For many reasons, both economic and geophysical, we are likely to see a substantial reduction in our centuries old habit of deriving energy from fossil fuels and more recently from nuclear fission and a rather quick but measured shift toward renewables. This is also a time of potentially major transition in other ways.
Climate change is upon us. The seas are warming and rising and the thermal patterns that have always moved over the earth are changing and perhaps intensifying. If we stop burning coal, gas and oil quickly, we will also be reducing entry of substantial particulates into the atmosphere, which by themselves have a cooling effect. Thus, a fairly quick transition to renewables may give us an additional warming trend even while we will be adding far fewer tons of greenhouse gases to the atmosphere. Simultaneous short term increases in volcanic activity would offset that effect to some extent. Fortunately, this will be unlikely. Coal, gas and oil will likely be burned less and less while renewables increase more and more. Over at least the next 20-25 years that will be a major trend. Thus, we’ll have a chance to measue what hapens as carbon dioxide rates decrease and particulate release from the burning of fossil fuels also decreases.
Whatever happens the melting of the Arctic will continue and will likely be completely open and ice-free at least during the summer months by 2040-2050. This seems to me to be a conservative estimate. The open water in the Arctic means that there is increasingly more solar energy absorption in the north during the summers, increasing with the increasing open water. Open water absorbs more solar energy while ice reflects it back into space, thus the more the open water during the summer months the more the heating effect of the sun will be. This does not mean that it will get warm in the Arctic. It just means that things will get warmer in relative terms; i.e., while the rest of the world rises in temperature by 2-3 degrees the Arctic may rise by 6-9 degrees. Much of it though will continue to ice over in the winter, and the winters will still be very cold, but perhaps not as bitterly cold as in the past. But the weather will likely change everywhere, not just in the Arctic. Indeed, the melting of the Arctic which has been the primary visual effect of global warming, is the catalyst that is introducing global “climate change.”
We really can’t predict with any certainty how climate change will go from month to month or even from year to year, particularly as the amount of open water in the Arctic during the summer months likely will be increasing over the next 15-20 years at least or until there is no longer any ice in the Arctic in the summers. In some ways we should be hopeful that will happen, because if it does not and the ice comes back that may likely mean that the heat has not been able to move off the equator to the Arctic to melt the ice — meaning it may be so hot near the equator that most living things can no longer live there. Basic geophysical fact: the polar regions cool the equatorial regions. The hot winds and warm seas move north and are cooled. Once they return they may be heated again.
As the Arctic warms, air and oceanic currents will change, but we don’t know enough to predict exactly how that will happen. The earth will, in effect, be experimenting with new ways to get heat off the equator. The presumption is that as the ice melts and the Arctic warms in relative terms it will get harder to cool the equatorial regions in relative terms. But some routes will be easier than others. The winds may rush through more open areas, meaning perhaps harsher winds may be seen in some locations and no wind in others. We just don’t know. But we do know that the weather has the chance to be harsher in some locations and not so harsh in others, that is, hotter and drier for some and wetter and colder for others. Within some years the patterns may become more evident than they are now, but for now we can’t really predict we can only observe.
These unusual climate patterns are likely to continue for some time. With any luck we will not see environmental or agricultural collapse, but we may need to make some adjustments. Things generally do not grow well in the midst of torrential continuous rains or in hot, extremely dry conditions especially where water resources are already scarce. In addition, in weather extremes either extremely hot and dry or extremely wet and cold with truncated growing seasons life for many species including humans may be challenged. Migratory species are the first to take up the challenge and will begin to change their boundaries from season to season. We can already see this happening. The range of birds will be a good marker for the climate changes which are occurring. Birders can tell you that the territorial ranges of many species are changing. Watch their reports. The tree line is also moving north as the north warms, but also many subterranean and above ground species of insects are changing their territorial boundaries as well.
People may have to move as well. In climates that have been extreme for some time human populations may comtinue to decline over time. Given a choice people seek more moderate and less extreme climates. Presently, we see that in harsh climates, either extremely cold or extremely hot, lives are compromised, particularly for the extremely old or the very young. In particular, people die in sudden cold snaps or heat waves. They always have and always will. Yet, now as patterns may begin to persist year over year, we may see major, and more serious human population relocations taking place. Humans will change their territory just as lower species and plants do when challenged by environment.
Finally, with the thermal expansion of the seas and the slow rise of sea water level, living on or near the coasts may become increasingly difficult. Storm surges may become quite dangerous, and the seas may invade normally high quality water systems in those regions. People will have to engineer expensive solutions to keeping the seas back or move off the coasts. These problems will likely be quite serious in currently low lying areas by mid century or before. We may be forced to move major facilities off the coasts as well. It is regrettable if we have to lose many expensive homes, but complex nuclear power facilities should be moved before they are inundated and compromised.
The wild cards going forward are the collapse of the major above sea level glaciers in Greenland and the West Antarctic. Should either or both of these collapse sea level around the world would increase some 4-6 meters additionally, completely inundating major coastal cities around the world. Fortunately, these glacier losses are not expected in this century, but as I have said, it is hard to know exactly what to expect.