would it be fair to assume that at an increase of 10ºC in average Canadian temperature would make the environment closer to what currently exists in Mexico? I think it is, at least, an interesting exercise.


Food production has been expressed as a concern of climate change.


Mexico has a land area which is only about 1/5 that of Canada, but in spite of that, the harvested areas in 2014 were very similar. Canada was at 66 million hectares while Mexico was at 61 million. This hints that Canada could gain substantial agricultural area with higher temperatures.


The value of food production was placed at about 35 billion for Canada versus 27 billion. That indicates that the value of Mexican production was about 15% less per hectare. That could be interpreted several ways, but I think most of it could be attributed to less soil degradation (a much shorter agricultural history) in Canada and perhaps better water availability. Water resources in Mexico are about 4000 cubic meters per year per person. In Canada, it is 82,000 cubic meters per year per person. Production does seem to be remarkably similar for the two countries, in spite of major differences in the environments..


It is interesting that Mexico exports almost half as much food as Canada while importing nearly the same. This is in spite of Mexican population being at least 3.5 times that of Canada. A warmer climate should result in fewer imports to Canada with an improved ability to produce fresh fruits and vegetables and longer seasons of local availability.


It seems highly unlikely that food production in Canada would be a problem, even under much higher temperature. Of course, there would be changes, with new problems for technology and techniques to deal with. Since even worst case scenarios do not envision such extreme warming for many centuries if ever, I do not think there is much doubt that technology can keep pace.


Can we compare the two countries in other ways? I don’t think air conditioning is any more prevalent in Mexico than Canada, and there is definitely less need for heating. They seem to rely more on design for comfort. I have stayed in hotels there, that had neither air conditioning nor central heating. That would be unheard of in Canada. Certainly, Canadian costs would go down with less need for heating.


Many Canadians spend some time and often the entire winter in warmer climates, including Mexico. The Canadian economy could benefit from a more balanced tourism industry.


Some are suggesting more extreme weather events or some extreme consequences of a warmer climate. There is very little evidence to support this. Most of Canada already has an extreme and dangerous climate that requires substantial adaptation in housing, clothing, and transportation. Infrastructure must be hardened substantially and maintenance is often high. Technology and increasing wealth have been rapidly reducing the impact of the climate. Hardening the infrastructure even more to extreme weather events makes considerable sense even if no extra extreme events are expected. The biggest vulnerabilities are the transportation facilities, the electrical grid, and development in flood-prone areas. Most of the danger occurs in winter and spring. A warmer climate should mean shorter winter seasons and shorter risk windows.


It seems that warming would prove a net benefit for Canada. Not so likely to be a benefit to Mexico, but it is uncertain if any major disadvantages would occur. An increase in rainfall would probably benefit both countries. It is unlikely that Mexico will warm as much as Canada and thus a lesser impact. Both countries have extensive coastlines, but the impact of rising sea levels would likely be felt more by Mexico, if only because a greater percentage of their populated area would be affected.